Photocatalytic NO removal: complete oxidation and reduction reaction for by-product inhibition and end-product recovery

Abstract

Nitrogen oxides (NOx, x = 1，2, the proportion of NO was about 95%), as one of primary precursors for particulate matter and ozone, limits the continuous improvement of air quality. Photocatalytic NO purification technology has aroused wide attention and much efforts have been made to realize photocatalytic NO complete oxidation and reduction for toxic by-product inhibition and end-product recovery. This work presents a timely overview of current research progress on the conversion of NO into nitrate/ ammonia (NO3−/NH3) that could be further recycled and utilized. According to the essence of heterogeneous photocatalysis and considering the significance of reaction microenvironment (surface active sites of photocatalyst, target pollutant and reaction medium), this review systematically summarized the progress about control strategy on photocatalyst surface structure and reaction medium. Specifically, the critical overview focused on various surface modification methods of photocatalyst, coping strategy on accelerating mass transfer process of gaseous NO, and the effect of additional introduction of reductant/ antioxidant into reaction system. Furthermore, the research trends and future prospects are discussed, aiming to provide an insight into the breakthroughs and boost the development of photocatalytic NO removal technology.