An efficient strategy for photocatalytic hydrogen peroxide production over oxygen-enriched graphitic carbon nitride with sodium phosphate

Photocatalytic hydrogen peroxide (H2O2) production is a promising strategy to replace the traditional production processes; however, the inefficient H2O2 productivity limits its application. In this study, oxygen-rich g-C3N4 with abundant nitrogen vacancies (OCN) was synthesized for photocatalytic H2O2 production. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy indicated that oxygen-containing functional groups (–COOH and C–O–C) were obtained. Electron paramagnetic resonance confirmed the successful introduction of nitrogen vacancies. OCN exhibited efficient photocatalytic H2O2 production performance of 1965 µmol L−1 h−1 in air under visible-light irradiation. The high H2O2 production was attributed to the enhanced adsorption of oxygen, enlarged specific surface area, and promoted carrier separation. An increased H2O2 production rate (5781 µmol L−1 h−1) was achieved in a Na3PO4 solution. The improved performance was attributed to the changed reactive oxygen species. Specifically, the adsorbed PO43− on the surface of the OCN promoted the transfer of holes to the catalyst surface. •O2− obtained by O2 reduction reacted with adjacent holes to generate 1O2, which could efficiently generate H2O2 with isopropanol. Additionally, PO43−, as a stabilizer, inhibited the decomposition of H2O2.