Unveiling Spin State-Dependent Micropollutant Removal using Single-Atom Covalent Triazine Framework

Single-atom materials, with unique electronic structure and maximized atom utilization, have shown huge application potential in the remediation of emerging organic pollutants (EOPs), but revealing intrinsic reaction mechanisms at spin state level remains a formidable challenge. Herein, a single-atom Ti-loaded covalent organic framework (Ti-1/CTF) is constructed for two-stage process that involved adsorption and photocatalytic synergy, and the essential role of the electronic spin state in regulating the intrinsic activity of the material is evidenced. Spin-polarized Ti-1-N-3/CTF-10 considerably enhances the adsorption capacity (453.285 mu mol g(-1)) and degradation kinetics (2.263 h(-1), 17.0-fold faster than CTF-0) for 2,2,4,4'-tetrehydroxybenzophenone (BP-2) and provides long-term stability (93.3% BP-2 removal in seven cycles) and favorable cost-effectiveness (4.45 kWh center dot m(-3) electrical energy per order) in natural water applications. Theoretical calculations and experimental results suggest that the Ti-1-N-3 moieties of single-atom Ti bonded to pyridine and triazine N induce electron spin-down polarization near the Fermi energy level of the active site, providing a strong dipole force and motive power for electron transfer. This study provides new insights into the adsorption, activation, and photodegradation of EOPs at the material interface from the electronic spin level and demonstrates promising solutions for water micropollution control.

Automated summary

In this study, a single-atom Ti-loaded covalent organic framework (Ti-1/CTF) was constructed and demonstrated to have great potential in the adsorption and photocatalytic degradation of organic pollutants. The essential role of the electronic spin state in regulating the material's activity was proven. The spin-polarized Ti-1-N-3/CTF-10 showed enhanced adsorption capacity and degradation kinetics for a specific pollutant, along with long-term stability and favorable cost-effectiveness in natural water applications.