Synergistic photocatalytic production of H2O2 and imines via oxygen-enriched acetonitrile medium and benzylamine oxidation

Abstract

Photocatalytic technology has emerged as a sustainable and efficient strategy for chemical synthesis, yet its application in H₂O₂ production is limited by low dissolved oxygen availability and inefficient charge carrier utilization. To overcome these limitations, we developed an innovative photocatalytic system that uses acetonitrile as the solvent. Due to its markedly higher oxygen solubility compared to water, this system significantly improves oxygen mass transfer and overall reaction kinetics. Furthermore, we introduced benzylamine oxidation as an alternative to the conventional water oxidation reaction. Benefiting from its favorable oxidation potential, the oxidation of benzylamine not only requires lower energy input, but also couples synergistically with H₂O₂ generation, forming a bifunctional catalytic system that significantly enhances the efficiency of H₂O₂ synthesis. The system achieves a high H₂O₂ production rate of 12.03 mmol g⁻¹ h⁻¹ and a concentration of 28.9 mmol L⁻¹, significantly outperforming conventional aqueous-phase systems. Subsequent distillation and extraction processes concentrated the aqueous H₂O₂ solution to 413.43 mM (>1 wt%), approaching the concentration of medical-grade H₂O₂. Mechanistic investigations confirm that the reaction follows a two-electron oxygen reduction pathway. This work not only presents a novel and sustainable route for H₂O₂ production, but also demonstrates potential for photocatalytic synthesis of other high-value chemicals.