Construction of Schottky Junction between Multitransition Metal Borides and ZnIn ₂ S ₄ to Enhance the Photocatalytic Hydrogen Evolution

The development of efficient and cost-effective photocatalysts for hydrogen production is crucial to addressing the global energy and environmental crisis. ZnIn₂S₄ (ZIS), a ternary sulfide with visible-light responsiveness, holds enormous potential for photocatalytic hydrogen evolution, yet its performance is hindered by severe charge carrier recombination. Herein, we report the synthesis of ternary amorphous FeCoNiB (FCNB) transition metal borides as non-noble metal cocatalysts to enhance the photocatalytic activity of ZIS. The optimized 5% FCNB/ZIS composite exhibited a remarkable hydrogen evolution rate of 3125 μmol g^-1 h^-1 under simulated sunlight, which is approximately 7 times higher than ZIS. The apparent quantum efficiency was measured as 34% at 420 nm. The enhanced performance is attributed to the characteristics of the amorphous structure of FCNB and the formation of a Schottky junction at the FCNB/ZIS interface. This junction facilitates efficient transfer of photogenerated electrons from ZIS to FCNB, enabling spatial separation of charges and effectively improving the utilization efficiency of visible light. Various experimental characterizations confirmed the amorphous nature of FCNB, its uniform dispersion on ZIS, and the synergistic interfacial interaction. This work highlights the promise of multitransition metal borides as low-cost, high-performance cocatalysts for advancing solar-driven hydrogen production, offering a sustainable strategy to replace noble metal-based systems.