Atomically dispersed Co-N4 to activate peroxymonosulfate for efficient atrazine degradation: Synergistic radical and non-radical ways
Yu Yin, Xuan Li, Wenning Li, Abdul Hannan Asif, Shuting Pan, Sheng Cui, Shaobin Wang, Hongqi Sun
Abstract
Cobalt based nanomaterials are widely employed as effective catalysts for peroxymonosulfate (PMS) activation in advanced oxidation processes (AOPs). Single atom catalysts (SACs) are state-of-the-art materials that endow active metal sites with maximal exposure to the reactants. In this study, molybdenum disulfide nanospheres with a crumpled surface (cnMoS2) were designed and synthesized to decorate atomically dispersed Co-N4 sites by immobilizing Co in its unique surface fold structure with a nitrogen/carbon coating. The resulting Co-N-C-cnMoS2 catalysts were used to activate PMS for rapid degradation of atrazine (ATZ). The Co-N4 sites were considered to be the main active sites, enabling the optimal 4.8Co-N-C-cnMoS2 catalyst to remove 100 % of ATZ within 20 min. In addition, 4.8Co-N-C-cnMoS2 catalyst also showed good durability, tolerance to inorganic anions and cations, and high activity in a wide pH range. The cnMoS2 provided a platform to hold atomically Co-N4 sites, played the degradation roles though it was secondary, and moreover accelerated Co2+/Co3+ cycles. In the 4.8Co-N-C-cnMoS2/PMS system, sulfate radical (SO4• ‾), hydroxyl radicals (•OH), superoxide radical (O2• ‾) and singlet oxygen (1O2) were generated, among which SO4• ‾ and 1O2 were the predominant active substances triggering the ATZ degradation.