CO2 photoreduction into solar fuels via vacancy engineered bismuth-based photocatalysts: Selectivity and mechanistic insights

• Selective CO 2 photoconversion into C 1 and C 2 products is emphasised. • Vacancy modulated Bismuth based photocatalysts for CO 2 conversion is highlighted. • Substantial engineering methods and identification tools for vacancies are explored. • Reaction pathways are presented using experimental and DFT calculation results. • Existing research gaps for scale-up photoconversion efficacy are suggested. Solar-driven CO 2 conversion into value-added C 1 and C 2 chemicals and fuels offer an attractive route to alleviate global environmental and energy issues. Vacancy modified Bi-based photocatalysts possessing fascinating layered framework, visible-light responsive features, and tunable electronic arrangement, are a preeminent candidate for photocatalytic CO 2 conversion. Vacancy engineering in Bi-based materials offers simultaneous modification in the electronic structure, surfacial active sites, and CO 2 adsorption/activation kinetics leading to efficacious selective CO 2 photoconversion. Herein, the phenomenon of CO 2 photoconversion directed by vacancy-modified bismuth-based photocatalysts has been systematically reviewed and presented. Starting from the fundamentals of CO 2 photoreduction, the potential role of vacancies in improving CO 2 adsorption and activation has been highlighted. Afterward, the advanced characterization tools for the identification of vacancies and various engineering methods for controlled vacancy generation are comprehensively discussed. Also, the impact of vacancy generation on the selective conversion of CO 2 into value-added C 1 and C 2 products has been thoroughly investigated. In conclusion, based on the understanding and relationships of vacancies with photocatalytic properties of bismuth-based materials, existing challenges and foresighted perspectives are mentioned.