Hierarchical TiO2–CuInS2core–shell nanoarrays for photoelectrochemical water splitting

Hierarchical TiO2–CuInS2 core–shell nanoarrays were fabricated directly on conducting glass substrates (FTO) via facile and low-cost hydrothermal and polyol reduction methods for photoelectrochemical (PEC) water splitting using TiO2 branched nanorod arrays (BNRs) as the reactive framework. An enhanced optical property of the core–shell structure was discovered. Firstly, TiO2 BNRs–CuS core–shell structure was synthesized through successive ionic layer adsorption and reaction (SILAR). Subsequently, TiO2 BNRs–CuInS2 core–shell structure was derived from TiO2 BNRs–CuS core–shell structure. On the basis of optimal thickness of the CuInS2 shell, such a TiO2 BNRs–CuInS2 core–shell structure exhibits higher photocatalytic activity, the photocurrent density and efficiency for hydrogen generation are up to 19.07 mA cm−2 and 11.48%, respectively, which are probably because of the improved absorption efficiency and the appropriate gradient energy gap structure. The TiO2 BNRs–CuInS2 core–shell structure can be promising building blocks in photoelectrochemical water splitting systems.