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Indium‐based materials can selectively reduce CO2 to formate, but their activities still fall short of expectations to be considered for practical applications. Structural engineering at the nanoscale offers a promising solution. However, it is challenging to directly prepare nanostructures of metallic indium because of its low melting point and high oxophilicity. Herein, a strategy to prepare highly dispersed indium oxide nanoparticles as the precatalyst supported on conductive carbon nanorods from annealing the MIL‐68 (In) precursor is proposed. When assessed in an H‐cell, the product enables CO2 reduction to formate with great faradaic efficiency of around 90% over a wide potential window in 0.5 m KHCO3. When applied in a gas‐diffusion‐electrode‐based flow cell, the catalyst delivers large current density of up to 300 mA cm−2 in 1 m KOH, great formate faradaic efficiency and decent stability. These results indicate the commercial viability of the catalyst even though the carbonate buildup at the gas diffusion electrode remains an issue of future research. [ABSTRACT FROM AUTHOR]

Alloying is a general strategy for modulating the electronic structures of catalyst materials. Compared to more common solid–solution alloys, intermetallic alloys feature well‐defined atomic arrangements and provide the unique platform for studying the structure‐performance correlations. It is, unfortunately, synthetically challenging to prepare the nanostructures of intermetallic alloys for catalysis research. In this contribution, we prepare intermetallic Pd3Bi nanocrystals of a uniform size via a facile solvothermal method. These nanocrystals can phase‐transform into solid solution alloy via thermal annealing while retaining a similar composition and size. In 0.1 M KHCO3 aqueous solution, the intermetallic Pd3Bi can selectively reduce CO2 to formate with high selectivity (≈100 %) and stability even at <‐0.35 V versus reversible hydrogen electrode, whereas the solid solution alloy has limited formate selectivity of <60 %. Such unique phase‐dependence is understood via theoretical simulations showing that the crystallographic ordering of Pd and Bi atoms within intermetallic alloys can suppress CO poisoning and enhance the *OCHO adsorption during electrochemical CO2 reduction to formate. [ABSTRACT FROM AUTHOR]

The size modulation of catalyst particles represents a useful dimension to tune catalytic performances by impacting not only their surface areas but also local electronic structures. It, however, has remained inadequately explored and poorly elucidated. Here, we report the interesting size‐dependent selectivity of electrochemical CO2 reduction on In2O3 nanocrystals. 5‐nm nanoparticles and 15‐nm nanocubes with focused size distribution are prepared via a facile solvothermal reaction in oleylamine by carefully controlling a set of experimental parameters. They serve as the precatalysts, and are reduced to In nanocrystals while largely inherit the original size feature during electrochemical CO2 reduction. Catalyst derived from 15‐nm nanocubes exhibits greater formate selectivity (>95 %) at lower overpotential and negligible side reactions compared to bulk‐like samples (indium foil and 200‐nm cubes) as well as the catalyst derived from smaller 5‐nm nanoparticles. This unique size dependence is rationalized as a result of the competition among different reaction pathways by our theoretical computations. Smaller is not always better in the catalyst design. [ABSTRACT FROM AUTHOR]

Selective CO2 reduction to formic acid or formate is the most technologically and economically viable approach to realize electrochemical CO2 valorization. Main group metal–based (Sn, Bi, In, Pb, and Sb) nanostructured materials hold great promise, but are still confronted with several challenges. Here, the current status, challenges, and future opportunities of main group metal–based nanostructured materials for electrochemical CO2 reduction to formate are reviewed. Firstly, the fundamentals of electrochemical CO2 reduction are presented, including the technoeconomic viability of different products, possible reaction pathways, standard experimental procedure, and performance figures of merit. This is then followed by detailed discussions about different types of main group metal–based electrocatalyst materials, with an emphasis on underlying material design principles for promoting the reaction activity, selectivity, and stability. Subsequently, recent efforts on flow cells and membrane electrode assembly cells are reviewed so as to promote the current density as well as mechanistic studies using in situ characterization techniques. To conclude a short perspective is offered about the future opportunities and directions of this exciting field. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: Electrocatalytic carbon dioxide reduction holds great promise for reducing the atmospheric CO2 level and alleviating the energy crisis. High‐performance electrocatalysts are often required in order to lower the high overpotential and expedite the sluggish reaction kinetics of CO2 electroreduction. Copper is a promising candidate metal. However, it usually suffers from the issues of poor stability and low product selectivity. In this work, bimetallic Cu‐Bi is obtained by reducing the microspherical copper bismuthate (CuBi2O4) for selectively catalyzing the CO2 reduction to formate (HCOO–). The bimetallic Cu‐Bi electrocatalyst exhibits high activity and selectivity with the Faradic efficiency over 90% in a wide potential window. A maximum Faradaic efficiency of ~95% is obtained at –0.93 V versus reversible hydrogen electrode. Furthermore, the catalyst shows high stability over 6 h with Faradaic efficiency of ~95%. This study provides an important clue in designing new functional materials for CO2 electroreduction with high activity and selectivity. Bimetallic Cu‐Bi CO2RR electrocatalysts were prepared via the cathodic conversion of hierarchical CuBi2O4 microspheres. They enabled the high‐performance electrocatalytic reduction of CO2 to formate with large current density, excellent selectivity, and sufficient durability. [ABSTRACT FROM AUTHOR]

Keywords: electrochemical CO2 reduction; formate; main group metals; nanostructures In article number 1902338, Youyong Li, Yanguang Li and co-workers review the current status, challenges and future opportunities of main-group-metal-based nanostructured materials for electrochemical CO SB 2 sb reduction to formate. Electrochemical CO2 reduction, formate, main group metals, nanostructures. [Extracted from the article]

The conversion of CO2 to value‐added products using electrical or solar energy represents an attractive means for the capture and utilization of atmospheric CO2. Formate is a popular product from CO2 reduction, but its reaction selectivity is usually unsatisfactory. Tin‐based materials have attracted the most attention for formate production at present. Unfortunately, most of them only exhibit moderate selectivity in a narrow and highly cathodic potential window. In this study, it is demonstrated that traditionally under‐explored bismuth has a much greater potential for formate production than tin or other materials. Mesoporous bismuth nanosheets are prepared here by the cathodic transformation of atomic‐thick bismuth oxycarbonate nanosheets. They enable the selective CO2 reduction to formate with large current density, excellent Faradaic efficiency (≈100%) over a broad potential window and great operation stability. Moreover, Bi nanosheets are integrated with an oxygen evolution reaction electrocatalyst in full cells, and achieve efficient and robust solar conversion of CO2/H2O to formate/O2. Cathodic transformation of atomic‐thick Bi2O2CO3 nanosheets to 2D mesoporous Bi nanosheets enables efficient CO2 reduction to formate with large current density, excellent selectivity over a broad potential window, and satisfactory stability. [ABSTRACT FROM AUTHOR]

The size modulation of catalyst particles represents a useful dimension to tune catalytic performances by impacting not only their surface areas but also local electronic structures. It, however, has remained inadequately explored and poorly elucidated. Here, we report the interesting size‐dependent selectivity of electrochemical CO2 reduction on In2O3 nanocrystals. 5‐nm nanoparticles and 15‐nm nanocubes with focused size distribution are prepared via a facile solvothermal reaction in oleylamine by carefully controlling a set of experimental parameters. They serve as the precatalysts, and are reduced to In nanocrystals while largely inherit the original size feature during electrochemical CO2 reduction. Catalyst derived from 15‐nm nanocubes exhibits greater formate selectivity (>95 %) at lower overpotential and negligible side reactions compared to bulk‐like samples (indium foil and 200‐nm cubes) as well as the catalyst derived from smaller 5‐nm nanoparticles. This unique size dependence is rationalized as a result of the competition among different reaction pathways by our theoretical computations. Smaller is not always better in the catalyst design. [ABSTRACT FROM AUTHOR]