Anchoring cobalt dual-atom pairs on open hollow-structured carbon via a facile in-situ synthetic strategy for enhanced advanced oxidation processes

Atomically dispersed catalysts offer unprecedented opportunities for high-efficiency Fenton-like oxidation of organic pollutants in water. However, the hazardous metal leaching of atomically dispersed catalysts hinders their practical application for wastewater treatment, while the inaccessible interior active sites in carbon substrates have been commonly overlooked. Herein, we develop a straightforward approach for tightly anchoring cobalt dual-atom pairs on nitrogen-doped open hollow carbon structure (Co-NOHC) via an in-situ polyelectrolyte nanosphere-guided strategy. The unique open hollow carbon structure benefits the electron/mass transfer and maximizes the exposure of active sites. As a result, the as-synthesized Co-NOHC exhibits outstanding peroxymonosulfate activation activity and Fenton-like performance in oxidation by taking rhodamine B degradation as an example. Remarkably, the turnover frequency of the Co-NOHC is 6.5, 26.5, and 9.3 times higher than that of the Co²⁺, cobalt, and its oxides, respectively, and its catalytic activity also greatly outperforms the pristine zeolitic-imidazole frameworks derived Co-based atomically dispersed catalysts. More importantly, benefitted from the stable anchoring of cobalt dual atoms, the Co²⁺ leaching from the Co-NOHC is greatly alleviated, as low as 0.1 mg/L after the catalytic reaction, showing outstanding stability as compared to most atomically dispersed catalysts. Furthermore, the reactive active species, including SO₄^[rad]−, ^[rad]OH and O₂^[rad]− radicals, and electron-transfer mechanism are demonstrated to dominate the rhodamine B removal. This work offers a new consideration for promoting the development of the advanced catalysts and their potential applications in advanced oxidation process.