Sulfate radical dominated rapid pollutants degradation leaded by selenium vacancies in core-shell N-doped carbon wrapped cobalt diselenide nanospheres

Abstract

Herein, a new heterogeneous CoSe_2-x@NC material with abundant selenium vacancies is synthesized via an in-situ carbonization-selenization process from cobaltic metal organic framework (Co-MOF). The obtained CoSe_2-x@NC has a unique electronic structure and rich active sites, which can activate peroxymonosulfate (PMS) to degrade carbamazepine (CBZ) with superior catalytic performance and stability. The quenchingexperiments and EPR test show that SO₄^•- is the dominant reactive oxidation species (ROSs) for CBZ degradation. Significantly, systemic electrochemical tests and theoretical calculations illustrated that the dominant role of SO₄^•- is attributed to the existence of abundant selenium vacancies in CoSe_2-x@NC, which can adjust the density of electron cloud of the Co atoms in CoSe_2-x@NC to improve the PMS adsorption and promoting the conversion of transition metallic redox pairs (Co³⁺/Co²⁺). This work provides a facile way to improve the activity and stability of CoSe₂ by defect engineering in the PMS based advanced oxidation process (AOPs).

Keywords: Co(3+)/Co(2+) redox; Core-shell; Metal organic framework; Sulfate radical (SO(4)(•−)) dominant; Vacancy engineering.