Mo-activated ZnIn₂S₄ photocatalyst for enhanced hydrogen evolution coupled with benzyl alcohol oxidation

Photocatalytic water splitting for hydrogen production provides a viable approach to address the energy crisis. However, the sluggish four-electron water oxidation severely restricts water splitting efficiency. Herein, with the Mo-doped ZnIn₂S₄ (Mo-ZIS) photocatalyst, the hydrogen production reaction is significantly facilitated through synergistic integration with the kinetically favourable oxidation of benzyl alcohol (BA). The high-valence and unsaturated Mo species promote not only the separation of photo carriers but also the activation of BA, thereby accelerating the oxidation of BA. Moreover, Mo doping adjusts the band structure of ZIS, enhancing the oxidation capability of the photocatalyst without inducing the excessive oxidation of BA. Consequently, Mo-ZIS efficiently produces both high-value-added H₂ and benzaldehyde (BAD) products, exhibiting a remarkable hydrogen evolution rate (16,353 µmol g⁻¹ h⁻¹) and BAD yield (13,942 µmolg⁻¹ h⁻¹) without the need for additional noble-metal cocatalysts, significantly surpassing the performance of pristine ZIS photocatalysts. Strikingly, by modulating the desorption process of intermediates on the Mo-ZIS surface through adjusting the hydrogen bonding network strength between BA and the solvent, the BAD production rate of Mo-ZIS is 23,068 µmol g⁻¹ h⁻¹, resulting in a 65% increase compared to acetonitrile solution. This work introduces a valuable strategy for combining photocatalytic hydrogen production with selective organic product transformation, providing new insights for the development of novel photocatalysts to achieve efficient solar energy conversion.