Thermal-Driven Coordination Microenvironment Reconstruction in Single-Atom Catalysts Unlocks Ultrafast Water Remediation

Fine-tuning the local coordination environments (LCEs) of single-atom catalysts (SACs) represents a promising strategy for enhancing the Fenton-like catalytic activity. However, the rational design of SACs with improved performance by controlling LCEs depends on time-consuming trial-and-error approaches, necessitating significant effort to elucidate the reaction mechanisms and structure–performance relationships. Herein, we present a solvent-free mechano-driven synthesis strategy that tunes LCEs in Fe-based SACs (Fe–N₄ and Fe–N₅) by adjusting pyrolysis temperature. SACs with optimal LCEs (SA-FeN₄) achieved exceptional phenol degradation with an apparent rate constant of 1.90 min^–1 for peroxymonosulfate (PMS) activation, ranking among the top performances of state-of-the-art SACs and nanoparticle catalysts. Density functional theory calculations indicate that the Fe–N₄ configuration induces symmetry electronic structures, which create electron-deficient Fe centers for accelerated interactions between the PMS and Fe–N sites. This configuration facilitates O–H bond stretching and reduces the energy barrier for singlet oxygen generation. Consequently, the phenol degradation efficiency was maintained at >99% in long-term stability tests at the device level after continuous operation for over 250 h, confirming the practical applicability of the as-fabricated catalyst for industrial-scale wastewater treatment. This work provides a rational approach for designing efficient and environmentally friendly catalysts for environmental remediation.