Chunde Wang

Synthesis of FeP2/C nanohybrids and their performance for hydrogen evolution reaction

Phosphorous-rich FeP2/C nanohybrids are synthesized via the pyrolysis of ferrocene (Fe(C5H5)2) and red phosphorus in an evacuated and sealed quartz tube at 500 °C. The nanohybrids contain orthorhombic FeP2 with conical carbon tubes. Based on the calculated electroactive surface area, the performance of the FeP2/C nanohybrids as a novel non-noble metal electrocatalyst for hydrogen evolution reaction (HER) in 0.50 M H2SO4 is investigated. These nanohybrids show good catalytic activity and stability in the acidic medium and might serve as a promising new class of non-noble metal catalysts for practical HER.

Ni12P5 nanoparticles decorated on carbon nanotubes with enhanced electrocatalytic and lithium storage properties

Transition-metal phosphides (TMPs) have been proved to be of great importance in electrochemical energy conversion and Li-ion storage. In this work, we have designed a useful one-pot hot-solution colloidal synthetic route for synthesizing a new kind of unique hybrid nanostructures (the Ni12P5/CNT nanohybrids) by direct in situ growth of Ni12P5 nanocrystals onto oxidized multiwall carbon nanotubes (CNTs). The CNTs can improve the conductivity of the hybrids and effectively prevent the aggregation of Ni12P5 nanoparticles in the cycle process. When they are evaluated as a novel non-noble-metal hydrogen evolution reaction (HER) catalyst operating in acidic electrolytes, the Ni12P5/CNT nanohybrids exhibit an onset overpotential as low as 52 mV and a Tafel slope of 56 mV dec(-1) and only require overpotentials of 65 and 129 mV to attain current densities of 2 and 10 mA cm(-2), respectively. Moreover, they also exhibit enhanced electrochemical performance for lithium-ion batteries serving as an anode material; the Ni12P5/CNT nanohybrids show a high capacity, excellent cycling stability and good rate performance. Their unusual properties arise from a synergetic effect between Ni12P5 and CNTs.

One-pot synthesis of carbon-coated Ni5P4 nanoparticles and CoP nanorods for high-rate and high-stability lithium-ion batteries

Carbon-coated transition-metal phosphide (TMPs@C) nanocomposites, including Ni5P4@C nanoparticles and CoP@C nanorods, have been fabricated via a simply developed synthetic route from the reaction of organometallic sources with triphenylphosphine (PPh3) in a sealed quartz tube. These nanocomposites as anode materials for lithium-ion batteries (LIBs) exhibit excellent rate capability and highly stable cycling performances. Typically, the Ni5P4@C nanoparticles present 612 mA h g−1 after 100 cycles at 0.2C, 462 mA h g−1 after 200 cycles at 1.0C and 424 mA h g−1 at 5.0C, and the CoP@C nanorods demonstrate 654 mA h g−1 after 100 cycles at 0.2C, 530 mA h g−1 after 200 cycles at 1.0C, and 384 mA h g−1 at 5.0C, respectively, which would be of great potential in energy storage and conversion.

3D architecture constructed via the confined growth of MoS2 nanosheets in nanoporous carbon derived from metal–organic frameworks for efficient hydrogen production

The design and synthesis of robust, high-performance and low-cost three-dimensional (3D) hierarchical structured materials for the electrochemical reduction of water to generate hydrogen is of great significance for practical water splitting applications. In this study, we develop an in situ space-confined method to synthesize an MoS2-based 3D hierarchical structure, in which the MoS2 nanosheets grow in the confined nanopores of metal-organic frameworks (MOFs)-derived 3D carbons as electrocatalysts for efficient hydrogen production. Benefiting from its unique structure, which has more exposed active sites and enhanced conductivity, the as-prepared MoS2/3D nanoporous carbon (3D-NPC) composite exhibits remarkable electrocatalytic activity for the hydrogen evolution reaction (HER) with a small onset overpotential of ∼0.16 V, large cathodic currents, small Tafel slope of 51 mV per decade and good durability. We anticipate that this in situ confined growth provides new insights into the construction of high performance catalysts for energy storage and conversion.

Alternative Synthesis of CuFeSe2 Nanocrystals with Magnetic and Photoelectric Properties

Monodisperse CuFeSe2 nanocrystals of high quality have been successfully synthesized for the first time using a hot-solution injection method from the reaction of metallic acetylacetonates with diphenyl diselenide (Ph2Se2) in oleylamine with addition of oleic acid at 255 °C for 90 min. The characterizations of X-ray diffraction, electron microscopy, and compositional analysis reveal that the resulting CuFeSe2 nanocrystals are of tetragonal phase with a stoichiometric composition. The CuFeSe2 nanocrystals exhibit well-defined quasi-cubic shape with an average size of ∼18 nm, and their shape can be tuned from quasi-cubes to quasi-spheres by adjusting the reaction parameters. Magnetic measurement reveals that the as-synthesized CuFeSe2 nanocrystals are ferromagnetic and paramagnetic at 4 and 300 K, respectively. Additionally, the current-voltage (I-V) behavior of the CuFeSe2 nanocrystals suggests that they are promising candidates for application in optoelectronics and solar energy conversion.

γ-ray radiation preparation and characterization of nanocrystalline manganese dioxide

Abstract Nanocrystalline manganese dioxide (MnO2) powders have been prepared by radiating potassium permanganate (KMnO4) aqueous solution with γ-ray at ambient pressure and temperature. The influence of the experimental conditions on the results has been studied in detail. TEM and XRD show that the smallest mean particle size of the product is about 6 nm and the particle size distribution is very narrow.

Fabrication of amorphous CoMoS4 as a bifunctional electrocatalyst for water splitting under strong alkaline conditions

With the socio economic development, people have paid more and more attention to energy source problems, especially to clean and renewable energy such as hydrogen. It is appealing but still challenging to find or design an appropriate catalyst which is inexpensive and efficient for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the same electrolyte. In this work, we develop a facile synthesis of amorphous defect-rich CoMoS4via a one-step hydrothermal method, and under alkaline conditions; the CoMoS4 electrode can generate a current density of 10 mA cm-2 at the overpotentials of 143 mV for HER and 342 mV for OER in 1.0 M KOH, respectively. A cell voltage of 1.72 V is required to achieve a current density of 10 mA cm-2 with long-term stability in an electrolyzer using the CoMoS4/CC electrode as both the anode and cathode.

Controlled Synthesis of Ultrathin Sb2Se3 Nanowires and Application for Flexible Photodetectors.

A new solvothermal approach is introduced to synthesize ultrathin Sb2Se3 nanowires with diameters ranging from 10 to 20 nm and with length up to 30 μm. The Sb2Se3 nanowire‐based photodetectors are firstly fabricated on polyethylene terephthalate and printing paper substrates, which exhibit excellent response to visible light with fast response time (0.18 and 0.22 s), high flexibility, and durability.

Design and construction of ultra-thin MoSe2 nanosheet-based heterojunction for high-speed and low-noise photodetection

Advances in the photocurrent conversion of two-dimensional (2D) transition metal dichalcogenides have enabled the realization and application of ultrasensitive and broad-spectral photodetectors. The requirements of previous devices constantly drive for complex technological implementation, resulting in limits in scale and complexity. Furthermore, the development of large-area and low-cost photodetectors would be beneficial for applications. Therefore, we demonstrate a novel design of a heterojunction photodetector based on solution-processed ultrathin MoSe2 nanosheets to satisfy the requirements of its application. The photodetector exhibits a high sensitivity to visible–near infrared light, with a linear dynamic range over 124 decibels (dB), a detectivity of ~1.2 × 1012 Jones, and noise current approaching 0.1 pA·Hz–1/2 at zero bias. Significantly, the device shows an ultra-high response speed up to 30 ns with a 3-dB predicted bandwidth over 32 MHz, which is far better than that of most of the 2D nanostructured and solution-processable photodetectors reported thus far and is comparable to that of commercial Si photodetectors. Combining our results with material-preparation methods, together with the methodology of device fabrication presented herein, can provide a pathway for the large-area integration of low-cost, high-speed photodetectors.

Ternary NiCoP nanoparticles assembled on graphene for high-performance lithium-ion batteries and supercapacitors

Transition metal phosphides have received considerable interest for electrochemical energy storage/conversion and catalysis. In this work, we designed a unique hybrid of NiCoP nanoparticles adhered on quasi-planar structured graphene by assembling 8.5 nm ternary NiCoP nanoparticles on graphene through a solution-phase self-assembly strategy. The NiCoP catalyst in the form of small-size particles wrapped in graphene provided more active sites, a buffer for volume alteration and enhanced conductivity for electrochemical reactions. Typically, the hybrid catalyst demonstrates a high specific capacity of around 532 mA h g−1, excellent cycling stability and superior rate performance when the hybrid material is evaluated as an anode material for lithium-ion batteries, and it shows excellent electrochemical properties with a specific capacitance of 646 F g−1 at 4 A g−1, maintaining 91% of this initial value after 2000 cycles functioning as a supercapacitor.