Rationally Designed Mn<sub>0.2</sub>Cd<sub>0.8</sub>S@CoAl LDH S-scheme Heterojunction for Efficient Photocatalytic Hydrogen Production

Abstract: Constructing an efficient and stable heterojunction photocatalyst system is a promising approach to achieve solar-driven water splitting to produce hydrogen. In this work, a novel Mn0.2Cd0.8S@CoAl LDH (MCCA) S-scheme heterojunction was successfully prepared through the efficient coupling of Mn0.2Cd0.8S nanorods and CoAl LDH nanosheets, employing a physical mixing method. The photoluminescence and photocurrent-time response results demonstrated that the internal electric field of the constructed MCCA S-scheme heterojunction could successfully accelerate charge separation and electron transfer between the Mn0.2Cd0.8S interface and the CoAl LDH. Critically, the introduction of the CoAl LDH effectively inhibited the recombination of photogenerated electrons and holes, thereby improving the photocatalytic hydrogen production activity of Mn0.2Cd0.8S. A maximum H2 production of 1177.9 µmol in 5 h was obtained with MCCA-3. This represents a significant improvement compared to what can be achieved with the pure Mn0.2Cd0.8S nanorods and CoAl LDH nanosheets individually. This work provides a simple and effective approach for the rational design of S-scheme heterojunction photocatalysts for photocatalytic hydrogen production.