Synergy effect of CuO on CuCo2O4 for methane catalytic combustion

Spinel oxides (AB2O4) have been widely studied as catalysts for methane combustion. Increasing attention was focused on the catalysis properties of the [B2O3] octahedron; however, the role of the [AO] tetrahedron in the catalytic activity was seldom discussed. Herein, a series of (CuO)x–CuCo2O4 (x = 0, 0.1, 0.2) composite oxides were synthesized by a solvothermal method. The structure, morphology, and physicochemical properties of the as-synthesized samples were characterized by the XRD, SEM, BET, and XPS techniques. The results of the catalytic activity tests showed that the coexistence of CuO with CuCo2O4 can improve the catalytic activity. The XPS results demonstrated that there were remarkable Cu+ ions present in the composite oxides, which can cause increases in the number of oxygen vacancies on the surface of the catalysts. In addition, the redox of Cu+ and Cu2+ may improve the oxygen exchange capacity for methane oxidation.