Defect-engineered cobalt-based solid catalyst for high efficiency oxidation of sulfite

Abstract

We report a defect-engineered Co-based solid catalyst, namely the Co3O4 nanocubes (NCs)/graphitic C3N4 (g-C3N4) hybrid, for enhancing the oxidation of magnesium sulfite (MgSO3) in the desulfurization of wet magnesia. Abundant oxygen vacancies were induced successfully on the Co3O4 NCs/g-C3N4 hybrid. The creation of oxygen vacancies promoted MgSO3 oxidation by enhancing the adsorption of reactant MgSO3 and accelerating the striping of product MgSO4 to refresh the Co active sites. The oxygen vacancies also promoted the transfer of oxygen molecules and subsequent activation of oxygen molecules to active oxygen species. The size effect of Co3O4 NCs, which may be a crucial factor for improving the catalytic activity, considerably enhanced the efficiency of Co species. Moreover, because the g-C3N4 support had a large surface area and large number of unpaired electrons, the coupling of Co3O4 NCs and g-C3N4 improved the dispersion of Co3O4 NCs, which substantially decreased the usage of Co species. During the MgSO3 oxidation reaction, the hybrid catalyst exhibited an unprecedented MgSO4 yield per Co site of 1678.9 mmol/mmol Co at 30 min and a rapid MgSO3 oxidation rate of 0.068 mmol·L−1·s−1.