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.