A step-scheme-based Cs₃Bi₂Br₉ perovskite quantum dots@mesoporous Nb₂O₅ photocatalyst with boosted charge separation...

Solar-energy-powered CO₂ reduction into valuable chemical fuels represents a highly promising strategy to address the currently energy and environmental issues. Owing to the nontoxicity and robust reduction capability, lead-free Cs₃Bi₂Br₉ perovskite quantum dots (PQDs) are regarded as an attractive material for CO₂ photoreduction. Nevertheless, the potential of their applications in this field has been restricted by the severe charge recombination, resulting in unsatisfactory photocatalytic performance. Herein, a step-scheme-based Cs₃Bi₂Br₉@Nb₂O₅ (CBB@Nb₂O₅) nanocomposite was fabricated by embedding the CBB PQDs into mesoporous Nb₂O₅. Experimental studies, along with theoretical calculations, revealed that the charge migration route in the CBB@Nb₂O₅ nanocomposite conformed to the step-scheme (S-scheme) mode, enabling effective charge separation and strong redox ability preservation. Profiting from the promoted charge separation, as well as the improved CO₂ adsorption contributed by mesoporous Nb₂O₅, the CBB@Nb₂O₅ nanocomposite unveiled superior CO₂ photoreduction performance, with CO evolution rate reaching 143.63 μmol g^-1h^-1. The present study provides a potential strategy to manufacture highly-efficient perovskite-based photocatalysts for achieving carbon neutrality.