N, O-Doped surface modulation of ZnIn₂S₄ with high hydrophilicity for enhanced photocatalytic hydrogen evolution

Heteroatom doping is a promising strategy for optimizing the photocatalytic activity of semiconductors. However, relying solely on single-element doping often poses challenges in modulating the capabilities of semiconductors. Herein, we adopt a strategy of simultaneously modifying ZnIn₂S₄ with the double non-metallic elements nitrogen (N) and oxygen (O) to form (N, O)-ZnIn₂S₄. Interestingly, (N, O)-ZnIn₂S₄ exhibits significantly higher hydrophilicity and specific surface area compared to pristine ZnIn₂S₄. The contact angle decreases from 24° to 21°, while the specific surface area increases from 56 m²/g to 75 m²/g. The hydrogen production rate of (N, O)-ZnIn₂S₄ reaches 400 μmol/h/g, which is 2.52 times higher than that of pristine ZnIn₂S₄. Photoelectrochemical characterization reveals that (N, O)-ZnIn₂S₄ has a lower overpotential, higher photocurrent, lower resistance, reduced fluorescence intensity, and shorter fluorescence lifetime. Additionally, co-catalyst loading boosts the hydrogen production activity of ZnCo₂S₄/(N, O)-ZnIn₂S₄ from 548 μmol/h/g to 810 μmol/h/g, compared to ZnCo₂S₄/ZnIn₂S₄. This study presents a dual non-metallic modification strategy to enhance semiconductor properties, achieving superior performance in photocatalytic hydrogen production.