Snowflake-like Cu₂S Coated with NiAl-LDH Forms a p–n Heterojunction for Efficient Photocatalytic Hydrogen Evolution

A NiAl-LDH(LDH-2) catalyst was prepared using hexamethylenetetramine as the template. The photocatalytic mechanism of the p–n heterojunction was established by coupling it with snowflake Cu2S to form a binary NiAl-LDH@Cu2S(LDH-2@Cu2S) composite layer reaction substrate. The composite catalyst (LDH-2@Cu2S) maintained the original snowflake structure of Cu2S; this unique branching structure made the light wave refract multiple times, enhancing the absorption opportunity of visible light; snowflake Cu2S was evenly coated with a layer of NiAl-LDH fragments, forming a dense contact interface and facilitating the transmission and separation of photocarriers. The comparison experiment and BET test showed that the enhanced photocatalytic activity of the LDH-2@Cu2S composite catalyst was closely related to its larger specific surface area. In addition, the construction of the p–n heterojunction also promoted the improvement of hydrogen production efficiency. The results of hydrogen production experiments showed that the hydrogen production activity of the composite catalyst LDH-2@Cu2S was 245 μmol in 5 h, which was 50 times that of unmodified NiAl-LDH(LDH-1). This work adopts a simple method to improve the performance of NiAl-LDH, so that it can play a greater application role in the field of photocatalytic hydrogen production.