Enhancing photocatalytic H2 evolution of Cd 0.5 Zn 0.5 S with the synergism of amorphous CoS cocatalysts and surface S2 adsorption

Designing surface phase is an efficient strategy to facilitate charge separation and photocatalytic H2-evolution performance. In this work, CoS cocatalysts were intimately anchored on Cd 0.5 Zn 0.5 S (denoted as CZS) photo- catalyst via in-situ precipitate transformation in S2 /SO32 solution with cobaltous phosphate (CoPi) as a precursor, meanwhile, S2 ions were adsorbed on the CZS to form a sulfur-rich surface (denoted as CZS-S). The photocatalytic H2-evolution rate of CoS/CZS-S is 2.02 mmol & sdot;g 1 & sdot; h 1 in 0.1 M Na2S/Na2SO3 sacrificial agent system. In addition, CoS/CZS-S exhibits excellent stability in both Na2S/Na2SO3 and lactic acid system. The theoretical calculations (DFT) and experimental results reveal that amorphous CoS can work as a highly effective cocatalyst for H2 evolution reaction and the intimate contact between CZS and CoS facilitates the photoelectrons transfer from CZS to CoS. The adsorbed S2 ions mainly work as effective hole acceptors. As a result of the synergism of CoS and adsorbed S2 ions, the boosted separation and immigration of photoelectrons and photoholes and high photocatalytic H2-evolution performance of CoS/CZS-S are realized. The present work highlights simultaneous reinforcing reduction and oxidation half-reaction dynamics via a facile and economic surface strategy to achieve efficient solar H2-evolution from H2O splitting.