Fe, Co, N co-doped hollow carbon capsules as a full pH range catalyst for pollutant degradation via a non-radical path in Fenton-like reaction.

Fe, Co, N atoms co-doped hollow carbon capsules was prepared and used as metal-free catalysts for PMS activation. In Fenton-like reaction, it displayed high degradation rate and outstanding adaptation to full pH range (0–14). [Display omitted] • Fe-Co-N@HCCs displays high PMS activation property in a full range of pH values. • k of Fe-Co-N@HCC is 3.1 and 1.4 times higher than N@HCCs and Fe-N@HCCs. • Contribution of radicals, 1O 2 , electron-transfer path is 13.3%, 30.1%, 56.6%. • PMS is activated on Fe-N 4 and Co-N 4 sites for 1O 2 , Co-N 4 site shows better activity. • Leached Fe and Co ions is 24.9 and 13.6 times lower than Fe-Co-N@HCCs/FeCo. Persulfate (PMS)-based Fenton-like reaction was a highly efficient technique for disposal of organic contaminants. However, high metal leaching and low environmental adaptation were the major concerns for further application. To overcome these two drawbacks, herein, Fe, Co, N atoms co-doped hollow carbon capsules (Fe-Co-N@HCCs) were prepared and used as catalysts for PMS activation. 92.6% of TC was degraded within 40 min and the mineralization efficiency was 55.7%. The degradation rate was 4.7, 3.1 and 1.4 times higher than those of activated carbon, N@HCCs, and Fe-N@HCCs, respectively. Thermodynamic study indicated the TC degradation was an exothermal, chaotic and non-spontaneous process. Radical trapping experiments, electron paramagnetic resonance spectrum, and electrochemical analysis indicated that 1O 2 production and electron-transfer path worked together for PMS activation. DFT calculation indicated that the catalytic activity of Co-N 4 site was higher than Fe-N 4 site for 1O 2 production. Fe-Co-N@HCCs were adapted well to the full pH range (0–14) and complex inorganic anions via non-radical PMS activation paths. Meanwhile, the leached Fe and Co ions were lowered to 0.201 and 0.457 mg/L, satisfying the China emission standard. This work gave a better comprehension on preparation of carbonaceous materials with high environmental adaptation and low leached metal ions for PMS activation. [ABSTRACT FROM AUTHOR]