Lanthanum orthovanadate/bismuth oxybromide heterojunction for enhanced photocatalytic air purification and mechanism exploration

Abstract

In this work, Lanthanum orthovanadate (LaVO4)/bismuth oxybromide (BiOBr) hybridized heterojunction was fabricated through a facile hydrothermal method for enhancing separation and transferring efficiency of photogenerated charge carriers in photocatalytic advanced oxidation process. The photoelectrochemical data demonstrate that the introduction of LaVO4 not only improves the solar energy harvesting efficiency due to decreasing of bandgap energies from 2.71 eV to 2.17 eV, but also reduces the transfer resistance of charge carriers in the hybridized system. Furthermore, the LaVO4/BiOBr heterojunctions exhibit enhanced photocatalytic degradation for gaseous air pollutants under visible light irradiation in comparison with bare LaVO4 and BiOBr. Among them, 3% LaVO4/BiOBr displays the best photocatalytic performance and degradation conversions of acetone and toluene achieve to 95.4% for 3 h and 87.1% for 4 h, respectively, which are 2.6 and 5.3 times higher than that of pristine BiOBr sample, respectively. Moreover, the OH and O2− were identified as the main radicals during the photo-degradation process. Based on the results of in-situ infrared spectra, a series of intermediates at different oxidation stages, including alcohols, aldehydes, and acids are captured, strongly supporting the proposed photoactive mechanism at gas/solid interface, which is beneficial for understanding the whole reaction process and pursuing new path to eliminating indoor air pollution.