Enhanced Productivity of Multi-carbon Organic Molecules in CO2 Electrolysis Applying Cu-based Cathode Catalyst

Abstract

Over the past few decades, there has been an increasing focus on the negative impact of carbon dioxide (CO2) emissions resulting from activities such as the burning of fossil fuels and other human-related actions. These emissions have been linked to the changes in global climate and the resulting environmental threats. While there are techniques such as carbon capture and sequestration (CCS) that can prevent CO2 from accumulating in the atmosphere, there are concerns about the limited capacity of geological storage and potential leaks. Against this backdrop, another approach has been proposed - converting CO2 into organic compounds that are widely available for recycling. This approach is considered more beneficial compared to CCS techniques. Among several methods, electrochemical conversion of CO2 using Cu-based electrodes appears to be a promising route to synthesize multi-carbon fuels and chemicals such as ethylene, ethanol, n-propanol and n-butanol. The conversion of CO2 into high-value liquid products, like long-chain oxygenated hydrocarbons, presents a promising opportunity for practical applications in fuel production. These hydrocarbons possess low volatility, allowing for convenient storage and transportation in tanks. Furthermore, their high volumetric energy density meets the essential criteria for fuel infrastructure, opening up a potential avenue for replacing fossil fuels. Nevertheless, producing valuable organic compounds from CO2 on a large scale remains a challenging task, as it necessitates the use of electrodes with substantial areas and high energy efficiency. There are three different perspectives when it comes to improving the production of multi-carbon through CO2 electrolysis. Firstly, our focus is on studying the catalytic activity of copper phosphide rich in phosphorus (CuP2). This is the first report on the production of 1-butanol through direct CO2 electrolysis using reliable values. By depleting *CO intermediates, this mechanism has a higher selectivity towards multi-carbon products, suggesting a new point of C-C coupling. In the following chapter, we provide experimental evidence for the aldehyde condensation reaction, which is further clarified by in-situ ATR-SEIRAS. Thirdly, we have attempted to develop a new system for the CuP2 catalyst to enhance the selectivity of multi-carbon fuels based on the experimental results explained in the previous chapters. Lastly, this thesis concludes by summarizing the series of research conducted, and prospects of electrochemical conversion of CO2 have been described in terms of fundamental and practical engineering studies.