钾离子掺杂对石墨型氮化碳光催化剂能带结构及光催化性能的影响

Effect of K^+ Doping on the Band Structure and Photocatalytic Performance of Graphitic Carbon Nitride Photocatalysts

以双氰胺和氢氧化钾为原料制备了能带可控的钾离子掺杂石墨型氮化碳(g-C3N4)光催化剂,并与碱处理的g-C3N4及g-C3N4/KOH复合催化剂进行了对比.采用X射线衍射(XRD)光谱、紫外-可见(UV-Vis)光谱、傅里叶变换红外(FTIR)光谱、N2吸附、电感耦合等离子体-原子发射光谱(ICP-AES)、荧光(PL)光谱、X光电子能谱(XPS)等分析手段对制备的催化剂进行了表征.结果表明,钾离子含量对氮化碳催化剂的价带及导带位置有显著影响.此外,钾离子的引入抑制了氮化碳晶粒的生长,提高了氮化碳的比表面积以及对可见光的吸收,降低了光生电子-空穴对的复合几率.以染料罗丹明B的降解为探针反应系统研究了钾离子掺杂对g-C3N4在可见光下催化性能的影响,研究了光催化反应机理.结果表明,钾离子掺杂后氮化碳的光催化性能显著提高.制备的钾离子掺杂氮化碳催化剂表现出良好的结构及催化稳定性.

A series of band gap-tunable K^＋ doped graphitic carbon nitride （g-C,N,） photocatalysts have been prepared using potassium hydrate and melamine as precursors, and fully characterized by X-ray diffraction （XRD）, UV-Vis spectroscopy, inductively coupled plasma-atomic emission spectroscopy （ICP-AES）, Fourier transform infrared （FTIR） spectroscopy, N2 adsorption, photoluminescence （PL）, and X-ray photoelectron spectroscopy （XPS）. The results of these analyses indicated that the positions of the valence and conduction bands were obviously changed as the concentration of K^＋ increased. The K^＋ ions were found to be embedded in the structural units of the g-C3N4 which inhibited the growth of the graphitic carbon nitride crystals, enhanced the surface area, and increased the separation rate of the photogenerated electrons and holes. The activity of K^＋ doped g-C3N4 catalysts was tested towards the photocatalytic degradation of rhodamine B （RhB） under visible light irradiation. The result indicated that the activity improved significantly after K^＋ doping. Furthermore, the K^＋ doped g-C3N4 catalysts exhibited outstanding structural and catalytic stability.