Construction of 1D/2D core-shell structured K6Nb10.8O30@Zn2In2S5 as S-scheme photocatalysts for cocatalyst-free hydrogen production

Constructing heterostructures is an effective strategy to achieve efficient photocatalysis. The determination of the heterojunction types depends on the photo-induced charge carrier transfer path. Therefore, understanding the charge carrier transfer mechanism of heterojunctions plays an irreplaceable role in guiding the construction of rational heterojunctions. However, it is challenging due to the microscopic nature of charge carrier transfer. Herein, an S-scheme K6Nb10.8O30@Zn2In2S5 (KNbO@ZIS) heterojunction with 1D/2D core-shell structure is designed for improving photocatalytic hydrogen production. KNbO@ZIS exhibits a greatly improved cocatalyst-free hydrogen generation activity (12.35 mmol h−1 g−1) compared to K6Nb10.8O30 (KNbO) and Zn2In2S5 (ZIS) under UV–visible illumination. The improvement of photocatalytic performance is mainly attributed to the suppressed recombination of photogenerated charge carriers by the S-scheme heterojunction. The 1D/2D core-shell structure further accelerates the charge carrier transfer in the photocatalysts. S-scheme heterojunction mechanism is also demonstrated by ex/in situ irradiated X-ray photoelectron spectroscopy and Kelvin probe force microscopy measurements as well as work function calculations. This work provides a powerful strategy for designing novel heterojunction composites.