Dual-Functional Engineering of Sn-doping and Polyaniline Coating for Cs3Bi2Br9 Perovskite: Boosting its Photocatalytic Activity and Photostability in Selective Oxidation of Benzyl Alcohol

Abstract

Although lead-free and environmentally benign Cs3Bi2Br9 perovskite is considered to be a promising photocatalyst for the selective oxidation of benzyl alcohol to benzaldehyde, its practical application is still restricted by its low activity and poor photostability. Herein, we employed a dual-modification strategy of Sn²⁺ doping and polyaniline (PANI) coating to address these problems. After visible light irradiation for 2 h, the benzyl alcohol conversion rate over the 7% Sn-doped Cs3Bi1.86Sn0.14Br8.86 sample reached 96%, which was a 2.58-fold improvement compared with the undoped Cs3Bi2Br9 (37.1%), along with a selectivity of 88% toward benzaldehyde. The cyclic experiments demonstrated that the PANI coating can significantly enhance the photostability of Cs3Bi1.86Sn0.14Br8.86. Based on a series of optical and photoelectrochemical analyses, it can be deduced that Sn doping enhances both the visible light absorption and charge carrier separation efficiency of Cs3Bi2Br9, while PANI coating restrains the photo-corrosion by promoting the electron transfer. This study provides a general strategy for simultaneously enhancing the catalytic activity and photostability of perovskite materials.