Unraveling the Synergistic Mechanism of Boosted Photocatalytic H2O2 Production over Cyano‐g‐C3N4/In2S3/Ppy Heterostructure and Enhanced Photocatalysis‐Self‐Fenton Degradation Performance

Abstract In this work, cyano contained g‐C 3 N 4 comodified by In 2 S 3 and polypyrrole (C≡N─CN/IS/Ppy) materials are synthesized for the photocatalytic production of H 2 O 2 and photocatalysis‐self‐Fenton reaction for highly efficient degradation of metronidazole. The results from UV–vis spectrophotometry, surface photovoltage, and Kelvin probe measurements reveal the promoted transport and separation efficiency of photoinduced charges after the introduction of In 2 S 3 and Ppy in the heterojunction. The existence of a built‐in electric field accelerates the photoinduced charge separation and preserves the stronger oxidation ability of holes at the valence band of C≡N─CN. Linear sweep voltammetry measurements, zeta potential analyzations, nitroblue tetrazolium determination, and other measurements show that Ppy improves the conversion ratio of • O 2 − to H 2 O 2 and the utilization ratio of • O 2 − , as well as suppresses decomposition of H 2 O 2 . Accordingly, the H 2 O 2 evolution rate produced via a two‐step single‐electron reduction reaction reaches almost 895 µmol L −1 h −1 , a value 80% and 7.2‐fold higher than those obtained with C≡N─CN/IS and C≡N─CN, respectively. The metronidazole removal rate obtained via photocatalysis‐self‐Fenton reaction attains 83.7% within 120 minutes, a value much higher than that recorded by the traditional Fenton method. Overall, the proposed synthesis materials and route look promising for the H 2 O 2 production and organic pollutants degradation.