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-C3N4 (ZCN) heterostructured nanocatalysts through a hydrothermal method for H2 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 H2 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 H2 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.