Integration of g-C₃N₄ with interdigitated biphase ZnS and their photoelectrochemical performance analysis

This work reports the facile synthesis of a g-C₃N₄ hybrid integrated with interdigitated biphase (wurtzite–sphalerite) zinc sulfide (ib-ZnS). The ib-ZnS in sphere, wire, and plate morphologies was synthesized via a cation exchange approach. The resulting ib-ZnS exhibits stacking faults that enhance visible-light absorption. Among the hybrids, the g-C₃N₄–ib-ZnS plate demonstrated a remarkable photocurrent density of 2.5 mA cm⁻² at 1.23 V vs. RHE, a prolonged carrier lifetime (5.4 s), and an improved electrochemical surface area (0.048 μF), outperforming both pristine g-C₃N₄ and other hybrid structures. Crystal defects in ib-ZnS were confirmed by photoluminescence (PL) spectroscopy, which also revealed multiphoton absorption behavior. The reduced PL intensity in the g-C₃N₄–ib-ZnS plate indicated efficient charge carrier separation. This enhanced performance is attributed to its unique 2D–2D morphology and type-II band alignment, which facilitate effective charge separation, broaden light absorption, and suppress carrier recombination. Overall, this study presents a novel strategy for engineering ib-ZnS morphologies with improved photoelectrochemical performance through integration with g-C₃N₄.