Design of a highly active interfacial catalyst based on synergistic S/Se dual vacancies for the degradation of the highly hazardous emerging pollutant octogen (HMX): Interfacial PMS activation mechanism and electron pathway optimization.

To address the urgent threat of energetic pollutants to soil and water, this study proposes a controllable dual-defect hydrothermal assembly strategy to anchor CoS and FeSe₂ onto phenolic resin-derived carbon spheres (PC), fabricating a 3D interfacial catalyst PC@CoS-FeSe₂ with abundant S/Se vacancies. The catalyst efficiently activates PMS over a wide pH range, achieving complete removal of HMX from aqueous solution within 10 min, with a maximum k of 0.5048 min⁻¹ . Synchrotron radiation and DFT calculations reveal that synergy between S/Se dual vacancies and the highly active CoS/FeSe₂ interface optimizes electron migration, significantly enhancing catalytic performance; band structure analysis confirms that the CoS-FeSe₂ interaction markedly improves electron filling efficiency near the Fermi level, accelerating charge transport across the heterojunction interface. EPR and quenching experiments verified the contributions of ROS to both radical and non-radical pathways during HMX degradation. MD simulations compared the dynamic evolution and bonding tendencies of PMS and HMX interacting with the catalyst and its individual components. HPLC-MS identified degradation intermediates, and four novel degradation pathways for HMX were proposed. Intermediates' toxicity was assessed using T.E.S.T. System practicality was evaluated by continuous-flow column experiments. The dual-defect-rich 3D catalyst PC@CoS-FeSe₂ shows promise for degrading hazardous nitramine pollutants and environmental remediation.