Construction of novel S/CdS type II heterojunction for photocatalytic H2 production under visible light: The intrinsic positive role of elementary α-S

Abstract

Traditional view points that the photocorrosion product sulfur clusters have negative effect on the activity of CdS system. Differently, in this paper, little amount of crystalline elementary α-sulfur (α-S) nanoparticles were loaded on the surface of CdS nanorods and resulted in enhanced photocatalytic H2 production activity under visible light (λ>420nm). The photocatalytic H2 production over 10% S/CdS composite was 8.14mmol and further rose to 30.02mmol in the presence of K2PtCl6 after 3h irradiation. In the novel S/CdS system, largely improved separation efficiency of photoexcited charges were achieved through the heterojunction interface role between α-S nanoparticles and CdS nanorods. The matching type II energy band structure ensures that α-S could quickly trapped electrons from the host CdS nanorods for reducing H+ to produce H2. After 10 cycles experiment, S/CdS still kept excellent photocatalytic H2 production activity. This study clearly demonstrates the intrinsic promoting effect of α-S in CdS photocatalyst even in other metal sulfide systems for enhancing photocatalytic H2 production activity under visible light.