DOI: 10.5061/dryad.rv15dv4mp
title: Maintaining local alkalinity of CO-electroreduction full cell by silica-confined electrocatalysts in membrane electrode assembly

description: CO electroreduction in alkaline membrane electrode assembly represents an
 effective approach to achieve carbon neutrality. However, its performance
 is currently limited by the insufficient modulation of local alkalinity at
 a full cell level. In this work, we reveal that confining the in-situ
 generated OH− at cathode and enriching the bulk OH− to anode are the key
 factors for an efficient CO-electroreduction full cell. We thereby propose
 a silica-confined strategy for electrocatalyst design to maintain high
 local alkalinity at both cathode and anode by the strong Lewis acid-base
 interaction between highly electrophilic Si atom and OH−. The developed
 Cu/SiO2 cathode and Co/SiO2 anode successfully promote cathodic
 multi-carbon formation and anodic oxygen evolution, thereby improving the
 full cell energy efficiency. Even under high-rate electrolysis at 900 mA
 cm −2, the selectivity and energy efficiency of multi-carbon
 products remains above 80% and 30%. This achievement highlights the
 significance of modulating the dynamic OH⁻ transport at full cell in
 enhancing CO electroreduction performance.
description: # Maintaining local alkalinity of CO-electroreduction full cell by
 silica-confined electrocatalysts in membrane electrode assembly Dataset
 DOI: [10.5061/dryad.rv15dv4mp](https://doi.org/10.5061/dryad.rv15dv4mp) ##
 Description of the data and file structure All data generated or analyzed
 during this study are included in the paper and the Supplementary
 Materials. ### Files and variables #### File: Source_data.xlsx Fig. 1C
 Measurement on anolyte OH^−^ transport across AEM under open circuit
 voltage (OCV). Fig. 1D In-situ OH^−^ adsorption curves recorded on Cu
 electrode before and after CORR at −100 mA cm^−2^ in 1 M KCl. Fig. 1E CORR
 performances on Cu cathodes modified with CEI (i.e. Nafion) or AEI (i.e.
 QAPPT). Fig. 1G In-situ OH^−^ adsorption curves recorded on Cu electrode
 after CORR or hydrogen evolution reaction (HER) at different current
 densities in 1 M KCl. Fig. 2D Cu *K*-edge XANES spectra of Cu, Cu/SiO~2~
 and the reference materials. Fig. 2E Fourier-transformed Cu *K*-edge EXAFS
 spectra of Cu, Cu/SiO~2~ and the reference materials. Fig. 2F Wavelet
 transformation plots of Cu *K*-edge EXAFS spectra of Cu, Cu/SiO~2~ and the
 reference materials. Fig. 3A Adsorption energy (E~ad~) of *OH on different
 Si and Cu sites of Cu/SiO~2~. Fig. 3B OH^−^ adsorption curves recorded on
 Cu/SiO~2~ and Cu electrodes in 1 M KOH. Fig. 3C ECSA normalized K^+^
 adsorption on Cu/SiO~2~ and Cu electrodes. Fig. 3D left In-situ Raman
 spectra during CORR recorded on Cu/SiO~2~ and Cu electrodes. Fig. 3D right
 In-situ Raman spectra during CORR recorded on Cu/SiO~2~ and Cu electrodes.
 Fig. 3E FE of all products during CORR on Cu/SiO~2~. Fig. 3F FE of C~2+~
 products on Cu/SiO~2~ and Cu. Fig. 3G Current densities of C~2+~ products
 and cell voltages by using Cu/SiO~2~ and Cu. Fig. 3H Free energy diagrams
 for 2*CO coupling to *OCCO on Cu and Cu/SiO~2~. Fig. 4A Cell voltages
 recorded in 0.5 M K~2~SO~4~ or 1 M KOH at 100 mA cm^−2^ with Cu cathode
 and IrO~2~ anode. Fig. 4D In-situ Raman spectra during OER recorded on
 Co/SiO~2~ and Co electrodes. Fig. 4E LSV curves for OER recorded on
 Co/SiO2, Co and IrO2 electrodes at 5 mV s−1 in 1 M KOH. Fig. 4F EIS
 results recorded at 1.53 V vs. RHE on Co/SiO~2~, Co and IrO~2~ electrodes
 from 100 kHz to 0.1 Hz with 5 mV amplitude. Fig. 4G Comparation on the
 R~ct~ of Co/SiO~2~ and IrO~2~ electrodes at different applied potentials.
 Fig. 4H LSV curves for MOR recorded on Co/SiO~2~ and IrO~2~ electrodes at
 5 mV s^−1^ in 1 M KOH with 1 M methanol. Fig. 4I Potential change from OER
 to MOR on Co/SiO~2~ and IrO~2~ electrodes at 100 mA cm^−2^. Fig. 4J OER
 durability test on Co/SiO~2~ electrode in 1 M KOH at 100 mA cm^−2^. Fig.
 5A FE of all products during CORR with Cu/SiO~2~ cathode, Co/SiO~2~ anode
 and 1 M KOH anolyte. Fig. 5B Comparation on cell voltage with different
 cathode and anode configurations. Fig. 5C Comparation on EE of C~2+~
 products with different cathode and anode configurations. Fig. 5D
 Comparation on current density of C~2+~ products with different cathode
 and anode configurations. Fig. S1B XRD pattern of Cu nanoparticles. Fig.
 S1C XPS spectra of Cu 2*p* of Cu nanoparticles. Fig. S1D XPS spectra of Cu
 *LMM* of Cu nanoparticles. Fig. S2 CORR performances of Cu electrode in
 flow cell and MEA with different electrolytes. Fig. S4B LSV curves for OER
 recorded on IrO~2~ electrode modified with AEI (i.e. QAPPT) and CEI (i.e.
 Nafion) at 5 mV s^−1^ in 1 M KOH. Fig. S4C left Bode plots recorded at
 different potentials. From 100 kHz to 0.1 Hz with 5 mV amplitude. Fig. S4C
 right Bode plots recorded at different potentials. From 100 kHz to 0.1 Hz
 with 5 mV amplitude. Fig. S7A XRD patterns of Cu silicate and Cu/SiO~2~.
 Fig. S7B XPS spectra of Cu 2*p* of Cu silicate and Cu/SiO~2~. Fig. S7C XPS
 spectra of Cu *LMM* of Cu silicate and Cu/SiO~2~. Fig. S7D XPS spectra of
 Si 2*p* of Cu silicate and Cu/SiO~2~. Fig. S8A Pb stripping curves
 recorded on Cu electrode. Fig. S8B Pb stripping curves recorded on
 Cu/SiO~2~ electrode. Fig. S9 Energy and temperature evolutions of
 Si~6~O~13~ cluster on Cu (111) surface by machine learning force field ab
 initio molecular dynamics at 1000 K. Fig. S11A NH~3~ TPD-MS test of
 Cu/SiO~2~ and Cu. TCD signals. Fig. S11B NH~3~ TPD-MS test of Cu/SiO~2~
 and Cu. MS signals. Fig. S12A EIS results recorded at a cell voltage of
 2.0 V with Cu/SiO~2~ and Cu cathodes. From 100 kHz to 0.1 Hz with 5 mV
 amplitude. Fig. S12B TOF of C~2+~ products on Cu/SiO~2~ and Cu cathodes.
 The calculation is based on Cu site. Fig. S12C SPCE on Cu/SiO~2~ and Cu
 cathodes. The gas flow rate is 5 mL/min and the CO content is 95%. Fig.
 S13A E~ad~ of 2*CO and *OCCO on Cu/SiO~2~ and Cu. Fig. S13B Density of
 states of Cu/SiO~2~ and Cu with adsorbed *OCCO. Fig. S14A FE of all
 products during CORR on Cu. Fig. S14C Free energy diagrams for *OCCOH to
 *HOCCOH or *CCO on Cu. Fig. S14D Free energy diagrams for *OCCOH to
 *HOCCOH or *CCO on Cu/SiO~2~. Fig. S15 CORR performances on Cu and
 Cu/SiO~2~ cathodes modified with different fractions of CEI (i.e. Nafion).
 Fig. S18A XRD patterns of Co silicate and Co/SiO~2~. Fig. S18B XPS spectra
 of Co 2*p* of Co silicate and Co/SiO~2~. Fig. S18C XPS spectra of Si 2*p*
 of Co silicate and Co/SiO~2~. Fig. S19 E~ad~ of *OH on Si sites and Co
 sites. Fig. S22A Free energy diagram for *OH migration from Si to Co. Fig.
 S22B Free energy change for *OH migration from Si to Co and the
 rate-determining step (RDS, *O to *OOH) of OER on Co. Fig. S23 Free energy
 diagrams for OER on Co with different *OH coverages. Fig. S24A NH~3~
 TPD-MS test of Co/SiO~2~ and Co. TCD signals. Fig. S24B NH~3~ TPD-MS test
 of Co/SiO~2~ and Co. MS signals. Fig. S25B XRD pattern of Co
 nanoparticles. Fig. S25C XPS spectra of Co 2*p* of Co nanoparticles. Fig.
 S26A CV curves recorded on Co/SiO~2~ and Co electrodes in 0.1 M KOH. Fig.
 S26B Redox potentials of Co/SiO~2~ and Co electrodes. Fig. S27A LSV curves
 for MOR and OER recorded on Co/SiO~2~ electrode. Fig. S27B LSV curves for
 MOR and OER recorded on IrO~2~ electrode. Fig. S28A LSV curves for OER
 recorded on Co/SiO~2~ electrode at 5 mV s^−1^ in 1 M KOH before and after
 adding 0.1 M thiourea. Fig. S28B Current density variation at 1.68 V vs.
 RHE before and after adding thiourea. Fig. S29 Full cell CO electrolysis
 durability.