In situ g-C₃N₄ self-sacrificial synthesis of a g-C₃N₄/LaCO₃OH heterostructure with strong interfacial charge transfer and separation for photocatalytic NO removal

Graphitic carbon nitride (g-C₃N₄) as a metal-free semiconductor photocatalyst has been continually struggling with the high recombination rate of photo-induced charge carriers. Developing a heterostructure is an effective way to suppress the photo-induced e^--h⁺ pair recombination. In this study, a novel heterostructured g-C₃N₄/hierarchical reuleaux triangle LaCO₃OH nanocomposite was controllably fabricated via a one-pot hydrothermal strategy for the first time rather than through the conventional solid state calcination reaction, relying on the dual-functional roles of g-C₃N₄. g-C₃N₄, serving as both the structure directing agent and CO₃^2- source in the reaction system, significantly influences the morphology engineering of LaCO₃OH. The time-dependent structural evolutions were discussed in detail. The strong interfacial charge transfer and separation are the dominant factors for activity enhancement of g-C₃N₄/LaCO₃OH towards gaseous nitric oxide (NO) degradation under visible light, as confirmed by experimental characterization and density functional theory (DFT) theoretical calculations. Combined with the identification of reaction intermediates and electron spin resonance (ESR) results, the photocatalytic degradation mechanism of NO over the g-C₃N₄/LaCO₃OH heterojunction was proposed. More importantly, this novel self-sacrificial synthesis strategy was successfully extended to synthesize both g-C₃N₄/Bi₂O₂CO₃ and g-C₃N₄/SrCO₃ composites, indicating that it can serve as a general method to synthesize g-C₃N₄/carbonate compounds. Copyright © 2018 The Royal Society of Chemistry.