Effect of External Electric Field on Methane Conversion on IrO2 (110) Surface: A Density Functional Theory Study

Catalytic conversion of methane to value-added chemicals is a promising application for gas versatility. In this work, we have investigated the methane oxidation over oxygen-rich IrO2 (110) surface by DFT calculations, as IrO2 is reported to be an effective catalyst for activating the C-H bond of methane. Compared to the methane reaction on the surface of stoichiometric IrO2 (110), the reaction barrier for each step of forming formaldehyde on the oxygen-rich IrO2 (110) is small. The calculations show that formaldehyde formation is the most favorable route in methane oxidation, but this process is limited by the high desorption energy of formaldehyde. To modify the reactivity of IrO2 (110), we conducted a study of the influence of an external electric field on the methane conversion reaction. The calculations show that the effects of external electric field on methane dehydrogenation and C-O coupling reactions are not so apparent. However, it is found that the desorption energy of the adsorbates can be regulated by applying an external electric field. Our study indicates that the use of an external electric field is crucial in regulating the catalytic reaction, and especially the application of a positive electric field promotes the oxidation of methane to formaldehyde over oxygen-rich IrO2 (110) surface.