Waste Eggshell-derived N, P, S Tri-doped Core-shell Catalysts for Efficient Fenton-like Catalysis

• Waste eggshell was conversed into N, P, S tri-doped core–shell catalyst. • The Co@NPSC was synthesized by a simple molten salt electrolysis. • The tri-doped Co@NPSC catalyst showed an ultra-high TOF value of 83.86 min −1 . • The synergistic essence of catalytic oxidation was revealed by DFT calculation. • The degradation of SMX equals detoxification was confirmed. Heteroatom-doped carbon materials have been proved as potent catalysts for the remediation of organic contaminants. Herein, molten salt electrolysis (MSE) was employed to convert waste eggshell and Co 3 O 4 into N, P, S tri-doped core–shell catalyst (Co@NPSC), achieving the conversion of waste eggshell into value-added materials. Impressively, Co@NPSC/peroxymonosulfate (PMS) system exhibited an exceptional ultra-high turnover frequency (TOF) value of 83.86 min −1 for sulfamethoxazole (SMX) degradation with a low catalyst dosage of 0.001 g L –1 . Subsequently, density functional theory (DFT) simulation clarified the synergistic essences of catalytic oxidation (i.e., the Co@NPSC catalyst reduced the adsorption energy of PMS molecular on its surface, reduced itself work function, enhanced the length of the O-O bond ( I O-O ) of PMS molecule, and facilitated electron transfer for PMS activation). In addition, both theoretical predictions and acute toxicity assay results indicated that the degradation of SMX equals detoxification. This work provides a new insight into the reutilization of waste eggshell and the design of heteroatom-doped core–shell catalysts.