Self-Photocatalytic Splitting of Carbon Dioxide Using Co-cationic Perovskite Nanocrystals in the Absence of Water

Environmental concerns demand efficient removal of CO2, a major greenhouse gas. For this purpose, a traditional chemical strategy implements a catalytic conversion of CO2 to CO, with H2O as the sacrificial agent to generate O2. Herein we report the first self-photocatalytic conversion of CO2 to generate CO and O2 in the absence of H2O, using co-cationic perovskite nanocrystal Cs0.55FA0.45PbBr3. We obtained a record production rate 105 μmol g–1 h–1 of CO, which is three times that with CsPbBr3 as photocatalyst at the gas–solid interface. During photocatalytic reaction, a phase transition occurred with an enlarged crystal size through the effect of Ostwald ripening, for which the CO yield approached 3.1 mmol g–1 within the reaction period of ∼60 h. During this process, both FA and oleylammonium cations were released to provide the proton source for the CO2 reduction to proceed and generate hydroxyl species required for oxidation. A self-photocatalysis mechanism involving bound hydroxyls is proposed.