Improved Interfacial Charge Transfer and Hydrogen Evolution (HER) Kinetics in TiO 2 /g-C 3 N 4 Heterostructure Electrocatalysts for Neutral Conditions

A TiO 2 /g-C 3 N 4 heterostructure electrocatalyst was constructed and evaluated for the hydrogen evolution reaction (HER) in neutral 0.1 M Na 2 SO 4 electrolyte. The as-prepared heterostructure exhibits significantly improved catalytic performance compared with pristine TiO 2 and g-C 3 N 4 . It delivers an onset potential of −0.476 V vs. RHE, an overpotential of 721 mV at 0.5 mA cm −2 , and a markedly reduced charge-transfer resistance (R ct = 80 kΩ · cm 2 ). Electrochemical analyses indicate that the enhanced HER activity originates from accelerated interfacial charge transfer and improved reaction kinetics, as evidenced by the lower Rct and reduced Tafel slope. These results suggest that heterointerface formation effectively modulates electron-transfer pathways and facilitates proton reduction under neutral conditions. The correlation between heterostructure engineering, interfacial charge transfer, and catalytic performance highlights the critical role of interface design in electrocatalysis. Overall, this work provides insight into heterointerface-driven charge-transfer enhancement and demonstrates a rational strategy for improving hydrogen evolution performance using TiO 2 /g-C 3 N 4 hybrid catalysts.