Z-scheme Bi/AgBiS2/P25 for enhanced CO2 photoreduction to CH4 and CO with photo-themal synergy

Highlights: • Z-scheme Bi/AgBiS₂/P25 showed higher CO and CH₄ production compared with P25. • Bi/AgBiS₂ enhanced light-harvesting and carrier separation and transfer efficiency. • Higher CO adsorption efficiency favors CO₂ → CH₄ by providing more CO intermediate. • Higher OH groups provide more protons and stabilize key intermediates for CH₄ production. • Photo-thermal synergy further enhances photocatalytic CO₂ reduction. A ternary Bi/AgBiS₂/P25 has been successfully designed by a one-step solvothermal treatment for enhanced photocatalytic CO₂ reduction. Bi/AgBiS₂ decoration enhances carriers separation and transfer efficiency of P25 by constructing AgBiS₂/P25 heterojunction and loading Bi as electron receiver. Besides, Bi/AgBiS₂ decoration contributes to enhanced light-harvesting capability and high surface area of composite, both of which favor CO₂ reduction. More importantly, increased OH and enhanced CO adsorption efficiency on Bi/AgBiS₂/P25 surface could enhance CH₄ production by providing more available protons and stabilizing more key intermediates for CH₄ formation. The CH₄ production was improved from 0.23 μmol/g/h of P25 to 4.31 μmol/g/h of Bi/AgBiS₂/P25, and CO production from 3.52 μmol/g/h to 6.37 μmol/g/h, respectively, which have surpassed most TiO₂ based works for CO₂ photoreduction. Additionally, photo-thermal synergy can further enhance photocatalytic performance.