Carbon Dioxide Anion Radicals Assisted Highly Efficient Photocatalytic H₂O₂ Production over Bi(C₂O₄)OH

Carbon dioxide anion radical (CO₂^•-) can act as a versatile single electron reductant, but its generation pathways are quite limited. Herein, we demonstrate that oxalic acid (OA) could be effectively and continuously utilized to produce CO₂^•- over Bi(C₂O₄)OH, a novel photocatalyst, under light irradiation. Bi(C₂O₄)OH would proceed with self-redox reactions under the light irradiation producing CO₂^•-, through the oxidation of C₂O₄^2-. OA in the solution could recoordinate with Bi³⁺, thus maintaining the structure of the photocatalysts and the stability of the reactions. Benefiting from the fast reaction between CO₂^•- and O₂ in forming ^•O₂^-, hydrogen peroxide (H₂O₂) would be efficiently produced (219.0 μmol/h). This study proposes a novel approach for harnessing OA containing wastewater and explores its potential application in the efficient production of H₂O₂.