Effect of partial substitution of Zn2+ with Co2+ on catalytic methane combustion performance of Zn1-xCoxGa2O4 (x=0, 0.1, 0.3) microspheres

The modified ZnGa2O4 microspheres were prepared by the conventional hydrothermal method and used to catalyze methane combustion reaction. Because Co2+ and Zn2+ have similar ion radii, so it seems that the Zn2+ at the tetrahedral (Td) position of ZnGa2O4 was partially replaced by Co2+ to adjust the oxygen distribution, and finally the Zn1-xCoxGa2O4 (x = 0.1, 0.3) microspheres catalysts was obtained. X-ray photoelectron spectroscopy (XPS) analysis exhibited that Co3+ were present in the Zn1-xCoxGa2O4 (0.1, 0.3) samples, and interstitial oxygen were formed to maintain electrical neutrality. Oxygen temperature programmed desorption (O2-TPD) profiles showed that there was only one oxygen species desorption from ZnGa2O4 sample, while the Zn1-xCoxGa2O4 (0.1, 0.3) samples had two oxygen desorption peaks, that is the first one is surface adsorbed oxygen, the second is lattice oxygen. The catalytic methane combustion performance of the samples indicated that the partial substitution of Co2+ for Zn2+ in ZnGa2O4 can effectively improve its activity.

Automated summary

Modified ZnGa2O4 microspheres were prepared using a conventional hydrothermal method for catalyzing methane combustion, with Co2+ partially replacing Zn2+ to enhance activity by adjusting oxygen distribution. XPS analysis confirmed the presence of Co3+ in the samples and the formation of interstitial oxygen for electrical neutrality maintenance. O2-TPD profiles showed improved oxygen desorption behavior in the Zn1-xCoxGa2O4 samples compared to ZnGa2O4, leading to enhanced catalytic performance in methane combustion.