Construction of a Pd(PdO)/Co3O4@SiO2 core-shell structure for efficient low-temperature methane combustion.

Catalytic combustion is a promising way to remove trace amounts of CH4 to alleviate serious environmental concerns. However, the reactivity of a catalyst at low temperature is usually limited because of the difficulty to activate the C–H bond of methane. Herein, we design a Pd(PdO)/Co3O4@SiO2 bimetallic oxide core–shell catalyst which shows much higher activity in the methane combustion reaction compared with Pd(PdO)/SiO2 and Co3O4@SiO2 catalysts without a core–shell structure. The T50% and T90% of Pd(PdO)/Co3O4@SiO2 are 357 °C and 445 °C, respectively, which decrease by 67 °C and 55 °C in comparison with those of Pd(PdO)/SiO2. Extensive characterization demonstrates that the bimetallic oxide core–shell structure can effectively enhance the metal interaction between Pd and Co, which can weaken the strength of the Co–O bond in Pd(PdO)/Co3O4@SiO2. The weakening of the Co–O bond could promote the release of more lattice oxygen species to participate in the C–H breaking, resulting in superior catalytic performance in methane combustion at low temperature.