Enhanced Methane Combustion Performance over Zinc-Aided Co3O4 by Engineering the Reactivity of Active Oxygen Species

Abstract

Engineering the lattice oxygen reactivity and activation of gaseous O2 is vital for boosting methane combustion over Co3O4. Herein, zinc was inserted into the Co3O4 matrix, driven by its slightly larger cationic radius and lower electronegativity than those of cobalt. The suitable doping of zinc offered the optimum occupation of Zn2+ at the tetrahedral sites, granting more active Co3+ sites. The formation of Co–Zn–O solid solution delivered the lattice disorder and endowed cobalt with richer electrons, which increased the oxygen vacancy density, oxygen storage capacity, migration property of surface lattice oxygen, and reducibility of catalysts, and tuned the surface acid–base properties. Also, the ability to adsorb and activate aerial O2 of catalysts was enhanced, which could realize more effective spillover of O2 to regenerate lattice oxygen. These entire properties allowed the redox cycles to proceed more smoothly on the Co3+–O pair sites for Zn0.6Co2.4O4 compared to its analogues. Consequently, Zn0.6Co2.4O4 manifested more effective methane combustion with its T90 at 380 °C while holding outstanding long-term stability.