The Catalyst Review July 2024 - 3

Independent Perspective
The views expressed are those of the individual author and may not reflect those of The Catalyst Review or TCGR.
Novel Membrane Electrode Assembly Design for Efficient CO2
Electrolysis
By Taye Demissie & Ramato Ashu Tufa, PhD.
The conversion of CO₂ into C₁ (e.g., methane, methanol and carbon monoxide) and C₂ (e.g., ethylene and ethanol) products
is a critical process in the effort to mitigate climate change and create sustainable chemical production pathways. This
transformation leverages catalytic technologies to convert CO₂ into valuable chemicals and fuels. Promising catalysts for
CO₂ conversion include both homogeneous and heterogeneous catalysts, with a notable focus on metal-based catalysts.
For instance, copper and its alloys have shown significant potential due to their ability to facilitate CO₂ reduction reactions to
produce C₁ and C₂ products. Additionally, single-atom catalysts incorporating single metal atoms (e.g., Ni, Fe) dispersed on
nitrogen-doped carbon supports, have also demonstrated high selectivity and activity for converting CO₂ to C₁ products (CO
and methanol).
Selectivity is essential for efficient CO₂ conversion, aiming to maximize desired products while minimizing by-products.
Enhancing selectivity of catalysts involves tuning electronic properties and surface structures, such as through alloying or
creating nanostructures. In this aspect, designing efficient catalysts involves approaches like employing advanced synthesis
techniques to create nanostructured materials with high surface areas and active sites, doping with other metals to create
bimetallic or alloy catalysts, surface morphology modification of the catalysts, and computational studies. For example,
nano-engineered catalysts with high surface areas can provide more active sites for CO₂ adsorption and subsequent
reduction, thereby enhancing catalytic activity. To integrate these novel catalytic designs into practical applications, they
can be effectively combined with gas-diffusion electrodes (GDE) and membranes, facilitating the development of advanced
membrane electrode assemblies (MEA) for efficient large-scale CO₂ reduction.
As such, bipolar membranes (BPMs) have emerged as promising materials outperforming the classical monopolar
membranes in many aspects, among others, due to their unique ability to maintain steady-state pH gradient in
electrochemical devices without significant efficiency loss. This makes BPMs highly suitable for integration with catalysts,
leading to development of BPM-electrode assembly (B-MEA) designs. In principle, catalysts integrated with unique GDEs
enable effective mass transfer of gaseous CO₂ to the catalyst surface across the large surface area of the porous structures,
leading to improved catalyst utilization and enhanced CO₂ reduction.
The key advantages of using a B-MEA in CO₂ reactors include: i) inhibition of not only product crossover, but also CO₂
crossover between compartments, enhancing CO₂ utilization efficiency, and ii) preservation of distinct pH environments on
either side of the membrane, which allows for the use of low-cost catalysts with improved activity and enhances catalytic
selectivity and stability during electrochemical CO₂ reduction. To achieve this, a deeper understanding of the membrane
structure-property-performance relationships under varying local environmental conditions at the membrane-electrode
interface is highly crucial. For instance, BPMs with thick membrane layers increase conductance and water permeance toward
the interface layer, thereby enhancing performance at high current densities. However, BPMs based on a thin membrane layer
also increase ion crossover, which reduces system efficiency. Despite this, efforts in the unique design of B-MEAs, compatible
with existing electrochemical systems, present a highly promising approach for scaling up and realizing electrochemical CO₂
reduction at an industrial scale.
Your Authors
ASSOCIATE PROFESSOR OF PHYSICAL & COMPUTATIONAL CHEMISTRY,
UNIVERSITY OF BOTSWANA
TAYE DEMISSIE
The Catalyst Review
Prof. Taye Demissie, associate professor of physical
and computational chemistry, has made significant
contributions to physical, organic, and materials
chemistry, particularly in computational studies of CO₂
activation and reduction reaction mechanisms. With
over 85 research papers in renowned journals, Taye has
held various academic positions in Ethiopia, Poland,
Norway, Czech Republic, and Botswana. Currently
he works at the Department of Chemistry, University
of Botswana. He is dedicated to STEM advocacy and
community engagement, inspiring and mentoring
future researchers in CO₂ reduction, drug design,
and basic research, leaving a lasting impact on the
community. Email: sene3095@gmail.com
RESEARCHER, UNIVERSITY OF CALABRIA
Dr. Ramato Ashu Tufa is a researcher at the University
of
Calabria, Italy, focusing on novel membrane
methods for extracting critical raw materials from
seawater. He previously held Marie Skłodowska-Curie
postdoc fellow positions at the Technical University
of Denmark and the University of Chemistry and
Technology Prague. He earned his Erasmus Mundus
joint PhD from the University of Calabria, the University
of Twente, and the University of Chemistry and
Technology Prague in Membrane Engineering. His
research interests include membrane material and
processes development for clean water and energy,
such as membrane distillation, electrodialysis, and
water/CO₂ electrolysis. Email: rashtey@gmail.com
RAMATO ASHU TUFA
July 2024
3

The Catalyst Review July 2024

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