Insights into the Operation of Noble-Metal-Free Cocatalyst 1T-WS2-Decorated Zn0.5Cd0.5S for Enhanced Photocatalytic Hydrogen Evolution

Due to inefficient charge separation and low surface catalytic conversion efficiencies, cocatalysts are required for achieving photocatalytic hydrogen evolution. Being a noble-metal-free cocatalyst, metallic 1T-WS2 with excellent conductivity can function for this reaction. Herein, 1T-WS2/Zn0.5Cd0.5S is constructed via a simple and feasible grinding approach. The composite containing 7.5 % 1T-WS2 in 1T-WS2/Zn0.5Cd0.5S achieves a hydrogen evolution rate of 61.65 mmol g(-1) h(-1) and an external quantum efficiency of 8.04 % at 420 nm, which is 37 times that of bare Zn0.5Cd0.5S (1.67 mmol g(-1) h(-1)). The electrical conductivity of metallic 1T-WS2 reduces the transfer impedance at the interface and thus accelerates the non-radiative energy transfer and electron transport rate. The different Fermi levels of 1T-WS2 and Zn0.5Cd0.5S form a Schottky junction, which promotes the transfer of photogenerated electrons from Zn0.5Cd0.5S to 1T-WS2. More importantly, the close interface contact between 1T-WS2 and Zn0.5Cd0.5S results in strong electron interactions, which is conducive to the spatial separation of photogenerated electrons and holes. This work will further expand the application of 1T-WS2 in the photocatalytic hydrogen evolution process.

Automated summary

By using 1T-WS2 as a cocatalyst, a 1T-WS2/Zn0.5Cd0.5S composite with high photocatalytic hydrogen evolution efficiency was successfully constructed in this study. The synergistic effect between 1T-WS2 and Zn0.5Cd0.5S promotes the electron transfer and separation, resulting in enhanced hydrogen evolution rate and external quantum efficiency.