Lead-free double perovskites with superior stability have been considered as promising non-toxic substitutes to their lead-contained counterparts in photocatalysis. However, the severe charge recombination greatly restricts their potential as high-performance photocatalysts. Herein, for the first time, we present a self-assembled heterostructure of lead-free double perovskite Cs2AgBiBr6 nanocrystals (NCs) on the surface of MXene nanosheets via mutual electrostatic attraction. The presence of MXene nanosheets effectively promotes the formation of free charge carriers in Cs2AgBiBr6 NCs via reducing the exciton binding energy. Additionally, the ultrafast photogenerated electron transfer from Cs2AgBiBr6 to MXene with a timescale of 1.1 ps largely prolongs the charge carrier lifetime by two times. As a result of the efficient charge separation and electron extraction, the Cs2AgBiBr6/MXene heterostructures achieve a high photoelectron consumption yield of 50.6 µmol g−1 h−1 for photocatalytic CO2 reduction, which surpasses most previously reported lead-free perovskite-based catalysts.
Scopus Subject Areas
- Environmental Science(all)
- Process Chemistry and Technology
- Charge transfer
- Double perovskite nanocrystals
- MXene nanosheets