Simultaneously Regulating charge separation and proton supply-demand in polyphenol amine for hydrogen peroxide photosynthesis

In the H2O2 photosynthesis, apart from the charge separation, the balance of proton supply and demand was also required between the kinetically faster oxygen reduction reaction (ORR) (μs ∼ ms) and the sluggish kinetics of water oxidation reaction (WOR) (s). Faced by this challenge, the article designed the heterojunction photocatalyst formed by in-situ polymerization of polyphenol amine on the surface of CdS under alkaline conditions. As a result, the synthesized CdS-Poly(catechol-hexamethylenediamine) (PCHA) produced 6.1 mM H2O2 after 8 h of visible light irradiation, which is 29 times that of CdS. The experimental results evidenced that the coating of PCHA increased the charge separation and mobility, inhibited the photocorrosion of CdS, and thus enhanced the stability and photoactivity. Moreover, the catechol units of PCHA could function as a proton supplier and regulate local protons concentrations around the catalytic active sites to balance the proton supply–demand in the ORR and WOR at different reaction time scales.