In Situ Electrical Detection of Methane Oxidation on Atomically Thin IrO2 Nanosheet Films Down to Room Temperature

Abstract

Abstract Activation of the CH bond is the first step in converting methane into valuable chemicals. Herein, the successful induction and electrical detection of a methane oxidation reaction are reported at room temperature using IrO2 nanosheets, a 2D form of IrO2. A clear decrease in electrical resistance upon exposure to methane is observed by using atomically thin IrO2 nanosheet films. The resistance decrease disappears upon simultaneous exposure to oxygen, suggesting that methane is oxidized by consuming the lattice oxygen of the IrO2 nanosheets and that the oxygen vacancies generated are recovered by oxygen in the atmosphere. The resistance decrease is observed even at 300 K, indicating the high methane oxidation ability of the IrO2 nanosheets. These results are confirmed by a shift of the Ir 4f peaks in ambient pressure X‐ray photoelectron spectra. Furthermore, deposition of amorphous carbon, that is, methane oxidation products, on IrO2 nanosheets is also confirmed by Raman scattering spectroscopy after prolonged methane exposure at high temperatures in the absence of oxygen. This study demonstrates the ability of IrO2 nanosheets to oxidize methane at least down to 300 K and is an important example of the usefulness and simplicity of chemical reaction monitoring using electrical resistance changes.

Keywords

• electrical detection
• IrO2 nanosheets
• methane oxidation
• redox reaction
• ambient‐pressure X‐ray photoelectron spectroscopy