SrTiO3/BiOI heterostructure: Interfacial charge separation, enhanced photocatalytic activity, and reaction mechanism

Abstract Heterostructured photocatalysts provide an effective way to achieve enhanced photocatalytic performances through efficient charge separation. Although both wide- and narrow-band-gap photocatalysts have been widely investigated, the charge separation and transfer mechanism at the contacting interface of the two has not been fully revealed. Here, a novel SrTiO3/BiOI (STB) heterostructured photocatalyst was successfully fabricated by using a facile method. The heterostructure in the photocatalyst extends the photoabsorption to the visible light range, and thus, high photocatalytic NO removal performance can be achieved under visible light irradiation. A combination of experimental and theoretical evidences indicated that the photogenerated electrons from the BiOI semiconductor can directly transfer to the SrTiO3 surface through a preformed electron delivery channel. Enhanced electron transfer was expected between the SrTiO3 and BiOI surfaces under light irradiation, and leads to efficient ROS generation and thus a high NO conversion rate. Moreover, in situ diffused reflectance infrared Fourier transform spectroscopy revealed that STB can better inhibit the accumulation of the toxic intermediate NO2 and catalyze the NO oxidation more effectively. This work presents a new insight into the mechanism of the interfacial charge separation in heterostructures and provides a simple strategy to promote the photocatalytic technology for efficient and safe air purification.