Hexagonal CdS single crystals coupled with layered CoAl LDH—a step-scheme heterojunction for efficient photocatalytic hydrogen evolution

CdS and layered double hydroxides (LDHs) have drawn wide attention for photocatalytic water decomposition due to their abundant structure and excellent properties. The construction of a heterogeneous structure is a widely used method for a single material to overcome their narrow spectral light response and inefficient charge separation. In this work, a CdS/CoAl LDH step-scheme (S-scheme) heterojunction photocatalyst was successfully constructed by coupling CdS and CoAl LDH based on the complementary properties of the two materials. Compared with single CdS and CoAl LDH, the prepared CdS/CoAl LDH composite photocatalyst shows excellent photocatalytic hydrogen production efficiency by efficient use of electrons and holes under visible light irradiation. A significant number of electrons in the S-scheme heterojunction photocatalyst can be efficiently used to participate in water splitting while the holes were consumed by the sacrificial reagent. Therefore, the building of the S-scheme heterojunction eventually improved the efficiency of photocatalyst hydrogen production by efficiently separating electrons and holes. At the same time, our work will provide a new approach for the practical application of such semiconductors.