通过简单的高温热聚合法制备了氧缺陷富氮氮化碳（C₃N₅-O）光催化剂，采用X射线衍射（XRD）、X射线光电子能谱（XPS）、电子顺磁共振波谱（EPR）、紫外可见漫反射光谱（UV-vis DRS）、光致发光光谱（PL）、瞬态光电流谱（TPC）和电化学交流阻抗谱（EIS）等技术手段对光催化剂的物相组成、元素组成、未成对电子、光谱吸收、光电子-空穴重组和电化学性质等进行了表征。C₃N₅-O光催化剂表现出优异的光催化活性和稳定性，可见光照射60 min，C₃N₅-O光催化剂对罗丹明B（RhB）的降解率达到97.49%，是纯C₃N₅的1.49倍，循环10次仍表现出优异的光催化活性，降解率仍高于96%。硅酸盐水泥、水和C₃N₅-O光催化剂混合均匀通过涂刷法均匀涂抹到混凝土基体表面，制备得到C₃N₅-O复合混凝土涂层，C₃N₅-O的最佳掺杂量为1.5%（质量分数），涂层具有良好的光催化性能和稳定性，可见光照射60 min时RhB的降解率达到97.31%，循环使用10次后RhB的降解率为96.94%。通过XRD、热重分析（TGA）和孔径分布（BJH）分析了涂层的水化产物、热失重和孔隙，研究了C₃N₅-O掺入后对水泥水化的影响。C₃N₅-O掺入后通过晶核效应和填充效应促进了水泥的水化进程，加快了水化产物的生成，提高了基体抗压强度，养护28 d混凝土的抗压强度提高了8.51%。

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%.