Engineering an AgZnInS@ZnS/g-C₃N₄ hybrid heterostructure for enhanced green hydrogen production

Developing the efficient catalysts for the hydrogen evolution reaction (HER) is essential for renewable hydrogen production but still a major challenge. Herein, we engineered a hybrid heterostructure AZIS@ZnS/g-C₃N₄ (CS QD/gCN) as an effective HER catalyst. CS QDs/g-C₃N₄ integration enabled superior charge transfer with lower resistance and higher photocurrent than AZIS QDs (C QDs), CS QDs, and C QD/gCN systems. The CS QD/g-C₃N₄ hybrid under visible light achieved extraordinary HER with 54 mV overpotential at 10 mA cm⁻² and 57 mV dec⁻¹ Tafel slope, closely matching Pt/C under dark conditions (45 mV, 53 mV dec⁻¹). The experimental performance is supported by Computational Density Functional Theory (DFT) calculations, which show that the CS QD/g-C₃N₄ hybrid has type-II band alignment that enhances the charge separation and extends the visible-light absorption. Furthermore, the computed Gibbs free energy for hydrogen adsorption (ΔGH* = −0.36 eV) gets closer to the thermodynamic optimum; it confirms that the HER has lower kinetic barriers. The engineering of composites based on quantum dots and 2D g-C₃N₄ has garnered increasing attention in catalysis for the hydrogen evolution reaction (HER). Here, the authors report an AZIS@ZnS/g-C₃N₄ (CS QD/gCN) hybrid heterostructure that achieves overpotential and Tafel slope values close to those of Pt/C electrodes.