Cobalt Single Atoms Anchored on Oxygen‐Doped Tubular Carbon Nitride for Efficient Peroxymonosulfate Activation: Simultaneous Coordination Structure and Morphology Modulation

Simultaneous regulation of the coordination environment of single‐atom catalysts (SACs) and engineering architectures with efficient exposed active sites are efficient strategies for boosting peroxymonosulfate (PMS) activation. We isolated cobalt atoms with dual nitrogen and oxygen coordination (Co−N3O1) on oxygen‐doped tubular carbon nitride (TCN) by pyrolyzing a hydrogen‐bonded cyanuric acid melamine–cobalt acetate precursor. The theoretically constructed Co−N3O1 moiety on TCN exhibited an impressive mass activity of 7.61×105 min−1 mol−1 with high 1O2 selectivity. Theoretical calculations revealed that the cobalt single atoms occupied a dual nitrogen and oxygen coordination environment, and that PMS adsorption was promoted and energy barriers reduced for the key *O intermediate that produced 1O2. The catalysts were attached to a widely used poly(vinylidene fluoride) microfiltration membrane to deliver an antibiotic wastewater treatment system with 97.5 % ciprofloxacin rejection over 10 hours, thereby revealing the suitability of the membrane for industrial applications.

Single-atom copper embedded in two-dimensional MXene toward peroxymonosulfate activation to generate singlet oxygen with nearly 100% selectivity for enhanced Fenton-like reactions

Theoretical study of local S coordination environment on Fe single atoms for peroxymonosulfate-based advanced oxidation processes

Transition metal single-atom embedded on N-doped carbon as a catalyst for peroxymonosulfate activation: A DFT study

The microenvironment regulation of Fe-N4 single atom catalysts (SACs) critically governs peroxymonosulfate (PMS) activation. Although conventional heteroatom substitution in primary coordination enhances activity, it disrupts Fe-N4 symmetry and compromises stability. Herein, we propose oxygen doping in the secondary coordination shell to construct Fe-N4-C6O2 SAC, which amplifies the localized electric field while preserving the pristine coordination symmetry, thus trading off its activity and stability. This approach suppresses Fe-N bond structural deformation (bond amplitude reduced from 0.875–3.175 Å to 0.925–2.975 Å) during PMS activation by lowering Fe center electron density to strengthen Fe-N bond, achieving extended catalytic durability (>240 h). Simultaneously, the weakened coordination field lowers the Fe=O σ* orbital energy, promoting electrophilic σ-attack of high-valent iron-oxo towards bisphenol A, and increasing its degradation rate by 41.6-fold. This work demonstrates secondary coordination engineering as a viable strategy to resolve the activity-stability trade-off in SAC design, offering promising perspectives for developing environmental catalysts.

The overlooked role of different Fe-N4Cx configuration in single atom catalyst for efficient peroxymonosulfate activation

Efficient diclofenac removal by superoxide radical and singlet oxygen generated in surface Mn(II)/(III)/(IV) cycle dominated peroxymonosulfate activation system: Mechanism and product toxicity

Bioinspired axial S-coordinated single-atom cobalt catalyst to efficient activate peroxymonosulfate for selective high-valent Co-Oxo species generation

Directing the persulfate activation reaction pathway by control of Fe-Nx/C single-atom catalyst coordination

Precise modulation of the axial coordination microenvironment in single-atom catalysts (SACs) to enhance peroxymonosulfate (PMS) activation represents a promising yet underexplored approach. This study introduces a pyrolysis-free strategy to fabricate SACs with well-defined axial-FeN4+1 coordination structures. By incorporating additional out-of-plane axial nitrogen into well-defined FeN4 active sites within a planar, fully conjugated polyphthalocyanine framework, FeN4+1 configurations are developed that significantly enhance PMS activation. The axial-FeN4+1 catalyst excelled in activating PMS, with a high bisphenol A (BPA) degradation rate of 2.256 min-1, surpassing planar-FeN4/PMS systems by 6.8 times. Theoretical calculations revealed that the axial coordination between N and the Fe sites forms an optimized axial FeN4+1 structure, disrupting the electron distribution symmetry of Fe and optimizing the electron distribution of the Fe 3d orbital (increasing the d-band center from -1.231 to -0.432eV). Consequently, this led to an enhanced perpendicular adsorption energy of PMS from -1.79 to -1.82eV and reduced energy barriers for the formation of the key reaction intermediate (O*) that generates 1O2. This study provides new insights into PMS activation through the axial coordinated engineering of well-defined SACs in water purification processes.

Coordination environment and architecture engineering over Co4N-based nanocomposite for accelerating advanced oxidation processes

Bio-porphyrin supported single-atom iron catalyst boosting peroxymonosulfate activation for pollutants degradation: A Singlet Oxygen-dominated nonradical pathway

Versatile pathways for oxidating organics via peroxymonosulfate activation by different single atom catalysts confining with Fe–N4 or Cu–N4 sites

Multi-pathway on peroxymonosulfate activation by single cobalt atoms incorporated on CuO with enriched oxygen vacancies for high-efficient oxidation of tetracycline

Novel Ag3PO4 modified tubular carbon nitride with visible-light-driven peroxymonosulfate activation: A wide pH tolerance and reaction mechanism