Zhongrui Li

Zhongrui Li
University of Arkansas at Little Rock | UALR · Nanotech

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82
Publications
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4,451
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Publications

Publications (82)
Article
Manipulating the ferromagnetism of diluted magnetic semiconductors by tuning the valence state of doped ions is found to be achievable in Mn-doped NiO. First-principles calculations predict that the interactions between substitutional Mn(3+) ions in NiO are ferromagnetic, while the Mn(2+) -Mn(2+) interactions are antiferromagnetic. This scenario is...
Article
Graphene and carbon nanotubes (CNTs) represent attractive materials for photovoltaic (PV) devices due to their unique electronic and optical properties. Graphene and single-wall carbon nanotubes (SWNTs) layers can be directly configured as energy conversion materials to fabricate thin-film solar cells, serving as both photogeneration sites and char...
Article
Any petal but a lotus: The hierarchically structured ZnO surface presents superhydrophobicity and a distinctive solid-liquid adhesion that can be attributed to the suitable size of nanostructures in combination with microscopic structures (see picture). Although the surface is superhydrophobic, water droplets continue to cling to the surface even w...
Article
We present a simple method to produce carbon nanotube-based films with exceptional superhydrophobicity and impact icephobicity by depositing acetone-treated single-walled carbon nanotubes on glass substrates. This method is scalable and can be adopted for any substrate, both flexible and rigid. These films have indicated a high contact angle, in th...
Article
Titanium implants are well known for their biocompatibility, especially if bioinertness is desired, due to the TiO2 native oxide which is thermodynamically and chemically very stable. One of the major problems with this material involve its inability to induce enhanced cellular adhesion and proliferation on its surface without complicated structura...
Article
A simple and easily processible photovoltaic device has been developed based on boron-doped single-walled carbon nanotubes (B-SWNTs) and n-type silicon (n-Si) heterojunctions. The SWNTs were substitutionally doped with boron atoms by thermal annealing, in the presence of B2O3. The samples used for these studies were characterized by Raman spectrosc...
Article
Full-text available
We developed a novel and facile method to hydrogenate graphene by using a conditioning catalyst upstream of the graphene sample to generate atomic hydrogen.
Article
Large area and few to multi-layer graphene sheets were synthesized on a bimetallic catalyst system via radio-frequency chemical vapor deposition (RF-CVD). Synthesis conditions were varied and their effects on the morphological properties of the graphene structures were observed. As the flow rate of the hydrocarbon was varied, the diameter of the gr...
Article
Graphitic shells coated ferromagnetic cobalt nanoparticles (C-Co-NPs) with diameters of around 7-9 nm cubic crystalline structures were synthesized by catalytic chemical vapor deposition (CCVD). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis indicated that the Co-NPs inside the carbon shells were preserved in the metall...
Article
Single-wall carbon nanotubes (SWNTs) are potentially an attractive material for PV applications due to their many unique structural and electrical properties. SWNTs can be directly configured as energy conversion materials to fabricate thin-film solar cells, with nanotubes serving as both photogeneration sites and charge carriers collecting/transpo...
Article
Graphitic nanomaterials such as graphene layers (G) and single-wall carbon nanotubes (SWCNT) are potential candidates in a large number of biomedical applications. However, little is known about the effects of these nanomaterials on biological systems. Here we show that the shape of these materials is directly related to their induced cellular toxi...
Article
Full-text available
Three types of graphitic shelled-magnetic core (Fe, Fe/Co, and Co) nanoparticles (named as C-Fe, C-Fe/Co, and C-Co NPs) were synthesized by radio frequency-catalytic chemical vapor deposition (RF-cCVD). X-ray diffraction and X-ray photoelectron spectroscopy analysis revealed that the cores inside the carbon shells of these NPs were preserved in the...
Article
Highly biocompatible luminescent superparamagnetic nanocomposites have been synthesized from Fe3O4/SiO2−QDs (IQ). Fe3O4 nanoparticles coated with a silica shell, Fe3O4/SiO2 (IOS), and water-soluble CdSe−ZnS quantum dots (QDs) were assembled together by the conjugation of an SH group. X-ray diffraction (XRD), transmission electron microscopy (TEM),...
Article
X-ray absorption fine structure spectroscopy (XAFS) is a unique probe for local atomic and electronic structure of absorbing centers in particulate science, physics, chemistry, and biology. During the past several decades, XAFS has gained dramatic advances in every aspect, including theoretical explanation and experimental applications. In this rev...
Article
Horizontally aligned long carbon nanotubes were efficiently synthesized on Si substrates by using a radio-frequency catalytic chemical vapor deposition method. The morphological as well as the growth properties of these nanotubes were systematically investigated with various analytical techniques including microscopy and Raman spectroscopy. Differe...
Article
Photovoltaic conversion was achieved from high-density p-n heterojunctions formed between polymer functionalized n-type single wall carbon nanotubes (SWNTs) and underlying p-type Si substrate. Functionalization of SWNTs by amine-rich polymers results in the evolution of tubes from p-type to n-type, and the polyethylene imine (PEI) functionalized SW...
Article
X-ray absorption near-edge structure (XANES) and first-principles calculations are employed to determine the Co spin state in the Co-doped TiO <sub>2</sub> thin films. Based on the experiments and the theoretical calculations, we find that the transition of Co 1s electron to the unoccupied Co 3d e<sub>g</sub> states is clarified from the pre-edge s...
Article
Carbon nanotubes and graphene represent attractive materials for photovoltaic devices. Single wall carbon nanotubes (SWNTs) and graphene layers can be directly configured as energy conversion materials to fabricate thin-film solar cells, serving as both photogeneration sites and charge carriers collecting/transport layers. SWNTs can be modified int...
Article
Functional nanomaterials that included gold, silver nanoparticles and single wall carbon nanotubes were delivered to two cell lines (MLO-Y4 osteocytic cells and HeLa cervical cancer cells) in various concentrations. The cells were found to uptake the nanomaterials in a relatively short time, a process that significantly affected the shape and the s...
Article
In previous pharmacological applications, single-wall carbon nanotubes (CNTs) have primarily been explored as potential drug carriers and delivery vehicles. Here, we investigate and demonstrate for the first time, that CNTs can be considered as anti-tumor agents and, when in combination with conventional drugs, can significantly enhance their chemo...
Article
A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible...
Article
This work reports a low-cost production method of carbon nanotubes (CNTs) and few-layer graphene sheets in large quantities through radio-frequency catalytic chemical vapor deposition (RF-cCVD). As the reaction temperature was varied over a range of 700−1000 °C, different types of high-quality carbon nanostructures were synthesized on a single Fe−C...
Article
The stability of the Pt/KL catalyst can be greatly enhanced by the presence of the rare earth Ce. The analysis of the X-ray absorption edges indicates that some electronic differences may indeed exist in the state of Pt supported on the Ce-KL compared to that on the unpromoted KL zeolite. Although the Pt particle size and location inside the zeolit...
Article
Single-walled carbon nanotubes (SWNTs) synthesized with different methods are investigated by using multiple characterization techniques, including Raman scattering, optical absorption, and X-ray absorption near edge structure, along with X-ray photoemission by following the total valence bands and C 1s core-level spectra. Four different SWNT mater...
Article
An important design approach for sensitive and robust surface enhanced Raman scattering (SERS) substrates is the use of metal nanoparticle aggregates with nanometer tailored interstitial distances between their surfaces, in order to confine the electromagnetic energy. The nanostructural instability of the aggregates to agglomeration due to their st...
Article
Carbon nanotubes (CNTs) were found to penetrate tomato seeds and affect their germination and growth rates. The germination was found to be dramatically higher for seeds that germinated on medium containing CNTs (10−40 μg/mL) compared to control. Analytical methods indicated that the CNTs are able to penetrate the thick seed coat and support water...
Article
A single-step process of radio frequency-catalytic chemical vapor deposition (RF-cCVD) was used for the synthesis of pelletized ceramic carbon nanotube (CNT) composites. The surface resistance of the insulating magnesium oxide (MgO) was found to drop dramatically as the result of the graphitic nanostructures formed within the ceramic matrix after t...
Article
In this work, we report a low-cost facile method for the production of few-layer graphene sheets in large quantities through radio-frequency chemical vapor deposition.
Article
Full-text available
The effects of nano-anatase TiO2 on light absorption, distribution, and conversion, and photoreduction activities of spinach chloroplast were studied by spectroscopy. Several effects of nano-anatase TiO2 were observed: (1) the absorption peak intensity of the chloroplast was obviously increased in red and blue region, the ratio of the Soret band an...
Article
Photovoltaic conversion was achieved from high-density p-n heterojunctions between single-wall carbon nanotubes (SWNTs) and n-type crystalline silicon produced with a simple airbrushing technique. The semitransparent SWNT network coating on n-type silicon substrate forms p-n heterojunctions and exhibits rectifying behavior. Under illumination the n...
Article
Pelletized ceramic carbon nanotube composites were synthesized through a one step process using Radio Frequency-Chemical Vapor Deposition (RF-CVD) method. Surface resistance of the insulating MgO was found to drop dramatically as the result of the graphitic nanostructures forming within the ceramic matrix through the catalytic assistance of Fe/Co....
Article
In situ polymerization of thiophene to poly(3-hexylthiophene) (P3HT) was carried out in the presence of different loadings of multiwall carbon nanotubes (MWNTs) (0.1−10 wt %). It was found that the nanotubes are dispersed uniformly in the polymer matrix and the polymer chains wrap around the nanotube walls. NMR analysis indicated the presence of bo...
Article
High quality single-wall carbon nanotubes were synthesized on a MgO supported Fe-Cocatalyst system using an inductive radio frequency catalytic chemical vapor deposition method with methane utilized as the hydrocarbon source. The synthesis temperature was varied between 700–1000 °C, and major differences when it comes to the size controllability of...
Article
In this work, the effects on nanoparticle growth by varying the Fe:Co ratio present in a Fe–Co/MgO catalyst system were studied. Single-wall carbon nanotubes were synthesized using an inductive radio frequency chemical vapor deposition method; methane and acetylene were used separately as hydrocarbon sources. The catalyst systems and their resultin...
Article
a b s t r a c t Multiwall carbon nanotubes, as indicated by electron microscopy and spectroscopy, were grown over a novel Co(5 wt.%)/ZnO catalyst by using a cold wall radio-frequency catalytic chemical vapor deposition method. The nanotubes were found to have a rather narrow diameter distribution, which can be explained by the formation over the Zn...
Article
Nano-TiO2 and superoxide dismutase (SOD, EC 1.15.1.1) have been added to cosmetics and used to prevent injury of skin from UV-radiation, which might be related to the decrease of oxidative damage of skin. In previous studies we had proven that nano-anatase could increase the activity of SOD and decrease the oxidative damage in vivo. The mechanisms...
Article
This brief review presents a comprehensive outline of the present research status on the fast moving carbon nanotube (CNT) field. It covers a short introduction to the relation between carbon nanotubes, graphite, and other forms of carbon and explains in detail the structure of CNTs. The electronic, electrical, and mechanical properties of CNTs, as...
Article
Lactate dehydrogenase (LDH, EC1.1.1.27), widely expressed in the heart, liver, and other tissues, plays an important role in glycolysis and glyconeogenesis. The activity of LDH is often altered upon inflammatory responses in animals. Nano-TiO(2) was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechan...
Article
Nanoparticles are intensively being explored as contrast agents for medical diagnostics and therapies using various optical methods. We present the first demonstration of the use of time-resolved Raman spectroscopy for in vivo real-time detection of circulating carbon nanotubes (CNTs) or cancer cells labeled with CNTs in the lymph, blood, and tissu...
Article
Nanophotothermolysis with long laser pulses for treatment of scattered cancer cells and their clusters is introduced with the main focus on real-time monitoring of temperature dynamics inside and around individual cancer cells labeled with carbon nanotubes. This technique utilizes advanced time- and spatially-resolved thermal radiometry imaging for...
Article
We report solar cells based on high-density p-n heterojunctions between single wall carbon nanotubes (SWCNTs) and a n -type silicon wafer. Chemical modification by thionyl chloride of the SWCNT coating films was found to significantly increase the conversion efficiency by more than 45% through adjusting the Fermi level and increasing the carrier co...
Article
This work reports a low-cost method for large scale production of high quality graphene via radio-frequency chemical vapor deposition. High quantities of graphene were successfully synthesized on the Fe-Co/MgO (2.5:2.5:95 wt.%) catalytic system utilizing acetylene as a hydrocarbon source at 1000 °C. The as-produced graphene sheets were purified in...
Conference Paper
Polyaniline (PANI) is a widely researched inherently conducting polymer (ICP) with applications in organic photovoltaic technology such as hole-transport layers. Less work has been reported on its use as an active layer in heterojunction solar cells. We report here that tanninsulfonic acid, a renewable resource, is a photoactive macromolecule that...
Article
Surface area (SA) of the oxide support was found to play a major role on the morphology, quality of the single wall carbon nanotubes (SWNTs) growth. Fe–Co bimetal was supported onto MgO powders with different surface areas, and used for the SWNTs synthesis from the pyrolysis of CH4 through radio frequency catalytic chemical vapor deposition (RF-CCV...
Article
Multiwall and single-wall carbon nanotubes were synthesized on Fe-Co/CaCO3 and a Fe-Co/MgO catalyst system, respectively, by using two different catalytic chemical vapor deposition methods, external furnace (EF) heating and radio frequency (RF) excitation. The carbon nanotubes synthesized with radio frequency excitation have a smaller outer diamete...
Article
Multiwall carbon nanotubes (CNTs) were grown using the chemical vapor deposition method by applying C2H2 fluxed over FexCo5−x/CaCO3 catalyst under radio frequency heating. Micro-Raman scattering investigations of the metal active species over the oxidic support allowed the understanding of the relationship between the compositional distribution amo...
Article
Graphitic carbon-coated ferromagnetic cobalt nanoparticles (C-Co-NPs) with diameters of around 7 nm and cubic crystalline structures were synthesized by catalytic chemical vapor deposition. X-ray diffraction and x-ray photoelectron spectroscopy analysis indicated that the cobalt nanoparticles inside the carbon shells were preserved in the metallic...
Article
Multiwall carbon nanotubes were synthesized on the FeCoCaO and FeMoCaO catalysts by RF-CCVD at 750 °C, 850 °C and 950 °C, using acetylene as the carbon source. Analytically, it was found that the nanotubes are well crystallized, with outside diameters ranging between 10 and 60 nm and a ratio of the outside to the inside diameters of 2 to 3. The nan...
Article
The influences of active species Fe-Co composition on the growth of carbon nanotubes (CNTs) were systemically investigated. CNTs were grown from the pyrolytic decomposition of C(2)H(2) over Fe-Co/CaCO(3) catalysts by radio frequency chemical vapor deposition (CVD). The catalyst stoichiometry was found to strongly influence the carbon deposition rat...
Article
Full-text available
We report on the role of CO(2) in improving carbon nanotube yield and crystallinity from catalytic chemical vapor deposition of hydrocarbons.
Article
The local structures and the devitrifications of Ni70B30 nano-amorphous alloys prepared by chemical reduction method were studied by in-situ X-ray absorption fine structure (XAFS). The results indicate that the preparation temperature strongly affects the local structures of Ni70B30 amorphous alloys. The coordination geometry surrounding Ni atoms i...
Article
Multiwalled carbon nanotubes (MWNTs) have a very high absorbance in the near-infrared (NIR) region of the electromagnetic spectrum. It is demonstrated that the temperature of MWNTs, measured using infrared thermography during NIR laser irradiation, is much higher than that of other carbonaceous materials such as graphite controls. Since most biolog...
Article
High-quality double-walled carbon nanotubes were synthesized by radio frequency (cold-walled) catalytic chemical vapor deposition from methane on a novel Fe - Mo/MgO catalyst obtained by coprecipitation. Transmission electron microscopy observations provided compelling evidence for the formation of double-walled carbon nanotubes, while the Raman re...
Article
Single wall carbon nanotubes were synthesized from thermal pyrolysis of methane on a FeMo/MgO catalyst by radio frequency catalytic chemical vapor deposition (RF-CVD) using argon as a carrier gas. Controlled amounts of hydrogen (H2/CH4=0–1 v/v) were introduced in separate experiments along with the carbon source. The properties and morphology of th...
Article
Full-text available
We compared conductive transparent carbon nanotube coatings on glass substrates made of differently produced single-wall (SWNT), double-wall, and multiwall carbon nanotubes. The airbrushing approach and the vacuum filtration method were utilized for the fabrication of carbon nanotube films. The optoelectronic performance of the carbon nanotube film...
Article
Conductive materials are at the forefront of materials science research because of the large number of applications that have been developed around their interesting and unique properties. This work reports for the first time a correlation between the structural, electrical, and thermal behavior of novel graphite-polyaniline (G-PANI) composites wit...
Article
The mechanism of carbon nanotube (CNT) nucleation and growth has been under investigation for 15 years, since the discovery of this most explored material of the 20th century. Prior models have attempted the extension of classical transport mechanisms used to explain the older, bigger, micron-sized filamentous carbon formations. In July 2000, a mor...
Article
A comparison of different catalyst systems (Fe–Mo, Co–Mo or Ni–Mo nanoparticles supported on calcium carbonate) has been performed in order to optimize the carbon nanotube (CNT) growth. The influences of the reaction temperature, metal loading and carbon source on the synthesis of CNTs were investigated. Dense CNT networks have been synthesized by...
Article
Some of the most exciting novel approaches for renewable solar energy conversion are the organic photovoltaic devices that take advantage of the unique properties of polymers such as poly(3-hexylthiphene) (P3HT). Although this type of devices present significant advantages (stability, price) their long-term performance has to be continuously improv...
Conference Paper
Carbon nanotubes (CNTs) with high crystallinity were synthesized on the MgO supported Fe-Co catalyst system using a chemical vapor deposition method. Methane was utilized as a hydrocarbon source and the reaction temperature was varied between 700 to 1000 °C. The influence of the temperature on the size of the metal nano-particles and the morphology...
Conference Paper
Four differently produced single-walled carbon nanotube (SWNT) materials (by arc discharge, HiPco, laser ablation, and CoMoCat method) with diameters ranging from 0.7 to 2.8 nm were investigated by using multiple characterization techniques, including Raman scattering, optical absorption, X-ray absorption near edge structure, along with X-ray photo...
Article
The effect of impurities on the properties of single-wall carbon nanotubes (SWNTs) was investigated with multiple analytical techniques. Charge transfer is believed to occur between the impurities and the SWNTs as observed by combining the Raman scattering and x-ray photoelectron measurements. The impurity condition (type and level) was found to st...
Article
Multiwalled carbon nanotubes were synthesized by catalytic chemical vapor deposition using two different methods of heating. By one method, an external resistive tube furnace was used, whereas the other method involved heating with radio frequency excitation by induction coil. A comprehensive comparison was made between these two methods with regar...
Article
The effects of nano-anatase TiO2 on light absorption, distribution, and conversion, and photoreduction activities of spinach chloroplast were studied by spectroscopy. Several effects of nano-anatase TiO2 were observed: (1) the absorption peak intensity of the chloroplast was obviously increased in red and blue region, the ratio of the Soret band an...
Article
X-ray absorption fine structure (XAFS) and first-principles calculations were employed to study the structure and ferromagnetism origin of Zn0.97Mn0.03O thin film grown by metal organic chemical vapor deposition. The magnetization measurements indicate that this sample is ferromagnetic at room temperature. The Mn ions are located at the substitutio...
Article
Full-text available
As electrically conductive and optically transparent thin coating material, double-wall carbon nanotube network was found to have better transparency-conductance performance as compared with single-wall carbon nanotube (SWNT) and multiwall carbon nanotube (MWNT). The electronic transportability and optical properties of the SWNT films can be altere...
Article
Zn <sub>0.96</sub> Mn <sub>0.04</sub> O and Zn <sub>0.96</sub> Mn <sub>0.04</sub> O : N thin films with wurtzite structure were grown by inductively coupled plasma enhanced chemical vapor deposition method. Although both samples exhibit ferromagnetism at room temperature, the saturation magnetic moment (1.4μ<sub>B</sub>/ Mn ) of the Mn- and N-codop...
Article
The formation mechanism of Ge nanocrystals embedded in a SiO2 matrix on Si(100) and quartz substrates was systemically studied with multiple techniques, including x-ray diffraction, transmission electron microscopy, and fluorescence x-ray absorption fine structure. It was found that, on the quartz substrate, the content of GeO2-like species keeps n...
Article
The electronic and geometric effects induced by preparation methods on small platinum particles supported on high surface-area zeolite HY were studied by X-ray absorption fine structure (XAFS) spectroscopy. Pt/HY catalysts were prepared by a variety of techniques, including incipient wetness impregnation (IWI) and vapor-phase impregnation (VPI). Re...
Article
A series of bi-metallic Pd-Pt catalysts supported on both pristine and fluorinated alumina supports were investigated with x-ray absorption spectroscopy. It was found that Pd and Pt form small alloy particles on the pristine alumina support; the composition and the cluster size of the PdPt bimetallic alloys, and the electronic properties of the met...
Article
The formation mechanism of Ge nanocrystals for Ge (60 mol%) embedded in a SiO2 matrix grown on Si(001) and quartz‐glass substrates was studied by fluorescence x‐ray absorption fine structure (XAFS). It was found that the formation of Ge nanocrystals strongly depends on the properties of the substrate materials. In the as‐prepared samples, Ge atom...
Article
Highly electrically conductive and optically transparent thin films were fabricated on conventional glass substrates using different purified carbon nanotubes, single-wall (SWNT), double-wall (DWNT), and multi-wall (MWNT) carbon nanotubes. The starting carbon nanotube materials were first made into homogenous solution with either sodium cholate or...
Article
The electrical and thermal properties of carbon nanotubes (CNT)-polymer nanocomposite materials have been studied. The carbon nanostructures were analyzed by several analytical techniques, including Electronic Microscopy, Raman Spectroscopy, and X-Ray Photoelectron Spectroscopy. Carbon nanotubes were grown by catalytic chemical vapor deposition on...
Article
Full-text available
Proteins containing Rieske-type [2Fe-2S] clusters play essential functions in all three domains of life. We engineered the two histidine ligands to the Rieske-type [2Fe-2S] cluster in the hyperthermophilic archaeal Rieske-type ferredoxin from Sulfolobus solfataricus to modify types and spacing of ligands and successfully converted the metal and clu...
Article
Full-text available
The repressor-activator MerR that controls transcription of the mercury resistance (mer) operon is unusual for its high sensitivity and specificity for Hg(II) in in vivo and in vitro transcriptional assays. The metal-recognition domain of MerR resides at the homodimer interface in a novel antiparallel arrangement of alpha-helix 5 that forms a coile...
Article
Full-text available
We heterologously overproduced a hyperthermostable archaeal low potential (E(m) = -62 mV) Rieske-type ferredoxin (ARF) from Sulfolobus solfataricus strain P-1 and its variants in Escherichia coli to examine the influence of ligand substitutions on the properties of the [2Fe-2S] cluster. While two cysteine ligand residues (Cys(42) and Cys(61)) are e...