Sustainable Membrane‐Coated Electrodes for CO₂ Electroreduction to Methanol in Alkaline Media

Abstract

CO 2 electroreduction has high potential to combine carbon capture utilization and energy storage from renewable sources. The key challenge is the construction of highly efficient electrodes giving optimal CO 2 conversion to high-value products. In this regard, research on electrode structures remains as an important task to face. Despite the advancements in gas diffusion electrodes (GDEs) to facilitate CO 2 transfer and electrode efficiency, the catalyst is still vulnerable to be swept by the gas and liquid electrolyte, reducing the stability. We report the fabrication of novel membrane-coated electrodes (MCEs), by coating an anion exchange membrane over a copper (Cu) : chitosan (CS) catalyst layer onto the carbon paper. CS and poly(vinyl) alcohol (PVA) were chosen for membrane preparation and catalyst binder, where Cu was embedded in the polymer matrix as nanoparticles or ion-exchanged in a layered stannosilicate or zeolite Y, to improve their hydrophilic, conductive, mechanical, and environmentally-friendly properties considered relevant to the sustainability of the electrode fabrication and performance. The intimate connection between the CS : PVA polymer membrane over-layer and the CS/Cu catalytic layer protects the MCEs from material losses, enhancing the CO 2 conversion to methanol, even in high alkaline medium. A maximum Faraday Efficiency to methanol of 68.05 % was achieved for the 10CuY/CS : PVA membrane over-layer.

Continuous Electrochemical Reduction of CO2 to Formate: Comparative Study of the Influence of the Electrode Configuration with Sn and Bi-Based Electrocatalysts

“…Finally, further research is still required to overcome current limitations and develop processes with performances that simultaneously optimize all the figures of merit analyzed in this study. In this regard, research efforts should focus on the development of new filter press configurations [ 70 , 71 ] such as the use of a three-compartment electrochemical reactor, bipolar membranes [ 72 ], or working electrode configurations [ 73 ] to enhance the mass transfer of the reagents and products in the counter and working electrode, and simultaneously address the synthesis of innovative electrocatalysts for both cathode [ 74 ] and anode [ 75 ] to reduce the energy consumption in both compartments of the electrochemical reactor.…”

An Analysis of Research on Membrane-Coated Electrodes in the 2001–2019 Period: Potential Application to CO2 Capture and Utilization

“…The papers published in the most productive journals resulting from the bibliometric search deal with the surface modification of carbon-based electrodes aimed at improving chemical sensing properties in biomedical or environmental applications. There is a significant presence of journals regarding surface and interface science and technology, such as ACS Interface Applied Materials, ACS Catalysis, and ChemElectroChem, which are already focusing on the effect of the coated thin film on the electrocatalytic behavior of the electrode [28,32,33].…”

“…[28,39,40] and metal oxide (mostly, SiO x ) matrices to metal catalyst nanoparticles [32,33,46] and Nafion as the principal solid polymer electrolyte membrane [36,47]. In fact, conductive poly(4-vinyl pyridine) (PVP) polymer and hydrophilic chitosan biopolymer were coated over Cu electrodes before the time range of this study in electrochemistry studies for electroreduction reaction [48] and enhancing Cu sensitivity in humidity sensors [49] and used again for the development of coated electrodes [28,50]. In addition, the keywords cited less than two times mostly deal with the insight in understanding the transport and reaction mechanisms and equations modeling, and they are not included in Figure 3, but they are mentioned here given their relevance to the development of the process.…”

“…The membrane-coated electrode configurations under investigation are schematized in Figure 1. Figure 1a is the configuration "Catalyst coated membrane electrode" as with M + @CCM over Nafion for CO 2 electroreduction to formic acid [27], and Figure 1b is slightly different in that a sustainable polymer blend-based over-layer has been coated on the catalytic layer over the porous substrate to generate a membrane-coated electrode [28].…”

“…The membrane-coated electrode configurations under investigation are schematized in Figure 1. Figure 1a is the configuration "Catalyst coated membrane electrode" as with M + @CCM over Nafion for CO2 electroreduction to formic acid [27], and Figure 1b is slightly different in that a sustainable polymer blend-based over-layer has been coated on the catalytic layer over the porous substrate to generate a membrane-coated electrode [28]. A bibliometric analysis is a tool needed to evaluate comprehensively the generally large number of reports published in a specific research field, thus facilitating researchers with up-to-date information and knowledge on the state-of-the-art of the trends and interests in their fields [29].…”