Effect of surface lattice Co-O bonds and interfacial interaction between CuO and Co3O4 in Cu-modified Co3O4 on catalytic complete oxidation of toluene and acetone

Modifying the electronic structure of Co₃O₄ and enhancing the rapid cycling ability between Co²⁺ and Co³⁺ are effective strategies to improve the catalytic oxidation of VOC by Co-based catalysts. The ionic radius of Cu is similar to that of Co, and the valence state of Cu is variable. Therefore, Cu_aCoO_x catalysts with varying Cu/Co molar ratios were synthesized through the hydrothermal method, followed by a comprehensive assessment of their oxidation performance for toluene and acetone degradation. Among them, Cu_0.55CoO_x can convert 90 % acetone and toluene at 169 and 217 °C (T₉₀), respectively, but it shows quickly deactivation in the long-term activity stability test. Through controlled variation of the Cu/Co molar ratio, the amount of metal ions incorporated into Co₃O₄ varies, which influences the electronic structure of the catalyst. Compared with Cu_0.55CoO_x, T₉₀ values over Cu_0.18CoO_x are177 and 222°C for the oxidation of acetone and toluene, respectively, but the activity can maintain stability in long time tests. These results show that the doping of Cu in Co₃O₄ can cause lattice distortion, produce a Cu–O-Co bond, weaken the bond energy of the Co-O bond, thus increasing the mobility of lattice oxygen. When Cu is excessive, the appearance of CuO changes the structure of the catalyst and forms the CuO-Co₃O₄ interface, which can also promote the generation of active oxygen at the interface. However, during the long-term test of toluene and acetone, the rate of active oxygen recycling is slow in the interface, resulting in poor stability.