Electrochemically Synthesized Anthraquinone‐Diphenylamine Polymer Photocatalyst for Enhanced Hydrogen Peroxide Production

The photochemical method is a promising approach for H₂O₂ production, requiring only sunlight and water. Electropolymerization and the use of the resulting electrode-supported DA polymers for photocatalytic H₂O₂ generation represent an attractive pathway for harvesting light energy. In this study, we synthesized the D-A polymer poly(2,6-bis(diphenylamino)anthraquinone) via two approaches: an electrochemical route (p-AQDPA/EP) and FeCl₃-mediated chemical polymerization (p-AQDPA/CP). Both polymers show extended absorption up to 800 nm. The photocatalytic activity of p-AQDPA/EP and p-AQDPA/CP was examined towards H₂O₂ production. The p-AQDPA/EP efficiently reduces molecular oxygen and produces H₂O₂ in a neutral aqueous medium at a rate up to 6128 µmol g⁻¹ h⁻¹ under light irradiation (λ ≥ 400 nm) without any sacrificial agents. The p-AQDPA/EP photocatalyst demonstrated higher activity of H₂O₂ generation as compared to p-AQDPA/CP, attributed to its lower charge-transfer resistance (electrochemical impedance spectroscopy (EIS)), higher photocurrent, reduced photoluminescence intensity, and longer average lifetime relative to p-AQDPA/CP. These results indicate a higher concentration of surface charge carriers and more efficient charge transfer. The catalyst reduces oxygen through a direct two-electron oxygen reduction pathway. The metal catalyst-free synthesis of electropolymers offers a sustainable method to create polymeric photocatalysts for H₂O₂ production.