Plasmonic CsPbBr3–Au nanocomposite for excitation wavelength dependent photocatalytic CO2 reduction

The optoelectronic performance of CsPbBr 3 nanocrystal (NC) has been dramatically limited by the severe charge carrier recombination and its narrow light absorption range, which are anticipated to be resolved via coupling with plasmonic Au nanoparticle (NP). In view of this, CsPbBr 3 –Au nanocomposite is fabricated and further employed as a concept model to study the electronic interaction between perovskite NC and Au NP for the first time. It has been found that the excitation-wavelength dependent carrier transfer behavior exists in CsPbBr 3 –Au nanocomposite. Upon illumination with visible light ( λ >420 nm), photo-generated electrons in CsPbBr 3 can inject into Au with an electron injection rate and efficiency of 2.84 × 10 9 s −1 and 78%, respectively. The boosted charge separation is further translated into a 3.2-fold enhancement in CO 2 photocatalytic reduction activity compared with pristine CsPbBr 3 . On the other hand, when solely exciting Au NP with longer wavelength light ( λ >580 nm), the localized surface plasmon resonance (LSPR) induced hot electrons in Au NPs can transfer to CsPbBr 3 NC and further participate in photocatalytic reaction towards CO 2 reduction. The present study provides new insights into preparing plasmonic nanostructure to enhance the performance of perovskite based optoelectronic devices. Excitation wavelength dependent carrier dynamic interactions in CsPbBr 3 –Au nanocomposite has been uncovered for the first time. LSPR induced hot electrons in Au can be extracted to CsPbBr 3 and further participate in the CO 2 reduction.