Engineered Bi₂S₃/SnTiO₂ Nanofibers for Enhanced Interfacial Charge Transfer and Improved Photocatalytic CO₂ Reduction to Methanol (CH₃OH)

Solar-powered semiconductor photocatalysts have attracted much attention as a promising approach to address the global energy crisis and environmental pollution. Surface-modified and heterostructure photocatalysts exhibit great potential for this application. In this study simple electrospinning and a solvothermal technique were used to synthesize Bi₂S₃/SnTiO₂ nanofibers heterostructure photocatalysts with modified surfaces. Coupling bismuth sulfide (Bi₂S₃) with tin-doped TiO₂ nanofibers (SnTiO₂ NFs) enhances charge transfer efficiency, leading to improved photocatalytic performance. A series of heterostructures were synthesized by varying the amount of Bi₂S₃, these heterostructures showed effective photocatalytic CO₂ conversion compared to TiO₂ NFs and SnTiO₂ NFs. Variety techniques, including FE-SEM, TEM, XRD, XPS, EPR, BET, PL, TR-PL, and PEC were used to study the morphology, microstructure, phase composition, and functional properties of synthesized photocatalysts. Superior Bi₂S₃/SnTiO₂ heterostructure photocatalyst exhibited effective photocatalytic conversion of CO₂ into CH₃OH, CO, and CH₄, with yielding rates of 422, 14 and 33 μmol.g^-1h^-1 respectively. Moreover, the optimal heterostructure photocatalyst showed the highest CO₂ photoreduction selectivity of 90%. This extraordinary activity may be attributed to uniform growth Bi₂S₃ nanoparticles on SnTiO₂ NFs, which enhanced their light absorption to visible regions and offered a significant number of active sites for activating and desorbing CO₂ during the reaction. This study provides general guidance for designing a high-activity photocatalyst.