A step-scheme-based Cs3Bi2Br9 perovskite quantum dots@mesoporous Nb2O5 photocatalyst with boosted charge separation and CO2 reduction

Solar-energy-powered CO 2 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 Cs 3 Bi 2 Br 9 perovskite quantum dots (PQDs) are regarded as an attractive material for CO 2 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 Cs 3 Bi 2 Br 9 @Nb 2 O 5 (CBB@Nb 2 O 5 ) nanocomposite was fabricated by embedding the CBB PQDs into mesoporous Nb 2 O 5 . Experimental studies, along with theoretical calculations, revealed that the charge migration route in the CBB@Nb 2 O 5 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 CO 2 adsorption contributed by mesoporous Nb 2 O 5 , the CBB@Nb 2 O 5 nanocomposite unveiled superior CO 2 photoreduction performance, with CO evolution rate reaching 143.63 μmol g −1 h −1 . The present study provides a potential strategy to manufacture highly-efficient perovskite-based photocatalysts for achieving carbon neutrality.