Electrochemical carbon dioxide reduction to isopropanol using novel carbonized copper metal organic framework derived electrodes

Electrochemical conversion of CO2 using metalorganic frameworks-based materials: A review on recent progresses and outlooks

Global warming has been mainly attributed to the excessive release of carbon dioxide (CO2) to the atmosphere. Several CO2 capture and conversion technologies have been developed in the past few decades with their own merits and limitations. Electrochemical conversion of CO2 is one of the most attractive techniques for combating CO2 emissions. However, the efficacy of the electrochemical reduction of CO2 hinges on the efficiency of the utilized materials (i.e., electrocatalysts). Metal organic frameworks (MOFs)-based materials have recently emerged as attractive tools for various applications, including the electrochemical conversion of CO2. Although there are some review articles on CO2 capture and conversion using different materials, reviews focusing specifically on the electrochemical conversion of CO2 using MOFs-based materials are still comparatively lacking. Additionally, the field of electrochemical conversion of CO2 into valuable chemicals is currently gaining high momentum, requiring comprehensive and recent reviews, which would provide researchers/professionals with a quick and easy access to the recent developments in this rapidly evolving research area. Accordingly, this article comprehensively reviews recent studies on the electrochemical conversion of CO2 using pristine/modified/functionalized MOFs as well as composite materials containing MOFs. Additionally, single atom catalysts (SACs) derived from MOFs and their applications for the electrochemical conversion of CO2 has also been reviewed. Furthermore, obstacles, challenges, limitations, and remaining research gaps have been identified, and future works to tackle them have been highlighted. Overall, this review article provides valuable discussion and insights into the recent advancements in the field of electrochemical conversion of CO2 into chemicals using MOFs-based materials.

Electrochemical CO2 Reduction Reaction: Comprehensive Strategic Approaches to Catalyst Design for Selective Liquid Products Formation

The escalating concern regarding the release of CO2 into the atmosphere poses a significant threat to the contemporary efforts in mitigating climate change. Amidst a multitude of strategies for curtailing CO2 emissions, the electrochemical CO2 reduction presents a promising avenue for transforming CO2 molecules into a diverse array of valuable gaseous and liquid products, such as CO, CH3OH, CH4, HCO2H, C2H4, C2H5OH, CH3CO2H, 1-C3H7OH and others. The mechanistic investigations of gaseous products (e. g. CO, CH4, C2H4, C2H6 and others) broadly covered in the literature. There is a noticeable gap in the literature when it comes to a comprehensive summary exclusively dedicated to coherent roadmap for the designing principles for a selective catalyst all possible liquid products (such as CH3OH, C2H5OH, 1-C3H7OH, 2-C3H7OH, 1-C4H9OH, as well as other C3-C4 products like methylglyoxal and 2,3-furandiol, in addition to HCO2H, AcOH, oxalic acid and others), selectively converted by CO2 reduction. This entails a meticulous analysis to justify these approaches and a thorough exploration of the correlation between materials and their electrocatalytic properties. Furthermore, these insightful discussions illuminate the future prospects for practical applications, a facet not exhaustively examined in prior reviews.

Cu-phen Coordination Enabled Selective Electrocatalytic Reduction of CO2 to Methane

Manipulation of selectivity in the catalytic electrochemical carbon dioxide reduction reaction (eCO2RR) poses significant challenges due to inevitable structure reconstruction. One approach is to develop effective strategies for controlling reaction pathways to gain a deeper understanding of mechanisms in robust CO2RR systems. In this work, by precise introduction of 1,10-phenanthroline as a bidentate ligand modulator, the electronic property of the copper site was effectively regulated, thereby directing selectivity switch. By modification of [Cu3(btec)(OH)2]n, the use of [Cu2(btec)(phen)2]n·(H2O)n achieved the selectivity switch from ethylene (faradaic efficiency (FE) = 41%, FEC2+ = 67%) to methane (FECH4 = 69%). Various in situ spectroscopic characterizations revealed that [Cu2(btec)(phen)2]n·(H2O)n promoted the hydrogenation of *CO intermediates, leading to methane generation instead of dimerization to form C2+ products. Acting as a delocalized π-conjugation scaffold, 1,10-phenanthroline in [Cu2(btec)(phen)2]n·(H2O)n helps stabilize Cuδ+. This work presents a novel approach to regulate the coordination environment of active sites with the aim of selectively modulating the CO2RR.

Al-Sehemi A, Alargarsamy S, Gajendran P, Ramachandran R. Development of Different Kinds of Electrocatalyst for the Electrochemical Reduction of Carbon Dioxide Reactions: An Overview

Significant advancements have been made in the development of CO2 reduction processes for applications such as electrosynthesis, energy storage, and environmental remediation. Several materials have demonstrated great potential in achieving high activity and selectivity for the desired reduction products. Nevertheless, these advancements have primarily been limited to small-scale laboratory settings, and the considerable technical obstacles associated with large-scale CO2 reduction have not received sufficient attention. Many of the researchers have been faced with persistent challenges in the catalytic process, primarily stemming from the low Faraday efficiency, high overpotential, and low limiting current density observed in the production of the desired target product. The highlighted materials possess the capability to transform CO2 into various oxygenates, including ethanol, methanol, and formates, as well as hydrocarbons such as methane and ethane. A comprehensive summary of the recent research progress on these discussed types of electrocatalysts is provided, highlighting the detailed examination of their electrocatalytic activity enhancement strategies. This serves as a valuable reference for the development of highly efficient electrocatalysts with different orientations. This review encompasses the latest developments in catalyst materials and cell designs, presenting the leading materials utilized for the conversion of CO2 into various valuable products. Corresponding designs of cells and reactors are also included to provide a comprehensive overview of the advancements in this field.

Coupling CO2-to-Ethylene Reduction with the Chlor-Alkaline Process in Seawater through In Situ-Formed Cu Catalysts

The overall commercial value of a CO₂ electroreduction system is hindered by the valueless product and high energy consumption of the oxygen evolution reaction (OER) at the anode. Herein, with an in situ-formed copper catalyst, we employed the alternative chlorine evolution reaction for OER, and high-speed formation of both C2 products and hypochlorite in seawater can be realized. The EDTA in the sea salt electrolyte can trigger an intense dissolution and deposition of Cu on the surface of the electrode, resulting in the in situ formation of dendrites of Cu with high chemical activity. In this system, a faradaic efficiency of 47% can be realized for C₂H₄ production at the cathode and a faradaic efficiency of 85% can be realized for hypochlorite production at the anode with an operation current of 100 mA/cm². This work presents a system for designing a highly efficient coupling system for the CO₂ reduction reaction and alternative anodic reactions toward value-added products in a seawater environment.

Alloying strategies for tuning product selectivity during electrochemical CO2 reduction over Cu

Excessive reliance on fossil fuels has led to the release and accumulation of large quantities of CO₂ into the atmosphere which has raised serious concerns related to environmental pollution and global warming. One way to mitigate this problem is to electrochemically recycle CO₂ to value-added chemicals or fuels using electricity from renewable energy sources. Cu is the only metallic electrocatalyst that has been shown to produce a wide range of industrially important chemicals at appreciable rates. However, low product selectivity is a fundamental issue limiting commercial applications of electrochemical CO₂ reduction over Cu catalysts. Combining copper with other metals that actively contribute to the electrochemical CO₂ reduction reaction process can selectively facilitate generation of desirable products. Alloying Cu can alter surface binding strength through electronic and geometric effects, enhancing the availability of surface confined carbon species, and stabilising key reduction intermediates. As a result, significant research has been undertaken to design and fabricate copper-based alloy catalysts with structures that can enhance the selectivity of targeted products. In this article, progress with use of alloying strategies for development of Cu-alloy catalysts are reviewed. Challenges in achieving high selectivity and possible future directions for development of new copper-based alloy catalysts are considered.

Pyrolysis of a metal-organic framework followed by in situ X-ray absorption spectroscopy, powder diffraction and pair distribution function analysis

Metal-organic frameworks (MOFs) can serve as precursors for new nanomaterials via thermal decomposition. Such MOF-derived nanomaterials (MDNs) are often comprised of metal and/or metal oxide particles embedded on porous carbon....

Application of Porous Materials for CO2 Reutilization: A Review

CO2 reutilization processes contribute to the mitigation of CO2 as a potent greenhouse gas (GHG) through reusing and converting it into economically valuable chemical products including methanol, dimethyl ether, and methane. Solar thermochemical conversion and photochemical and electrochemical CO2 reduction processes are emerging technologies in which solar energy is utilized to provide the energy required for the endothermic dissociation of CO2. Owing to the surface-dependent nature of these technologies, their performance is significantly reliant on the solid reactant/catalyst accessible surface area. Solid porous structures either entirely made from the catalyst or used as a support for coating the catalyst/solid reactants can increase the number of active reaction sites and, thus, the kinetics of CO2 reutilization reactions. This paper reviews the principles and application of porous materials for CO2 reutilization pathways in solar thermochemical, photochemical, and electrochemical reduction technologies. Then, the state of the development of each technology is critically reviewed and evaluated with the focus on the use of porous materials. Finally, the research needs and challenges are presented to further advance the implementation of porous materials in the CO2 reutilization processes and the commercialization of the aforementioned technologies.

Synthesis of Cu2O Nanostructures with Tunable Crystal Facets for Electrochemical CO2 Reduction to Alcohols

Electrochemical CO₂ reduction enables the conversion of intermittent renewable energy to value-added chemicals and fuel, presenting a promising strategy to relieve CO₂ emission and achieve clean energy storage. In this work, we developed nanosized Cu₂O catalysts using the hydrothermal method for electrochemical CO₂ reduction to alcohols. Cu₂O nanoparticles (NPs) of various morphologies that were enclosed with different crystal facets, named as Cu₂O-c (cubic structure with (100) facets), Cu₂O-o (octahedron structure with (111) facets), Cu₂O-t (truncated octahedron structure with both (100) and (111) facets), and Cu₂O-u (urchin-like structure with (100), (220), and (222) facets), were prepared by regulating the content of a polyvinyl pyrrolidone (PVP) template. The electrochemical CO₂ reduction performance of the different Cu₂O NPs was evaluated in the CO₂-saturated 0.5 M KHCO₃ electrolyte. The as-synthesized Cu₂O nanostructures were capable of reducing CO₂ to produce alcohols including methanol, ethanol, and isopropanol. The alcohol selectivity of the different Cu₂O NPs followed the order of Cu₂O-t < Cu₂O-u < Cu₂O-c < Cu₂O-o (with the total Faradaic efficiencies of alcohol products of 10.7, 25.0, 26.2, and 35.4%). The facet-dependent effects were associated with the varied concentrations of oxygen-vacancy defects, different energy barriers of CO₂ reduction, and distinct Cu-O bond lengths over the different crystal facets. The desired Cu₂O-o catalyst exhibited good reduction activity with the highest partial current density of 0.51 mA/cm² for alcohols. The Faradaic efficiencies of alcohol products were 4.9% for methanol, 17.9% for ethanol, and 12.6% for isopropanol. The good electrochemical CO₂ reduction performance was also associated with the surface reconstruction of Cu₂O, which endowed the catalyst with abundant Cu⁰ and Cu⁺ sites for promoted CO₂ activation and stabilized CO* adsorption for enhanced C-C coupling. This work will provide a new route for enhancing the alcohol selectivity of nanostructured Cu₂O catalysts by crystal facet engineering.

Investigation into the Re-Arrangement of Copper Foams Pre- and Post-CO2 Electrocatalysis

The utilization of carbon dioxide is a major incentive for the growing field of carbon capture. Carbon dioxide could be an abundant building block to generate higher-value chemical products. Herein, we fabricated a porous copper electrode capable of catalyzing the reduction of carbon dioxide into higher-value products, such as ethylene, ethanol and propanol. We investigated the formation of the foams under different conditions, not only analyzing their morphological and crystal structure, but also documenting their performance as a catalyst. In particular, we studied the response of the foams to CO2 electrolysis, including the effect of urea as a potential additive to enhance CO2 catalysis. Before electrolysis, the pristine and urea-modified foam copper electrodes consisted of a mixture of cuboctahedra and dendrites. After 35 min of electrolysis, the cuboctahedra and dendrites underwent structural rearrangement affecting catalysis performance. We found that alterations in the morphology, crystallinity and surface composition of the catalyst were conducive to the deactivation of the copper foams.

Nanoengineering Metal-Organic Framework-Based Materials for Use in Electrochemical CO2 Reduction Reactions

Electrocatalytic reduction of carbon dioxide to valuable chemicals is a sustainable technology that can achieve a carbon-neutral energy cycle in the environment. Electrochemical CO₂  reduction reaction (CO₂ RR) processes using metal-organic frameworks (MOFs), featuring atomically dispersed active sites, large surface area, high porosity, controllable morphology, and remarkable tunability, have attracted considerable research attention. Well-defined MOFs can be constructed to improve conductivity, introduce active centers, and form carbon-based single-atom catalysts (SACs) with enhanced active sites that are accessible for the development of CO₂  conversion. In this review, the progress on pristine MOFs, MOF hybrids, and MOF-derived carbon-based SACs is summarized for the electrocatalytic reduction of CO₂ . Finally, the limitations and potential improvement directions with respect to the advancement of MOF-related materials for the field of research are discussed. These summaries are expected to provide inspiration on reasonable design to develop stable and high-efficiency MOFs-based electrocatalysts for CO₂ RR.

Metal-Organic Frameworks as a Platform for CO2 Capture and Chemical Processes: Adsorption, Membrane Separation, Catalytic-Conversion, and Electrochemical Reduction of CO2

The continuous rise in the atmospheric concentration of carbon dioxide gas (CO2) is of significant global concern. Several methodologies and technologies are proposed and applied by the industries to mitigate the emissions of CO2 into the atmosphere. This review article offers a large number of studies that aim to capture, convert, or reduce CO2 by using a superb porous class of materials (metal-organic frameworks, MOFs), aiming to tackle this worldwide issue. MOFs possess several remarkable features ranging from high surface area and porosity to functionality and morphology. As a result of these unique features, MOFs were selected as the main class of porous material in this review article. MOFs act as an ideal candidate for the CO2 capture process. The main approaches for capturing CO2 are pre-combustion capture, post-combustion capture, and oxy-fuel combustion capture. The applications of MOFs in the carbon capture processes were extensively overviewed. In addition, the applications of MOFs in the adsorption, membrane separation, catalytic conversion, and electrochemical reduction processes of CO2 were also studied in order to provide new practical and efficient techniques for CO2 mitigation.