Defective carbon encapsulating bimetallic Co-Ti for the excellent degradation of sucralose: Regulating the generation and enhancement action of singlet oxygen

Abstract

Sucralose (SUC) is a prevalent artificial sweetener with bio-accumulative effects, which is difficult to be removed by conventional wastewater treatment. A bimetallic carbon material of Co_xTi_y/C containing a high concentration of oxygen vacancies (O_V) was successfully synthesized using one-pot solvothermal and carbon reduction methods. The characterization results showed that Co_xTi_y/C ensured well dispersion of bimetallic Co-Ti elements within the material. The Co₁Ti₂/C-PMS system presented excellent performance in the catalytic decomposition of SUC, and also achieved outstanding performance of anti-interference and cyclic stability. Due to the activity discrepancy of two metal for competing oxygen atoms, the high O_V content of Co₁Ti₂/C was well presented, and triggered the SUC degradation pathway dominated by singlet oxygen (¹O₂) and complemented by hydroxyl radicals (•OH) and electron transfer. Based on the intermediates measured by LC-MS, the frontier molecular orbitals and Fukui functions of SUC were calculated using quantum chemistry to speculate the possible degradation pathways of SUC, and the eco-toxicity of its intermediates was also assessed, which showed that its intermediates were much lower than that of SUC. It was believed that Co₁Ti₂/C can serve a highly efficient and green catalyst for the degradation of organic pollutants. This study provides insights for the rational design and development of catalysts for artificial sweetener wastewater treatment.