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The efficient conversion of CO2 to value‐added products represents one of the most attractive solutions to mitigate climate change and tackle the associated environmental issues. In particular, electrochemical CO2 reduction to fuels and chemicals has garnered tremendous interest over the last decades. Among all products from CO2 reduction, formic acid is considered one of the most economically vital CO2 reduction products. P‐block metals (especially Bi, Sn, In, and Pb) have been extensively investigated and recognized as the most efficient catalytic materials for the CO2 electroreduction to formate. Despite remarkable progress, the future implementation of this technology at the industrial‐scale hinges on the ability to solve remaining roadblocks. In this review, the current research status, challenges, and prospects of p‐block metal‐based catalysts primarily for CO2 electroreduction to formate are comprehensively reviewed. The rational design and nanostructure engineering of these p‐block metal catalysts for the optimization of their electrochemical performances are discussed in detail. Subsequently, the recent progress in the development of state‐of‐the‐art operando characterization techniques together with the design of advanced electrochemical cells to uncover the intrinsic catalysis mechanism is discussed. Lastly, a perspective on future directions including tackling critical challenges to realize its early industrial implementation is presented. [ABSTRACT FROM AUTHOR]

The efficient conversion of CO2 to value‐added products represents one of the most attractive solutions to mitigate climate change and tackle the associated environmental issues. In particular, electrochemical CO2 reduction to fuels and chemicals has garnered tremendous interest over the last decades. Among all products from CO2 reduction, formic acid is considered one of the most economically vital CO2 reduction products. P‐block metals (especially Bi, Sn, In, and Pb) have been extensively investigated and recognized as the most efficient catalytic materials for the CO2 electroreduction to formate. Despite remarkable progress, the future implementation of this technology at the industrial‐scale hinges on the ability to solve remaining roadblocks. In this review, the current research status, challenges, and prospects of p‐block metal‐based catalysts primarily for CO2 electroreduction to formate are comprehensively reviewed. The rational design and nanostructure engineering of these p‐block metal catalysts for the optimization of their electrochemical performances are discussed in detail. Subsequently, the recent progress in the development of state‐of‐the‐art operando characterization techniques together with the design of advanced electrochemical cells to uncover the intrinsic catalysis mechanism is discussed. Lastly, a perspective on future directions including tackling critical challenges to realize its early industrial implementation is presented. [ABSTRACT FROM AUTHOR]

The preparation of Bi nanoclusters confined in porous carbon (Bi NCs@PC) efficiently converts CO 2 to formic acid. In addition, Bi nanoclusters have excellent stability due to the protection of micropores. [Display omitted] • Excellent stability maintaining zero valences of Bi for long-term storage. • High Faradaic efficiency of formic acid above 90 % in a wide voltage range of 500 mV. • In-situ Raman and DFT calculations revealed the reaction intermediates and mechanisms. Electrochemical reduction of CO 2 to formate via renewable electricity is a cost-effective route. However, the existing bismuth-based electrocatalysts are in oxide form and involve in-situ reduction to metallic bismuth during CO 2 reduction. In this work, we demonstrate a nanocomposite electrocatalyst by confining Bi nanoclusters into porous carbons (Bi NCs@PC). In particular, the Bi NCs show excellent stability that can maintain zero valences during long-term electrocatalysis or after months of storage in the air. The as-synthesized Bi NCs@PC catalyst achieves up to 96 % formate Faradaic efficiency (FE) at −1.15 V versus reversible hydrogen electrode. Notably, the FE only attenuates by 7.3 % after 30 days of storage under ambient conditions. In-situ Raman spectrum identify the key intermediates during formate formation. Moreover, Bi NCs encapsulated in carbon micropores could significantly reduce the formation energy of the intermediate *OCHO by density functional theory. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabrication of f-Cu 2 O catalyst enclosed with rich oxygen vacancy defects. • The f-Cu 2 O catalyst can electrochemical reduction CO 2 to ethanol and formate. • The peak Faradaic efficiency for liquid products was up to 95.5%. • The Faradaic efficiency of ethanol can reach 52.6% in a H-cell. • In-situ Raman spectra and DFT calculation reveal the reaction mechanism. The electrochemical reduction of CO 2 presents a promising pathway for storing intermittent renewable energy in the form of chemical bonds, thereby mitigating CO 2 emissions and enabling the production of sustainable fuels. In this work, we demonstrate nanoscale engineering of oxygen vacancy and morphology simultaneously on Cu 2 O catalysts for electrochemical reduction of CO 2 to liquid products (formate and ethanol). By comparing the performance of cube- and tetrakaidecahedron-like Cu 2 O catalysts, we have demonstrated that the flower-like Cu 2 O catalyst, enclosed with rich oxygen vacancy defects, exhibited superior performance in the reduction of CO 2 to liquid products. Moreover, the synergetic role of Cu+ also contributed to the enhanced activity by promoting CO 2 adsorption and facilitating C–C coupling. As a result, the peak Faradaic efficiency (FE) for liquid products of 95.5 % was obtained, associated with a high ethanol FE of 52.6 % and formation rate of 23.8 μmol h−1 cm−2 within a H-cell. Furthermore, within a flow cell configuration, we have observed a significant improvement in the generation of formate, maintaining FE values above 70 % even under high current densities of up to 400 mA cm−2. In-situ Raman spectroscopic measurements allow us to identify and track key intermediates involved in the CO 2 reduction to formate and ethanol. This detailed understanding of the reaction pathways adds to our fundamental knowledge and provides valuable insights for the development of morphology-controlled electrocatalysts targeting efficient conversion of CO 2 into liquid products. [ABSTRACT FROM AUTHOR]