Xu Huan-Yan, Wu Li-Cheng, Zhao Hang, Jin Li-Guo, Qi Shu-Yan
School of Materials Science and Engineering, Harbin University of Science and Technology, Harbin, P. R. China.
PLoS One. 2015 Nov 13;10(11):e0142616. doi: 10.1371/journal.pone.0142616. eCollection 2015.
Graphitic carbon nitride (g-C3N4) used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB) under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500) had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500), which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO) was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed.
本工作中使用的石墨相氮化碳（g-C3N4）分别通过在不同温度下加热双氰胺和三聚氰胺获得。通过X射线衍射、傅里叶变换红外光谱、扫描电子显微镜、透射电子显微镜、X射线光电子能谱、紫外可见漫反射光谱和BET比表面积分析仪，分别研究了不同前驱体制备的g-C3N4在相组成、官能团、表面形貌、微观结构、表面性质、带隙和比表面积方面的差异。活性阳离子染料亚甲基蓝（MB）在可见光照射下的光催化褪色表明，500°C下由三聚氰胺制备的g-C3N4（CN-M500）比500°C下由双氰胺制备的g-C3N4（CN-D500）具有更高的吸附容量和更好的光催化活性，这归因于CN-M500更大的表面积。CN-M500上MB的褪色率受初始MB浓度和光催化剂用量的影响。反应120分钟后，MB溶液的蓝色完全消失。随后，基于对不同pH值下CN-M500表面Zeta电位的测量，选择活性阴离子染料甲基橙（MO）作为与MB对比的目标污染物，以揭示吸附和光催化之间的协同效应。最后，对光催化机理进行了讨论。
