Novel electron donor boosting the electron supply capacity of hierarchical structure carbon nitride for efficient photocatalytic hydrogen peroxide production

A large number of residual amino groups may be formed in graphitic carbon nitride (g-C3N4), leading to the destruction of active sites and increased carrier recombination centers. Herein, we develop a meaningful material (benzo[b]thiophene-3-carboxaldehyde post-grafting three-dimensional agaric-shaped g-C3N4 (3DA-CN): CNBT) that solves the problems above by prolonging the delocalization of π electrons and changing the intrinsic semiconductor properties. CNBT has a special hierarchical structure, excellent visible light absorption capacity and high carrier separation efficiency. The introduction of BTC promotes the activation of O2 and spontaneously produces more H2O2. The H2O2 production rate of CNBT-7 is 2249 μM in 2 h, which is 5.95 times higher than that of 3DA-CN (378 μM). The formation rate constant value of CNBT-7 (31.45 μM·min−1) increased to 8.71 times higher than that of 3DA-CN (3.61 μM·min−1). The H2O2 production mechanism follows two-step single electron reaction path and has been deeply studied by experiments and density functional theory (DFT) calculations. This work provides a meritorious activity strategy to enhance photocatalytic H2O2 production.