Methane is the major component of natural gas and it is considered as an important feedstock in petrochemical industry for producing value-added chemicals. The current industrial processes have low selectivity and require conditions of high temperature and pressure for production of synthesis gas. Therefore, developing new methods for direct conversion of methane to methanol or higher hydrocarbons is necessary. Among the possible game-changing new chemistries, the electrochemical approach has its own advantages for both practical applications and fundamental studies and therefore represents emerging alternative opportunities to the conventional steam reforming and combustion of methane. This is because as electrochemical reactions are driven by either potential or current, they can most likely take place at room or mildly high temperature (<100 °C). Moreover, as the potential or current can be precisely controlled, so can be the electrochemical reactions, which is ideal for in situ mechanistic studies.
Here, we examined several metal-based materials as electrocatalysts for methane electro-oxidation in CH4-saturated aqueous solution using Cyclic Voltammetry and Chronoamperometry methods. The in situ SEIRAS (Surface Enhanced IR Reflection Absorption Spectroscopy) spectra recorded during the Chronoamperometry measurement of CH4 oxidation was used to investigate the intermediates and products on catalyst surface. Our findings confirms that redox chemistry of metals with more than one oxidation state can be utilized to generate active oxygen species (e.g. O2-, O-, O22-) on the surface and facilitate efficient oxidation of methane. We will also compare the electrochemical oxidation of methane on these metal-based catalysts.
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