Unraveling the Synergistic Mechanism of Boosted Photocatalytic H 2 O 2 Production over Cyano-g-C 3 N 4 /In 2 S 3 /Ppy Heterostructure and Enhanced Photocatalysis-Self-Fenton Degradation Performance.

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.