Recent progress and perspective of electrochemical CO2 reduction towards C2-C5 products over non-precious metal heterogeneous electrocatalysts

Electroreduction of carbon dioxide (CO2ER) into value-added chemical compounds has presented as a promising route for renewable carbon cycle, which alleviates global warming concern. Compared with traditional C-1 products, high-value multicarbon products converted from atmospheric CO2 via CO2ER have attracted dramatic interest due to their significant economic efficiency, however desired catalytic selectivity of multicarbon products is difficult to achieve because of the high thermodynamic barriers and complex reaction pathways. To replace currently used precious-metal based catalysts, developing highly efficient and precious-metal-free CO2ER catalysts based on earth abundant elements is the top priority to meet the requirements of industrialization. Although certain progress has been made, there are still few systematic reports on the non-precious metal heterogeneous (NPMH) CO2ER electrocatalysts for efficient conversion of CO2 to multicarbon products. Herein, we summarize the latest research advances in recent developments of NPMH electrocatalysts, including nanostructured Cu, Cu-based bimetallic catalysts, Cu-based complexes, and carbon-based Cu-free catalysts for electroreduction of CO2 into high-value multicarbon products. The corresponding CO2ER performances are discussed in the order of the types of multicarbon products, specifically for ethanol (C2H5OH), ethylene (C2H4), ethane (C2H6), acetic acid (CH3COOH), propanol (C3H7OH), and other C2+ products with a special attention paid to understand the structure-activity relationship. Moreover, key strategies and characterization techniques for catalytic mechanism insights, and unsolved issues and future trends for enhancing the CO2ER performance of NPMH electrocatalysts are highlighted, which provides a constructive guidance on the development of CO2ER electrocatalysts with high activity and selectivity for multicarbon products.