Unveiling Z-Scheme Charge Transfer in ZnS/g-C ₃ N ₄ Nanosheets for Photo-, Electro-, and Photoelectrocatalytic Hydrogen Production

Hydrogen production via water splitting has attained profound relevance for green energy. Herein, we report highly efficient Z-scheme ZnS/g-C 3 N 4 (ZCN) heterostructured nanocatalysts through a hydrothermal method for H 2 production via photocatalysis and photo-/electrocatalysis. The as-fabricated nanocatalysts were designed as a cost-effective and result-driven alternative for exorbitant noble metal catalysts. The ubiquity of ZnS over g-CN nanosheets precisely leveraged the interfacial junctions with explicit active sites in the ZCN heterostructure as confirmed from their structural, optical, and morphological studies. The 10 ZCN heterostructure revealed the maximal H 2 generation of 4.46 mmol g –1 h –1, notably surpassing 20 ZCN (4.16 mmol g –1 h –1 ). The refined 10 ZCN heterostructure executed a momentous 2-fold increment yielding impressive AQY of 35.13% than pristine g-CN (17.52%) and ZnS (16.98%). Moreover, the electrocatalytic studies confirmed the outstanding H 2 evolution performance of 10 ZCN, exhibiting overpotential of 1.00 V and Tafel slope of 105.90 mV/dec. Further, the enhancement in the efficiency results from photoelectrochemical analysis, Tafel slope is 2.1 times lower than that of pristine g-CN (199.40 mV/dec) and ZnS (202.02 mV/dec). Impedance spectroscopy defined low charge-transfer resistance, while PL analysis confirmed the photogenerated charge transfer across the junction of 10 ZCN than g-CN and ZnS. XPS revealed the surface interactions and charge-transfer behavior, strongly supporting the Z-scheme mechanism. These findings interpret compelling routes for shaping and blazing the trail for future catalytic applications.