Atomically dispersed Co-N4 to activate peroxymonosulfate for efficient atrazine degradation: Synergistic radical and non-radical ways

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.