Chapter

Diamond Nanostructures and Nanoparticles: Electrochemical Properties and Applications

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Macro-sized diamond films have been widely applied as the electrode for electrochemical and electroanalytical applications. Due to the non-uniform doping in diamond, boundary effects, and the varied ratios of graphite to diamond, only averaged electrochemical signals are detected over the full electrode. The studies of diamond electrochemistry at the nanoscale are thus highly required. In this chapter we overview recent progress and achievements about electrochemical properties and applications of diamond nanostructures and nanoparticles. After a brief introduction of the formation of these nanostructures and nanoparticles, electrochemical behavior of diamond nanostructures (e.g., diamond nanotexures, nanowires, networks, etc.) and nanoparticles (undoped, doped nanoparticles) in the presence/absence of redox probes is summarized. Their electroanalytical (e.g., electrochemical, biochemical sensing, etc.) and electrochemical (e.g., energy storage using capacitors and batteries, electrocatalysis, etc.) applications are shown. Diamond nanoelectrode array is introduced and highlighted as a promising tool to investigate diamond electrochemistry at the nanoscale as well.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Lately, the diamond composites become an attractive novel materials combine the properties of continuous diamond films along with single ND particles advances. Such an approach plays a crucial for time-stable and low ecotoxic photoand electro-catalytic applications [19,20]. Up to date, a few important works have been published reviewing applications of NDs in biotechnology, photonics, electronics, and catalysis [18,21,22]. ...
Article
Rapid industrial and urban development jointly with rising global population strongly affect the large-scale issues with drinking, groundwater, and surface water pollution. Concerns are not limited to environmental issues but also human health impact becoming serious global aspect. Organic pollution becomes a primarily serious hazard, therefore, the novel sophisticated approaches to treat them are thoroughly investigated. Among numerous materials, functionalized nanodiamonds are specific versatile nanocarbon material attracted ample attention thanks to their exceptional chemical, optical and electronic properties beneficial in the decomposition of harmful organic chemicals. This work delivers a comprehensive review of progress and perspectives on the green-friendly nanodiamonds, which are suitable for the degradation of emerging organic pollutants using numerous approaches utilizing them as an electro-oxidation catalyst; photocatalyst; oxidation agent, or adsorbing surface. Novel modification strategies of nanodiamonds (i.e., persulfates, oxides, or metals) remarkably improve pollutant removal efficiency and facilitate charge transfer and surface regeneration. Furthermore, we evaluated also the influence of various factors like pH, natural organic matters, or radical scavengers on the removal efficiency combining them with nanodiamond properties. The identified missing research gaps and development perspectives of nanodiamond surfaces in water remediation relating to other nanocarbon and metal catalysts were also here described.
Article
Full-text available
A novel modified pyrolytic graphite electrode with nano-diamond/graphite was fabricated. The electro-chemical response characteristics of the modified electrode toward the epinephrine (EN) and uric acid (UA) were studied by means of cyclic and linear sweep voltammetry. The structural morphology and thickness of the film was characterized by SEM technique. The prepared electrode showed an excellent catalytic activity in the electrochemical oxidation of EN and UA, leading to remarkable enhancements in the corresponding peak currents and lowering the peak potentials. The prepared modified electrode acts as a highly sensitive sensor for simultaneous determination of EN and UA in the presence of ascor-bic acid (AA). The electrode showed an excellent activity to resolving EN and UA peaks and completely eliminates the interfering effect of AA. The current response of the electrode showed a linear relationship with the concentrations of EN and UA in the range of 0.01–10 M and 0.01–60 M, respectively. In these measurements a detection limit of 3 nM is resulted for both compounds. This sensor exhibited very good reproducibility, repeatability and sensitivity for the determination of EN in the human blood serum, urine and the corresponding injecting samples. Moreover, the linear range and the detection limit of the determinations in the real samples remained constant in comparison with the measurements in the pure buffer solution.
Article
Full-text available
A boron-doped diamond/carbon nanotube (BDD–CNT) hybrid material with a core-shell three-dimensional random network structure was fabricated using the electrostatic self-assembly of nanodiamond. In general, CNTs are easily etched out as hydrocarbons or transformed to graphitic clusters at defect sites in hydrogen-rich environments (that is, the typical conditions employed for diamond deposition). However, attaching a dense layer of nanodiamond particles to the outer wall of the CNTs suppressed CNT etching and promoted BDD growth. To attach the dispersed nanodiamond particles on the CNT surface, we used an electrostatic self-assembly technique in which the surface charges on the CNTs and the nanodiamond were controlled using cationic and anionic polymers. Following BDD deposition, the electrochemical properties of the BDD–CNT structures were examined by cyclic voltammetry and electrochemical impedance spectroscopy. The results indicated that the BDD–CNTs exhibited enhanced electron transport efficiency, large effective surface areas and high sensitivity, with a remarkably low detection limit.
Article
Full-text available
We report on the novel composite nanostructures based on boron-doped diamond thin film grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (textasciitilde200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman Spectroscopy. The composite electrodes TiO2/BDD are characterized by the significantly higher capacitive current comparing to BDD film deposited directly onto Ti substrate. The novel composite electrode of TiO2 nanotube array overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver specific capacitance of 2.10, 4.79, 7.46 mF cm-2 at a scan rate of 10 mV/s for [B]/[C] ratio 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and excellent rate capability could be attributed to synergistic effect of TiO2 treatment in CH4:H2 plasma and high electrical conductivity of BDD layer. Analysis of electrochemical impedance spectra according to electric equivalent circuit allows to determine surface area on the basis of value of constant phase element.
Article
Full-text available
Modification of an electrode with an immobilised layer of nanodiamond is found to significantly enhance the recorded currents for reversible oxidation of ferrocene methanol (FcMeOH). Current enhancement is related to nanodiamond diameter, with enhancement increasing in the order 1000 nm < 250 nm < 100 nm < 10 nm < 5 nm. We attribute the current enhancement to two catalytic processes: i) electron transfer between the solution redox species and redox-active groups on the nanodiamond surface; ii) electron transfer mediated by FcMeOH+ adsorbed onto the nanodiamond surface. The first process is pH dependent as it depends on nanodiamond surface functionalities for which electron transfer is coupled to proton transfer. The adsorption-mediated process is observed most readily at slow scan rates and is due to self-exchange between adsorbed FcMeOH+ and FcMeOH in solution. FcMeOH+ has a strong electrostatic affinity for the nanodiamond surface, as confirmed by in situ infrared experiments.
Article
Full-text available
We report a high yield exfoliation of few-layer-graphene (FLG) with up to 17% yield from expanded graphite, under 5 h sonication time in water, using graphene oxide (GO) as a surfactant. The aqueous dispersion of GO attached FLG (FLG-GO), with less than 5 layers, is used as a template for further decoration of nanodiamonds (NDs). The hybrid materials were self-organized into 3D-laminated nanostructures, where spherical NDs with a diameter of 4-8 nm are homogeneously distributed on the surface of the FLG-GO complex (referred to as FLG-GO@NDs). It was found that GO plays a dual role, it (1) mediated exfoliation of expanded graphite in aqueous solution resulting in a FLG-GO colloid system, and (2) incorporated ND particles for the formation of composites. A high catalytic performance in the dehydrogenation of ethylbenzene on FLG-GO@ND metal-free catalyst is achieved; 35.1% of ethylbenzene conversion and 98.6% styrene selectivity after a 50 h reaction test are observed which correspond to an activity of 896 mmol(ST) g(catalyst)(-1) h(-1), which is 1.7 and 5 times higher than those of the unsupported NDs and traditional catalysts, respectively. The results demonstrate the potential of the FLG-GO@ND composite as a promising catalyst for steam-free industrial dehydrogenation applications.
Article
Full-text available
The paper reports on coating boron-doped diamond nanowires (BDD NWs) with a conducting polymer, poly[3-(pyrrolyl)carboxylic acid]. Polymer coating was achieved through electropolymerization of 3-(pyrrolyl)carboxylic acid at the electrode interface by amperometrically biasing the BDD NWs interface until a predefine charged has passed. The poly[3-(pyrrolyl)carboxylic acid] modified BDD NWs (PPA-BDD NWs) were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV). Using a deposition charge of 11 mC cm-2 resulted in a thin polymer film deposition. The availability of the carboxylic groups of the polymer coated BDD NWs electrode was demonstrated through copper ion (Cu2+) chelation. The resulting complex was successfully used for the site-specific immobilization of histidine-tagged peptides. The binding process was followed by electrochemical impedance spectroscopy (EIS). The Cu2+-chelated PPA-BDD NWs interface showed peptide loading capability comparable to that of commercially available interfaces and can be easily regenerated several times using ethylenediaminetetraacetic acid (EDTA).
Article
Full-text available
Nanodiamonds have emerged as a subject of tremendous research interest in recent years due to their unique combination of properties, such as large diameter, small and accessible surface, and excellent mechanical properties. Outstanding performance of these nanocomposites basically arises from their structure. When incorporated appropriately, this carbon nanomaterial can remarkably improve physical characteristics of polymer matrix even at extremely small loading content. Physical techniques summarizing thermal, morphological, mechanical, electrical and other properties of polymer/nanodiamond nanocomposites have been discussed. Furthermore, the review elaborates their uses in Li-ion battery, as well as current challenges associated and future prospective for this exciting class of nanocomposites.
Article
Full-text available
Nanostructured boron-doped diamond has been investigated as a sensitive impedimetric electrode for the detection of immunoglobulin G (IgG). The immunosensor was constructed in a three-step process: (i) reactive ion etching of flat boron-doped diamond (BDD) interfaces to synthesize BDD nanowires (BDD NWs), (ii) electrochemical deposition of nickel nanoparticles (Ni NPs) on the BDD NWs, and (iii) immobilization of biotin-tagged anti-IgG onto the Ni NPs. Electrochemical impedance spectroscopy (EIS) was used to follow the binding of IgG at different concentrations without the use of any additional label. A detection limit of 0.3 ng mL(-1) (2 nM) with a dynamic range up to 300 ng mL(-1) (2 μM) was obtained with the interface. Moreover, the study demonstrated that this immunosensor exhibits good stability over time and allows regeneration by incubation in ethylenediaminetetraacetic acid (EDTA) aqueous solution.
Article
Boron-doped diamond has been applied as an outstanding electrode material for electrochemical applications. Using templated growth techniques, a variety of diamond nanostructures like diamond wires and diamond foams can be fabricated [1, 2]. Using quartz or glass fiber paper as growth templates, porous diamond membranes are fabricated [3]. Compared to polymer membranes or membranes based on sp ² carbons, diamond membranes can survive in aggressive media and high temperature conditions. Also, the ion selectivity can be controlled by surface terminations as well as the bias potential of the membrane. Therefore, this kind of membranes is very promising for the electrochemical separation processes such as desalination, pollutants concentration and protein separation. However, both the fabrication and application of diamond membranes are so far reported only in very limited cases. In this paper, we report our recent progress with respect to the templated diamond growth using quartz fiber paper as the growth template. With optimized microwave CVD growth, nanocrystalline diamond film is fully coated onto the quartz fiber as has been confirmed via SEM. The growth conditions in terms of temperature, methane concentration and boron/carbon ratio are investigated in detail. The diamond quality is evaluated via Raman spectroscopy, and the boron concentration is determined via SIMS. The potential window of the diamond membrane is determined via cyclic voltammetry in an aqueous NaClO 4 solution to be ~2.5 V. By applying potential to the membrane, ions will accumulate inside the membrane and change its porosity. As a result, the ion flux through the membrane can be well tuned. This ion selectivity can be used to separate charged molecules. As an example, 5-Carboxyfluorescein and substance P are separated by the diamond membrane under different biases. In a neutral solution, for example, negatively charged 5-caboxyfluorescein can penetrate a positively charged membrane, while the positively charged substance P cannot. Therefore, this membrane can potentially be used for separation processes in biochemical and biomedical applications. Finally, due to the robustness of diamond, the membrane can be cleaned via a high potential (+3 V vs Ag/AgCl) oxidation process in 2 M H 2 SO 4 . Metal deposits and organic contaminants are proved to be removable by this method. Therefore, this membrane is also suitable for applications like undersea activities where only simple in-situ maintenances are possible. [1] F. Gao, M.T. Wolfer, C.E. Nebel, Carbon, 80 (2014) 833-840. [2] F. Gao, G. Lewes-Malandrakis, M.T. Wolfer, W. Müller-Sebert, P. Gentile, D. Aradilla, T. Schubert, C.E. Nebel, Diamond Relat. Mater., 51 (2015) 1-6. [3] S. Ruffinatto, H.A. Girard, F. Becher, J.C. Arnault, D. Tromson, P. Bergonzo, Diamond Relat. Mater., 55 (2015) 123-130.
Chapter
A core concept in electrochemistry is activated electron transfer (ET) between an electrode, usually a conducting solid, and a redox system in the nearby solution. The vast literature on ET kinetics describes the importance of ET to chemical and biological processes, and the underlying phenomenon of coupling a chemical reaction to the flow of current is the basis of > $300 billion of annual gross national product. Chapter 1 in this volume describes ET in nanoscale systems, mainly at an interface between an electrode and an electrolyte solution. A widely studied example of ET kinetics of relevance to the current chapter deals with ET occurring through a self-assembled monolayer (SAM) to a redox molecule (e.g., ferrocene) bonded to the SAM at the solution interface, as shown in Figure 7.1a. Such experiments stimulated a large research effort to understand the relationship between ET from a solid to a redox system through a nonredox active SAM and the thoroughly investigated dependence of ET within molecules, such as occur in biological metabolism and photosynthesis. An important conclusion about ET at electrodes as well as between two molecules in solution is the fact that the electrode and redox center (or the two redox centers in solution) need not be in direct contact to transfer electrons. It is possible, and quite common, for electrons to transfer through a SAM or intervening spacer (even a vacuum) by quantum mechanical tunneling, as described in Chapters 1 and 6 and in Section 7.3. For ET at both electrodes in solution and between redox centers within molecules, the ET rate depends on the driving force in terms of free energy and on the composition of the intervening solution or molecular structure. In addition to tunneling, ET in such systems may occur by other mechanisms, such as redox exchange, superexchange, and a sequence of ETs between distinct redox centers.
Book
This book focuses on new research fields of diamond, from its growth to applications. It covers growth of atomically flat diamond films, properties and applications of diamond nanoparticles, diamond nanoparticles based electrodes and their applications for energy storage and conversion (supercapacitors, CO2 conversion etc.). Diamond for biomimetic interface, all electrochemical devices for in vivo detections and photo-electrochemical degradation of environmental hazards are highlighted.
Article
Carbon electrodes have the advantages of being chemical inert at negative potential ranges in all media and high off-set potentials for hydrogen evolution in comparison to metal electrodes, and therefore are the most suitable electrodes for electrochemistry and electrochemical conversion of CO2 into valuable chemicals. Herein we summarize on carbon electrodes the voltammetry, electrochemical and electrocatalytic CO2 reduction as well as electronsynthesis using CO2 and carbon electrodes. The electrocatalytic CO2 reduction using carbocatalyts and the future activities about electrochemical CO2 conversion are highlighted.
Article
Silicon nanowires (SiNWs) were successfully coated by uniform, adherent and homogenous ultra-thin crystalline diamond films through microwave enhanced chemical vapor deposition (MWCVD). The as-grown functionalized nanowires were employed as electrodes in a symmetric micro-supercapacitor (MSC) using a protic ionic liquid electrolyte [triethylammonium bis(trifluoromethylsulfonyl)imide; Et3NH TFSI]. The electrochemical performance of the device delivered a specific capacitance of 1.5 mF cm− 2 and a power density of 25 mW cm− 2 using an enlarged cell voltage of 4 V. Furthermore, a remarkable cycling stability was evaluated after 1 · 106 galvanostatic cycles at a high current density of 10 mA cm− 2 with an excellent capacitive behavior. These results confirm that diamond-coated SiNW micro-supercapacitors exhibit very promising performances dealing with MSCs based on CVD-grown SiNWs.
Article
Diamond electrochemistry using planar macroscopic diamond films has been widely investigated. Due to the non-uniform doping in diamond, boundary effects, and the varied ratios of graphite to diamond, such systems only provide averaged electrochemical signals over the full electrode. To clarify electrical and electrochemical properties of diamond at the nanoscale, the use of diamond nanostructures (e.g., nanotextures, nanowires, networks, porous film, nanoelectrodes, etc.) and particles (e.g., undoped nanoparticles, boron-doped particles), is highly important. In this review, recent progress and achievements concerning diamond nanoelectrochemistry are considered. After a brief introduction of synthetic strategies to form diamond nanostructures and particles, their electrochemical properties in the presence and absence of redox probes are shown, followed by their use in electroanalysis (e.g., electrochemical, biochemical sensing, etc), electrochemical energy storage (e.g., electrochemical capacitors, batteries, etc.), electrocatalysis, and related applications. Topical problems and future of diamond nanoelectrochemistry are discussed.
Article
This review provides a brief historical perspective on the use of carbon electrode materials in electroanalysis, and highlights recent progress and applications of various nanostructured carbon materials. We hope that this mini-review provides the reader with some general knowledge of how these modern carbon materials are being used in electroanalysis.
Article
Abstract In this paper we present nanocrystalline boron-doped diamond nanoelectrode arrays (BDD-NEAs) for the low-level detection of biogenic substances such as dopamine (DA) without the need for a selective membrane. We achieved a sensitive and reproducible detection of dopamine in the presence of ascorbic acid (AA) with oxygen (O-) terminated BDD-NEAs. To improve the peak separation between dopamine and ascorbic acid, differential pulse voltammetry (DPV) was employed. Therewith, it was possible to measure dopamine with a sensitivity of 57.9 nA μM−1 cm−2. The detection limit was less than 100 nM with a linear behavior up to a concentration of 20 μM. The choice of the appropriate termination, the combination of the advantages of nanoelectrode arrays together with the outstanding electrochemical properties of boron-doped diamond and the right measurement method allowed successful measurement of dopamine in physiological concentrations in the presence of ascorbic acid.
Article
Diamond foams composed of hollow spheres of polycrystalline boron-doped diamond are chemically modified with two donor-acceptor type molecular dyes, BT-Rho and CPDT-Fur, and tested as electrode materials for p-type dye-sensitized solar cells with an aqueous electrolyte solution containing methyl viologen as a redox mediator. Reference experiments with flat polycrystalline diamond electrodes evidence full blocking of the methyl viologen redox reaction by these dyes, whereas only partial blocking is observed for the diamond foams. This is ascribed to sp2-carbon impurities in the foam, viz. trans-polyacetylene and graphite-like carbon. Cathodic photocurrents under solar light illumination are about 3 times larger on foam electrodes compared to flat diamond. Long-term (1-2 days) illumination of the sensitized foam electrodes with chopped light at 1 sun intensity causes an increase of the cathodic photocurrent density to ca. 15-22 μA cm-2. These photocurrent densities represent the largest values reported so far for dye-sensitized diamond electrodes. The photoelectrochemical activation of the sensitized diamond electrodes is accompanied with characteristic changes of the dark voltammogram of the MV2+/MV+ redox couple and with gradual changes of the IPCE spectra. This journal is
Article
Boron-doped diamond has been utilized as an electrode material to construct an electric double layer capacitor (EDLC) as well as an electrode support to form a pseudocapacitor. In 1.0 M NaSO4 solution, the capacitance of diamond EDLC is in the range of 3.6-7.0 μF cm-2, comparable with those of EDLCs based on other carbon materials. During a charge/discharge process for 1000 cycles at a scan rate of 100 mV s-1, the capacitance only decreases 5%, indicating high stability and a long lifetime of such an EDLC. To improve the capacitance of diamond EDLCs, diamond was coated with a MnO2 film to construct a pseudosupercapacitor. The MnO2 films were electrodeposited at a constant potential of 0.9 V vs Ag/AgCl in 0.2 M MnSO4 solution. The mass of MnO2 deposited per unit area, called the area density, calculated from the deposition charge, was controlled via the deposition time. The MnO2 films were characterized using various techniques like SEM, XPS, Raman spectroscopy, etc. In 1.0 M NaSO4 solution, the capacitance of the MnO2/diamond-based pseudosupercapacitor rises with an increase of the mass of MnO2 on diamond. Its maximum capacitance was found to be reached at a MnO2 area density of 24 μg cm-2. The capacitance obtained from voltammetry is 384 μF, or 326 F g-1 at a scan rate of 10 mV s-1, which is comparable with the value of 406 μF, or 349 F g-1, obtained from charge/discharge process at a current density of 3 A g-1 in the potential range 0 to 0.8 V. The capacitance was reduced by 34% after 1000 subsequent charge/discharge cycles carried out at a scan range of 100 mV s-1. The comparison of the performance of the MnO2/diamond pseudosupercapacitor with that of those pseudosupercapacitors based on MnO2 and other carbon materials indicates that diamond could be suitable for electrochemical supercapacitor applications.
Article
In this Spotlight on Applications, we describe our recent progress on the fabrication of surface-enlarged boron-doped polycrystalline diamond electrodes, and evaluate their performance in supercapacitor applications. We begin with a discussion of the fabrication methods of porous diamond materials. The diamond surface enlargement starts with a top-down plasma etching method. While the extra surface area provided by surface roughening or nanostructuring provides good outcome for sensing applications, a capacitance value < 1 mF cm^-2 or a surface-enlargement factor < 100 fail to meet the requirement of a practical supercapacitor. Driven by the need for large surface areas, we recently focused on the tempated-growth method. We worked on both supported and free-standing porous diamond materials to enhance the areal capacitance to the "mF cm^-2" range. With our newly developed free-standing diamond paper, areal capacitance can be multiplied by stacking multilayers of the electrode material. Finally, considering the fact that there is no real diamond-based supercapacitor device up to now, we fabricated the first prototype pouch-cell device based on the free-standing diamond paper to evaluate its performance. The results reveal that the diamond paper is suitable for operation in high potential windows (up to 2.5 V) in aqueous electrolyte with a capacitance of 0.688 mF cm^-2 per layer of paper (or 0.645 F g^-1). Impedance spectroscopy revealed that the operation frequency of the device exceeds 30 Hz. Due to the large potential window and the ability to work at high frequency, the specific power of the device reached 105 W kg^-1. In the end, we made estimations on the future target performance of diamond supercapacitors based on the existing information.
Article
Nano titania modified nanodiamond (TiO2/ND) was prepared by a microwave hydrolysis method, and then platinum nanoparticles (NPs) were deposited on the TiO2/ND support using a microwave-assisted polyol method. TiO2/ND supported Pt (Pt/TiO2/ND) electrocatalyst was characterized by X-ray diffraction and transmission electron microscopy. The electrocatalytic activity for methanol oxidation reaction (MOR) was investigated by cyclic voltammetry and chronoamperometry. It was found that anatase TiO2 NPs with the sizes of 4∼8 nm were distributed on the ND surface uniformly, and Pt NPs highly dispersed on the TiO2/ND support. The electrochemical results showed that the Pt/TiO2/ND catalyst possessed higher electrocatalytic activity for MOR compared with the Pt/ND in acid medium. A high stability of Pt/TiO2/ND catalyst was ascribed to an anchoring effect of the TiO2 layer and a high stability of the TiO2/ND support in acid solution.
Article
Electrochemical reduction of CO2 is an attractive technique for reducing CO2 emission and converting it into useful chemicals, but it suffers from high overpotential, low efficiency or poor product selectivity. Here, N-doped nano-diamond/Si rod array (NDD/Si RA) was proposed as an efficient nonmetallic electrocatalyst for CO2 reduction. It preferentially and rapidly converted CO2 to acetate over formate with an onset potential of -0.36 V (vs RHE), overcoming the usual limitation of low selectivity for C2 products. Moreover, faradic efficiency of 91.2 ~ 91.8% has been achieved for CO2 reduction at -0.8 ~ -1.0 V. Its superior performance for CO2 reduction can be attributed to its high overpotential for hydrogen evolution and N doping, where N-sp3C species was highly active for CO2 reduction. Electrokinetic data and in situ infrared spectrum revealed the main pathway for CO2 reduction might be CO2 → CO2• - → (COO)2• → CH3COO-.
Article
Over the last decades, carbon-based nanostructures have generated a huge interest from both fundamental and technological viewpoints owing to their physicochemical characteristics, markedly different from their corresponding bulk states. Among these nanostructured materials, carbon nanotubes (CNTs), and more recently graphene and its derivatives, hold a central position. The large amount of work devoted to these materials is driven not only by their unique mechanical and electrical properties, but also by the advances made in synthetic methods to produce these materials in large quantities with reasonably controllable morphologies. While much less studied than CNTs and graphene, diamond nanowires, the diamond analogue of CNTs, hold promise for several important applications. Diamond nanowires display several advantages such as chemical inertness, high mechanical strength, high thermal and electrical conductivity, together with proven biocompatibility and existence of various strategies to functionalize their surface. The unique physicochemical properties of diamond nanowires have generated wide interest for their use as fillers in nanocomposites, as light detectors and emitters, as substrates for nanoelectronic devices, as tips for scanning probe microscopy as well as for sensing applications. In the past few years, studies on boron-doped diamond nanowires (BDD NWs) focused on increasing their electrochemical active surface area to achieve higher sensitivity and selectivity compared to planar diamond interfaces. The first part of the present review article will cover the promising applications of BDD NWS for label-free sensing. Then, the potential use of diamond nanowires as inorganic substrates for matrix-free laser desorption/ionization mass spectrometry, a powerful label-free approach for quantification and identification of small compounds, will be discussed.
Article
In the present work, we report the fabrication and application of a sensitive nonenzymatic hydrogen peroxide (H2O2) sensor, using a nanocomposite, based on the nanodiamonds (NDs) decorated with silver nanoparticles (AgNPs/NDs). The AgNPs/NDs nanocomposite was prepared via a facile and efficient process. The field emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction were applied for characterization of the obtained nanocomposite. The electrochemical investigations have shown that the resulting AgNPs/NDs nanocomposite modified electrode has strong electrocatalytic activity toward H2O2 reduction which is attributed to the NDs that promoted the formation, uniform distribution, and electrocatalytic activity of the AgNPs. In the optimum conditions, the linear response range of the constructed H2O2 sensor was from 0.1 to 34.0 µM at applied potential of −0.2 V with a detection limit of 0.01 μM (S/N = 3). Also, the proposed sensor showed high sensitivity of 1.59 × 106 µAM−1 and was applied to measure the concentration of H2O2 in real samples. These results indicate that the AgNPs/NDs nanocomposite with high conductivity and stability has a promising potential in electrochemical sensors development. Graphical abstract Electroreduction of H2O2 on the AgNPs/NDs/GCE.
Article
In this paper diamond foam (DF) is introduced as a new material for thin-film supercapacitor application. Geometrical, structural, and electrical and electrochemical properties with respect to capacitance, electrochemical window and power are discussed in details. Diamond foam shows a 2.5 V potential window in aqueous solution. Discharge rate as high as 1000 V s−1 was measured which is three magnitudes higher than conventional supercapacitors. The power performance of diamond foam (807 W cm−3) approaches that of electrolytic capacitors, but the energy storage is more than one magnitude higher. Therefore, this new material is very promising for high-power micro-supercapacitor applications.
Article
Pseudocapacitive materials exhibit high energy storage, but their energy release is slow. In this paper we aim at solving this problem by using diamond-nickel hydroxide composite wires as a high power supercapacitor material. Diamond nanowires serve as a 3D substrate and current collector. The morphology of the sample was monitored with SEM during the fabrication process. Measured by electrochemical techniques, the material achieved a gravitational capacitance of 1601 F/g (∼80% of the theoretical value). A high power density up to 3 × 105 W/kg was confirmed, which is more than one magnitude higher than state of the art values. The reason for the high rate performance is also determined and discussed in detail, and fast ion diffusion inside the 3D composite is confirmed.
Article
Electrically conducting diamond powder was prepared by coating insulating diamond powder (8-12 μm diam, ∼2 m 2 /g) with a thin boron-doped layer using microwave plasma-assisted chemical vapor deposition. Deposition times from 1 to 6 h were evaluated. Scanning electron microscopy (SEM) revealed that the diamond powder particles become more faceted and more secondary growths form with increasing deposition time. Fusion of neighboring particles was also observed with increasing growth time. The first-order diamond phonon line appeared in the Raman spectrum at ca. 1331 cm - 1 for deposition times up to 4 h, and was downshifted to as low as 1317 cm - 1 for some particles after the 6-h growth. Electrical resistance measurements of the bulk powder (no binder) confirmed that a conductive diamond overlayer formed, as the conductivity increased from near zero (insulating, <10 - 5 S/cm) for the uncoated powder to 1.5 S/cm after the 6-h growth. Ohmic behavior was seen in current-voltage curves recorded for the 4-h powder between ′10 V. Cyclic voltammetric i-E curves for Fe(CN) 3 - / 4 - 6 and Ru(NH 3 ) 3 + / 2 + 6 were recorded to evaluate the electrochemical properties of the conductive powder when mixed with a polytetrafluoroethylene binder. At scan rates between 10 and 500 mV/s, ΔE p for both redox systems was high, ranging from 140 to 350 mV, consistent with significant ohmic resistance within the powder/binder electrode. Our results at this point suggest that the resistance is mainly due to poor particle-particle connectivity. Anodic polarization at 1.6 V vs Ag/AgCl for 1 h (25°C) was performed to evaluate the morphological and microstructural stability of the conductive diamond in comparison with graphite and glassy carbon (GC) powders. The total charge passed during polarization was largest for the GC powder (0.88 C/cm 2 ) and smallest for conductive diamond powder (0.18 C/cm 2 ). SEM images taken of conductive diamond powder after polarization showed no evidence of microstructural degradation, while significant morphological and microstructural changes were seen for the GC powder.
Article
Surface graphitized nanodiamond (GND) with a diamond core covered by a graphitic carbon shell was prepared by annealing ND at the temperature of 1300 degrees C in a vacuum of 10(-3) Pa. PtNi electrocatalysts were prepared by a microwave heating polyol method using the prepared GND as a support. The composition and morphology of the PtNi electrocatalysts supported on GND (PtNi/GND) were characterized by X-ray diffraction, transmission electron microscopy and energy dispersion spectra. The results showed that nano-scaled PtNi alloy particles with an atomic ratio of approximately 1:1 were uniformly deposited on the GND through co-reduction process. The electrocatalytic activities of the PtNi/GND electrocatalysts for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) were investigated by cyclic voltammetry, chronoamperometry and linear sweep voltammetry. The PtNi/GND exhibited better electrocatalytic activities than the Pt/GND either for MOR and ORR. In comparison with traditional carbon support Vulcan XC-72, GND showed higher oxidation-resistance, and consequently led to greater stability for the PtNi/GND than PtNi/XC-72.
Article
In this study, novel diamond porous membranes are developed through a reliable process providing unique pathway towards large surface area and porous materials. Mainly deposited onto flat surface so far, we demonstrate here that diamond coating is possible on very complex 3D shapes, even nanoporous, through an original nanoseeding process and adapted growth conditions. Such membranes or filters exhibit outstanding features thanks to the unique mechanical properties and surface chemistry of diamond. Indeed, the straightforward tuning of their surface properties associated to their high stability ensures diamond porous membranes applications in the scope of filtration, separation and extraction. Preliminary electrochemical studies highlight the membranes potential to be used for high specific area electrodes applications. After an extensive characterization of these new diamond porous membranes, their potential for proteins extraction will be demonstrated through mass spectrometry detection.
Article
A porous diamond network with three-dimensionally interconnected pores is of technical importance but difficult to be produced. In this contribution we demonstrate a simple, controllable and "template-free" approach to fabricate diamond networks. It combines the deposition of diamond/β-SiC nanocomposite film with a wet-chemical selective etching of the β-SiC phase. The porosity of these networks was tuned from 15% to 68%, determined by the ratio of the β-SiC phase in the composite films. The electrochemical working potential and the reactivity of redox probes on the diamond networks is similar to those of a flat nanocrystalline diamond film, while their surface areas are hundreds times larger than that of a flat diamond film (e.g. 490-fold enhancement for a 3 µm thick diamond network). The marriage of the unprecedented physical/chemical features of diamond with inherent advantages of the porous structure makes the diamond network a potential candidate for various applications such as water treatment, energy conversion (batteries or fuel cells) and storage (capacitors), as well as electrochemical and biochemical sensing.
Article
In this work, we report the modification of a gold electrode with undoped diamond nanoparticles (DNPs) and its applicability to the fabrication of electrochemical biosensing platforms. DNPs were immobilized onto a gold electrode by direct adsorption and the electrochemical behavior of the resulting DNPs/Au platform was studied. Four well-defined peaks were observed corresponding to the DNPs oxidation/reduction at the underlying gold electrode, which demonstrate that, although undoped DNPs have an insulating character, they show electrochemical activity as a consequence of the presence of different functionalities with unsaturated bonding on their surface. In order to develop a DNPs-based biosensing platform, we have selected glucose oxidase (GOx), as a model enzyme. We have performed an exhaustive study of the different steps involved in the biosensing platform preparation (DNPs/Au and GOx/DNPs/Au systems) by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and cyclic voltammetry (CV). The glucose biosensor shows a good electrocatalytic response in the presence of (hydroxymethyl)ferrocene as redox mediator. Once the suitability of the prototype system to determine glucose was verified, in a second step, we prepared a similar biosensor, but employing the enzyme lactate oxidase (LOx/DNPs/Au). As far as we know, this is the first electrochemical biosensor for lactate determination that includes DNPs as nanomaterial. A linear concentration range from 0.05mM to 0.7mM, a sensitivity of 4.0µAmM(-1) and a detection limit of 15µM were obtained. Copyright © 2015 Elsevier B.V. All rights reserved.
Article
The preparation of nanostructured diamond electrodes, decorated with Pt nanoparticles is described in this work. The method involves the electrodeposition of Pt particles on the diamond electrode surface, after which the structure is treated with either an oxygen plasma or an hydrogen plasma. In the former treatment, the Pt particles serve as a hard resist during the oxygen plasma etching of the diamond, yielding structures consisting of Pt particles located on the top of diamond nanorods. In the latter treatment, the Pt catalysed gasification of diamond in the hydrogen plasma occurs, leading to the localisation of the Pt particles in nanopits on the electrode interface. The electrochemical activity of this latter structure with regard to the electrochemical oxidation of both glucose and methanol is demonstrated. It is shown that the hydrogen plasma treatment provides a viable route for the preparation of Pt decorated electrodes with significantly improved chemical stability.
Article
A two-step thermal treatment method was developed for the fabrication of porous conductive boron-doped diamond (BDD) electrodes. The first step involved graphitization of the BDD thin film surface to form a fine microstructure by heating in an argon atmosphere at 1000 degrees C. The second step was removal of the graphitic components by oxidation in air at 425 degrees C. The heat treatment resulted in the formation of dense pores with several tens to several hundred nanometer sizes or smaller on the BDD surface. The pore formation mechanism was discussed by microscopic observation of the (111) and (100) crystal facets on the treated BDD surface. The porous BDD electrode exhibited a double-layer capacitance (C-dl) of ca. 140 mu F cm(-2), which was estimated from cyclic voltammetry (CV) and galvanostatic measurements in an aqueous electrolyte. This C-dl value was approximately 40 times larger than that for the as-deposited BDD electrode, while the potential window remained wide at ca. 3 V.
We summarized in this paper the fabrication, properties, and electrochemical applications of diamond nanostructures, mainly diamond nanotextures and diamond nanowires. The characterizations of nanostructures were introduced with different techniques. As example of applications, electrochemical DNA sensing and protein trapping on diamond nanotextures are shown.
Article
Heavily boron-doped diamond electrode has been applied as a robust substrate for Pt based catalyst. However, by simply applying a planar electrode the effective surface area of the catalyst is limited. In this article we for the first time prepared vertically aligned Pt-diamond core-shell nanowires electrode in a convenient and scalable method (up to 6-inch wafer size). The diamond nanowires are first fabricated with reactive ion etching with metal nanoparticles as etching masks. The following Pt deposition was achieved by DC sputtering. Different amounts of Pt were coated on to the nanowires and the morphology of the core-shell wires is characterized by SEM and TEM. The catalytic oxygen/hydrogen adsorption/desorption response are characterized by cyclic voltammetry. The results show that the active Pt surface area is 23 times higher than a planar Pt electrode, and 4.3 times higher than previously reported on Pt nanoparticles on diamond by electro-deposition. Moreover, this highly active surface is stable even after 1000 full surface oxidation and reduction cycles.
Article
Conductive polyaniline (PANI) was electropolymerised on undoped nanodiamond (ND) powder by potentiodynamic deposition in sulphuric acid solution containing aniline monomer. The influences of anodic potential limit and concentrations of aniline monomer and H 2 SO 4 on cyclic voltammetry behaviour were investigated. The results showed that PANI was deposited on the ND powder electrode under an anodic potential limit of 1.1-1.5 V. However, a high anodic potential above 1.0 V was only necessary to initiate the polymerisation in initial cycles, so PANI was further grown from 0.2 to 0.9 V to avoid overoxidation and degradation. The PANI growth rate increased with the increasing concentrations of aniline monomer and H 2 SO 4 , but it decreased when the monomer concentration was higher than 0.3 M. Fourier transform infrared spectrum and scanning electron microscope confirmed the presence of PANI. At the initial polymerisation, the PANI nanoparticles were deposited on the ND surfaces. The fibril PANI increased during further growth and linked the ND particles together, forming a porous network structure. The impedance of the PANI/ND electrode was far lower than that of the ND powder electrode. The composite electrode demonstrated higher conductivity and better capacitance behaviour.
Article
Nanodiamond (ND) powder was fluorinated through direct interaction of elemental fluorine with diamond surfaces and then aminated by chemical substitution reactions using the fluorinated-ND as an intermediate. The effects of the surface terminations on electrochemical properties of ND electrodes were investigated in aqueous solutions containing Fe(CN) 6 3-/Fe(CN) 6 4-and Fe 3+ /Fe 2+ redox couples. The results showed that both redox reactions of Fe(CN) 6 3-/Fe(CN) 6 4-and Fe 3+ /Fe 2+ were quasi-reversible on the pristine ND/solution interfaces. The redox kinetics of the Fe(CN) 6 3-/Fe(CN) 6 4-and Fe 3+ /Fe 2+ systems became slower after fluorination on ND surface. The followed amino modification accelerated the electron exchange between the electrode and Fe(CN) 6 3-/Fe(CN) 6 4-but slowed the redox reaction of Fe 3+ /Fe 2+ cations. The electrochemical activity of ND powder can be tunable via surface functionalizations.
Article
Detonation-synthesized nanodiamond (DND) supported platinum electrocatalyst (Pt/DND) were fabricated using a microwave-heating polyol method. The Pt/DND nanocomposites were characterized by energy-dispersive spectroscopy, transmission electron microscopy, and X-ray diffraction. The Pt nanoparticles with the mean size of 3-4 nm were highly dispersed on DND supports. The electrochemical measurements demonstrated that the Pt/DND nanocomposite prepared exhibited high electrocatalytic activity for methanol electrooxidation reaction just like other sp 2 -bonded carbon supported catalyst.
Article
A novel core-shell support material was designed with nanodiamond (ND) as core possessed excellent stability and TiN as shell improved the conductivity of support. The nano-TiN shell was decorated on the surface of ND by annealing TiO2 in nitrogen atmosphere, and the obtained ND@TiN was employed to support Pt nanoparticles (NPs). The ND@TiN support and Pt/ND@TiN electrocatalyst were characterized by X-ray diffraction and transmission electron microscopy. ND particles were coated uniformly by the TiN layer and Pt NPs with a mean size of 4.2 nm were highly dispersed on the surface of ND@TiN. The electrochemical results confirmed that the ND@TiN support possessed a much more stability than the carbon black and exhibited a bigger background current density than the ND. The Pt/ND@TiN catalyst showed higher catalytic activity and better stability in methanol oxidation and oxygen reduction reactions compared with the Pt/C and Pt/ND.
Article
A nanograss array boron-doped diamond (BDD) electrode-based toxicity sensor, using shewanella loihica PV-4 planktonic cells as recognition element in bioelectrochemical systems (BES), was developed for detection of tobramycin. An oxidative 3.3 A/cm2 current was generated on the nanograss array BDD electrode poised at 0.2 V in the BES, in the presence of S. loihica PV-4 cells. After addition of tobramycin in the range of 1.0–20.0 g/mL, the current was decreased from 3.0 A/cm2 to 1.3 A/cm2, with current inhibition ratio exponentially increased from 7.6% to 59.6%. The electrochemical responses from tobramycin concentrations in the nanograss array BDD electrode-based BES were further evaluated by cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The redox peak currents of CVs were decreased exponentially with tobramycin concentrations and CV profiles changed from peak shape to nearly plateau shape. The semicircle diameter of EIS increased with the increase of tobramycin concentration. These results provide preliminary information about tobramycin concentration responses in the nanostructured BDD electrodes-based BES as a toxicity sensor.
Article
The nanodiamond/carbon nitride (ND/CNx) nanoarchitectures with the stacked carbon nitride layer covering on nanodiamond have been successfully fabricated through a facile pyrolysis approach of pristine nanodiamond and melamine at the temperature of 650, 700, and 750 oC, which challenges the long-held axiom that the CNx layer only can be formed at the condensation temperature less than 600 oC but the it decomposes and inserts into carbon matrix at the temperature higher than 600 oC. The structure and surface chemical properties of ND/CNx nanomaterials are strongly dependent on pyrolysis temperature and the mass ratio of nanodiamond to melamine. The optimized ND/CNx hybrid carbon nanoarchitecture exhibits synergistically enhanced catalytic performance for direct dehydrogenation of ethylbenzene to styrene under oxidant- and steam-free conditions. The 4.0 mmol g-1 h-1 of steady-state styrene rate with 99% of selectivity over the developed catalyst can be achieved, but only 2.7 and 2.0 mmol g-1 h-1 of steady-state styrene rate with 95% and 96% of selectivity can be obtained over the pristine nanodiamond and mesoporous carbon nitride, respectively, under the same reaction conditions, ascribed to the synergistic effect between nanodiamond and carbon nitride of the hybrid material with appropriate CNx layer amount and surface chemical properties. The developed ND/CNx carbon hybrid nanoarchitecture demonstrates 1.48 and 4.15 times the steady-state styrene rate of the established ND and the industrially used K-Fe catalyst, respectively, which allows it to be a potential catalyst for future industrial application for the styrene production through metal-free dehydrogenation of ethylbenzene under oxidant- and steam-free conditions. This work also presents a facile method to create new carbon nitride layer-containing hybrid nanocarbon materials in diverse applications with excellent application properties.
Article
Nanodiamondgraphite (NDG) decorated with Ag nanoparticles (AgNPs‐NDG) was prepared and used to construct a novel sensitive sensor for the voltammetric determination of thioridazine (TR). The results indicate a remarkable increase in the oxidation peak currents together with a negative shift in the oxidation peak potentials, in comparison to the bare pyrolytic graphite electrode. Remarkable enhancement in microscopic area of the electrode along with strong adsorption of TR on the surface of the modified electrode resulted in a considerable increase in the peak current of TR. The surface morphology and the nature of the composite film deposited on PGE were characterized by scanning electron microscopy, atomic force microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Experimental variables, such as the deposited amount of the modifier suspension, pH of the supporting electrolyte, the accumulation potential and time are optimized by monitoring the CV responses of TR. Under the optimal conditions, the modified electrode showed a wide linear response to the concentration of TR in the range of 0.08–100 µM with a detection limit of 0.01 µM. The prepared modified electrode showed several advantages: simple preparation method, high stability and uniformity in the composite film, high sensitivity, long‐term stability and remarkable voltammetric reproducibility in response to TR. The modified electrode can be successfully applied for accurate determination of trace amounts of TR in pharmaceutical and clinical preparations.
Article
The production of boron-doped diamond nanoparticles enables the application of this material for a broad range of fields, such as electrochemistry, thermal management, and fundamental superconductivity research. Here we present the production of highly boron-doped diamond nanoparticles using boron-doped CVD diamond films as a starting material. In a multistep milling process followed by purification and surface oxidation we obtained diamond nanoparticles of 10-60 nm with a boron content of approximately 2.3 × 10(21) cm(-3). Aberration-corrected HRTEM reveals the presence of defects within individual diamond grains, as well as a very thin nondiamond carbon layer at the particle surface. The boron K-edge electron energy-loss near-edge fine structure demonstrates that the B atoms are tetrahedrally embedded into the diamond lattice. The boron-doped diamond nanoparticles have been used to nucleate growth of a boron-doped diamond film by CVD that does not contain an insulating seeding layer.
Book
The book gives an overview on the current development status of synthetic diamond films and their applications. Its initial part is devoted to discuss the different types of conductive diamond electrodes that have been synthesized, their preparation methods, and their chemical properties and characterization. The electrochemical properties of diamond films in different scientific areas, with special attention in electroanalysis, are further described. Different strategies to modify these electrodes are also discussed as important technologies with ability to change their electrochemical characteristics for a more specific electroanalytical use. The second part of the book deals with practical applications of diamond electrodes to the industry, organic electrosynthesis, electrochemical energy technology, and biotechnology. Special emphasis is made on the properties of these materials for the production of strong oxidizing species allowing the fast mineralization of organics and their use for water disinfection and decontamination. Recent biotechnological development on biosensors, microelectrodes, and nanostructured electrodes, as well as on neurochemistry, is also presented. The book will be written by a large number of internationally recognized experts and comprises 24 chapters describing the characteristics and theoretical fundaments of the different electrochemical uses and applications of synthetic diamond films.
Article
While chemical vapor deposition of diamond films is currently cost prohibitive for biosensor construction, in this paper we show that sonication-assisted nanostructuring of biosensing electrodes with nanodiamonds (NDs) allows harnessing the hydrolytic stability of the diamond biofunctionalization chemistry for real-time continuous sensing, while improving the detector sensitivity and stability. We find that the higher surface coverages were important for improved bacterial capture, and can be achieved through proper choice of solvent, ND concentration, and seeding time. A mixture of methanol and dimethyl sulfoxide provides the highest surface coverage (33.6 ± 3.4%) for the NDs with positive zeta potential, compared to dilutions of dimethyl sulfoxide with acetone, ethanol, isopropanol, or water. Through impedance spectroscopy of ND seeded interdigitated electrodes (IDEs), we found that the ND seeds serve as electrically conductive islands only a few nanometers apart. Also we show that the seeded NDs are amply hydrogenated to be decorated with antibodies using the UV-alkene chemistry and higher bacterial captures can be obtained than our previously reported work with diamond films. When sensing bacteria from 106 cfu/ml E. coli O157:H7, the resistance to charge transfer at the IDEs decreased by ~38.8%, which is nearly 1.5 times better than that reported previously using redox probes. Further in case of 108 cfu/ml E. coli O157:H7, the charge transfer resistance changed by ~46%, which is similar to the magnitude of improvement reported using magnetic nanoparticle based sample enrichment prior to impedance detection. Thus ND seeding allows impedance biosensing in low conductivity solutions with competitive sensitivity.
Article
Nanostructuring boron-doped diamond (BDD) films increases their sensitivity and performance when used as electrodes in electrochemical environments. We have developed a method to produce such nanostructured, porous electrodes by depositing BDD thin film onto a densely packed “forest” of vertically aligned multiwalled carbon nanotubes (CNTs). The CNTs had previously been exposed to a suspension of nanodiamond in methanol causing them to clump together into “teepee” or “honeycomb” structures. These nanostructured CNT/BDD composite electrodes have been extensively characterized by scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Not only do these electrodes possess the excellent, well-known characteristics associated with BDD (large potential window, chemical inertness, low background levels), but also they have electroactive areas and double-layer capacitance values 450 times greater than those for the equivalent flat BDD electrodes.