Application of Fourier Transform Infrared (FTIR) Spectroscopy on the Electrochemical Reduction of Carbon Dioxide

Abstract

The global challenge today is that of climate change which is mainly attributed to the excess emission of greenhouse gases, especially carbon dioxide produced from the burning of fossil fuels. The sources of carbon dioxide are anthropogenic and the include power generation, transport, industrial sources, chemical production, petroleum production and agricultural practices. Most of these sources burn coal, oil, and natural gas, which releases carbon dioxide as a by-product. One of the ways to reduce carbon dioxide emission is to use renewable energy resources. Photovoltaic technology which uses solar energy can generate enormous amounts of electricity whose excess can be used to electrochemically reduce carbon dioxide into fuels and other chemicals. Storing renewable energy into chemicals is a very important technique since renewable energy sources are intermittent which is due to seasonal variations. The ability to show what happens in the electrochemical reduction reaction of carbon dioxide to produce fuels and other valuable chemicals is a prerequisite for the development of electrochemical reactions. Fourier Transform Infrared (FTIR) spectroscopy techniques of transmittance and attenuated total reflectance are capable of revealing most the functional groups of the important intermediate species and products of carbon dioxide reduction reactions. The choice for FTIR techniques over the other spectroscopic techniques such as, atomic, ultraviolet and visible, Raman NMR and mass spectroscopy is that, FTIR techniques are faster and reliable in sample analysis, and are not destructive to the samples. Having an insight into how the electrochemical reduction of carbon dioxide works and the ideal conditions of the reaction, is key towards the development and upscaling of carbon dioxide reduction technology. FTIR application on carbon dioxide reduction reaction identifies and profile’s reaction species of reagents, intermediates, products and by-products of the reaction. This work looks at the application of FTIR techniques (transmittance and attenuated total reflectance) on the electrochemical reduction of carbon dioxide, so as to have an insight in to the products formed using the ex-situ approach. In this work, five samples of saturated carbon dioxide in potassium hydrogen carbonate, purged with various concentration of folic acid were analyzed using the FTIR techniques of transmittance and attenuated total reflectance. The results from both techniques showed the functional group hydroxyl ion (OH-) of carboxylic acid, carbon monoxide and carbon dioxide in all the samples analyzed. Similar results were also shown in a gas chromatography device with the same samples v analyzed in the FTIR. Hydrogen was not seen in the FTIR results but showed up in the gas chromatogram, and in addition, showed the concentration of the gas products in the samples. A combination of hydrogen and carbon monoxide (H2 and CO) in the right ratio can be used to produce green fuel(syngas) in the Fischer-Tropsch process, with the use of photovoltaic technology as a source of electricity to power the reactions.