Dual-Functional 2D-3D Zn₂In₂S₅ for photocatalytic degradation of azo dye and hydrogen production

In this study, we synthesized a two-dimensional-three-dimensional (2D-3D) flower-like Zn₂In₂S₅ (ZIS225) photocatalyst via the hydrothermal method. The photocatalytic performance of ZIS225 was systematically evaluated for the degradation of methyl orange (MO) and hydrogen production under visible light irradiation. ZIS225 achieved a 100 % degradation rate of MO within 60 min, with a reaction rate constant of 6.11 h⁻¹, significantly outperforming commercial anatase TiO₂ (degradation rate of 42.7 % and reaction rate constant of 0.54 h⁻¹). Moreover, ZIS225 demonstrated the ability to simultaneously degrade MO and produce hydrogen, with a hydrogen production rate of 4.9 μmol g⁻¹h⁻¹ and a MO degradation rate of 99.7 %. The hydrogen production rate increased to 35.3 μmol g⁻¹h⁻¹ upon in-situ photodeposition of 1 % Pt, maintaining stable performance over three cycles. Photoelectrochemical and electron paramagnetic resonance (EPR) analyses identified superoxide radicals (•O₂⁻) and photogenerated holes (h⁺) as the primary active species. This research provides valuable insights for the development of efficient photocatalytic materials and offers technical references for dye pollution treatment and clean energy conversion.