Oxygen vacancy engineering of Bi2O3/Bi2O2CO3 heterojunctions: Implications of the interfacial charge transfer, NO adsorption and removal

Abstract

Efficient enrichment of targeted gaseous pollutants and fast diffusion rates of charge carriers are essential for the photocatalytic removal of nitric oxides at ambient concentration levels. Here we demonstrate that the construction of nano-structured Bi2O3/Bi2O2CO3 heterojunctions with oxygen vacancies, increasing the photocatalytic NO removal activity, durability and selectivity for final products nitrate formation. Combining the experimental and density-functional theory calculations, it was elucidated that the presence of surface oxygen vacancies not only work as adsorption sites of low concentration NO, but also offer an intimate and integrated structure between surface defects and the light-harvesting heterojunctions, which can facilitate solar energy conversion and charge carrier transfer (more than 2 times). Control experiments with pristine Bi2O3/Bi2O2CO3 also confirmed the crucial role of surface oxygen vacancies on the improvement of NO adsorption and removal ability during the photocatalytic degradation process. We explain the enhanced removal of NO through the synergistic effect of oxygen vacancy and heterojunction, which not only guaranteed the generation of more OH radicals, but also provided another route to produce hydrogen peroxide. Our findings may provide an opportunity to develop a promising catalyst for air pollution control.