In situaddition of Ni salt onto a skeletal Cu₇S₄integrated CdS nanorod photocatalyst for efficient production of H₂under solar light irradiation

Development of earth-abundant, low cost, skeletal-type copper sulfide superstructures plays a prominent role in various potential applications, owing to the properties of superstructures such as excellent permeability of charge and mass. In this study, we synthesized hollow superstructures of crystallinity-controlled polyhedral skeletal-type copper sulfide (Cu₇S₄), which were integrated with cadmium sulfide (CdS) nanorods. The photocatalytic hydrogen production by water splitting was investigated under solar light irradiation with lactic acid as a hole scavenger. The Cu₇S₄/CdS composite exhibited a H₂production rate of 6.25 μmol h⁻¹, which was 3 times higher than that of CdS. Moreover, the addition of a small amount of nickel salts to the reaction solution significantly improved the activity of Cu₇S₄/CdS for H₂production (45 μmol h⁻¹), which was 20 times higher than that of CdS and 7 times higher than that of Cu₇S₄/CdS. The enhancement of activity in Ni-Cu₇S₄/CdS (Cu₇S₄/CdS with Ni salts in the reaction solution) was attributed to the effective separation of charge carriers due to the unique properties of the skeletal-type Cu₇S₄cages and the superior charge transportation of Ni salts in the reaction solution. The Cu₇S₄/CdS system containing Ni salts in the reaction solution is reported for photocatalytic hydrogen production for the first time, to the best of our knowledge, which promises new and inspiring research for the development of photocatalytic water splitting applications.