Boosting alkaline photocatalytic H2O2 generation by incorporating pyrophosphate on g-C3N4 for effective proton shuttle and oxygen activation

A novel pyrophosphate-based proton shuttle strategy has been proposed to boost on-site photocatalytic H2O2 generation in alkaline waters for organic pollutant treatment. Pyrophosphate-incorporated g-C3N4 (PCN) photocatalyst was prepared by facile thermal polymerization to address the issue of lack of protons in alkaline conditions. The PCN shows a record-high alkaline H2O2 synthesis rate (e.g. 1071.7 μmol gcat−1 h−1 at pH 9) under visible light together with an apparent quantum yield (ΦAQY) of 8.7 % (at 420 nm). Mechanism study demonstrates that the pyrophosphate could serve as proton shuttle to effectively adsorb and provide protons, and act as advanced active sites for O2 adsorption and activation to promote O2 reduction, which greatly benefits the capture of nearby protons by the activated O2 to form H2O2. This work provides a promising approach to prepare photocatalysts with superior alkaline H2O2 synthesis efficiency for on-site treatment of organic pollutants.