Ti₃C₂ MXene quantum dots-modified 2D/3D Ni₂P/Zn_0.5Cd_0.5S heterostructures for efficient solar-driven hydrogen evolution

Precise control over the composition and interface engineering of Zn_xCd_1−xS-based photocatalysts is critical for advancing solar-driven hydrogen production. In this study, a ternary Ni₂P/Zn_0.5Cd_0.5S@Ti₃C₂ MXene quantum dot photocatalyst was synthesized via direct impregnation of etched Ti₃C₂ MXene onto Ni₂P/Zn_0.5Cd_0.5S. The MXene quantum dots serve as electron mediators, mitigating charge recombination and enhancing conductivity, while Ni₂P acts as a co-catalyst to promote interfacial charge transfer. The resulting composite achieved a hydrogen evolution rate of 18.07 mmol·g⁻¹_cat under 6 h of simulated solar light irradiation, representing a 21-fold improvement compared to bare Zn_0.5Cd_0.5S. Structural, morphological, and optical analyses confirmed successful component integration, bandgap narrowing, and reduced charge carrier recombination. Electrochemical impedance spectroscopy and Mott–Schottky analyses further demonstrated enhanced interfacial charge separation. In addition to hydrogen production, the composite was simultaneously evaluated for butyric acid photoreforming in a 5 mM aqueous solution, demonstrating its dual capability for organic contaminant degradation and sustainable fuel generation. These findings highlight a rational design strategy for multicomponent photocatalysts with improved photoactivity, offering promising potential for solar-to-hydrogen energy conversion and wastewater valorization.