Recent progress and perspective of electrochemical CO 2 reduction towards C 2 -C 5 products over non-precious metal heterogeneous electrocatalysts

Electroreduction of carbon dioxide (CO 2 ER) 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 CO 2 via CO 2 ER 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 CO 2 ER 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) CO 2 ER electrocatalysts for efficient conversion of CO 2 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 CO 2 into high-value multicarbon products. The corresponding CO 2 ER performances are discussed in the order of the types of multicarbon products, specifically for ethanol (C 2 H 5 OH), ethylene (C 2 H 4 ), ethane (C 2 H 6 ), acetic acid (CH 3 COOH), propanol (C 3 H 7 OH), and other C 2+ 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 CO 2 ER performance of NPMH electrocatalysts are highlighted, which provides a constructive guidance on the development of CO 2 ER electrocatalysts with high activity and selectivity for multicarbon products.