Zhang Shuting, Li Guoqiang, Duan Liyuan, Wang Hongyu, Zhao Yongle, Zhang Yongfa
Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province, Taiyuan University of Technology Taiyuan 030024 China
RSC Adv. 2020 May 22;10(33):19669-19685. doi: 10.1039/d0ra02454f. eCollection 2020 May 20.
Graphitic carbon nitride (g-CN) was prepared by a simple thermal polymerization method in this work. The effects of precursor type, thermal polymerization temperature, constant temperature time and atmosphere on the crystal structure, morphology, elemental composition, valence distribution, light absorption properties and photocatalytic activity of the prepared photocatalytic materials were investigated. Taking rhodamine B (RhB) as the target degradant, the blue light catalytic activity of the photocatalytic material was studied in detail. The experimental results showed that the final pyrolysis temperature and constant temperature time are positively related to the adsorption characteristics and photocatalytic ability of the prepared materials. In addition, the adsorption capacity and photocatalytic activity of the products obtained in Ar and H atmospheres are better than those produced in CO and CH, which can be attributed to the combined effect of large specific surface area and structural defects of the materials. The sample's large specific surface area, wide band gap, and excellent photogenerated carrier separation and transfer capabilities make the adsorption performance and photocatalytic performance of the products obtained with ammonium thiocyanate and thiourea as precursors better than those prepared from melamine and dicyandiamide. g-CN prepared by using ammonium thiocyanate as precursor at 550 °C for 5 h under a hydrogen atmosphere showed the best catalytic activity for the degradation of RhB under blue light. It was demonstrated that g-CN prepared exhibited good stability and reusability after four repeat experiments. The active components that play major roles in the degradation of RhB described herein were holes and superoxide radicals, which was inferred by free radical trapping experiments. This work provides a theoretical basis for the idea of converting the mixed salts of desulfurization waste liquid containing ammonium thiocyanate into an excellent photocatalyst g-CN with visible light response.
本工作采用简单的热聚合方法制备了石墨相氮化碳（g-CN）。研究了前驱体类型、热聚合温度、恒温时间和气氛对所制备的光催化材料的晶体结构、形貌、元素组成、价态分布、光吸收性能和光催化活性的影响。以罗丹明B（RhB）为目标降解物，详细研究了光催化材料的蓝光催化活性。实验结果表明，最终热解温度和恒温时间与所制备材料的吸附特性和光催化能力呈正相关。此外，在Ar和H气氛中获得的产物的吸附容量和光催化活性优于在CO和CH气氛中产生的产物，这可归因于材料的大比表面积和结构缺陷的综合作用。样品的大比表面积、宽带隙以及优异的光生载流子分离和转移能力使得以硫氰酸铵和硫脲为前驱体制备的产物的吸附性能和光催化性能优于由三聚氰胺和双氰胺制备的产物。在氢气气氛下，以硫氰酸铵为前驱体，于550℃下热聚合5h制备的g-CN对蓝光下RhB的降解表现出最佳的催化活性。结果表明，所制备的g-CN在四次重复实验后表现出良好的稳定性和可重复使用性。通过自由基捕获实验推断，在本文所述的RhB降解过程中起主要作用的活性成分是空穴和超氧自由基。本工作为将含硫氰酸铵的脱硫废液混合盐转化为具有可见光响应的优异光催化剂g-CN这一设想提供了理论依据。
