Regenerative in situ formed Bi nanoparticles on Bi2O2CO3 nanosheets with Bi-vacancies for efficient and stable photocatalytic CO2 reduction to formate

Abstract

Photocatalytic CO₂ reduction to formate suffers from poor productivity, selectivity, stability and recyclability. To conquer these drawbacks, a new facile strategy has been utilized to create regenerative in situ formed Bi⁰ nanoparticles on Bi₂O₂CO₃ nanosheets for photocatalytic CO₂ reduction to formate by taking advantage of the self-photoreduction of Bi³⁺ to Bi⁰. It has been proven that Bi⁰ nanoparticles and Bi vacancies are in situ generated simultaneously and adjacently on Bi₂O₂CO₃ nanosheets under illumination (namely BOC-L) via in situ XPS, PXRD, AC-STEM, and FT-IR. Further mechanistic studies have revealed that the contacted corner between the Bi⁰ nanoparticles and Bi₂O₂CO₃ matrix serves synergistically as the catalytic center for CO₂ conversion to formate, while Bi vacancies boost CO₂ adsorption. As an integral result, high productivity (33.5 mmol g⁻¹ h⁻¹) and selectivity (99%) have been achieved. Notably, Bi₂O₂CO₃ can be easily regenerated from BOC-L via a wet chemical method and keep the initial productivity with little decline after 55 cycles with 5 hours per cycle. Moreover, the chemically stable Bi₂O₂CO₃ ensures the maintained performance of CO₂ conversion to formate even after over two months of storage in ambient conditions. This work provides a universal approach to construct highly efficient and robust photocatalysts towards desired reactions for practical applications.