In situ addition of Ni salt onto a skeletal Cu ₇S ₄ integrated CdS nanorod photocatalyst for efficient production of H ₂ under solar light irradiation

Abstract

Development of earth-abundant, low cost, skeletal-type copper sulfide superstructures and in situ addition of Ni salts plays a prominent role to enhance the activity of CdS semiconductor nanostructures for photocatalytic H ₂ production.

Abstract

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 (Cu ₇S ₄), 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 Cu ₇S ₄/CdS composite exhibited a H ₂ production 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 Cu ₇S ₄/CdS for H ₂ production (45 μmol h ⁻¹), which was 20 times higher than that of CdS and 7 times higher than that of Cu ₇S ₄/CdS. The enhancement of activity in Ni–Cu ₇S ₄/CdS (Cu ₇S ₄/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 Cu ₇S ₄ cages and the superior charge transportation of Ni salts in the reaction solution. The Cu ₇S ₄/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.