Low-dimensional II–VI semiconductors for photocatalytic hydrogen generation

Controlled preparation of hollow Zn0.3Cd0.7S nanospheres modified by NiS1.97 nanosheets for superior photocatalytic hydrogen production

Developing durable and efficient photocatalysts for H₂ evolution is highly desirable to expedite current research on solar-chemical energy conversion. In this work, a novel photocatalytic H₂ evolution system based on Zn_0.3Cd_0.7S/NiS_1.97 nanocomposite was rationally designed for the first time. In this advanced composite structure, NiS_1.97 nanosheets as a co-catalyst were intimately coupled to the inner surface of the hollow spherical Zn_0.3Cd_0.7S. The construction of the hollow spherical shell shortened the distance of charge migration to the surface site and increased the multiple absorption of incident light. The introduction of NiS_1.97 nanosheets increased the light absorption capacity of the composite system and also greatly improved the separation and migration behavior of photo-generated carriers due to its narrower band gap and relatively low conduction band position, which had been confirmed by DRS, EIS and PL. As a result, the hollow Zn_0.3Cd_0.7S/NiS_1.97 composite material exhibited excellent photocatalytic activity. At the loading amount of NiS_1.97 up to 15 at.%, the hollow Zn_0.3Cd_0.7S/NiS_1.97 composite exhibited the best photocatalytic activity with a corresponding H₂ production rate of 22.637 mmol g^-1h^-1, which was 1.42 times and 1.85 times that of hollow Zn_0.3Cd_0.7S and solid Zn_0.3Cd_0.7S, respectively. Moreover, this novel catalyst also displayed a long-term stability without apparent debasement in H₂ evolution activity. It is expected that this work could provide new inspiration to the design and development of other highly active photocatalytic systems for water splitting.