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Recently, the research group led by Professor Gao Minrui from the University of Science and Technology of China discovered that in the electroreduction of carbon dioxide, the rate-determining step for copper catalysts varies significantly depending on the crystal face: on the copper (100) surface, carbon-carbon bond coupling is the rate-determining step, whereas on the copper (111) surface, the protonation of adsorbed carbon monoxide and water is the rate-determining step. Using a catalyst with copper (100) as the primary exposed crystal face, the researchers achieved a 72% Faradaic efficiency for ethylene production in a neutral medium, as well as an industrial-grade partial current density, and maintained stable catalytic conversion of carbon dioxide to ethylene for over 100 hours. The relevant findings were published in the American journal **Proceedings of the National Academy of Sciences**. Currently, the use of green electricity to reduce carbon dioxide into polycarbon chemicals such as ethylene still faces significant challenges due to issues including low Faradaic efficiency, slow reaction rates, and complex reaction mechanisms. The researchers employed a plasma treatment strategy to create oxygen vacancies in copper oxide nanosheets. Density functional theory calculations predict that the presence of oxygen vacancies facilitates the adsorption of carbon monoxide and promotes the formation of copper (100) during the catalyst reduction process. Copper oxide without oxygen vacancies tends to form the lower-energy copper (111) crystal planes during reduction. Scanning electron microscopy showed that the samples after reduction retained the morphology of the parent catalyst, while high-resolution transmission electron microscopy and electrochemical hydroxide adsorption experiments indicated that the surfaces of the two prepared catalysts were dominated by copper (100) and copper (111), respectively. The researchers evaluated the performance of the catalyst in flow cell and membrane electrode systems. The results showed that at 500 milliamps per square centimeter, the ethylene Faradaic efficiency of catalysts with copper (100) as the dominant exposed crystal face was 72%, which is significantly higher than that of catalysts with copper (111) as the dominant crystal face. In-situ spectroscopic and electrodynamic experimental results show that the formation of ethylene follows different reaction pathways on samples with different exposed crystal facets of the host material. On catalysts with copper (100) as the dominant crystal face, carbon monoxide exhibits a higher coverage, stronger adsorption, and predominantly adopts a terminal adsorption mode; the rate-determining step in the conversion of ethylene is the coupling process of the two adsorbed molecules of carbon monoxide ； On catalysts with copper (111) as the dominant exposed crystal face, the rate-determining step in ethylene conversion is the proton coupling process between adsorbed carbon monoxide and water molecules. The results of density functional theory calculations also support these experimental findings.