The excellent photocatalytic NO removal performance relates to the synergistic effect between the prepositive NaOH solution and the g-CN photocatalysis.

Photocatalysis technology is used to remove the low concentration NO in recent years. However, the effect of this process is not very satisfactory. In this study, it was found that the prepositive NaOH solution could significantly improve the photocatalytic NO removal activity of g-CN. The apparent quantum yield of g-CN in the NO removal process was increased 3.5 times by the prepositive NaOH solution. The reason is that there was a synergistic effect formed between the prepositive NaOH solution and the photocatalytic NO removal process. The prepositive NaOH solution not only could increase the humidity and pH value in the photocatalytic unit, but also could improve the adsorption ability of g-CN for the HO, NO, and O. Moreover, the prepositive NaOH solution reduced the difficulty of the photogenerated carriers' transport and the ·OH generation. This study provided a new idea for the removal of low-concentration NOx.