Stable and efficient n-type scaffolded semiconductor for photocatalytic hydrogen production under tungsten light irradiation

Abstract The production of green hydrogen (H 2 ) is a sustainable strategy to address the current energy crisis without contributing to long-term greenhouse gas emissions. Many powder-based photocatalysts have shown great promise for light-driven H 2 generation; however, in either bulk or nanostructured powder form they suffer from slow electron-transfer kinetics, material loss and poor recyclability, resulting in low hydrogen-evolution performance. In this work, we uniquely report the synthesis of an n-type scaffolded Si–Zn x Mg 1-x O semiconductor composite with an illuminated surface area of 27.72 cm 2 for efficient hydrogen production without the use of any sacrificial electron donor. The scaffolded composites were characterized using optical, structural, electrical, and theoretical analyses. The effect of the defect content on photocatalysis was investigated by adjusting the ratio of Zn and Mg content. The optimized Si–Zn 0.3 Mg 0.7 O scaffold achieved a hydrogen evolution rate of 1954 μmolh -1 cm -2 , corresponding to an apparent quantum yield (AQY) of 36.47%. The synergistic effects of heterojunction formation and defect engineering promote efficient charge separation, resulting in enhanced photocatalytic activity. Notably, the catalyst maintained stable hydrogen production activity over more than 30 h of continuous irradiation. This work highlights the potential for designing robust and stable photocatalytic scaffold for H 2 production, paving the way for scalable commercial applications.