<h3>Title</h3>
<p><strong><span style="color: #0000ff;">Electrochemical Reduction of Carbon Dioxide to Syngas</span></strong></p>
<p><strong><span style="text-decoration: underline;">Abstract</span> :</strong></p>
<p style="text-align: justify;">Over the past few years, electrochemical reduction of CO<sub>2</sub> (ERC) has attracted a lot of interest among researchers to convert CO<sub>2</sub> into value-added products using renewable energy. Through ERC, CO<sub>2</sub> and water using renewable energy can be co-electrolyzed to produce many chemicals such as CH<sub>4</sub>, C2H<sub>4</sub>, C<sub>2</sub>H<sub>6</sub>, HCOOH, CH<sub>3</sub>OH, and syngas (CO + H<sub>2</sub>), which are important industrial chemicals. However, CO<sub>2</sub> is a very stable molecule, and thus it is very difficult to reduce it. Therefore, the primary focus of research has been developing an electrocatalyst selective to CO<sub>2</sub> reduction. ERC is carried out in the presence of water. Thermodynamically, the reduction potentials of ERC and hydrogen evolution reaction (HER) potential are close to each other. Moreover, HER has fast kinetics as compared to ERC. Thus, the electrical charge spent during ERC is used by the facile HER instead of ERC. Thus suppression of HER poses a huge challenge.</p>
<p style="text-align: justify;">Depending upon the electrode potential, electrolyte, electrocatalyst, and reaction conditions. Sixteen different products can be formed using Cu as an electrocatalyst. However, it requires high overpotential (~1.0 V), have poor selectivity, and fast deactivation are the biggest challenges. The research work in this thesis is focused on the selective formation of syngas using Zn and Cu based electrocatalysts. The effect of the nature of the electrocatalyst layer on the ERC selectivity has been studied. It was found that the degree of gas entrapped in different types of layers was different, leading to different selectivity. The role of the addition of Cu into the ZnO has also been studied for the synthesis of syngas. On varying the concentration of Cu into the ZnO, it was found that at a certain fraction of Cu into the ZnO, charge transfer resistance towards ERC is reduced, which ultimately reduces the overpotential requirements. The role of pressure in gas phase ERC was also investigated. It was found that a mild increase in pressure leads to a shift in Zn/Cu selectivity towards syngas formation by changing the orientation of the adsorbed CO<sub>2</sub> molecule.</p>