Studies on the design and the role of organic layers on the copper electrode surface under electrochemical CO$_2$ reduction reaction

Abstract

The intensification of global warming and climate change, induced by the discharge of carbon dioxide into the atmosphere through fossil fuel usage, has urged the dire need to restrict its use. Nonetheless, when copious amounts of energy are required, such as in factory operations, an innovative methodology of transforming the emitted carbon dioxide into high-value-added materials, such as multi-carbon (C2+) compounds, is imperative. In this regard, electrochemical carbon dioxide reduction (CO2RR) has been widely studied due to its economic advantages and the fact that it can be carried out at room temperature and pressure. However, the hydrogen evolution reaction proceeds together in an aqueous electrolyte solution, and the complexity of the C2+ production pathway poses significant challenges in understanding the reaction mechanism. In this Ph.D. dissertation, the design of organic layers on the copper (Cu) catalyst surface is studied to improve the selectivity and the understanding of the reaction mechanism in CO2RR. Chapter 2 outlines the manipulation of the density of organic capping ligands on Cu nanoparticles, elucidating the correlation between the shielding rate of the ligand and the selective production of multi-carbon materials and the morphological transformation of nanoparticles during electrocatalysis. Chapter 3 describes the development of a four nm-thick nanofilm of an organic framework containing triazine moiety, coating planar Cu catalyst. In addition, operando spectroscopic analysis using infrared and Raman spectroscopy was carried out to study the inhibition of hydrogen evolution reaction and the generation of C2+ intermediate species on the well-defined, two-dimensional catalyst surface during electrochemical CO2RR.