Removal of Nitric Oxide through Visible Light Photocatalysis by g-C3N4 Modified with Perylene Imides

For photocatalytic removal of nitric oxide (NO), two major issues need to be addressed: incomplete oxidation of NO and deactivation of the photocatalyst. In this study, we aimed to solve these two problems by constructing an all-solid-state Z-scheme heterojunction (PI-g-C3N4) consisting of g-C3N4 surface modified with perylene imides (PI). PI-g-C3N4 exhibits significant enhancement in photocatalytic activity (in comparison to pristine g-C3N4) when examined for NO removal. More importantly, the Z-scheme charge separation within PI-g-C3N4 populates electrons and holes into the increased energy levels, thereby enabling direct reduction of O-2 to H2O2 and direct oxidation of NO to NO2. H2O2 can further oxidize NO2 to NO3- ion at a different location (via diffusion), thus alleviating the deactivation of the catalyst. The results presented may shed light on the design of visible photocatalysts with tunable reactivity for application in solar energy conversion and environmental sustainability.