In Situ Utilization of Co-Existing Metal Ions to Fabricate Single-Atom Catalyst for Boosting Fenton-Like Activity

Heavy metals and organic pollutants commonly co-exist in the industrial wastewaters, and traditional treatment processes always treat them separately. Heavy metals can be effective active sites in heterogeneous Fenton-like catalysts, and their potential for in situ utilization and enhancement for organic pollutant degradation is promising but still underexplored. Herein, the metal-free TQBQ-COF is employed with abundant pre-designed metal-2N anchoring sites for the in situ capture of Cu²⁺ ions for boosting organic pollutant degradation. The co-existing Cu²⁺ can be successfully utilized to in situ fabricate a novel single-atom catalyst (SAC) within 1 min. The coordinated Cu significantly enhances visible-light absorption and charge separation ability, thereby substantially improving the catalyst's Fenton-like performance (the k value is 240 folds higher than that in the absence of TQBQ-COF). Singlet oxygen (¹O₂) and photogenerated holes (h⁺) are identified as the main active species. In real wastewater with exceptionally high concentrations of Cu and chemical oxygen demand (COD), effective synergistic removal of organic pollutants and heavy metals can still be achieved, further demonstrating the applicability of this strategy. This work provides new insights into catalyst design and a new strategy of "treating waste with waste" for heterogeneous water-treatment technologies.