High light harvesting efficiency CuInS2 quantum dots/TiO2/MoS2 photocatalysts for enhanced visible light photocatalytic H2 production

Abstract

Expanding the photoresponse range of TiO₂-based photocatalysts is of great interest for photocatalytic H₂ production. Herein, noble-metal-free CuInS₂ quantum dots were employed as a novel inorganic dye to expand the visible light absorption of TiO₂/MoS₂ for solar H₂ generation. The as-prepared CuInS₂/TiO₂/MoS₂ photocatalysts exhibit broad absorption from the ultraviolet to near-infrared region. Under visible light irradiation (λ > 420 nm), the CuInS₂/TiO₂/MoS₂ photocatalyst with 0.6 mmol g⁻¹ CuInS₂ and 0.5 wt% MoS₂ showed the highest H₂ evolution rate with a value of 1034 μmol h⁻¹ g⁻¹. Moreover, a considerable H₂ evolution rate of 141 μmol h⁻¹ g⁻¹ was obtained under the irradiation of the optimized CuInS₂/TiO₂/MoS₂ photocatalyst with >500 nm light. The reaction mechanism of the CuInS₂/TiO₂/MoS₂ photocatalyst for photocatalytic H₂ evolution was investigated in detail by photoluminescence decay study, and the results showed that the photoexcited electrons of CuInS₂ can be transferred efficiently through TiO₂ to MoS₂ and then react with the absorbed protons to generate H₂. The reported sensitization strategy tremendously improves the visible light absorption capacity and the photocatalytic performance of TiO₂-based photocatalysts.