Controlled synthesis of hollow carbon ring incorporated g-C3N4 tubes for boosting photocatalytic H2O2 production

H2O2 production through solar-driven photocatalytic route has received increasing attention. Herein, a carbon ring incorporated hollow g-C3N4 tubes (CHCN) was successfully fabricated via a novel supramolecular self-assembly strategy, co-inducing by hydrogen bond and covalent bond. The optimum H2O2 yield over the CHCN-0.02 reached up to 1.58 mmol L−1 h−1 (AQE= 28.10%, 420 nm), which was 5.4 times significantly higher than that of bulk g-C3N4 (0.29 mmol L−1 h−1) under visible light irradiation. Experimental and density functional theory (DFT) calculations revealed that the CHCNs not only expedited the charge carrier transfer/separation but also favored molecular oxygen adsorption and regulated bandgap structure under the in-plane electronic field induced by continuous π-conjugated Cring, which boosted the ORR efficiency for photocatalytic H2O2 synthesis. The optimized CHCN catalyst demonstrated adequate hybrid ORR routes, consisting of a dominated selective one-step two-electron ORR pathway and highly efficient two-step single-electron ORR for H2O2 production. Therefore, this work not only provides a new strategy for an efficient H2O2 formation using a g-C3N4-based photocatalyst but also explores the functionary mechanism of the ORR process and enlightens the way to highly efficient H2O2 generation.