The_Catalyst_Review_December_2023 - 9

SPECIAL FEATURE
Nanostructuring of catalytic materials introduces unique morphological features, such as high surface-area-to-volume ratios and
exposed active sites, thereby augmenting catalytic performance. Advanced characterization tools, including spectroscopy and
microscopy, enable a detailed understanding of the electrocatalyst's behavior at the molecular level, aiding in the refinement of design
strategies for optimal functionality.
Electrocatalysis-Powered Conversion of CO2
into Fuels and Chemicals
The rapid increase in atmospheric CO2 levels and its associated environmental repercussions necessitate innovative strategies for
mitigating climate change. Electrochemical CO2 conversion presents an attractive solution, offering the dual benefits of carbon capture
and utilization. Electrocatalysis-driven transformations enable the selective reduction of CO2
into valuable compounds, simultaneously
offering a way to store renewable energy and produce essential chemicals and fuels.
The utilization of CO2
as a resource for producing valuable industrial chemicals has gained traction as a promising approach to
mitigate environmental concerns and simultaneously foster industrial growth (Le et al., 2021; Peng et al., 2021). Simultaneously, the
expansion of electricity production from renewable sources has introduced challenges due to the intermittent nature of such energy
generation (Haegel et al., 2017). To address these dual challenges, the electrochemical conversion of CO2
emerges as an appealing
avenue, offering a means to store surplus renewable energy within chemical bonds. This stored energy can be harnessed when
required, thereby mitigating issues associated with intermittent energy sources.
Compared with alternative methods like photocatalytic, chemo-biocatalytic, or chemo-enzymatic CO2
conversion (Bhardwaj et al.,
2021; Cihan et al., 2021; Sharma et al., 2020), the electrochemical conversion strategy leverages renewable or nuclear energy on
a significantly larger scale, utilizing electricity to exploit anthropogenic CO2
synthesizing sustainable fuels, often referred to as power-to-X technology (Sa et al., 2020). By doing so, this approach effectively
addresses both environmental concerns linked with CO2
associated with it.
However, the activation of thermodynamically stable
CO2
molecules for electrochemical conversion
necessitates a substantial energy input. Consequently,
ongoing research efforts have been devoted to
enhancing the efficiency and conversion rates of
electrochemical CO2
reduction reactions (Marques
Mota and Kim, 2019; Zhang et al., 2018), which
draw parallels to the principles of fuel cells or water
electrolysis cells. Within CO2
reduction reactions, a
plethora of value-added chemicals can be generated.
Electrocatalytic CO2
multi-electron reduction of CO2
Figure 1. Electrochemical conversion of CO2
Source: Author
into various products
reduction reactions involve the
to yield a variety of
products. The product distribution depends on the
reaction conditions, electrolyte composition, and
most importantly, the electrocatalyst. By modulating
the catalyst composition, structure, and active
sites, researchers can tune the reaction pathways
and product selectivity, enabling the synthesis of
products ranging from hydrocarbons to oxygenates.
The most common products of Carbon Dioxide
Reduction Reaction (CO2
RR) are outlined in Figure
1. The electron transfer mechanisms involved in the
production of each product, along with the primary
competing reaction, hydrogen evolution reaction
(HER), are succinctly summarized in Table 1.
Table 1. Summary of common CO2
RR and hydrogen evolution reaction (HER), products in
alkaline solution (pH 14), standard potentials with respect to reversible hydrogen electrode
[V vs. RHE] at 1 atm and 25 °C and the number of electrons transferred (Lin et al., 2020)
The Catalyst Review
Recently, state-of-the-art electrocatalysts have been
documented for selectively reducing CO2
to fuel
products such as CO (Au, Ag, Zn, etc.), formate (Sn,
Bi, Pb, In, etc.), or hydrocarbons (Cu with unique
December 2023
9
gas as an economical and abundant carbon source for
gas, mainly stemming from fossil fuel combustion, and the energy demand

The_Catalyst_Review_December_2023

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