Wuhan University of Technology

About: Wuhan University of Technology is a education organization based out in Wuhan, China. It is known for research contribution in the topics: Microstructure & Photocatalysis. The organization has 40384 authors who have published 36724 publications receiving 575695 citations. The organization is also known as: WUT.

New understanding on the different photocatalytic activity of wurtzite and zinc-blende CdS

Abstract: In general, wurtzite CdS exhibits a higher photocatalytic activity than zinc-blende CdS. However, the underlying physicochemical reasons responsible for the differences of photocatalytic activity between the wurtzite and zinc-blende CdS are still unclear. In this work, the structural characteristics, band structures, density of states, bond populations, optical properties and charge carrier effective mass of wurtzite and zinc-blende CdS were investigated based on first-principle theoretical calculations. The calculated results indicate that the distortion of CdS4 tetrahedron units results in the formation of internal electric field in wurtzite CdS, which is beneficial for the efficient separation and diffusion of photogenerated charge carriers. Contrarily, the internal electric field is absent in zinc-blende CdS. Moreover, the effective masses of photogenerated charge carriers of wurtzite CdS are smaller than those of zinc-blende CdS, implying faster migration of photogenerated charge carriers to perform photocatalytic reactions on wurtzite CdS surfaces. All the above factors result in the lower recombination rate of photogenerated charge carriers within wurtzite CdS. Therefore, it is not surprising that wurtzite CdS usually shows a higher photocatalytic activity than zinc-blende CdS. This investigation will provide some new understanding on the difference of photocatalytic activity between wurtzite and zinc-blende CdS.

Vanadium Sulfide on Reduced Graphene Oxide Layer as a Promising Anode for Sodium Ion Battery.

Abstract: As an alternative system of rechargeable lithium ion batteries, sodium ion batteries revitalize researchers’ interest due to the low cost, abundant sodium resources, and similar storage mechanism to lithium ion batteries. VS4 has emerged as a promising anode material for SIBs due to low cost and its unique linear chains structure that can offer potential sites for sodium storage. Herein, we present the growth of VS4 on reduced graphene oxide (rGO) as SIBs anode for the first time. The VS4/rGO anode exhibits promising performance in SIBs. It delivers a reversible capacity of 362 mAh g–1 at 100 mA g–1 and a good rate performance. We also investigate the sodium storage behavior of the VS4/rGO. Different than most transition metal sulfides, the VS4/rGO composite experiences a three-step separation mechanism during the sodiation process (VS4 to metallic V and Na2S, then the electrochemical mechanism is akin to Na–S). The VS4/rGO composite proves to be a promising material for rechargeable SIBs.

Understanding of the Extremely Low Thermal Conductivity in High-Performance Polycrystalline SnSe through Potassium Doping

Abstract: P-type polycrystalline SnSe and K0.01Sn0.99Se are prepared by combining mechanical alloying (MA) and spark plasma sintering (SPS). The highest ZT of ≈0.65 is obtained at 773 K for undoped SnSe by optimizing the MA time. To enhance the electrical transport properties of SnSe, K is selected as an effective dopant. It is found that the maximal power factor can be enhanced significantly from ≈280 μW m−1 K−2 for undoped SnSe to ≈350 μW m−1 K−2 for K-doped SnSe. It is also observed that the thermal conductivity of polycrystalline SnSe can be enhanced if the SnSe powders are slightly oxidized. Surprisingly, after K doping, the absence of Sn oxides at grain boundaries and the presence of coherent nanoprecipitates in the SnSe matrix contribute to an impressively low lattice thermal conductivity of ≈0.20 W m−1 K−1 at 773 K along the sample section perpendicular to pressing direction of SPS. This extremely low lattice thermal conductivity coupled with the enhanced power factor results in a record high ZT of ≈1.1 at 773 K along this direction in polycrystalline SnSe.

Power generation and thermoelectric cooling enabled by momentum and energy multiband alignments.

Abstract: Thermoelectric materials transfer heat and electrical energy, being useful for power generation or cooling applications. Many of these materials have narrow bandgaps, especially for cooling applications where this property has been seen as particularly important for enhancing the thermoelectric properties. We developed SnSe crystals with a wide bandgap Eg ~ 33 kBT with attractive thermoelectric properties through Pb alloying. The momentum and energy multiband alignment promoted by Pb alloying resulted in an ultra-high power factor ~75 μWcm–1K–2 at 300 K, and a ZTave ~ 1.90. We show that a 31-pair thermoelectric device can produce a power generation efficiency ~4.4% and a cooling ΔTmax ~ 45.7 K. These results demonstrate that wide bandgap compounds can be used for thermoelectric cooling applications.