The mechanisms of interfacial charge transfer and photocatalysis reaction over Cs3Bi2Cl9 QD/(BiO)2CO3 heterojunction

We report a series of Cs3Bi2Cl9/(BiO)2CO3 (labeled as C-B-X, X = 0.5, 1, 3) heterojunctions synthesized by the ectopic precipitation method. Density functional theory calculation cooperated with experimental results reveals the high-efficiency electron transport between (BiO)2CO3 and Cs3Bi2Cl9, resulting in an internal electric field at interfaces and efficiently separating the charge carriers, thus promoting more photo-induced charge to participate in the photocatalytic process. Electron spin resonance results unveil a higher amount of OH and O2− formation on C-B-1 heterojunction benefited from the highly efficient charge delivery under visible light irradiation. In situ diffuse reflectance infrared Fourier transform spectroscopy studies verify the effective improvement in NO adsorption/activation and reaction intermediates conversion after constructing the hybrid interface. These factors synergistically enable the NO purification rate of C-B-1 higher than (BiO)2CO3 by 35.0%. This endeavor gives original insights into the mechanism of interfacial charge separation in perovskite quantum dot-based heterogeneous structures and provides a new perspective for promoting safe and potent air pollution control with photocatalytic technology.