The search for non-noble metal catalysts with high activity for the hydrogen evolution reaction (HER) is crucial for efficient hydrogen production at low cost and on a large scale. Herein, we report a novel WO3-x catalyst synthesized on carbon nanofiber mats (CFMs) by electrospinning and followed by a carbonization process in a tubal furnace. The morphology and composition of the catalysts were tailored via a simple method, and the hybrid catalyst mats were used directly as cathodes to investigate their HER performance. Notably, the as-prepared catalysts exhibit substantially enhanced activity for the HER, demonstrating a small overpotential, a high exchange current density, and a large cathodic current density. The remarkable electrocatalytic performances result from the poor crystallinity of WO3-x, the high electrical conductivity of WO3-x, and the use of electrospun CNFs. The present work outlines a straightforward approach for the synthesis of transition metal oxide (TMO)-based carbon nanofiber mats with promising applications for the HER.
Transition metal dichalcogenides (TMD) have recently attracted substantial attention due to their potential application to the catalysis of the hydrogen evolution reaction (HER). In this study, triangular WSe2 and W(SexS1-x)2 nanoflakes uniformly dispersed on the surface of electrospun carbon nanofiber mats were synthesized in a chemical vapor deposition (CVD) system. The morphology and structure of these products were systematically characterized, revealing that WSe2 nanoflakes are configured in the 2H phase with high crystallinity, and the W(SexS1-x)2 nanoflakes are configured in the alloy form without any obvious phase separation. The hybrid catalyst mats were directly used as hydrogen evolution cathodes to investigate their HER activity. Excellent HER performances, including low overpotential, high current density and longterm stability, were achieved by optimizing the content of the initial W precursor and the appropriate substitution of selenium with sulfur, which was resulted from the appropriate cover density and thickness of the WSe2 nanoflakes and the defective structure of the W(SexS1-x)2 nanoflakes.
SiC semiconductor is the focus of recent international research. It is also an important raw material for China to achieve carbon emission peak and carbon neutrality. After nearly 20 years of research and development, we focus on the three types SiC crystals, n-type, p-type and semi-insulating, indicating the development of Shandong University for crystal growth. And defects control, electrical property, atomic polishing, and corresponding device authentication all obtain great progress. Total dislocation density of 6-inch n-type substrates decreases to 2307 cm−2, where BPD (Basal Plane Dislocation) lowers to 333 cm−2 and TSD (Threading Screw Dislocation) 19 cm−2. The full width at half maximum (FWHM) (0004) rocking curves is only 14.4 arcsec. The resistivity reaches more than 1E + 12 Ω·cm for semi-insulating SiC and lower than 20 mΩ·cm for n-type SiC. The impurity concentrations in 6-inch high-purity semi-insulating (HPSI) SiC crystals reach extreme low levels. The devices made of various substrate materials have good performance.
Photocatalytic conversion of CO2 into value-added chemicals is considered to be a promising strategy to capture greenhouse gas as well as produce energy. The exploration of efficient and stable photocatalysts...
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