Carbon Materials as Cathode Constituents for Electrochemical CO2 Reduction—A Review

Abstract

This work reviews the latest developments of cathodes for electrochemical CO 2 reduction, with carbon black, mesoporous carbons, carbon nanofibers, graphene, its derivatives and/or carbon nanotubes as constituents. Electrochemical CO 2 reduction into fuels and chemicals powered by renewable energy is a technology that can contribute to climate change mitigation. Strategies used in this fast-evolving field are discussed, having in mind a commercial application. Electrochemical performance of several materials is analyzed, using in some cases the findings of theoretical computational studies, which show the enormous potential of these materials. Considerable challenges still lie ahead to bring this technology into industrial deployment. However, the significant progress achieved so far shows that further R&D efforts might pay off.C 2019, 5, 83 2 of 26 considering the findings of theoretical computational studies, are in some cases analyzed, when this type of study is available. Knowledge gaps and new promising R&D trends of nanocarbon-based materials development for this application are highlighted. Carbon BlackCarbon black is produced by the incomplete combustion of petroleum heavy fractions. It is a form of para-crystalline carbon of high surface area. Although activated carbon has a more favorable surface area to volume ratio (>1000 m 2 /g) than carbon black, its low electrical conductivity makes it unsuitable as electrode material. Commercial carbon blacks, such as Vulcan or Ketjen black have been most frequently used as support to ensure large electrochemical reaction surfaces and to reduce noble metal loading. Metal and Metal-Derived Particles Supported on Carbon BlackCO 2 ER can be carried out in gas phase, where gaseous CO 2 is fed to the cathode through gas diffusion electrodes (GDE), or in liquid phase, where CO 2 dissolved in the liquid electrolyte contacts the electrode. Figure 1 presents a schematic diagram of two possible configurations of both operation modes.C 2019, 5, x FOR PEER REVIEW 2 of 25 discussed, having in mind a commercial application. Electrochemical performances of several materials, considering the findings of theoretical computational studies, are in some cases analyzed, when this type of study is available. Knowledge gaps and new promising R&D trends of nanocarbonbased materials development for this application are highlighted. Carbon BlackCarbon black is produced by the incomplete combustion of petroleum heavy fractions. It is a form of para-crystalline carbon of high surface area. Although activated carbon has a more favorable surface area to volume ratio (>1000 m 2 /g) than carbon black, its low electrical conductivity makes it unsuitable as electrode material. Commercial carbon blacks, such as Vulcan or Ketjen black have been most frequently used as support to ensure large electrochemical reaction surfaces and to reduce noble metal loading. Metal and Metal-Derived Particles Supported on Carbon BlackCO2ER can be carried out in gas phase, where gaseous CO2 is fed to the cathode thro...

Carbon-Based Materials for Electrochemical Reduction of CO2 to C2+ Oxygenates: Recent Progress and Remaining Challenges

“…Until now, most reviews on the electroreduction of CO 2 into C 2+ products have focused on metal copper, copper oxide, and copper alloy materials and have emphasized on the strategies of C–C coupling by controlling crystals, oxidizing surfaces, and constructing bimetallic catalysts. ,,, Some reviews have referred to the carbon-related materials; however, the role of carbon materials in C–C bond formation has not been discussed. There are also reviews on electrocatalytic CO 2 reduction with carbon-based materials, including modified diamond, porous carbon, graphene, and carbon nanotubes. − Most of these reviews emphasize the advantages of carbon materials and highlight the strategies for improving CO 2 reduction activity. These reviews aim to introduce the active site for activating CO 2 molecules and accelerating CO 2 reduction.…”

From CO2 to Value-Added Products: A Review about Carbon-Based Materials for Electro-Chemical CO2 Conversion

“…The use of metal nanoparticles dispersed on carbonaceous materials can also be part of gas diffusion electrodes (GDE), which allow the supply of CO 2 in the gaseous phase to the electrochemical cell, thus avoiding the limited solubility that CO 2 has in the electrolyte and reducing the limitations of mass transfer [214]. Specifically, the metal nanoparticles together with the carbonaceous support are part of the catalytic layer, which is deposited on a conductive material such as carbon paper, glassy carbon, carbon cloth, or metal meshes [215]. Several authors have used this strategy as an electrode in flow cells, for example Ma and co-workers [216] incorporated Ag nanoparticles in multiwall carbon nanotubes that were homogeneously distributed over the gas diffusion electrodes, obtaining a high catalytic activity towards CO (FE =< 95%, Jco = 350 mA/cm 2 ).…”

Applications of Carbon Dots for the Photocatalytic and Electrocatalytic Reduction of CO2

“…Carbonaceous materials, including carbon nanotubes (CNT), graphite, graphene and porous carbon, are known to possess good chemical and mechanical stability, excellent electrical conductivity and tunable electrical structure, representing ideal components for energy conversion devices [ 10 , 11 , 12 ]. In the past few years, various carbon-based nanomaterials have been successfully employed for an efficient catalytic CO 2 reduction, either in combination of metal/metal oxide-based catalysts or as metal-free catalysts themselves [ 13 , 14 , 15 , 16 ]. They have even been reported for the obtention of C ≥2 products [ 13 , 17 ] on account of their capability to decrease the energy barrier of the C−C coupling [ 18 ].…”