Fabrication of Bi₂O₂CO₃/g-C₃N₄ heterojunctions for efficiently photocatalytic NO in air removal: In-situ self-sacrificial synthesis, characterizations and mechanistic study

Layer-structured Bi₂O₂CO₃/g-C₃N₄ heterojunction photocatalysts were successfully prepared via one-pot hydrothermal method for the first time, in which graphitic carbon nitride (g-C₃N₄) served as the self-sacrificial reagent to supply carbonate anions simultaneously. Our results showed that the in situ fabricated Bi₂O₂CO₃/g-C₃N₄ heterojunction exhibited superior visible-light-driven photocatalytic activity for NO photocatalytic oxidation, which can be ascribed to the morphology and structure modulation during the sacrificial synthesis processes. Heterojunctions formation pathways underlying temperature- and time-dependent structure evolution were discussed in detail. The sample fabricated at 160 °C for 12 h (BOC-CN-160) showed high stability and durability, and the highest NO removal rate which is up to 34.8% under visible light irradiation. Results from photocurrent tests and electrochemical impedance spectroscopy (EIS) demonstrated that the BOC-CN-160 sample presents much more effective interface charge separation efficiency, which can contribute to its remarkably improved photocatalytic performance. Reactive radicals during the photocatalysis processes were identified by electron spin resonance (ESR) study. Combined with the quantification of reaction intermediates, the photocatalytic degradation mechanism of NO over Bi₂O₂CO₃/g-C₃N₄ heterojunction photocatalyst was proposed. The novel approach developed in this study may be further extended to synthesize a series of novel and highly efficient g-C₃N₄-based carbonate heterojunction photocatalysts for visible light-harvesting and energy conversion applications. Copyright © 2016 Elsevier Ltd.