Internal electric field induced S-scheme heterojunction MoS2/CoAl LDH for enhanced photocatalytic hydrogen evolution.

The requisite interfacial contact of heterojunction photocatalysts has a significant contribution in separation of interfacial charge carriers for photocatalytic hydrogen (H2) evolution in a more efficient manner. Herein, an internal electric field (IEF)-induced S-scheme system comprised of two-dimensional (2D) CoAl layered double hydroxide (LDH) and 2D molybdenum disulfide (MoS2) was constructed via a simple hydrothermal process. In the presence of visible-light irradiation, the 2D/2D MoS2/CoAl LDH hybrid demonstrates eightfold greater photocatalytic H2 generation rate as compared with that of CoAl LDH. The mechanism was investigated in the light of the results of the X-ray photoelectron spectroscopy (XPS) and work-function calculated by density functional theory (DFT) simulation, and the improved activity was ascribed to that the rapid detachment of the electron-hole (e--h+) combinations and high redox ability, both are simultaneously realized in MoS2/CoAl LDH hybrid with a 2D/2D S-scheme charge transfer mechanism induced by the IEF across interface of the MoS2 and CoAl LDH. Furthermore, favorable 2D/2D structure and better H* adsorption behavior of MoS2/CoAl LDH also promoted the improvement of water reduction performance. This work is a valuable guideline in developing of IEF-induced S-scheme photocatalysts with 2D/2D architecture for improved photocatalytic performance.