Efficient Peroxymonosulfate Activation over Cobalt-Encapsulated Nitrogen-Doped Carbon Hollow Nanospheres toward Tetracycline Degradation: Performance and Catalytic Mechanism
Jin Qian, Sai Bai, Guoping Xiang, Dandan Zhang, Junmei Zhou, Minxian Cheng, Xiaohong Zhao, Xinying Chen, Yichu Zhang, Yueping Bao, Xiangning Xu
Abstract
In this study, cobalt-encapsulated nitrogen-doped carbon hollow nanospheres (Co@NCs) were synthesized for peroxymonosulfate (PMS) activation and tetracycline (TC) degradation. Co@NCs synthesized at a high pyrolysis temperature exhibited relatively higher graphitic N and C═C contents, which effectively regulated the electron density of Co sites, enhancing the PMS activation efficiency. In the Co@NCs-900/PMS system, remarkable TC removal efficiency (97.14%, k obs = 0.179 min –1 ) and TOC removal (63.62%) were achieved within 60 min. Based on the quenching tests, EPR technology, and electrochemical measurements, a synergistic radical and nonradical pathway was unveiled, with SO 4 •–, 1 O 2, and ETP dominated. Co@NCs-900/PMS showed efficient catalytic performance and practical application potentials without interference from organic and inorganic compounds under the experimental background. Additionally, over 80% TC removal could be achieved after the seven-cycle catalytic reaction and showed negligible Co 2+ leaching, indicating superior recyclability. Chemical analysis and DFT calculation revealed that PMS adsorption and activation could be strengthened by modulating the electron density with Co and N serving as the active sites. Overall, this study provides valuable insights into the incorporation of metal sites on N-doped carbonaceous catalysts for Fenton-like reactions in water purification applications.