Revolutionizing electrochemical CO2 reduction to deeply reduced products on non-Cu-based electrocatalysts

Producing deeply reduced (net number of electrons transferred per carbon atom greater than two, > 2e(-)) products from electrochemical CO2 reduction reaction (eCO(2)RR) is an attractive and sustainable approach for CO2 utilization. Current research on deeply reduced products in eCO(2)RR focuses on copper (Cu)-based electrocatalysts, and significant advances in improving the activity and selectivity have been achieved in the past decade. However, the intrinsically low selectivity (broad product profile) and poor stability still constitute the bottleneck of Cu-based eCO(2)RR technology. Non-Cu-based electrocatalysts are promising alternatives to convert CO2 into deeply reduced products. Nonetheless, current understanding of such a process on non-Cu surfaces is relatively limited, and a comprehensive review in this direction is still lacking. This review summarizes recent research progress in non-Cu-based electrocatalysts capable of producing deeply reduced products at an appreciable rate and selectivity, and outlines considerations in the screening of non-Cu-based electrocatalysts. Firstly, the fundamentals of eCO(2)RR are introduced, with particular focus on reaction pathways and selectivity-determining intermediates found exclusively on non-Cu surfaces. We highlight C-C coupling pathways unique to non-Cu surfaces, and also the trend that the greater the number of electrons transferred prior to the C-C coupling step, the higher the single selectivity of the deeply reduced product. Next, recently reported design strategies on non-Cu-based electrocatalysts are summarized, followed by a survey on novel catalyst screening via combined density functional theory calculations and machine learning, with prospective potent catalysts highlighted. Finally, key considerations and research directions are proposed for developing advanced non-Cu-based electrocatalysts. This review aims to provide comprehensive insights into designing high-performance non-Cu-based eCO(2)RR catalysts and to stimulate more research endeavors in this increasingly important direction.