Electrochemical CO2 reduction based on advanced Cu-based materials

Abstract

Electrochemical CO₂ reduction reaction (CO₂RR) has exhibited great potential in alleviating the issue of global warming and producing value-added products within industrial production levels. Nevertheless, diversified reaction preferences on the catalyst and tedious reaction pathways for several target products impede the progress towards industrialization. Therefore, it is particularly important to obtain a comprehensive understanding of the relationship between the reaction preference (pathways and intermediates) and the structure of the catalyst and interface reaction, aiming to achieving effective generation of target product with high selectivity, high conversion rate and low overpotential. Cu has been considered as an extremely promising candidate for electrochemical CO₂RR owing to its moderate binding energies with key intermediates possibly involved in the reaction, resulting in relatively smooth pathways toward various target products. In this dissertation, advanced Cu-based materials were utilized as the catalyst and take two crucial intermediates (*CO and *OCHO) and an important process (C-C coupling) in electrochemical CO₂RR as the research objectives. Firstly, we studied the pathway toward C2+ products through *CO intermediate and the subsequent C-C coupling process and explored the relationship between the defective extent in the Cu-based catalyst and the efficiency of C-C coupling. Secondly, S element was doped into the Cu-based catalyst to switch the preference of underwent intermediate from *CO to *OCHO, thereby leading to efficient generation toward formate by high retention of S-S bonds in the catalysts. Furthermore, a stable triple-phase interface was established among the catholyte, gas and catalyst by applying the flow-cell configuration, thus greatly enhancing the conversion rate toward formate. Last but not the least, according to the understanding of the reaction intermediates, the electrochemical CO₂RR was coupled with nitrate reduction reaction catalyzed by a suitable Cu-based catalyst. In this case, urea can be efficient generated by coupling the intermediates of *COOH and *NHO.

Date of Award	2024
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Minhua SHAO (Supervisor) & Ping GAO (Supervisor)