关键词: 富氮氮化碳, 氧缺陷, 光催化, 混凝土涂层, 罗丹明B

Abstract:

The oxygen-deficient nitrogen-rich carbon nitride（C₃N₅-O） photocatalyst was prepared by a simple high-temperature thermal polymerization method.The phase composition，elemental composition，unpaired electrons，spectral absorption，photoelectron-hole recombination and electrochemical properties of the photocatalyst were characterized by X-ray diffraction（XRD），X-ray photoelectron spectroscopy（XPS），electron paramagnetic resonance spectroscopy（EPR），UV-vis diffuse reflectance spectroscopy（UV-vis DRS），photoluminescence spectroscopy（PL），transient photocurrent spectroscopy（TPC） and electrochemical impedance spectroscopy（EIS）.The C₃N₅-O photocatalyst showed excellent photocatalytic activity and stability.The degradation rate of rhodamine B（RhB） by C₃N₅-O photocatalyst reached 97.49% after visible light irradiation for 60 min，which was 1.49 times that of pure C₃N₅.After 10 cycles，it still showed excellent photocatalytic activity，and the degradation rate was still higher than 96%.Portland cement，water and C₃N₅-O photocatalyst were uniformly mixed and uniformly applied to the surface of concrete matrix by brushing method to prepare C₃N₅-O composite concrete coating.The optimum doping amount of C₃N₅-O was 1.5%（mass fraction）.The coating had good photocatalytic performance and stability.The degradation rate of RhB reached 97.31% within 60 min under visible light irradiation，and the degradation rate of RhB was 96.94% after 10 cycles.The hydration products，thermal weight loss and pores of the coatings were analyzed by XRD，thermogravimetric analysis（TGA） and pore size distribution（BJH）.The effect of C₃N₅-O incorporation on cement hydration was studied.The incorporation of C₃N₅-O promoted the hydration process of cement through the nucleation effect and filling effect，promoted the formation of hydration products，and improved the compressive strength of the matrix，the compressive strength of concrete cured for 28 d was increased by 8.51%.

Key words: nitrogen rich carbon nitride, oxygen defects, photocatalysis, concrete coating, rodamine B