Exploring efficient and economical electrocatalysts for hydrogen evolution reaction is of great significance for water splitting on an industrial scale. Tungsten oxide, WO, has been long expected to be a promising non-precious-metal electrocatalyst for hydrogen production. However, the poor intrinsic activity of this material hampers its development. Herein, we design a highly efficient hydrogen evolution electrocatalyst via introducing oxygen vacancies into WO nanosheets. Our first-principles calculations demonstrate that the gap states introduced by O vacancies make WO act as a degenerate semiconductor with high conductivity and desirable hydrogen adsorption free energy. Experimentally, we prepared WO nanosheets rich in oxygen vacancies via a liquid exfoliation, which indeed exhibits the typical character of a degenerate semiconductor. When evaluated by hydrogen evolution, the nanosheets display superior performance with a small overpotential of 38 mV at 10 mA cm and a low Tafel slope of 38 mV dec. This work opens an effective route to develop conductive tungsten oxide as a potential alternative to the state-of-the-art platinum for hydrogen evolution.
In this article, water-soluble polymer polyvinyl alcohol solution was used to exfoliate the graphene-like two-dimensional materials (MoS 2 and WS 2 ). The concentrations of the two disulfide nanosheets were 0.092 and 0.087 mg/mL in the 10% aqueous solution of PVA. UV-Vis and Raman spectrum demonstrated that the two dispersions were the few layer nanosheets in the solution. Then, taking the exfoliated WS 2 as filler, a series of PVA/WS 2 composites showing the pale yellow transparent films were prepared by solution process method. Composite films showed good thermal performance. When 1 wt% were added in the PVA matrix, the T 90% improved 44 C in the air. Furthermore, the three kinds of characteristic temperature of T 10% , T 50% , and T 90% had obvious increase in the N 2 . The main reason may be the physical barrier of the 2D nanosheets and the strong interaction force of the S atom of exfoliated 2D nanosheets. The composites could slow the thermal decomposition.
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