Xinjian Feng

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (23)179.46 Total impact

  • ruosa Zeng · ke Li · Xia Sheng · Liping Chen · Haijiao Zhang · Xinjian Feng

    No preview · Article · Jan 2016 · Chemical Communications
  • Xia Sheng · Liping Chen · Tao Xu · Kai Zhu · Xinjian Feng
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    ABSTRACT: Charge transport within electrode materials plays a key role in determining the optoelectronic device performance. Aligned single-crystal TiO2 nanowire arrays offer an ideal electron transport path and are expected to have higher electron mobility. Unfortunately, their transport is found not to be superior to that in nanoparticle films. Here we show that the low electron transport in rutile TiO2 nanowires is mainly caused by surface traps in relatively deep energy levels, which cannot be removed by conventional approaches, such as oxygen annealing treatment. Moreover, we demonstrate an effective wet-chemistry approach to minimize these trap states, leading to over 20-fold enhancement in electron diffusion coefficient and 62% improvement in solar cell performance. On the basis of our results, the potential of TiO2 NWs can be developed and well-utilized, which is significantly important for their practical applications.
    No preview · Article · Dec 2015 · Chemical Science
  • Yongjiu Lei · Ruize Sun · Xiangcheng Zhang · Xinjian Feng · Lei Jiang
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    ABSTRACT: The fabrication of novel superhydrophobic electrodes is described, which have an air-liquid-solid three-phase interface, where oxygen is sufficient and constant. Oxygen is an effective natural electron acceptor for oxidase, and plays a key role in the development of reliable bioassays. Such an electrode allows detection of glucose concentration, linearly from 50 nm to 156 mm with good sensitivity and accuracy without analyte dilution. This strategy offers a unique route to address the gas-deficit problem of many reaction systems.
    No preview · Article · Dec 2015 · Advanced Materials
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    ABSTRACT: Developing nanostructured electrocatalysts, with low overpotential, high selectivity and activity has fundamental and technical importance in many fields. We report here rhodium nanoparticle and mesoporous silicon nanowire (RhNP@mSiNW) hybrids for hydrogen peroxide (H2O2) detection with high electrocatalytic activity and selectivity. By employing electrodes that loaded with RhNP@mSiNW nanohybrids, interference caused from both many electroactive substances and dissolved oxygen were eliminated by electrochemical assaying at an optimal potential of +75 mV. Furthermore, the electrodes exhibited a high detection sensitivity of 0.53 μA/mM and fast response (< 5 s). This high-performance nanohybrid electrocatalyst has great potential for future practical application in various oxidase-base biosensors.
    Preview · Article · Jan 2015 · Scientific Reports
  • Dongqing He · Xia Sheng · Jie Yang · Liping Chen · Kai Zhu · Xinjian Feng
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    ABSTRACT: Crystallographic orientation and microstructure of metal oxide nanomaterials have great impact on their properties and applications. Here, we report [101̅0] oriented ZnO nanowire (NW) arrays with a multichannel mesostructure. The NW has a preferential growth of low energy (101̅0) crystal plane and exhibits 2-3 orders of magnitude faster electron transport rate than that in nanoparticle (NP) films. Furthermore, the surface area of the as-prepared NW arrays is about 5 times larger than that of conventional NW arrays with similar thickness. These lead to the highest power conversion efficiency of ZnO NW array-based sensitized solar cells. We anticipate that the unique crystallographic orientation and mesostructure will endow ZnO NW arrays new properties and expand their application fields.
    No preview · Article · Nov 2014 · Journal of the American Chemical Society
  • Qinglong Jiang · Xia Sheng · Bing Shi · Xinjian Feng · Tao Xu
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    ABSTRACT: Current lead halide perovskite solar cells use high work function (φ) precious metals, such as gold (φ = 5.1 eV), as the back cathode to maximize the attainable photovoltage. We report herein a set of perovskite-type solar cells that use nickel (φ = 5.04 eV), an earth-abundant element and non-precious metal, as back cathode and achieve the same open-circuit voltage as gold and an efficiency of 10.4%. This work opens a “nickel”-and-dimed (low-cost) way toward high-efficient perovskite solar cells.
    No preview · Article · Nov 2014 · The Journal of Physical Chemistry C
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    Qinglong Jiang · Xia Sheng · Yingxuan Li · Xinjian Feng · Tao Xu
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    ABSTRACT: Different lengths of single crystal rutile TiO2 nanowires (NW) with wide-open space for effective material filling were used as photoanodes for perovskite solar cells. Cells with 900 nm nanowires as photoanodes exhibit current density of 22 mA/cm2 and efficiency of 11.7%, exceeding the reported TiO2 nanowire-based perovskite solar cells.
    Full-text · Article · Oct 2014 · Chemical Communications
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    ABSTRACT: Developing nanostructured electrocatalysts, with low overpotential and high activity, has fundamental and technical importance in many fields. A new electrocatalyst for H2O2 oxidation based on strongly coupled rhodium nanocrystal/reduced graphene oxide (Rh/RGO) hybrid nanomaterials is described. The Rh/RGO nanohybrids markedly reduce the oxidation potential to about +0.1 V, which is 0.5 V lower than that of a traditional platinum electrode. The nanohybrids have a strong synergetic effect and are catalytically more active than single-component Rh and RGO and state-of-the-art commercial Rh/C catalysts.
    No preview · Article · Sep 2014
  • Xia Sheng · Dongqing He · Jie Yang · Kai Zhu · Xinjian Feng
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    ABSTRACT: Developing high surface area nanostructured electrodes with rapid charge transport is essential for artificial photosynthesis, solar cells, photocatalysis, and energy storage devices. Substantial research efforts have been recently focused on building 1D nano-blocks with fast charge transport into 3D hierarchical architectures. However, except for the enlargement in surface area, there is little experimental evidence of fast electron transport in these 3D nanostructure-based solar cells. In this communication, we report single-crystal-like 3D TiO2 branched nanowire arrays consisting of 1D branch epitaxially grown from the primary trunk. These 3D branched nanoarrays not only demonstrate 71% enlargement in large surface area (compared with 1D nanowire arrays) but also exhibit fast charge transport property (comparable to that in 1D single crystal nanoarrays), leading to 52% improvement in solar conversion efficiency . The orientated 3D assembly strategy reported here can be extended to assemble other metal oxides with one or multiple component, and thus represents a critical avenue towards high-performance optoelectronics.
    No preview · Article · Mar 2014 · Nano Letters
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    ABSTRACT: A rapid solvothermal approach was used to synthesize aligned 1D single-crystal rutile TiO(2) nanowire (NW) arrays on transparent conducting substrates as electrodes for dye-sensitized solar cells. The NW arrays showed a more than 200 times faster charge transport and a factor four lower defect state density than conventional rutile nanoparticle films.
    No preview · Article · Mar 2012 · Angewandte Chemie International Edition
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    ABSTRACT: We report on low-cost, all solution fabrication of efficient air-stable nanostructured thin film photovoltaics comprised of n-type Sb(2)S(3) chemically deposited onto TiO(2) nanowire array films, forming coaxial Sb(2)S(3)/TiO(2) nanowire hybrids vertically oriented from the SnO(2):F coated glass substrate, which are then intercalated with poly(3-hexylthiophene) (P3HT) for hole transport and enhanced light absorption.
    No preview · Article · Feb 2012 · Chemical Communications
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    Ningzhong Bao · Xinjian Feng · Craig A. Grimes
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    ABSTRACT: We review the use of self-assembled, vertically oriented one-dimensional (1D) titania nanowire and nanotube geometries in several third-generation excitonic solar cell designs including those based upon bulk heterojunction, ordered heterojunction, Förster resonance energy transfer (FRET), and liquid-junction dye-sensitized solar cells (DSSCs).
    Preview · Article · Jan 2012 · Journal of Nanotechnology
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    ABSTRACT: Using a rapid microwave-assisted solvothermal approach ultrafine Ptnanoparticles are synthesized and deposited in situ within high aspect ratio nanotube arrays. Adjusting the initial concentration of metal ion precursor inside the nanotube support controls the resulting Ptnanoparticle sizes. The Pt-nanoparticle/TiO2nanotube composite is shown to greatly promote the photocatalytic conversion of carbon dioxide and water vapor into methane, a behavior attributed to the homogeneous distribution of metal co-catalyst nanoparticles over the TiO2nanotube array surface providing a large number of active reduction sites. The novelty and flexibility of the technique, described herein, could prove useful for the deposition of metal, metal alloy, or metal oxidenanoparticles within a variety of nanotubular or nanoporous material systems with the resulting nanocomposites useful in catalysis, photocatalysis, photovoltaic, and photoelectrochemical applications.
    No preview · Article · Aug 2011 · Journal of Materials Chemistry
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    ABSTRACT: Photocorrosion stable WO(3) nanowire arrays are synthesized by a solvothermal technique on fluorine-doped tin oxide coated glass. WO(3) morphologies of hexagonal and monoclinic structure, ranging from nanowire to nanoflake arrays, are tailored by adjusting solution composition with growth along the (001) direction. Photoelectrochemical measurements of illustrative films show incident photon-to-current conversion efficiencies higher than 60% at 400 nm with a photocurrent of 1.43 mA/cm(2) under AM 1.5G illumination. Our solvothermal film growth technique offers an exciting opportunity for growth of one-dimensional metal oxide nanostructures with practical application in photoelectrochemical energy conversion.
    No preview · Article · Jan 2011 · Nano Letters

  • No preview · Article · Jan 2011 · MRS Online Proceeding Library
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    ABSTRACT: Tantalum nitride (Ta3N5) has a band gap of approximately 2.07 eV, suitable for collecting more than 45% of the incident solar spectrum energy. We describe a simple method for scale fabrication of highly oriented Ta3N5 nanotube array films, by anodization of tantalum foil to achieve vertically oriented tantalum oxide nanotube arrays followed by a 700 degrees C ammonia anneal for sample crystallization and nitridation. The thin walled amorphous nanotube array structure enables transformation from tantalum oxide to Ta3N5 to occur at relatively low temperatures, while high-temperature annealing related structural aggregation that commonly occurs in particle films is avoided. In 1 M KOH solution, under AM 1.5 illumination with 0.5 V dc bias typical sample (nanotube length approximately 240 nm, wall thickness approximately 7 nm) visible light incident photon conversion efficiencies (IPCE) as high as 5.3% were obtained. The enhanced visible light activity in combination with the ordered one-dimensional nanoarchitecture makes Ta3N5 nanotube arrays films a promising candidate for visible light water photoelectrolysis.
    No preview · Article · Oct 2010 · Nano Letters
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    ABSTRACT: Nanodrähte in der Sonne: Durch Hydrothermalsynthese wurden homogen tantaldotierte Titanoxid-Nanodrahtanordnungen auf transparenten leitfähigen Oxidsubstraten hergestellt. Mit dieser Methode sollten Titanoxid-Nanodrähte mit unterschiedlichen Übergangsmetallen dotiert werden können. So hergestellte Funktionseinheiten sind leistungsstärker, wie farbstoffsensibilisierte Solarzellen mit sehr hoher Photo-Ruhespannung belegen (siehe Bild).
    No preview · Article · Oct 2009 · Angewandte Chemie International Edition
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    ABSTRACT: We report on the self-assembled fabrication and photoelectrochemical properties of α-Fe2O3 (hematite) nanotube arrays, prepared by potentiostatic anodization of iron foil in an ethylene glycol electrolyte containing NH4F and deionized water. Vertically oriented nanotube arrays provide a highly ordered material architecture of high surface area that is nearly ideal for efficient transport and separation of photogenerated charges. We have achieved iron oxide nanotube arrays over a potential range of 30−60 V, using an electrolyte comprised of 0.2−0.5 wt % NH4F, and 2−4% DI water. The resulting nanotube arrays have a pore diameter ranging between 30 and 80 nm, with a minimum wall thickness of 10 nm. Nanotube formation is strongly dependent on the anodization bath temperature and fluoride concentration, with higher temperatures leading to increased rates of nanotube array growth, and with lower temperatures required in order to obtain identifiable nanotubes arrays for increased F− ion concentration. Crystallization of the as-synthesized, amorphous, iron oxide nanotube arrays to hematite is achieved through annealing in an oxygen-deficient ambient.
    No preview · Article · Sep 2009 · The Journal of Physical Chemistry C
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    ABSTRACT: In this article, we present recent advances that we have achieved toward improving the properties of anodically formed semiconducting TiO 2 nanotubes as well as nanowire arrays as electrodes for oxidative photoelectro-chemistry. The morphology, crystallinity, composition, and illumination geometry of nanotube or nanowire arrays are critical factors in their performance as photoelectrodes. We discuss the key aspects relating to each factor and the advances achieved in improving each. With respect to the more fully investigated nanotube arrays, the ability to control the morphological parameters such as pore size, tube length, and wall thickness of the nanotube architecture has enabled high performance in applications such as water photoelectrolysis, photocatalysis, dye-sensitized solar cells, and heterojunction TiO 2 -polymer hybrid solar cells. We begin by reviewing the photoelectrochemical performance of state-of-the-art nanotube arrays fabricated on planar substrates. We then present more recent results related to the growth of TiO 2 nanotube arrays on nonplanar substrates designed in such a way that reflected light normally lost to free space is instead directed to a different point on the device, in turn improving overall photoconversion efficiency. Insofar as the crystallinity of the nanotubes is concerned, the use of a high-temperature oxygen or air-ambient anneal to crystallize the nanotube arrays is disadvantageous, since it results in a thick barrier layer where recombination losses occur and also because it precludes compatibility with polymeric substrates. In this regard, we discovered a two-step fabrication process for synthesis of crystallized nanotube arrays at low-temperatures. The photoelectro-chemical applications of TiO 2 are limited by its large electronic band gap. We briefly review the cationic and anionic doping approaches popularly used to modify the TiO 2 band gap. We consider the use of ternary oxide systems containing titania as both a structural support and corrosion-inhibitor, in particular fabrication and performance of n-type Ti-Fe-O nanotubes and p-type copper-rich Cu-Ti-O nanotubes, with a note on our recent synthesis of iron oxide nanotube arrays by anodic oxidation of iron. Fabrication and photoelec-trochemical properties of CdS-TiO 2 and CdTe-TiO 2 nanotube array heterojunction photoelectrodes are discussed. The article concludes by examining low temperature synthesis, and resulting properties, of single crystal vertically oriented TiO 2 nanowire arrays on transparent conductive glass substrates; preliminary investigation of these nanowire array photoelectrodes for water photolysis reveals them to have low series resistance and provide excellent separation of photogenerated charges.
    Full-text · Article · Apr 2009 · The Journal of Physical Chemistry C
  • Karthik Shankar · Xinjian Feng · Craig A Grimes
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    ABSTRACT: Modern excitonic solar cells efficiently harvest photons in the 350-650 nm spectral range; however, device efficiencies are typically limited by poor quantum yields for red and near-infrared photons. Using Forster-type resonance energy transfer from zinc phthalocyanine donor molecules to ruthenium polypyridine complex acceptors, we demonstrate a four-fold increase in quantum yields for red photons in dye-sensitized nanowire array solar cells. The dissolved donor and surface anchored acceptor molecules are not tethered to each other, through either a direct chemical bond or a covalent linker layer. The spatial confinement of the electrolyte imposed by the wire-to-wire spacing of the close-packed nanowire array architecture ensures that the distances between a significant fraction of donors and acceptors are within a Förster radius. The critical distance for energy transfer from an isolated donor chromophore to a self-assembled monolayer of acceptors on a plane follows the inverse fourth power instead of the inverse sixth power relation. Consequently, we observe near quantitative energy transfer efficiencies in our devices. Our results represent a new design paradigm in excitonic solar cells and show it is possible to more closely match the spectral response of the device to the AM 1.5 solar spectrum through use of electronic energy transfer.
    No preview · Article · Apr 2009 · ACS Nano

Publication Stats

2k Citations
179.46 Total Impact Points


  • 2014-2015
    • Chinese Academy of Sciences
      Peping, Beijing, China
    • Illinois State University
      • Department of Chemistry
      Worcester, Massachusetts, United States
    • Northern Illinois University
      • Department of Chemistry and Biochemistry
      Декаб, Illinois, United States
  • 2008-2012
    • Pennsylvania State University
      • • Department of Chemistry
      • • Department of Electrical Engineering
      • • Materials Research Institute
      University Park, Maryland, United States
  • 2009
    • William Penn University
      Worcester, Massachusetts, United States