Self-assembled lead-free double perovskite-MXene heterostructure with efficient charge separation for photocatalytic CO2 reduction

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 het-erostructure 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 inCs(2)AgBiBr(6 ) NCs via reducing the exciton binding energy. Additionally, the ultrafast photo-generated electron transfer from Cs(2)AgBiBr(6 )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 Cs2Ag-BiBr6/MXene heterostructures achieve a high photoelectron consumption yield of 50.6 mu mol g(-1 )h(-1) for pho-tocatalytic CO2 reduction, which surpasses most previously reported lead-free perovskite-based catalysts.

Automated summary

Lead-free double perovskite Cs2AgBiBr6 nanocrystals (NCs) were assembled on the surface of MXene nanosheets through mutual electrostatic attraction. The presence of MXene nanosheets promoted the formation of free charge carriers in Cs2AgBiBr6 NCs and extended their lifetime through ultrafast photo-generated electron transfer. The heterostructures exhibited a high photoelectron consumption yield for photocatalytic CO2 reduction.