A computational study of a reduced dye and its O2 reduction: Implication on H2O2 production with dye-sensitized photocathodes

•Reduced p-type dyes and their complexes with O2 were computationally investigated.•The dye−• and O2 afforded neutral dye and O2−•, forming C–H∙∙∙O hydrogen bonds.•The restored dyes were not involved in the subsequent O2−• reactions with H+ and HO2•.•The findings support the theory of H2O2 production from O2 reduction by reduced dyes.