The_Catalyst_Review_December_2023 - 15

Ag+-Doped InSe Nanosheets for Membrane Electrode Assembly Electrolyzer toward Large-current
Electroreduction of CO2
to Ethanol
Strategies aimed at reducing greenhouse emissions include CO2 electroreduction (CO2ER) to produce value-added fuels and chemicals such
as ethanol. However, industrial-scale electroreduction of CO2
Cu-based catalysts to sustain large current flow. Herein, the authors present the design of Ag+
which enables CO2
Based on this design, the authors suggest that the CO2
ER to yield a single liquid product (ethanol) in an membrane electrode assembly (MEA) electrolyzer.
In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization, combined with density functional theory (DFT)
calculations of these nanosheets, reveals that the Ag+
the Ag site and O-terminal adsorption on the In site. This, in turn, promotes the generation of bridged *COB
at Ag sites. Consequently, *COL is further protonated to *CHO* and coupled with *COB
electron transfer from Ag to Se can stabilize In2+
sites to ensure durable CO2
achieve an ethanol Faradaic Efficiency (FEC2
26.1% at 3.0 V, in an MEA electrolyzer by coupling cathodic CO2
To investigate the reaction intermediates formed during the CO2
to eventually generate ethanol. Furthermore, the
H5OH) of 68.7% and a partial current density of 186.6 mA cm_ 2
ER with anodic oxygen evolution reaction (OER).
(DRIFTS) are performed for InSe and Ag0.015In0.985Se0.734 (Figure 1).
Figure 1. a) Time-dependent in situ DRIFTS spectra of InSe at - 0.6 V. b) In 3d XPS spectra of InSe before and after 13 min CO2
ER.
ER at - 0.6 V.
c) Time-dependent in situ DRIFTS spectra of Ag0.015In0.985Se0.734 at - 0.6 V. d) In 3d XPS spectra of Ag0.015In0.985Se0.734 before and
after 13 min CO2
ER. As a result, the optimized Ag0.015In0.985Se0.734 nanosheets
with a full-cell energy efficiency of
ER process, in situ diffuse reflectance infrared Fourier transform spectra
ions doping modifies the electronic structure of InSe and diversities the active sites.
molecule is activated and hydrogenated to *CO*OH with C-terminal adsorption on
at Ag_Ag site and linear *COL
to ethanol has not yet been achieved due to the inability of the commonly used
-doped InSe nanosheets with Se vacancies,
The DRIFTS characterization, coupled with DFT calculations, provides the reaction pathway for CO2
ER to ethanol on Agx
Doping with Ag+ induces Se vacancies, electron transfer from Ag to Se, and diversities of the active sites, resulting in the accumulation of
electrons on the In sites near Se vacancies. These results lead to the effective capture of CO2
CO2 into bent *CO2*-. The subsequent protonation of *CO2
binding to In site. Further hydrogenation of *CO*OH produces *COL
In1- x Sey
nanosheets.
molecules and promote the conversion of linear
*- generates *CO*OH with C-terminal adsorption on the Ag site and O-terminal
and *COB, located at the Ag and bridge Ag-Ag sites, respectively. After
*COL is hydrogenated into *CHO* with C-terminal adsorption on the Ag site and O-terminal binding to In site, it undergoes further coupling
with *COB
to produce *COCHO*. The further hydrogenation of *COCHO* generates a two-oxygen bridge-bonded *OHCCHO* with one
O-terminal adsorption on the Ag site and the other on the In site. After multiple proton-coupled electron transfer steps, *OHCCHO* is
The Catalyst Review
December 2023
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