A novel dinuclear cobalt-bis(thiosemicarbazone) complex as a cocatalyst to enhance visible-light-driven H2 evolution on CdS nanorods and a mechanism discussion

Abstract

Photocatalytic water splitting to produce hydrogen has gradually become a research hotspot in recent years, and molecular cocatalysts especially cobalt-based complexes as proton reduction cocatalysts have attracted wide attention due to their high activity and selectivity. In this study, CdS nanorods were employed as photosensitizers, and a novel dinuclear cobalt-bis(thiosemicarbazone) complex with definite structure was used as a cocatalyst to improve visible-light-driven hydrogen evolution. Under the optimum conditions, this noble metal-free system exhibited an average hydrogen evolution rate of 1045 μmol·h−1 in 8 h irradiation. This system could work for 24 h with a TON of 16,400, and the average apparent quantum yield of this system is ∼21% at 420 nm. On the basis of photoelectrochemical studies and electrochemical analysis, we proposed a possible mechanism for hydrogen production in this three-component system.