WSe2 and W(SexS1−x)2 nanoflakes grown on carbon nanofibers for the electrocatalytic hydrogen evolution reaction

Abstract

Transition metal dichalcogenides (TMDs) have recently attracted substantial attention due to their potential application in the catalysis of the hydrogen evolution reaction (HER). In this study, triangular WSe₂ and W(Se_xS_1−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(Se_xS_1−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 long-term stability, were achieved by optimizing the content of the initial W precursor and the appropriate substitution of selenium with sulfur, which resulted from the appropriate cover density and thickness of the WSe₂ nanoflakes and the defective structure of the W(Se_xS_1−x)₂ nanoflakes.