Boosted charge transfer and photocatalytic CO2 reduction over sulfur-doped C3N4 porous nanosheets with embedded SnS2-SnO2 nanojunctions

Abstract

Two-dimensional porous nanosheet heterostructure materials, which combine the advantages of both architecture and components, are expected to feature a significant photocatalytic performance toward CO 2 conversion into useful fuels. Herein, we provide a facile strategy for fabricating sulfur-doped C 3 N 4 porous nanosheets with embedded SnO 2 -SnS 2 nanojunctions (S-C 3 N 4 /SnO 2 -SnS 2 ) via liquid impregnation-pyrolysis and subsequent sulfidation treatment using a layered supramolecular structure as the precursor of C 3 N 4 . A hexagonal layered supramolecular structure was first prepared as the precursor of C 3 N 4 . Then Sn 4+ ions were intercalated into the supramolecular interlayers through the liquid impregnation method. The subsequent annealing treatment in air simultaneously realized the fabrication and efficient exfoliation of layered C 3 N 4 porous nanosheets. Moreover, SnO 2 nanoparticles were formed and embedded in situ in the porous C 3 N 4 nanosheets. In the following sulfidation process under a nitrogen atmosphere, sulfur powder can react with SnO 2 nanoparticles to form SnO 2 -SnS 2 nanojunctions. As expected, the exfoliation of sulfur-doped C 3 N 4 porous nanosheets and ternary heterostructure construction could be simultaneously achieved in this work. Sulfur-doped C 3 N 4 porous nanosheets with embedded SnO 2 -SnS 2 nanojunctions featured abundant active sites, enhanced visible light absorption, and efficient interfacial charge transfer. As expected, the optimized S-C 3 N 4 /SnO 2 -SnS 2 achieved a much higher gas-phase photocatalytic CO 2 reduction performance with high yields of CO (21.68 µmol g −1 h −1 ) and CH 4 (22.09 µmol g −1 h −1 ) compared with the control C 3 N 4 , C 3 N 4 / SnO 2 , and S-C 3 N 4 /SnS 2 photocatalysts. The selectivity of CH 4 reached 80.30%. Such a promising synthetic strategy can be expected to inspire the design of other robust C 3 N 4 -based porous nanosheet heterostructures for a broad range of applications. Keywords: sulfur-doped C 3 N 4 , porous nanosheets, SnO 2 -SnS 2 nanojunctions, tunable composition, CO

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