Concentrating photoelectrons on sulfur sites of Zn_xCd_1–xS to active H–OH bond of absorbed water boosts photocatalytic hydrogen generation

Highly hydrophobic polypyrrole (PPy), as a promising conjugated polymer with good electron conductivity and excellent environmental stability, has received active attention in various fields. As is well known, the adsorption and dissociation of water molecules are the rate–limiting step of photocatalytic hydrogen evolution (PHE) reaction in the alkaline media. Herein, highly–hydrophilic polypyrrole–poly(sodium–p–styrenesulfonate) (PPy–PSS) were sectionally wrapped on the surface of Zn_xCd_1–xS (ZCS) nanorods via redox initiate polymerization to improve the hydrophily of ZCS, which favors water absorption. The density functional theory (DFT) calculation shows the sulfur electronic structure of ZCS is modulated in PPy–PSS–ZCS (PP–ZCS) composite. Specifically, the constituent PPy and PSS polymers through strong electronic interactions with ZCS could improve the water dissociation and the adsorption/desorption of hydrogen intermediates on ZCS component. After activating H–OH bond, the optimized PP–ZCS composite reveals an improved PHE efficiency of 46.1 mmol h⁻¹ g⁻¹ without an obvious decrease for continuous 24 h in visible light, which is 8.67 and 1.68 times higher than those of ZCS and PPy–ZCS. This strategy paves a new way for activating Zn_xCd_1–xS–based composite by highly hydrophilic and conductive conjugated polymer.