Electrolytic core–shell Co@C for diethyl phthalate degradation

Abstract

• A high-value utilization strategy of CO 2 converted carbon materials was provided. • CO 2 was used as a feedstock to prepare Co@C catalyst. • Co@C was synthesized by the molten salt electrochemical conversion. • Co@C catalyst showed a high turnover frequency value of 2.28 min −1 . • DFT calculations identified the activation mechanism of PMS by Co@C. Greenhouse gases carbon dioxide (CO 2 ) can be converted into high value-added carbon materials by molten salt electrolysis. Herein, we employ CO 2 as the inorganic carbon source to prepare a core–shell catalyst (Co@C) by molten salt electrolysis for the activation of peroxymonosulfate (PMS) to degrade diethyl phthalate (DEP). The electrolytic Co@C catalyst presents a high catalytic performance for the degradation of DEP with a high turnover frequency (TOF) value (2.28 min −1 ), a relatively low catalyst dosage (Cat = 50 mg L –1 ), low oxidant concentration (PMS = 0.46 mM), a wide range of pH applicability (pH = 3–9), and low activation energy ( E a = 38.88 kJ mol −1 ). In addition, the Co leaching rate is low (<1 mg L –1 ) in the pH range of 5–11 and the total organic carbon (TOC) removal was reached 78.9% under the catalyst dosage was 50 mg L –1 . The DEP degradation pathways mainly involved ethyl formate elimination, ethoxy abstraction, carboxyl abstraction, decarboxylation, hydroxy abstraction, esterification and ring cleavage of DEP. Further, theoretical calculations confirm that Co nanoparticles (Co NPs) encapsulated with graphitized carbon shell derived from CO 2 reduce the work function (WF) of catalysts, enhance the length of bond O–O ( I O-O ) of PMS molecule, and facilitate the charge transfer from the catalysts to PMS molecule. This work provides a new insight into the utilization of CO 2 served as inorganic carbon sources and the design of heterogeneous catalysts.