Construction of ZnCoP/CdLa2S4 Schottky Heterojunctions for Enhancing Photocatalytic Hydrogen Evolution

Abstract

Photocatalytic hydrogen evolution by heterojunction photocatalysts is considered an effective way to address environmental and energy crises. In this work, a novel ZnCoP/CdLa₂S₄ Schottky heterojunction was prepared via a physical mixing method assisted by water bath heating and used to enhance the efficiency of photocatalytic hydrogen production. Owing to the higher work function and metallic conductivity of ZnCoP, the photoinduced electrons can transfer from CdLa₂S₄ to ZnCoP through the ZnCoP/CdLa₂S₄ interface, which suppresses the recombination of photoinduced electrons and holes. Moreover, the Schottky heterojunction formed at the interface between ZnCoP and CdLa₂S₄ inhibits electron backflow from ZnCoP to CdLa₂S₄, which further promotes the separation of electron-hole pairs. Meanwhile, the ZnCoP/CdLa₂S₄ heterojunction exhibited enhanced visible light absorption compared to CdLa₂S₄. In addition, ZnCoP acts as an electron acceptor and hydrogen evolution active site. The synergistic effect of the tight ZnCoP/CdLa₂S₄ interface, the higher work function and metallic conductivity of ZnCoP, and the formation of Schottky junctions significantly enhance the photocatalytic hydrogen production evolution performance of CdLa₂S₄. When the amount of ZnCoP was 30 wt% (wt%, mass fraction), the 30ZCP/CLS composite showed the highest photocatalytic performance, and the hydrogen production rate reached 10.26 mmol·g⁻¹·h⁻¹ under visible light irradiation and with Na₂S and Na₂SO₃ as sacrificial agents, which was 7.7 times that of CdLa₂S₄. Combined with the activity data and characterization results, a potential mechanism for photocatalytic hydrogen production over ZnCoP/CdLa₂S₄ Schottky heterojunctions was proposed.

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