Abstract: The potassium-doped graphitic carbon nitride was prepared by using dicyandiamide, thiourea, melamine, potassium hydroxide and potassium iodide as raw materials under different conditions. The influence of different preparation temperature, potassium source and doping amount on the photocatalytic performance was systematically investigated. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection absorption spectrum (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and specific surface area analysis (BET). The results show that the doped samples reduce the bandwidth, increase the absorption of visible light, reduce the recombination rate of photogenerated electron-hole pairs and significantly improve the photocatalytic performance of the samples, compared with the pure graphite carbon nitride (g-C3N4). The results of photocatalytic degradation of samples with different temperatures and different doping ratios were compared. It is found that the samples using thiourea and potassium iodide as raw materials have best photocatalysis effect, which are obtained at 550 ℃, with the calcination time of 4 h and under the preparation condition that the doping ratio of potassium ion to carbon nitride is 0.1. Its photocatalytic degradation rate was 4.29 times higher than that of g-C3N4.

Key words: highway engineering, graphitic carbon nitride, photocatalysis, potassium, methylene blue (MB)

摘要： 采用二氰二胺、硫脲、三聚氰胺、碘化钾和氢氧化钾为原料制备钾掺杂石墨相氮化碳，系统地研究了不同制备温度、钾源、掺杂量等条件对其光 催化性能的影响。通过X射线衍射（XRD）、紫外-可见漫反射吸收光谱（UV-vis）、扫描电镜（SEM）、透射电镜（TEM）、比表面积分析（BET）等对样品 进行表征分析。结果表明：掺杂后的样品与纯石墨相氮化碳（g-C3N4）相比，减小了能带宽度，提高了对可见光的吸收，降低了光生电子-空穴对的复合 率，进而显著提高了样品的光催化性能。对比不同温度、不同掺杂比的样品的光催化降解实验结果，发现以硫脲和碘化钾为原料，在550 ℃、煅烧时间 为4 h，钾离子与氮化碳掺杂摩尔比为0.1的制备条件下所得的样品光催化效果最佳，其光催化降解速率是g-C3N4的4.29倍。

关键词: 道路工程, 石墨相氮化碳, 光催化, 钾, 亚甲基蓝