Freeze-drying precursor to construct carbon nitride photocatalyst with low addition and high adsorption performance

Abstract

BackgroundIn photocatalytic reactions, how to maintain the high efficiency of the photocatalysts with a small number of catalysts is a key challenge. MethodsIn this paper, the alkali metal ions (Na+ or K+) doped carbon nitride (Na-CN/K-CN) were prepared by the combination of freeze-drying and molten salt assisted calcination to solve this problem. Significant findingsAlkali metal salts and dicyandiamide were rapidly nucleated and interconnected during the freeze-drying stage. After calcination, Na-CN and K-CN with strong interaction between Na+/K+ and carbon nitride were obtained. This strong interaction reduced the electron cloud density near the N atom and further caused strong adsorption capacity and high oxidation capacity, thus improving the photocatalytic performance of Na-CN and K-CN. Compared with K-CN, Na-CN had stronger electron-hole separation ability, which made it exhibit higher photocatalytic activity. After 60 min of visible light irradiation, only 5 mg of Na-CN could degrade 63.79% of MB with a concentration of 30 mg/L.