Highly efficient binuclear cobalt-bis(4-methylthiosemicarbazone) complex co-catalyst to support Cd0.5Zn0.5S NPs for enhanced photocatalytic hydrogen evolution

Abstract

Photocatalytic water splitting to produce H2 is a promising method to directly convert solar energy into chemical energy, which is a superb solution to the human energy shortage. This work constructed an efficient photocatalyst using Cd0.5Zn0.5S NPs (CZS) as the photosensitizer, water-soluble binuclear cobalt bis(4-methothiocarbazide) complex as the molecular co-catalyst. The complex could effectively transport photogenerated electrons on CZS, thus inhibiting charge recombination and significantly improving the activity and stability of the present photocatalytic system. Under optimal conditions, the experimental results showed that the highest turnover number (TON) of H2 production was 5699 after the reaction of the photocatalytic system with visible light (λ > 420 nm) for 24 h. The average H2 evolution rate of 1221 μmol∙h−1 was 6.4 times higher than that of pure CZS. The highest apparent quantum yield (AQY) at 420 nm was ∼26%.