At least five: Benefit origins of potassium and sodium co-doping on carbon nitride for integrating pharmaceuticals degradation and hydrogen peroxide production

Benefit origins of potassium (K) and sodium (Na) co-doping on carbon nitride for integrating pharmaceutical degradation and hydrogen peroxide (HO) production was investigated. K and Na co-doped carbon nitride (CN-K/Na) with modified crystallinity and surface structure was synthesized by ionothermal polymerization of urea. The CN-K/Na exhibited an apparent quantum yield of 26.2 % in HO photosynthesis at 400 nm (isopropanol as proton donor), and it was better at extracting proton from pharmaceutical-laden wastewater to produce HO than pristine carbon nitride. These superior performances are attributed to the benefits directly or indirectly caused by the co-doping: i) Na optimizes in-plane charge transfer, ii) K builds channel for interplane charge transfer, iii) cyano group as Lewis acid site adsorbs and activates oxygen, iv) amino group as Lewis base site extracts and releases protons, v) increased visible-light absorption. This work offers significant insights into designing polymeric photocatalysts for environmental management and energy conservation.