Research Progress on Photocatalytic/Photoelectrocatalytic Oxidation of Nitrogen Oxides

Abstract The emission of nitrogen oxides (NO x ) increases year by year, causing serious problems to our livelihoods. The photocatalytic oxidation of NO x has attracted more attention recently because of its efficient removal of NO x , especially for low concentrations of NO x . In this review, the mechanism of the photocatalytic oxidation of NO x is described. Then, the recent progress on the development of photocatalysts is reviewed according to the categories of inorganic semiconductors, bismuth-based compounds, nitrogen carbide polymer, and metal organic frameworks (MOFs). In addition, the photoelectrocatalytic oxidation of NO x , a method involving the application of an external voltage on the photocatalytic system to further increase the removal efficiency of NO x , and its progress are summarized. Finally, we outline the remaining challenges and provide our perspectives on the future directions for the photocatalytic oxidation of NO x .