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Electrochemical CO2 reduction reaction (eCO2RR) to value‐added multicarbon (C2+) products offers a promising approach for achieving carbon neutrality and storing intermittent renewable energy. Copper (Cu)‐based electrocatalysts generally play the predominant role in this process. Yet recently, more and more non‐Cu materials have demonstrated the capability to convert CO2 into C2+, which provides impressive production efficiency even exceeding those on Cu, and a wider variety of C2+ compounds not achievable with Cu counterparts. This motivates us to organize the present review to make a timely and tutorial summary of recent progresses on developing non‐Cu based catalysts for CO2‐to‐C2+. We begin by elucidating the reaction pathways for C2+ formation, with an emphasis on the unique C−C coupling mechanisms in non‐Cu electrocatalysts. Subsequently, we summarize the typical C2+‐involved non‐Cu catalysts, including ds‐, d‐ and p‐block metals, as well as metal‐free materials, presenting the state‐of‐the‐art design strategies to enhance C2+ efficiency. The system upgrading to promote C2+ productivity on non‐Cu electrodes covering microbial electrosynthesis, electrolyte engineering, regulation of operational conditions, and synergistic co‐electrolysis, is highlighted as well. Our review concludes with an exploration of the challenges and future opportunities in this rapidly evolving field. [ABSTRACT FROM AUTHOR]

Despite the advantage of high carbon utilization, CO2 electroreduction (CO2ER) in acid is challenged by the competitive hydrogen evolution reaction (HER). Designing confined catalysts is a promising strategy to suppress HER and boost CO2ER, yet the relationship between the confined structure and catalytic performance remains unclear, limiting rational design. Herein, using Cu2O@mesoporous SiO2 core‐shell catalysts as a well‐defined platform, a volcano‐shaped relationship is found between the thickness of mesoporous SiO2 layer and productivity of multicarbon (C2+) products in CO2 electroreduction. The optimal shell thickness of 15 nm is identified, with in situ spectroscopies and theoretical simulations attributing this to the trade‐off between the local alkalinity and CO2 concentration, arising from the nanoconfinement effect. At this optimal thickness, the Cu2O@ mesoporous SiO2 catalyst achieves a C2+ Faradaic efficiency of 83.1% ± 2.5% and partial current density of 687.8 mA cm−2 in acidic electrolytes, exceeding most reported catalysts. This work provides valuable insights for the rational design of confined catalysts for electrocatalysis. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction to multicarbon products faces challenges of unsatisfactory selectivity, productivity, and long-term stability. Herein, we demonstrate CO2 electroreduction in strongly acidic electrolyte (pH ≤ 1) on electrochemically reduced porous Cu nanosheets by combining the confinement effect and cation effect to synergistically modulate the local microenvironment. A Faradaic efficiency of 83.7 ± 1.4% and partial current density of 0.56 ± 0.02 A cm−2, single-pass carbon efficiency of 54.4%, and stable electrolysis of 30 h in a flow cell are demonstrated for multicarbon products in a strongly acidic aqueous electrolyte consisting of sulfuric acid and KCl with pH ≤ 1. Mechanistically, the accumulated species (e.g., K+ and OH−) on the Helmholtz plane account for the selectivity and activity toward multicarbon products by kinetically reducing the proton coverage and thermodynamically favoring the CO2 conversion. We find that the K+ cations facilitate C-C coupling through local interaction between K+ and the key intermediate *OCCO. Attaining high selectivity for CO2 electroreduction in acid is usually difficult due to competing hydrogen evolution. Here, the authors demonstrate efficient CO2 reduction to multicarbon products in strongly acidic medium (pH ≤ 1) on a porous Cu catalyst by combining confinement and cation effects. [ABSTRACT FROM AUTHOR]

Electrochemical structural reconstruction of catalysts may generate real active sites that differ from the initial catalyst, but is often ignored. Herein, combining in situ and ex situ techniques, it is identified that the bismuth nanosheets (NS) dotted with large numbers of coordinatively unsaturated pit sites is produced via the in situ structural reconstruction of Bi(OH)3 NS. Such reconstructed Bi NS shows greatly improved catalytic activity toward CO2 electroreduction, with a 2.6‐fold increase in current density compared with intact Bi NS, high Faradaic efficiency for HCOO− production (>95%), and an extraordinary turnover frequency of 0.35 s−1 at −0.98 VRHE. In addition, it delivers industrial‐relevant current density of 325 mA cm−2 without compromising selectivity in a flow cell. The mechanistic studies demonstrate that these coordinatively unsaturated sites acting as the real active sites favor the stabilization of key intermediate *OCHO, which thus facilitate the reaction kinetics for HCOO− production. This work not only provides a unique perspective on the construction of efficient catalysts for CO2 electroreduction, but also implies the importance in recognition of structural reconstruction. [ABSTRACT FROM AUTHOR]

Modulating the local coordination structure of metal single-atom catalysts (SACs) is extensively employed to tune the catalytic activity, but rarely involved in regulating the reaction pathway which fundamentally determines the product selectivity. Herein, we report that the product selectivity of electrochemical CO2 reduction (CO2RR) on the single-atom indium-NxC4−x (1 ≤ x ≤ 4) catalysts could be tuned from formate to CO by varying the carbon and nitrogen occupations in the first coordination sphere. Surprisingly, the optimal In SAC showed great promise for CO production with the maximum Faradic efficiency of 97%, greatly different from the reported In-based catalysts where the formate is the dominant product. Combined experimental verifications and theoretical simulations reveal that the selectivity switch from formate to CO on In SACs originates from active sites shift from indium center to the indium-adjacent carbon atom, where the indium site favors formate formation and the indium-adjacent carbon site prefers the CO pathway. The present work suggests the active sites in metal SACs may shift from the widely accepted metal center to surrounding carbon atoms, thereby offering a new implication to revisit the active sites for metal SACs. [ABSTRACT FROM AUTHOR]

Advancing the development of electrocatalytic CO2 reduction reaction (CO2RR) to address the environmental issues caused by excessive consumption of fossil fuels requires rational design of remarkable electrocatalysts, where the identification of active sites and further understanding of structure–performance relationship are the bases. However, the notable dynamic evolution often appears on the catalysts, with typical examples of Cu‐based catalysts, under operating conditions, causing great difficulty in identifying the real active sites and further understanding the correlations between structure and catalytic property. In this context, understanding the dynamic evolution process of catalytically active sites during CO2RR is of particular importance, which inspires to organize the present review. Herein, the fundamental principles of dynamic evolution in CO2RR including thermodynamics and kinetics aspects, followed by the introduction of operando techniques employed to probe the evolution under operating conditions are first highlighted. The dynamic evolution behaviors, involving atomic rearrangement and change in chemical state, on typical catalysts are further discussed, with emphasis on the correlations between evolution behaviors and catalytic properties (activity, selectivity, and stability). The emerging CO2 pulsed electrolysis technique that behaves promise to manipulate the dynamic evolution and future opportunities are finally discussed. [ABSTRACT FROM AUTHOR]