Highly dispersed MoSx nanodot-modified TiO2 photocatalysts: vitamin C-mediated synthesis and improved H2 evolution activity

Abstract

Unsaturated S atoms on exposed edges of MoS₂ are demonstrated to be critical H₂-generation active sites, and the strategy to fabricate a MoS_x cocatalyst with a small size is promising in exposing more unsaturated S atoms to enhance its H₂-evolution performance. In this article, highly dispersed MoS_x nanodots with an ultrasmall size of ca. 1 nm are evenly loaded on the TiO₂ surface via a thin-layered carbon supporter by applying a vitamin C-mediated method. Herein, vitamin C not only functions as an effective modifier to suppress the aggregation of MoS_x nanodots for more exposed unsaturated S atoms to promote the interfacial H⁺-reduction reaction, but also works as a suitable precursor for the formation of a thin-layered carbon supporter for the MoS_x nanodots and the host TiO₂ to modify their interfacial coupling. The photocatalytic results show that the fabricated TiO₂@C/MoS_x (0.7 wt%) photocatalyst attains the highest H₂-evolution rate of 971.4 μmol h⁻¹ g⁻¹, which is about two times higher than that of the TiO₂/MoS_x owing to the perfect synergistic effect of the thin-layered carbon for efficient photoelectron transfer and the ultrasmall MoS_x nanodots for accelerated interfacial H₂-evolution reaction. The present strategy, using a mediator for the simultaneous realization of the nanosized cocatalyst and improved cocatalyst-host interaction, could provide alternative idea for the further enhancement of photocatalytic H₂-generation activity.