Insights into photocatalytic mechanism over a novel Cu ₂ WS ₄ /MoS ₂ S‐scheme heterojunction

Abstract

Abstract A novel efficient Cu 2 WS 4 /MoS 2 step‐scheme (S‐scheme) heterojunction photocatalyst was constructed for the first time and applied in the removal of environmental pollutants. Among the as‐prepared photocatalysts, the Cu 2 WS 4 /MoS 2 ‐8% heterojunction photocatalyst demonstrates the optimal photocatalytic performance, with the catalytic oxidation efficiency of tetracycline (TC) and the catalytic reduction efficiency of Cr 6+ reaching 93.3% and 82.1%, respectively. The excellent catalytic properties of Cu 2 WS 4 /MoS 2 heterojunction photocatalysts are attributed to the effective separation pathways of charges and the presence of S‐scheme heterojunctions, together with stronger redox capabilities. It is speculated that the photogenerated carrier migration path of the Cu 2 WS 4 /MoS 2 catalyst follows the typical S‐scheme photocatalytic mechanism, which is verified by the in‐depth experimental study and simulated calculations including the electron paramagnetic resonance (EPR) analysis, free radical quenching experiments, charge density distribution, and simulated built‐in electric field formation at the interface, which acts as driving force to promote the separation of photoinduced electrons and holes. Finally, the photocatalytic mechanism of S‐scheme photogenerated carrier migration for the Cu 2 WS 4 /MoS 2 catalyst is revealed based on the systematic experimental techniques and simulated calculations, accounting for its superior photocatalytic oxidation and reduction activities. This study provides inspiring implications to develop high‐efficient S‐scheme photocatalytic systems for versatile applications in solar‐energy conversion.