Ultra-stable type-II heterojunctions Bi4O5I2/FeVO4 of reinforced photocatalytic NOx removal abilities in visible light

In this investigation, a sequence of binary composites Bi4O5I2/FeVO4 (BF) were prepared through a facile solvothermal route and were systematically characterized by various analytical techniques. As verified from HRTEM images and XPS analyses, these composites were comprised of both expected components in hetero-junction structures. Under visible light, as-prepared composites displayed reinforced photocatalytic performance over NOx removal at the ppb level in comparison to both bare components. Particularly, the best candidate BF2.5 possessed NOx removal around 40% with a selectivity for nitrate/nitrite species approaching 100%, which surpassed those by Bi4O5I2 and FeVO4, mainly attributing to favorable physicochemical merits such as the enhanced visible-light harvesting, effective transfer and separation of charge carriers and further boosted generation of reactive radicals, and the suitable composition in morphological harmony. These composites were quite robust and maintained photocatalytic performance well even up to five successive runs without surface cleaning. Eventually, an elementary photocatalysis mechanism of these composites was deduced in a type-II manner by entrapping experiments, ESR analyses, and band structural estimation.