Acta Physico-Chimica Sinica

Special Issue: CO2 Reduction

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Recent Advances in Electrochemical CO2 Reduction Using CopperBased Catalysts

Yichen Meng, Siyu Kuang, Hai Liu, Qun Fan, Xinbin Ma, Sheng Zhang   

  1. Key Laboratory for Green Chemical Technology of Ministry of Education, Collaborative Innovation Centre of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
  • Received:2020-06-12 Revised:2020-06-28 Accepted:2020-06-29 Published:2020-07-02
  • Supported by:
    The project was supported by the Key Research and Development Project of Tianjin (18ZXJMTG00180, 19ZXNCGX00030)

Abstract: Burning of fossil fuels increases CO2 concentration in the atmosphere, resulting in a series of climate- and environment-related concerns such as global warming, sea-level rise, and melting of glaciers. Therefore, utilization of renewable energy to reduce the CO2 concentration, in order to realize a sustainable development, is urgent. Capturing and utilizing CO2, a greenhouse gas, can not only address these concerns but also alleviate the current scenario of energy shortage. Thermal catalytic CO2 hydrogenation offers various pathways with high conversion efficiencies to produce fuels and industrial chemicals including CO, HCOOH, CH3OH, and CH4. However, CO2 is chemically inert due to the highly stable C=O bond. Thus, harsh reaction conditions such as high temperature and pressure are required for CO2 hydrogenation.
Electrocatalytic CO2 reduction using renewable electricity and water is a promising alternative to thermocatalysis. This technology can not only store and transport the intermittent solar or wind energy but can also use water as the proton source instead of H2, which is indispensable for thermal CO2 hydrogenation. Electrochemical CO2 reduction under ambient conditions is a proton-coupled electron transfer process. The key to promote the electrochemical reduction of CO2 is to develop highly selective and active catalysts with high stability. Among various CO2 electrocatalysts, copper-based catalysts have attracted significant attention and have been extensively investigated, since they exhibit good selectivity and efficiency for the reduction of CO2 to hydrocarbons and alcohols. A broad range of products, up to 16 different gases and liquids, can be obtained in the CO2electroconversion on copper. Copper is the only metal that has a negative adsorption energy for *CO and a positive adsorption energy for *H. Thus, it has a unique property of generating >2e- transfer products. However, selectivity of the target product is still low, especially for high value-added C2+ species (C2H4, C2H5OH, CH3COOH, CH3CHO, n-C3H7OH, etc.).
The selectivity of various products on copper-based catalysts could be enhanced by surface engineering techniques such as tuning the morphologies, particle sizes, surface facets, strains levels, and atomic coordination. Electrolyte engineering could also aid in CO2 electroreduction. Therefore, improving the selectivity of C2+ products by modifying copper-based catalysts could be a hot research topic. In addition, C-C coupling is a key step in forming C2+ products, though the C2+ product formation pathway is complex, and the mechanisms are still unclear. Considering these, this paper mainly reviews the research progress in copper-based catalysts producing C2+ species in the last five years. It also discusses the possible reaction mechanisms and the factors that affect the product selectivities. In the end, further research directions are proposed.

Key words: Carbon dioxide, Electrochemical reduction, Copper-based catalysts, C2+ products, Selectivity


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