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

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 SrTiO 3 /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 SrTiO 3 surface through a preformed electron delivery channel. Enhanced electron transfer was expected between the SrTiO 3 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 NO 2 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. SrTiO 3 /BiOI heterojunction photocatalysts were designed and fabricated to simultaneously enhance the efficiency of NO purification in air under visible light irradiation and inhibit the generation of toxic intermediates.