Department of Chemistry, Amirkabir University of Technology (Tehran Polytechnic) , P.O. Box 15875-4413, Tehran, Iran.
Langmuir. 2017 Jul 18;33(28):7062-7078. doi: 10.1021/acs.langmuir.7b01767. Epub 2017 Jul 6.
Mesoporous sulfur-doped graphitic carbon nitride (MCNS) materials were successfully synthesized using thiourea as a low-cost precursor and SiO gel solution as a template through a simple thermal condensation method. The effects of three synthesis key factors, namely, the reaction temperature, the reaction time, and the weight ratio of SiO/thiourea, and also their interactions on the removal rate of methyl orange (MO) were investigated using response surface methodology, and the samples were subjected to several characterization techniques. Results showed that the optimized physicochemical properties could be achieved for the MCNS samples by controlling the synthesis key factors, and it was found that the reaction temperature and the reaction time had significant influences on the MO photocatalytic removal. Among bulk graphitic carbon nitride (g-CN), CN (undoped g-CN), CNS (sulfur-doped g-CN without template), and TiO (Degussa P25) samples, the optimized MCNS-4 illustrated the highest photocatalytic activity toward the removal of MO under visible light irradiation. The enhanced performance originated from the synergistic effects of high surface area, mesoporous texture, sulfur doping, and high visible light absorption, which were helpful for the separation and transportation of the photogenerated electron-hole pairs. Furthermore, MCNS-4 revealed high reusability and stability without any significant decrease in its efficiency. Our findings not only confirm the importance of simultaneous sulfur doping and mesoporous structure to synthesize highly active photocatalysts but also might provide a new insight into textural engineering of carbon nitride materials only by the optimization of the synthesis key variables, considering their interactions without relying on extra metal oxides.
采用硫掺杂介孔石墨相氮化碳（MCNS）材料作为模板，通过简单的热缩聚法，以硫脲为低成本前体、SiO 凝胶溶液为模板，成功合成了 MCNS 材料。采用响应面法考察了三个合成关键因素（反应温度、反应时间和 SiO/硫脲的质量比）及其相互作用对甲基橙（MO）去除率的影响，并对样品进行了多种表征技术。结果表明，通过控制合成关键因素，可以获得 MCNS 样品的最佳物理化学性能，发现反应温度和反应时间对 MO 的光催化去除有显著影响。在块状石墨相氮化碳（g-CN）、CN（未掺杂 g-CN）、CNS（无模板硫掺杂 g-CN）和 TiO（Degussa P25）样品中，优化后的 MCNS-4 表现出在可见光照射下对 MO 去除的最高光催化活性。性能的提高源于高比表面积、介孔结构、硫掺杂和高可见光吸收的协同效应，这有助于光生电子-空穴对的分离和传输。此外，MCNS-4 表现出高的可重复使用性和稳定性，没有任何效率的显著下降。我们的研究结果不仅证实了同时进行硫掺杂和介孔结构合成高活性光催化剂的重要性，而且可能为氮化碳材料的结构工程提供了新的思路，只需优化合成关键变量，考虑它们的相互作用，而不依赖于额外的金属氧化物。
