Noble metal electrocatalysts (e.g., Pt, Ru, etc.) suffer from sluggish kinetics of water dissociation for the electrochemical reduction of water to molecular hydrogen in alkaline and neutral pH environments. Herein, we found that an integration of Ru nanoparticles (NPs) on oxygen-deficient WO3-x manifested a 24.0-fold increase in hydrogen evolution reaction (HER) activity compared with commercial Ru/C electrocatalyst in neutral electrolyte. Oxygen-deficient WO3-x is shown to possess large capacity for storing protons, which could be transferred to the Ru NPs under cathodic potential. This significantly increases the hydrogen coverage on the surface of Ru NPs in HER and thus changes the rate-determining step of HER on Ru from water dissociation to hydrogen recombination.
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.
In this study, novel titanium dioxide (TiO 2) and zinc oxide (ZnO) hybrid photocatalysts in the form of nanofibres were fabricated by a facile method using electrospinning followed by a calcination process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the morphology and structure of the heterogeneous nanofibres. The photocatalytic performances were evaluated via the photodegradation of Rhodamine B (RhB) under irradiation with UV light. Due to the low recombination rate of photo-induced charge carriers, the high utilization efficiency of UV light and the large contact area with the target molecules, the ZnO/TiO 2 hybrid nanofibres exhibited high catalytic activity towards the Rhodamine B, and the amount of Zn(OAc) 2 in the precursor of these nanofibres played an important role in determining the photo decomposition performance.
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