Catalyst Design for Electrochemical Reduction of CO₂ to Multicarbon Products

Abstract

solve this problem with electricity converted from renewable energies (such as solar and wind energy) to transform CO 2 into fuels and industrial raw materials. From the thermodynamic view, there are many potential products that could be obtained from CO 2 RR, such as CO, CH 4 , C 2 H 4 , HCOOH, and C 2 H 5 OH. Meanwhile, hydrogen evolution reaction (HER) is always competing with CO 2 RR in aqueous solutions, usually potassium bicarbonate solutions. Possible CO 2 RR paths are listed in Figure 1 : [4][5][6][7][8] i) CO 2 molecules in the electrolyte are adsorbed on the surface of catalysts; ii) after a proton-coupled electron transfer step, the as-adsorbed CO 2 molecules are transformed into *COOH or *OCHO, which are important intermediates for CO and HCOOH, respectively; iii) if the catalyst has a strong binding energy for *CO, the generated C 1 intermediates on the surface will continue to anticipate reactions. The C 1 intermediates could be hydrogenated to CH 4 or coupled with each other to form multicarbon (C 2+ ) products, such as ethanol, ethylene and n-propanol. CO 2 RR to CO or HCOOH only requires the transfer of two electrons, and is relatively facile to achieve, while it is highly challenging to obtain C 2+ products by CC coupling processes. However, selectively producing C 2+ products by CO 2 deep reduction is of significant importance, since C 2+ products have higher energy density and wider applications. [9][10][11][12] For instance, ethylene is the raw material to synthesize various chemicals such as polyethylene. Also, ethylene could be directly used as fuels for welding or as a component in natural gases. In conventional industries, ethylene is produced by hydrogenation of CO or CO 2 , which consumes a large amount of energy and causes unavoidable influence on environment. In contrast, selective CO 2 RR to ethylene with renewable electricity is a green and sustainable route. [13] In addition to ethylene, ethanol is another major C 2+ product. Ethanol is widely used in many fields including medicine, chemical industry, foodstuff, etc. Moreover, ethanol is a kind of energy sources for vehicles. Currently, the synthesis of ethanol needs to use ethylene or agricultural feedstocks, which also demands much energy. [14] In contrast, producing ethanol by selective CO 2 RR not only decreases CO 2 emission, but also brings economic benefits. Therefore, it is a potential and alternative route to produce ethanol by CO 2 RR.To date, many catalysts have been reported to promote the production of certain C 2+ product via CO 2 RR (Table 1). Among these catalysts, Cu-based materials stand out because of their Electrochemical reduction of CO 2 (CO 2 RR), driven by renewable energy (such as wind and solar energy), is an effective route toward carbon neutralization. The multicarbon (C 2+ ) products from CO 2 RR are highly desirable, since they are important fuels, chemicals, and industrial raw materials. However, selective reduction of CO 2 to C 2+ products is especially challenging, due to low selectivity, poor yiel...

Structure‐Function Correlation and Dynamic Restructuring of Cu for Highly Efficient Electrochemical CO2 Conversion

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Nanostructured Copper-Based Electrodes Electrochemically Synthesized on a Carbonaceous Gas Diffusion Membrane with Catalytic Activity for the Electroreduction of CO2

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3D Continuously Porous Graphene for Energy Applications

“…Although the mechanisms of CO 2 and N 2 reduction are still not conclusive, numerous studies have shown that defects and heteroatom dopants (e.g., N, B, P) can modify the band gap, charge distribution, and spin density of graphene and thereby boost the catalytic activity and selectivity toward CO 2 and N 2 reductions. [122][123][124][125][126][127] Graphene-supported metal nanoparticles and single-atom catalysts have also been proven as promising electrocatalysts for CO 2 and N 2 reductions. [128][129][130][131][132] Given the flexibility to tailor the topological defects and chemical dopants and to host nanoparticulate and single-atom metal catalysts, the 3D continuously porous graphene shows great promise for applications in electrochemical CO 2 and N 2 reductions with rationally optimized performance.…”