Enwrapping g-C₃N₄ on In₂O₃ hollow hexagonal tubular for photocatalytic CO₂ conversion: Construction, characterization, and Z-scheme mechanism insight

The reduction of CO₂ achieved by photocatalysis can simultaneously alleviate the energy crisis and solve environmental issues. Nevertheless, it remains challenging for the rational design of photocatalysts with high-efficiency carrier migration ability. Herein, the Z-scheme g-C₃N₄/In₂O₃ (CN/INO) heterostructure was fabricated via metal–organic frameworks (MOFs) assisted thermal deposition which could form a fully encapsulated hollow tubular structure. The unique structure was based on the MOFs-derived hollow hexagonal In₂O₃ tubular integrated with ultrathin g-C₃N₄. The Z-scheme CN/INO heterojunction exhibited a larger specific surface area and excellent charge separation efficiency. Benefiting from the above features, the Z-scheme CN/INO heterojunction demonstrated superior performance on photocatalytic CO₂ reduction. The formation of CO and CH₃OH over the optimized CN/INO-2 catalyst was 7.94 and 1.44 µmol⋅g⁻¹⋅h⁻¹, respectively. Moreover, the density functional theory (DFT) calculations and Kelvin probe force microscopy (KPFM) was carried out to further investigate the situation of charge transfer on the interface of CN/INO. The in-situ Fourier transform infrared spectroscopy (FTIR) was measured to confirm the immediate products and the possible mechanism of photocatalytic CO₂ reduction was proposed. This work provided a MOFs-assisted strategy to construct a Z-scheme system for photocatalytic CO₂ reduction.