In-situ detection technique for charge transfer behavior of direct Z-scheme BiVO4/UiO-66-NH2 composites during photocatalytic thioanisole conversion
Xuemeng Sun, Jianan Liu, Hong Wang, Qi Li, Jing Zhou, Pengju Li, Ke Hu, Cheng Wang, Baojiang Jiang
Abstract
The photocatalytic efficiency can be enhanced by constructing Z-scheme heterostructures. However, there is still a lack of comprehensive and direct evidence regarding the charge transfer pathway and mode during the photocatalytic process. A composite photocatalyst BiVO 4 /UiO-66-NH 2 (BVO/U6N) was prepared by in-situ loading BiVO 4 nanoparticles onto the surface of UiO-66-NH 2 using a hydrothermal method. This catalyst effectively promotes the photocatalytic conversion of thioanisole to sulfoxide. The differences between BiVO 4 and UiO-66-NH 2 in band structure and Fermi energy level enable the composite to act according to the Z-scheme charge transfer pattern, which significantly enhances charge separation efficiency. In-situ X-ray photoelectron spectroscopy (in-situ XPS) combined with DFT calculation confirmed the transfer of electrons from UiO-66-NH 2 to BiVO 4 , driven by an internal electric field (IEF) upon hybridization. This demonstrates the formation of a Z-scheme photogenerated charge transfer pathway in the BVO/U6N composite. The direct Z-scheme system significantly enhances the carrier redox, resulting in a sulfoxide yield of 95.21% for the optimized sample in methanol, which is 5 times and 4.1 times higher than that of UiO-66-NH 2 and BiVO 4 , respectively. BVO/U6N exhibits efficient photocatalysis and selectivity towards various substrate sulfides, making it a highly promising heterogeneous photocatalyst.