WO2024160799A1 - Électroréduction de co2 dans des conditions acides à l'aide d'un catalyseur ayant une double génération de co et une fonction de couplage c-c - Google Patents

Électroréduction de co2 dans des conditions acides à l'aide d'un catalyseur ayant une double génération de co et une fonction de couplage c-c Download PDF

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WO2024160799A1
WO2024160799A1 PCT/EP2024/052203 EP2024052203W WO2024160799A1 WO 2024160799 A1 WO2024160799 A1 WO 2024160799A1 EP 2024052203 W EP2024052203 W EP 2024052203W WO 2024160799 A1 WO2024160799 A1 WO 2024160799A1
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catalyst
catalyst layer
support
catalytic system
metal
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Yuanjun CHEN
Xiaoyan Li
Zhu CLARK
Edward H. Sargent
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Totalenergies Onetech
The Governing Council Of The University Of Toronto
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/25—Reduction
    • C25B3/26—Reduction of carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/052—Electrodes comprising one or more electrocatalytic coatings on a substrate
    • C25B11/053—Electrodes comprising one or more electrocatalytic coatings on a substrate characterised by multilayer electrocatalytic coatings
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
    • C25B11/095—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one of the compounds being organic
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/01—Products
    • C25B3/03—Acyclic or carbocyclic hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/23—Carbon monoxide or syngas

Definitions

  • the present invention generally relates to CO 2 electroreduction techniques, and more particularly to a catalyst allowing the decoupling of CO 2 reduction reactions in a single electrode.
  • BACKGROUND [002]
  • alkaline and neutral electrolytes can be used to suppress the hydrogen evolution reaction (HER) and facilitate a C-C coupling step during the CO 2 RR.
  • WO2021/075638 A1 and US2023/243051 A1 disclose a catalyst structure for electrochemical CO 2 reduction.
  • the catalyst structure includes carbon nanofibers doped with nitrogen (N), and copper (Cu) particles dispersed on the carbon nanofibers. At least portions of the carbon nanofibers at interfaces with the Cu particles may have a pyridinic-N structure.
  • US2021/115577 A1 discloses a tandem electrode for electrochemically reducing carbon dioxide.
  • the electrode includes a first distinct catalyst layer and a second distinct catalyst layer.
  • the first distinct catalyst is selected from the group consisting of Cu, Cu alloys, doped Cu, nitrogen doped carbon materials, boron doped carbon materials, nitrogen and boron co-doped carbon materials, and functionalized carbon materials.
  • the second catalyst is selected from Au, Ag, Zn, ZnO, Fe—N—C, Ni—N—C, Co—N—C, N doped CNT, N doped graphene, and other materials that are selective for CO formation.
  • Cascade photoelectrocatalysis is a possible method to improve the selectivity of solar-driven CO2 reduction (CO2 R) wherein different CO 2 R catalysts are coupled to different subcells in a multijunction photovoltaic (PV) stack.
  • CO2 R solar-driven CO2 reduction
  • PV photovoltaic
  • the document discuss the motivation for having methanol as the sole CO 2 R product, the documented application of metallomacrocyclic catalysts for CO 2 R applications, and recent advance in catalyzing CO 2 to methanol with cobalt phthalocyanine-based catalysts.
  • CO 2 RR presents various challenges that are known in the field, such as the above-mentioned drawbacks that may result from the used of an acidic medium, that still need to be addressed.
  • a method to decouple the CO2-to-C 2 + reaction into two reduction steps including a C02-to-CO reduction step and a CO-to-C 2 + reduction step.
  • a modified cathode including a CO 2 RR catalyst having two distinct catalyst layers, each being tailored to catalyze one of the two reduction steps to achieve the desired transformation of CO 2 into multi- carbon products.
  • the modified cathode includes a first catalyst layer that can comprise atomically dispersed cobalt phthalocyanine to favour reduction of CO 2 to CO, thereby increasing local CO availability of CO.
  • the modified cathode further includes a second catalyst layer comprising metal nanoparticles, such as copper, and an ionomer to enhance the C-C coupling reduction step from the locally available CO.
  • operation of an electrolyzer including the modified cathode can achieve 54% C 2 H 4 Faradaic efficiency (FE) and 80% C 2+ FE at 800 mA cm -2 , as well as an SPCE of 87%.
  • a carbon dioxide reduction reaction (CO 2 RR) catalytic system having a dual catalysis function for the electroreduction of CO 2 into multi-carbon products.
  • the catalytic system comprises: a first catalyst layer comprising a support and a first metal-based catalyst wherein the first metal-based catalyst comprises cobalt phthalocyanine (CoPc), nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), iron phthalocyanine (FePc) or any combinations thereof; wherein the support is a carbon-based material derived from a metal organic framework, wherein the first metal-based catalyst is atomically dispersed on the support as determined by energy-dispersive X-ray spectroscopy (EDS); and a second catalyst layer comprising a second metal-based catalyst that comprises copper or copper-based alloys; wherein the first catalyst layer is positioned above the second catalyst layer to generate CO between the first catalyst layer and the second catalyst layer, and wherein the support of the first catalyst
  • the first metal-based catalyst is configured to sustain reduction of CO 2 into CO and second metal-based catalyst is configured to sustain C-C coupling mechanisms to yield multi-carbon products from CO.
  • the support of the first catalyst layer comprises between 0.5 wt.% and 10 wt.% of the N-containing compounds based on the total weight of the first catalyst layer and as determined by energy-dispersive X-ray spectroscopy (EDS) measurements, preferably between 1 wt.% and 8 wt.%, and further preferably between 2 wt.% and 6 wt.%.
  • the first metal-based catalyst is or comprises nanoparticles.
  • the first metal-based catalyst can comprise one or more metals selected from Au, Ag, Co, Ni, Cu, Fe and any mixtures thereof, preferably the first metal-based catalyst comprises Co.
  • the first metal-based catalyst can comprise a molecule having a metal center which is able to bond with four nitrogen atoms (Me-N 4 ) of the one or more N-containing compounds.
  • the metal center (Me) can be Co, Ni, Cu, Fe or any combinations thereof.
  • the first metal-based catalyst comprises cobalt phthalocyanine (CoPc), nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), iron phthalocyanine (FePc) or any combinations thereof.
  • the first metal-based catalyst can be cobalt phthalocyanine (CoPc).
  • the first metal-based catalyst can be uniformly dispersed on the support as determined by energy-dispersive X-ray spectroscopy (EDS).
  • EDS energy-dispersive X-ray spectroscopy
  • the support can be a carbon-based material derived from a metal organic framework.
  • the metal organic framework can be a zeolitic metal organic framework.
  • the metal organic framework can be a zeolitic imidazolate framework comprising one or more metallic ions selected from Zn, Fe, Co, Cu or any combinations thereof, preferably zinc.
  • the metal organic framework can be a zeolitic imidazolate framework (ZIFs) comprising one or more ZIF systems selected from ZIF-8, ZIF-67, ZIF-68, ZIF-69, ZIF-70, ZIF-90 and any combinations thereof, preferably ZIF-8.
  • ZIFs zeolitic imidazolate framework
  • the support has a hollow structure as determined by transmission electron microscopy.
  • the support can have a hollow polyhedral morphology as determined by transmission electron microscopy.
  • the support is a carbon support having a hollow polyhedral morphology.
  • the support can comprise pores having a diameter size of ranging between 0.3 nm and 5 nm, as determined by Brunauer-Emmett-Teller (BET) method, preferably between 0.5 nm and 4.5 nm, or between 1 nm and 4 nm.
  • BET Brunauer-Emmett-Teller
  • the support can be co-doped with one or more of P-containing compounds, and/or with one or more of S-containing compounds.
  • the support of the first catalyst layer can include between 0.25 wt.% and 5 wt.% of the one or more P-containing compounds based on the total weight of the first catalyst layer and as determined by energy-dispersive X-ray spectroscopy (EDS) measurements, preferably between 0.5 wt.% and 4 wt.%, and further preferably between 1 wt.% and 3 wt.%.
  • EDS energy-dispersive X-ray spectroscopy
  • the support of the first catalyst layer can include between 0.25 wt.% and 5 wt.% of the one or more of S-containing compounds based on the total weight of the first catalyst layer and as determined by energy-dispersive X-ray spectroscopy (EDS) measurements, preferably between 0.5 wt.% and 4 wt.%, and further preferably between 1 wt.% and 3 wt.%.
  • the first catalyst layer has a catalyst content between 3 wt.% and 5 wt.% based on the total weight of the first catalyst layer as determined by inductively coupled plasma optical emission spectrometry, or between 3.5 wt.% and 4.5 wt.%.
  • the second metal-based catalyst can comprise copper or copper- based alloys.
  • said copper-based alloys comprise CuAg, CuAu, CuPd, CuAl, CuBi, CuSn, CuIn, or any combinations thereof.
  • the second metal-based catalyst can be provided as nanoparticles, nanowires, nanosheets, nanodendrites, or a combination thereof.
  • the second catalyst layer can further comprise an ionomer.
  • the ionomer can be a perfluorinated sulfonic acid ionomer.
  • the ionomer can be 1,1,2,2- tetrafluoroethene;1,1,2,2-tetrafluoro-2-[1,1,1,2,3,3-hexafluoro-3-(1,2,2-trifluoroethenoxy)propan-2- yl]oxyethanesulfonic acid copolymer, tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7- octenesulfonic acid copolymer, or any combinations thereof.
  • the second catalyst layer can comprise an underlayer consisting of the second metal-based catalyst and a top layer comprising the ionomer and the second metal-based catalyst.
  • the top layer can be a three-dimensional catalyst:ionomer bulk heterojunction (Cu-CIBH) top layer consisting of Cu nanoparticles (CuNP) and perfluorosulfonic acid (PFSA) ionomer.
  • Cu-CIBH catalyst:ionomer bulk heterojunction
  • the catalyst-ionomer bulk heterojunction can have a CIBH thickness ranging between 50.0 nm to 25.0 ⁇ m as determined by scanning electron microscopy, preferably between 60.0 nm and 24.0 ⁇ m, further preferably between 70.0 nm and 23.0 ⁇ m, yet further preferably between 100.0 nm and 20.0 ⁇ m.
  • the catalyst-ionomer bulk heterojunction can have a ratio of catalyst material to ion-conducting polymer ranging from 0.1 to 10.0, preferably ranging from 0.2 to 9.0, further preferably ranging from 0.3 to 8.0, even further preferably ranging from 0.4 to 7.0, yet further preferably ranging from 0.5 to 5.0 or ranging from 0.5: to 2.0, even further preferably ranging from 0.6 to 2.0 or from 1.0 to 1.6.
  • the second catalyst layer can have a catalyst content between 50 wt.% and 100 wt.% based on the total weight of the second catalyst layer.
  • a modified electrode configured for the electroreduction of CO 2 into multi-carbon products in acidic conditions.
  • the modified electrode comprises: a gas diffusion layer being a porous support; and the CO 2 RR catalytic system as defined herein, wherein the second catalyst layer is deposited on the gas diffusion layer.
  • the porous support can be selected from polytetrafluoroethylene (PTFE), porous carbon paper, and any combination thereof.
  • the porous support can be PTFE.
  • the porous support shows pores with a diameter size ranging between 100 nm and 5000 nm, as determined by Brunauer-Emmett-Teller (BET) method.
  • BET Brunauer-Emmett-Teller
  • a CO 2 electrolyzer system for reducing CO 2 into multi- carbon products.
  • the CO 2 electrolyzer system comprises: a cathodic compartment comprising: a reactant inlet that is configured to supply a gas stream comprising CO 2 in the cathodic compartment, a cathode being the modified electrode as defined herein, a product outlet configured to release a gas-liquid mixture comprising CO 2 and the multi-carbon products from the cathodic compartment; an anodic compartment comprising: an anodic inlet that is configured to supply an anolyte in the anodic compartment, an anode, and an anodic outlet that is configured to release used anolyte from the anodic compartment; and a cationic exchange membrane that is positioned between the cathodic compartment and the anodic compartment.
  • the cationic exchange membrane can be a proton exchange membrane.
  • the cationic exchange membrane can be a perfluorinated membrane.
  • the CO 2 electrolyzer system can be a one-gap catholyte-containing electrolyzer, wherein the cathodic compartment further comprises a catholyte inlet that is configured to be supplied with a catholyte.
  • the CO 2 electrolyzer system can be a zero- gap electrolyzer, such as a membrane electrode assembly.
  • the process comprises: providing a CO 2 electrolyzer system as defined herein, supplying a CO 2 -containing gas stream to the reactant inlet of the cathodic compartment; supplying an acidic electrolyte having a pk a measured at 25°C ranging between 3 and 12 to the anolyte inlet of the anodic compartment of the CO 2 electrolyzer; applying a current density to the CO 2 electrolyzer between 100 and 1200 mA.cm -2 ; and recovering a gas-liquid mixture from a product outlet of the cathodic compartment, the gas- liquid mixture comprising the multi-carbon products.
  • the acidic electrolyte can comprise H 3 PO 4 , KH 2 PO 4 , KCl, H 2 SO 4 , or any combinations thereof.
  • the pka measured at 25°C of the acidic electrolyte can be between 7 and 8.
  • the applied current density can be between 100 mA.cm -2 and 1200 mA.cm -2 , preferably between 400 and 800 mA.cm -2 .
  • the supplying of the CO 2 -containing gas stream can be performed with an inlet flow rate of CO 2 being between 1 sccm and 100 sccm.
  • a method for preparing the carbon dioxide reduction reaction catalytic system as herein.
  • the method comprises: a. providing a metal organic framework; b. coating said metal organic framework with a ligand to obtain a chelated metal organic framework; c. performing pyrolysis of the chelated metal organic framework obtained at step (b) to obtain a hollow carbon support; d. dispersing one or more first metal-based compounds on the hollow carbon support obtained at step (c) to obtain a first metal-based catalyst dispersed on a support; e. adding an ionomer to said first metal-based catalyst dispersed on a support to obtain an ink; f.
  • step (b) can comprise a first sub-step of dispersing said metal organic framework into one or more polar organic solvents to obtain a dispersion, a second sub-step of adding one or more anchoring agent into said dispersion, a third sub-step of adding a chelating agent and a fourth sub-step of adding one or more basic compounds.
  • said one or more polar organic can be one or more protic solvents, preferably selected from methanol and/or propanol.
  • the one or more anchoring agent can be bis(4-hydrophenyl)sulfone, bis(4-aminophenyl) ether, dicyandiamide, melamine, or any combinations thereof.
  • the chelating agent can be phosphonitrilic chloride trimer, pyrrole, aniline, dopamine, or any combinations thereof.
  • the one or more basic compounds can be triethylamine, ammonium persulphate, or a combination thereof.
  • step (b) is carried out under stirring for at least 12 hours and/or at a temperature range comprises between 15°C and 30°C.
  • step (c) can be carried out at a temperature ranging between 800°C and 1200°C, preferably between 900°C and 1100°C, and/or during a time ranging between 1h and 5h, preferably between 2h and 4h. Further preferably, step (c) can be carried out under an inert atmosphere, preferably under Ar, N2, He, more preferably under Ar. [0039] In some implementations, step (d) can be performed by sonication for a time ranging between 15 minutes and 1 hour; and then by mechanical stirring for at least 12 hours. [0040] In some implementations, spraying the ink during step (f) can be performed by airbrushing.
  • Figure 1 Reaction free energies for H intermediate formation on Cu surface under different CO coverages.
  • Figure 2 Energy profiles for initial states, transition states (TSs), and final states of CO dimerization on Cu surface under different CO coverages.
  • Figure 3 FEs of H 2 , C 2 H 4 , and C 2+ on the Cu electrode toward CO 2 RR and CORR at different current densities in an acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl. Values are means, and error bars represent the standard deviation from three independent measurements.
  • FIG 4 Schematic of the ion transport and reactions in acidic CO 2 RR system with schematic illustration of the spatially-decoupled strategy via tandem catalysis in acidic CO 2 RR system.
  • PEM proton exchange membrane. Synthesis and structural analysis of atomically dispersed CoPc@HC.
  • Figure 5 Schematic illustration of the synthesis process of CoPc@HC.
  • Figure 6 SEM image of CoPc@HC.
  • Figure 7 HAADF-STEM image and the corresponding EDS mapping images (Co; C; N; P; S) of CoPc@HC.
  • Figure 8 Aberration-corrected HAADF-STEM image of CoPc@HC.
  • Figure 9 Co K-edge XANES spectra of CoPc@HC and reference samples (Co foil, CoO, Co3O4, CoPc).
  • Figure 10 Fourier-transformed magnitudes of Co K-edge EXAFS spectra of CoPc@HC and reference samples.
  • Figure 11 Comparison of CO FE on CoPc@HC electrode and CoPc/C electrode toward acidic CO 2 RR. Acidic CO 2 RR performance of CoPc@HC/Cu tandem electrode.
  • Figure 12 Cross-sectional SEM image of CoPc@HC/Cu tandem electrode, withTEM image of upper CoPc@HC catalyst layer and with SEM image of lower Cu catalyst layer with catalyst- ionomer bulk heterojunction interface.
  • Figure 13 Schematic of the spatially-decoupled strategy via tandem catalysis, showing the electron transfer and mass transport in acidic CO 2 RR.
  • Figure 14 FEs of CO 2 RR products on CoPc@HC/Cu tandem electrode in an acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl. The flow rate of inlet CO 2 is 10 sccm. Values are means, and error bars represent the standard deviation from three independent measurements.
  • Figure 15 FEs of CO 2 RR products on Cu electrode in an acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • the flow rate of inlet CO 2 is 10 sccm. Values are means, and error bars represent the standard deviation from three independent measurements.
  • Figure 16 Partial current densities of C 2 H 4 and H 2 .
  • Figure 17 FEs toward CO 2 RR products and SPCE on CoPc@HC/Cu tandem electrode at 800 mA cm -2 with different inlet flow rates of CO 2 . Values are means, and error bars represent the standard deviation from three independent measurements.
  • Figure 18 Current density toward CO 2 RR products on CoPc@HC/Cu tandem electrode and Cu electrode.
  • Figure 19 Comparison of the SPCE, FE and partial current density of C 2 +, partial current density of ethylene, and energy consumption for ethylene production of CoPc@HC/Cu tandem electrode with those of state-of-the-art electrodes. DFT calculations and in situ Raman studies.
  • Figure 20 Free energy diagram of CO 2 RR on CoN4-C/Cu tandem electrode and Cu electrode.
  • Figure 21 The corresponding atomic configurations from CO to the hydrogenation of *CHCO are presented.
  • Figure 22 In situ Raman spectra of CO for a Cu electrode under different applied potentials.
  • Figure 23 In situ Raman spectra of CO for a CoPc/Cu tandem electrode under different applied potentials.
  • Figure 24 In situ Raman spectra of CoPc/Cu tandem electrode with high CoPc coverage on the Cu surface.
  • Figure 25 In situ Raman spectra of CoPc/Cu tandem electrode with agglomerated CoPc on the Cu surface.
  • Figure 26 The periodic model of Cu(111) covered a layer of water consisting of six water molecules.
  • Figure 27 The initial, transitional, and final states of C-C coupling on Cu(111) at the CO coverage of 2/9 ML, 3/9 ML, 4/9 ML. The distances of C-C in the transition states are plotted and labelled.
  • Figure 28 The initial, transitional, and final states of C-C coupling on Cu(111) at the CO coverage of 2/9 ML, 3/9 ML, 4/9 ML.
  • Figure 29 Acidic CO 2 RR performance of the state-of-the-art carbon-supported cobalt phthalocyanine (CoPc/C) catalyst: CO and H 2 FE on CoPc/C catalyst at various current densities in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • CoPc/C state-of-the-art carbon-supported cobalt phthalocyanine
  • Figure 30 Acidic CO 2 RR performance of the state-of-the-art carbon-supported cobalt phthalocyanine (CoPc/C) catalyst: The partial current densities of CO and H 2 on CoPc/C catalyst at various current densities in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • Figure 31 The stability test of the CoPc/C catalyst at the current density of 300 mA cm -2 toward acidic CO 2 RR in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • Figure 32 High-resolution transmission electrode microscopy (HRTEM) images of the CoPc/C catalyst after stability test (scale of 10 nm). The nanoparticles were observed in the post- reaction CoPc/C catalyst, suggesting the agglomeration of CoPc into Co clusters and small-size Co nanoparticles after stability test.
  • Figure 33 High-resolution transmission electrode microscopy (HRTEM) images of the CoPc/C catalyst after stability test (scale of 2 nm). The nanoparticles were observed in the post- reaction CoPc/C catalyst, suggesting the agglomeration of CoPc into Co clusters and small-size Co nanoparticles after stability test.
  • HRTEM High-resolution transmission electrode microscopy
  • Figure 34 Structural characterization of N, P, S co-doped hollow carbon (HC) by transmission electron microscopy (TEM).
  • Figure 35 Structural characterization of N, P, S co-doped hollow carbon (HC) by powder X- ray diffraction (XRD).
  • Figure 36 Transmission electron microscopy (TEM) image of CoPc@HC.
  • Figure 37 Powder X-ray diffraction (XRD) pattern of CoPc@HC in comparison to CoPc molecules.
  • Figure 38 The first derivative curves of CoPc@HC and reference samples.
  • Figure 42 Co K-edge EXAFS first-shell fitting analysis of CoPc in k space.
  • Figure 43 Co K-edge EXAFS first-shell fitting analysis of CoPc in R space
  • Figure 44 Co K-edge EXAFS fitting analysis of CoO in k space.
  • Figure 45 Co K-edge EXAFS fitting analysis of CoO in R space.
  • Figure 46 Co K-edge EXAFS fitting analysis of Co 3 O 4 in k space.
  • Figure 47 Co K-edge EXAFS fitting analysis of Co 3 O 4 in R space.
  • Figure 48 Co K-edge EXAFS fitting analysis of Co foil in k space.
  • Figure 49 Co K-edge EXAFS fitting analysis of Co foil in R space.
  • Figure 50 Acidic CO 2 RR performance of the CoPc@HC catalyst. CO and H 2 FE on CoPc@HC toward acidic CO 2 RR at various current densities in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • Figure 51 Acidic CO 2 RR performance of the CoPc@HC catalyst. The partial current density of CO and H 2 on CoPc@HC toward acidic CO 2 RR in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • Figure 52 H 2 FE on CoPc@HC electrode and CoPc/C electrode toward acidic CO 2 RR at different current densities.
  • Figure 53 The stability test of CoPc@HC at the current density of 300 mA cm -2 toward acidic CO 2 RR in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • Figure 54 FEs of CO, C 2 H 4 and C 2 + on CoPc@HC/sCu tandem electrode in an acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • the flow rate of inlet CO 2 is 10 sccm.
  • Figure 55 H 2 FE on CoPc@HC/Cu electrode and Cu electrode toward acidic CO 2 RR at different current densities. Error bars represent the standard deviation of three independent samples. Data are presented as mean values ⁇ standard deviation.
  • Figure 56 The stability of CoPc@HC/Cu electrode at the current density of 800 mA cm -2 , which shows CoPc@HC/Cu electrode maintains the stable potential and C 2 H 4 FE for 16 h.
  • Figure 57 The cross-sectional SEM image of the used CoPc@HC/Cu electrode after the stability test.
  • Figure 58 FEs toward CO 2 RR products and SPCE on Cu electrode at 800 mA cm with different flow rates of CO 2 inlet in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl. Values are means, and error bars represent the standard deviation from three independent measurements.
  • Figure 59 The acidic CO 2 RR performance of CoPc@HC/Cu tandem electrode in slim flow cell.
  • Figure 60 The acidic CO 2 RR performance of Cu electrode in slim flow cell.
  • Figure 61 Performance comparison CoPc@HC/Cu electrode and Cu electrode toward acidic CO 2 RR in slim flow cell.
  • FIG. 62 Performance comparison CoPc@HC/Cu electrode and Cu electrode toward acidic CO 2 RR in slim flow cell.
  • Figure 63 Partial current densities of C 2 + products on CoPc@HC/Cu tandem electrode and Cu electrode toward acidic CO 2 RR in the slim flow cell.
  • Figure 64 The energy efficiency of C 2 H 4 production in acidic CO 2 RR on CoPc@HC/Cu electrode and Cu electrode.
  • Figure 65 The energy intensity for the production of C 2 H 4 on CoPc@HC/Cu tandem electrode and Cu electrode as well as the benchmark of prior alkaline/neutral/acidic system based on the Tables 4 and 5.
  • Figure 66 C 2 H 4 FE of CoPc@HC/Cu tandem electrode and Cu electrode toward CO reduction reaction (CORR) performance in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl. Error bars represent the standard deviation of three independent samples. Data are presented as mean values ⁇ standard deviation.
  • Figure 67 H 2 FE of CoPc@HC/Cu tandem electrode and Cu electrode toward CO reduction reaction (CORR) performance in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl. Error bars represent the standard deviation of three independent samples. Data are presented as mean values ⁇ standard deviation.
  • Figure 68 Comparison of the ratio of C 2 H 4 FE and H 2 FE on CoPc@HC/Cu tandem electrode and Cu electrode toward CO reduction reaction performance in the acidic buffer electrolyte of 0.5 M H 3 PO 4 /0.5 M KH 2 PO 4 with 2.5 M KCl.
  • CoPc@HC/Cu tandem electrode exhibits obviously higher C 2 H 4 FE and lower H 2 FE in CORR compared to CO 2 RR from 400 to 800 mA cm -2 , suggesting, besides reducing CO 2 to CO and suppressing the evolution of H 2 in acidic media, the CoPc@HC catalyst layer was able to accelerate C-C coupling to C 2 H 4 .
  • Figure 69 The model of (6 ⁇ 6) Cu(111) covered a charged water-layer consisting of twenty-four molecules with/without two-dimensional CoN 4 -Graphene structure.
  • Figure 70 Free energy diagram of the production of C 2 H 4 on Cu(111). Two possible reaction pathways on Cu(111).
  • Figure 71 Free energy diagram of the production of C 2 H 4 on Cu(111). The corresponding atomic configuration for each reaction intermediate.
  • Figure 72 Free energy diagram of the production of C 2 H 4 on CoN 4 -C/Cu(111). The possible reaction pathway on the CoN 4 -C/Cu(111). Under the influence of CoN 4 -C structure, the pathway 1 similar as in figure 70 does not exist because the key intermediate *CHCHO is hard to stabilize adsorption on Cu(111).
  • Figure 73 Free energy diagram of the production of C 2 H 4 on CoN4-C/Cu(111). The corresponding atomic configurations for each reaction intermediate.
  • a modified electrode for example a cathode, having a dual catalytic function.
  • the modified electrode comprises a first metal-based catalyst favoring the first reaction step of reduction of CO 2 into CO, and a second metal-based catalyst favoring the second reaction step of C-C coupling mechanisms to form C 2+ products.
  • the highly efficient and selective CO 2 -to-CO conversion enabled by the first catalyst allows the formation of a high local concentration of CO hereby generated nearby the second catalyst surface to further favour the C-C coupling reactions.
  • the first and second catalysts are provided as distinct layers in the modified electrode.
  • the modified electrode particularly includes two spatially-decoupled catalyst layers having each distinct catalytic properties.
  • the first catalyst layer can be referred to as a CO-producing layer and the second catalyst layer can be referred to as a C-C coupling layer.
  • the term “spatially-decoupled” can be understood as referring to a nanoscale gap/space that is present between the first catalyst layer and the second catalyst layer.
  • the nanoscale space can thus function as a nanoreactor, thereby allowing generation of a high concentration of CO at a surface of the first catalyst layer and nearby the second catalyst layer, thus further promoting C-C coupling reactions at a surface of the second catalyst layer.
  • First catalyst function – CO 2 to CO reduction [00118]
  • the first catalyst layer includes a supported catalyst, and more particularly a support and the first metal-based catalyst that is configured to sustain reduction of CO 2 into CO.
  • the first catalyst layer favoring reduction of CO 2 to CO in acidic media can, for example, be a catalyst material with high performance for electrochemical CO 2 reduction to CO, and can include carbon-supported Au nanoparticles, Au film, carbon-supported Ag nanoparticles, Ag film, carbon-supported nickel phthalocyanine, carbon-supported iron phthalocyanine, carbon-supported copper phthalocyanine, carbon-supported cobalt phthalocyanine, carbon-supported metal single-atom (including iron, cobalt, nickel), or any combinations thereof.
  • Cobalt phtalocyanine (CoPc) molecules are known to improve CO selectivity in alkaline conditions but typically poorly perform in acidic media with a CO Faradaic Efficiency (FE) limited to 70% that rapidly decrease over time.
  • FE CO Faradaic Efficiency
  • the first catalyst layer includes an atomic dispersion of molecules of the first metal-based catalyst on a strong interaction support to allow reaching a higher initial CO FE, e.g. 94%, and maintaining such value over the course of operation.
  • the strong interaction support can be understood as a support including species that can form electronic interaction with the Co metal center of the CoPc molecules.
  • the first metal- based catalyst is thus provided atomically dispersed on the support such that the first metal-based catalyst molecules are bonded to the support via a strong metal support interaction.
  • the support can be a carbon support that is doped with one or more atoms to enhance electronic interaction between the catalyst molecules and the support.
  • the support can be doped with N species providing electronic interactions with Co on the support, thereby contributing to the atomic dispersion and stabilization of CoPc molecules.
  • the support can be a hollow carbon support including N species serving as anchoring sites to stabilize the CoPc molecules, with some electrons from the Co metal center of the CoPc molecules transferring to the N species of the hollow carbon support, thereby leading to the electron-deficient nature of Co metal center and the formation of a Co-N coordination between Co metal center and N species of support.
  • the first catalyst layer can include a hollow carbon support (HC) and atomically dispersed CoPc on the hollow carbon support (CoPc@HC), where the individual CoPc molecules are anchored (i.e., chemically bonded) to species of the hollow carbon support via chemical bonding.
  • the support can have a hollow structure, for example a hollow polyhedral morphology as determined by transmission electron microscopy. It should be further noted that the hollow structure of the support can facilitate the mass transfer to achieve a higher performance (than in absence of the hollow structure).
  • the support can be a carbon-based support as detailed herein and can include graphene, nitrogen doped graphene, heteroatom doped graphene, nitrogen doped carbon, heteroatom doped carbon, or a combination thereof.
  • the carbon-based support is a carbon-based material derived from a metal organic framework, for example pyrolysis of the metal organic framework.
  • the metal organic framework can be a zeolitic metal organic framework comprising one or more metallic ions selected from Zn, Fe, Co, Cu or any combinations thereof.
  • the zeolitic metal organic framework can be a zeolitic imidazolate framework (ZIFs) comprising one or more ZIF systems selected from ZIF-8, ZIF-67, ZIF-68, ZIF-69, ZIF-70, ZIF-90 and any combinations thereof.
  • the support from the first catalyst layer can be characterized as being porous and can comprise pores having a diameter size of ranging between 0.3 nm and 5 nm, as determined by Brunauer-Emmett-Teller (BET) method, preferably between 0.5 nm and 4.5 nm, or between 1 nm and 4 nm.
  • BET Brunauer-Emmett-Teller
  • the first catalyst layer can be characterized as having a catalyst content between 0.5 wt.% and 10 wt.%, preferentially between 1 wt.% and 8 wt.%, or between 2 wt.% and 6 wt.%.
  • the catalyst content is a CoPc weight content in the layer. If the catalyst consists of metal (i.e., no support), the catalyst content can be equal to the metal content of the first catalyst layer.
  • the first catalyst layer such as exemplified with the CoPc@HC layer, offers an avenue to rapidly convert CO 2 into CO, which does not transform into carbonates in local alkaline conditions.
  • a first catalyst layer CoPc@HC comprising an N, P, and S co-doped HC support and atomically dispersed CoPc catalyst was studied based on transmission electron microscopy (TEM) images (see figures 34 and 36), powder X-ray diffraction (XRD) pattern (see figure 35) and scanning electron microscopy (SEM) images (see figure 6).
  • TEM transmission electron microscopy
  • XRD powder X-ray diffraction
  • SEM scanning electron microscopy
  • SEM scanning electron microscopy
  • TEM transmission electron microscopy
  • the metal content, and more particularly the Co content in the CoPc@HC first catalyst layer was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) as 0.44 wt.%, corresponding to 4.3 wt.% of CoPc in CoPc@HC.
  • ICP-OES inductively coupled plasma optical emission spectrometry
  • Synchrotron-radiation-based X-ray absorption fine structure (XAS) analysis was further carried out to investigate the electronic structure and coordination environment of the example CoPc@HC first catalyst layer of the modified electrode.
  • Figures 9 and 38 show the X-ray absorption near-edge structure (XANES) spectra of CoPc@HC and other reference catalyst layers consisting of CoPc, Co 3 O 4 , CoO or Co foil.
  • XANES X-ray absorption near-edge structure
  • the XANES curve of CoPc@HC exhibits a higher absorption-edge energy compared with CoPc, suggesting the electron-deficient nature of the Co center of CoPc@HC, ascribed to the strong electronic interaction between CoPc and the N species of HC substrate.
  • a Co K-edge of the CoPc@HC first catalyst layer exhibits a similar Fourier transformed (FT) extended X-ray absorption fine structure (FT-EXAFS) spectrum to that of a CoPc catalyst layer, suggesting the main peak observed in approximately 1.3 ⁇ is associated with the Co-N coordination.
  • FT Fourier transformed
  • FT-EXAFS Fourier transformed X-ray absorption fine structure
  • the wavelet transform (WT) contour plot of CoPc@HC displays one intensity maximum at about 4.3 ⁇ ⁇ 1 , associated with the contribution of Co-N scattering path by comparing with the WT analysis of CoPc, Co foil, CoO and Co 3 O 4 catalyst layers.
  • the intensity maximum at about 6.8 ⁇ ⁇ 1 indexed to Co-Co coordination is not detected in CoPc@HC.
  • quantitative least-squares EXAFS curve-fitting analysis was performed to extract the coordination configuration.
  • b Fitting range 2 ⁇ k (/ ⁇ ) ⁇ 10 and 1 ⁇ R ( ⁇ ) ⁇ 3.
  • c Fitting range 2.0 ⁇ k (/ ⁇ ) ⁇ 9.7 and 1.0 ⁇ R ( ⁇ ) ⁇ 3.
  • d Fitting range 2.0 ⁇ k (/ ⁇ ) ⁇ 12.0 and 1.0 ⁇ R ( ⁇ ) ⁇ 3.50.
  • e Fitting range 2.0 ⁇ k (/ ⁇ ) ⁇ 8.0 and 1.0 ⁇ R ( ⁇ ) ⁇ 1.9.
  • f Fitting range 2.0 ⁇ k (/ ⁇ ) ⁇ 8.0 and 1.0 ⁇ R ( ⁇ ) ⁇ 2.0.
  • the electronic catalyst-support interaction contributes to reducing Co agglomeration and improving performance of the modified electrode when operated in an acidic medium.
  • the electronic catalyst-support interaction offers beneficial chemical bonding and associated charge transfer at the interface between the catalyst molecule center and the support, e.g., the Co center of CoPc molecule and the support being hollow carbon support with N doping.
  • Second catalyst function – C-C coupling [00135]
  • the second catalyst can be referred to as a tandem catalyst, that is configured to unite on a single support the CO 2 -to-CO reduction and the C-C coupling steps.
  • the second catalyst is also a metal-based catalyst that is provided as a second catalyst layer in the modified electrode.
  • the second CO-to- C 2 + catalyst layer is positioned below the first CO 2 -to-CO catalyst layer.
  • “Below” should be understood herein as a position of the second catalyst layer being such that the first catalyst layer is an upper layer in contact with the acidic electrolyte and the second catalyst layer is in contact with a cathodic flow field supplying gaseous CO 2 .
  • the modified electrode as encompassed herein thus includes a bilayer structure having a dual catalysis function.
  • the bilayer structure of the modified electrode allows enrichment of CO coverage on Cu surface, thereby suppressing HER and promoting multi-carbon (C 2 +) product formation in acidic CO 2 RR.
  • the decoupling of the overall CO 2 -to-C 2 + reaction into two steps: CO 2 -to-CO and CO-to-C 2 + is enabled the dual catalysis function of the modified electrode integrating two functionally distinct catalysts.
  • the second metal-based catalyst can be provided as a Cu-based material, including Cu nanomaterials with different morphologies, such as nanoparticles, nanowires, nanosheets.
  • the Cu-based material can also include Cu-based alloy materials, such as CuAg, CuAu, CuPd, CuBi, CuAl, CuSn, CuIn or any combinations thereof.
  • the second metal-based catalyst particles can have an average size between 10 nm and 1000 nm.
  • the second catalyst layer can have a catalyst content between 50 wt.% and 100 wt.% based on the total weight of the second catalyst layer.
  • the modified electrode further includes a porous support that is positioned in contact with the second and inner catalyst layer to ensure gas diffusion to the catalyst layers.
  • the porous support can be selected, for example, from polytetrafluoroethylene (PTFE) and porous carbon paper.
  • PTFE polytetrafluoroethylene
  • the porous support can have pores with a diameter size ranging between 100 nm and 5000 nm, as determined by Brunauer-Emmett-Teller (BET) method.
  • BET Brunauer-Emmett-Teller
  • the method to manufacture the modified electrode can thus include, for example, sputtering the second metal-based catalyst, such as copper nanoparticles, onto the porous support to form the second catalyst layer onto the porous support.
  • the second catalyst layer can further include an ionomer.
  • the ionomer can be 1,1,2,2-tetrafluoroethene;1,1,2,2-tetrafluoro-2-[1,1,1,2,3,3- hexafluoro-3-(1,2,2-trifluoroethenoxy)propan-2-yl]oxyethanesulfonic acid copolymer, tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymer, or any combinations thereof.
  • the second catalyst layer when including an ionomer, can be prepared by depositing an ionomer-containing ink comprising the ionomer and the second metal-based catalyst onto the porous support.
  • the ionomer- containing ink can be airbrushed, or drop-casted.
  • the second metal-based catalyst loading in the ionomer-containing ink can be between 0.1 wt.% and 2 wt.% based on the total weight of the ionomer- containing ink, preferably between 0.5 wt.% and 1.5 wt.%.
  • the ionomer loading in the ionomer- containing ink can be between 0.5 wt.% and 5 wt.% based on the total weight of the ionomer- containing ink, preferably between 1 wt.% and 4 wt.%.
  • the second catalyst layer can include an ionomer-containing top layer and a pure metal-based catalyst underlayer.
  • the pure metal- based catalyst underlayer can be for example formed by sputtering a metal or metal alloy onto the porous support.
  • the ionomer-containing top layer can be formed by depositing, e.g. by airbrushing, a ionomer-containing ink onto the pure metal-based catalyst underlayer.
  • the ionomer- containing ink comprising the ionomer and the second metal-based catalyst can be directly deposited onto the porous support such that the modified electrode does not include any sputtered metal underlayer.
  • CO interaction characterization with example CoPC@HC/Cu modified electrode [00144] The interaction between the produced CO and the modified electrode was studied with an example CoPc@HC/Cu modified electrode (also referred to as a CoPc/Cu tandem electrode), including a CoPC@HC first and upper catalyst layer, and a Cu second and inner catalyst layer by probing CO adsorption on the Cu surface using in-situ Raman spectroscopy.
  • Figure 22 shows the Raman spectra of CO for a Cu electrode under different applied potentials (in V).
  • the peak at 361 cm -1 is ascribed to the Cu-CO stretch. This peak emerged at -1.2 V vs. Ag/AgCl, indicating that CO 2 is converted to CO on the Cu surface.
  • Figure 23 shows the Raman spectra of CO for the CoPc/Cu tandem electrode. The peak at 365 cm -1 is blue-shifted to 389 cm -1 , indicating a stronger binding of CO on the Cu sites as a result of CoPc in the vicinity of adsorbed CO. Additionally, a new peak at 532 cm -1 is observed and associated to Co-CO bending vibration upon interaction between CO and the Co species in CoPc molecules.
  • the modified cathode can be used in a CO 2 electrolyzer system for reducing CO 2 into multi-carbon products; with preference, the multi-carbon products comprise ethylene.
  • the system comprises a cathodic compartment having a reactant inlet configured for receiving a CO 2 -containing gas stream and including the modified electrode.
  • the system can be operated by applying a current density between 100 mA.cm -2 and 1200 mA.cm -2 for a cell surface between 1 cm 2 and 5 cm 2 .
  • the CO 2 -containing gas stream includes gaseous CO 2 and can include one or more additional gas(es) such as CO and N 2 .
  • An inlet CO 2 flow rate between 50 v/v% and 100 v/v% can be supplied to the reactant inlet of the cathodic compartment of the system.
  • the system can be a flow cell, a slim flow cell, or a membrane electrode assembly.
  • a first CoPc@HC/sCu tandem electrode consisting of the second C-C coupling catalyst layer followed by an upper layer of first CO 2 -to-CO catalyst was tested.
  • the first CoPc@HC catalyst was layered on the top of a sputtered Cu layer acting as the second catalyst layer to construct the CoPc@HC/sCu tandem electrode.
  • the acidic CO 2 RR performance of the CoPc@HC/sCu tandem electrode in a buffered acidic electrolyte containing 0.5 M H 3 PO 4 , 0.5 M KH 2 PO 4 , and 2.5 M KCl was evaluated when used to build a flow cell electrolyzer.
  • the second catalyst layer can be designed to include a three-dimensional catalyst:ionomer bulk heterojunction (Cu-CIBH) top layer consisting of Cu nanoparticles (CuNP) and perfluorosulfonic acid (PFSA) ionomer, and a sputtered Cu underlayer, thereby forming a CoPc@HC/Cu tandem electrode as better seen in figures 12-13.
  • Cu-CIBH three-dimensional catalyst:ionomer bulk heterojunction
  • CuNP Cu nanoparticles
  • PFSA perfluorosulfonic acid
  • the catalyst-ionomer bulk heterojunction can have a CIBH thickness ranging between 50.0 nm to 25.0 ⁇ m as determined by scanning electron microscopy, preferably between 60.0 nm and 24.0 ⁇ m, more preferably between 70.0 nm and 23.0 ⁇ m, more preferably between 100.0 nm and 20.0 ⁇ m.
  • the catalyst-ionomer bulk heterojunction can have a ratio of catalyst material to ion- conducting polymer ranging from 0.1 to 10.0, preferentially ranging from 0.2 to 9.0, more preferentially ranging from 0.3 to 8.0, even more preferentially ranging from 0.4 to 7.0, most preferentially ranging from 0.5 to 5.0 or ranging from 0.5: to 2.0, even most preferentially ranging from 0.6 to 2.0 or from 1.0 to 1.6.
  • the CoPc@HC/Cu tandem electrode exhibited ⁇ 10% H 2 FE compared with >35% in the case of the Cu electrode (figure 55). This indicates that the CO produced by the CoPc@HC layer during CO 2 RR could suppress the competing HER on Cu surface in acidic media. These results are consistent with the following DFT predictions wherein higher CO concentrations on Cu surface lower the barrier to C ⁇ C coupling and suppress HER. [00157] Using DFT, reaction energetics of CO 2 RR on copper being used as catalyst were studied, noting the dependence on the surface concentration of the reaction intermediates (i.e., CO) and the adsorbed H (H*, * indicating a surface site).
  • the example nanoscale-engineered CoPc@HC/Cu tandem electrode achieved 54% C 2 H 4 FE and 80% C 2 + FE at 800 mA cm -2 while maintaining ⁇ 10% H 2 FE.
  • the example modified electrode also enabled a record high SPCE of 87%.
  • PSA pressure swing adsorption
  • the model uses the performance metrics of the slim-flow cell as the input.
  • the metrics provided in Table 3 include a Faradaic efficiency of 54%, a full-cell voltage of 3.76 V, a single pass conversion efficiency of 17%, and a current density of 500 mA cm -2 . It should be noted that the full- cell voltage is to be understood as a total input voltage to power the CO 2 electrolysis in the acidic system.
  • the cathodic gas stream is modelled to be composed of ethylene, unreacted CO 2 , and hydrogen.
  • the model considers a cost of $1989043 for a flow rate of 1000 m 3 h ⁇ 1 by using a scaling factor of 0.7 and energy input of 0.25 kWh m ⁇ 3 .
  • the energy consumption was calculated using equation (5a) as follows: [00172]
  • the flow rate of the cathodic stream was calculated by determining the flow rate of ethylene under the standard conditions, as follows: [00173] The flow rates of unreacted CO 2 , product ethylene, and byproduct hydrogen was calculated at the cathode outlet.
  • the flow rate of unreacted CO 2 at the cathode outlet is calculated by using the single pass conversion efficiency at a constant pressure. It is worth noting that this single pass conversion efficiency merely relates to the amount of CO 2 reduced to the CO 2 that passes through the cathode stream, unreacted.
  • the output CO 2 flow rate has been determined as follows: [00174] Since H 2 is the only byproduct at the cathode stream, the current toward H 2 was determined as follows: [00175] The H 2 production rate can be defined as follows: [00176] Assuming an ideal gas under standard conditions, the flow rate of H 2 was calculated as follows: [00177] The total flow rate at the cathodic downstream was then calculated by summing the flow rate of ethylene, unreacted CO 2 , and H 2 using supplementary Equations 6, 7b, and 10b.
  • Phosphonitrilic chloride trimer (98%) (CAS 940-71-6), and bis(4-hydroxyphenyl) sulfone (CAS 80-09- 1) were purchased from Alfa Aesar. Copper nanoparticles (25 nm) were purchased from US Research Nanomaterials, Inc. Nafion 117 membrane, platinum mesh and gas diffusion layer (Freudenberg H23C3), and carbon powder (Vulcan XC-72R) were received from Fuel Cell Store. The polytetrafluoroethylene (PTFE) gas diffusion layer with 450 nm pore size was obtained from Beijing Zhongxingweiye Instrument Co., Ltd. Copper target (>99.99%) was purchased from Kurt J. Lesker.
  • PTFE polytetrafluoroethylene
  • the conductive gas-diffusion layer was prepared by sputtering 150 nm Copper layer on the PTFE substrate using pure copper target with a deposition rate of 1 ⁇ /sec in an Angstrom Nexdep sputtering system.
  • the distilled water with a resistivity of 18.2 M ⁇ cm obtained from a Milli-Q reference water- purification system was used to prepare the aqueous solutions in all the experiments. All chemicals were used without any further purification.
  • Manufacture of the example modified electrodes [00181]
  • the CoPc@HC catalyst layer that was used in most of the experiments described herein included a second catalyst layer made of CoPc atomically dispersed on a hollow carbon support.
  • the hollow carbon support (HC) was first prepared by synthesizing ZIF-8 (zeolitic imidazolate framework-8, a class of metal-organic framework), then ZIF-8@PZS (poly(cyclotriphospazene-co-4,4'-sulfonyldiphenol), a class of polymer), and then HC.
  • ZIF-8 zeolitic imidazolate framework-8, a class of metal-organic framework
  • ZIF-8@PZS poly(cyclotriphospazene-co-4,4'-sulfonyldiphenol), a class of polymer
  • HC hollow carbon support
  • ZIF-8@PZS 400 mg of as-prepared ZIF-8 powder was dispersed in 40 mL of methanol. Then, 100 mL of methanol containing 325 mg bis(4-hydroxyphenyl) sulfone and 152 mg phosphonitrilic chloride trimer was added and stirred for 15 min. Subsequently, 1 mL of N,N-diethylethanamine was slowly dripped into the above dispersion, followed by stirring for 15 h at room temperature.
  • the resulting precipitate marked as ZIF- 8@PZS was collected, washed and finally dried in a vacuum at 80°C for 12 h.
  • the as-prepared ZIF-8@PZS powder was placed in a quartz boat and maintained 950°C for 3 h in a tube furnace with a heating rate of 5°C min -1 under a flowing Ar atmosphere to obtain HC.
  • 4 mg of CoPc and 60 mg of HC were dispersed in 60 mL of DMF using sonication, respectively. Then, the CoPc dispersion solution was added to HC suspension.
  • the state-of-the-art CoPc/C electrode was prepared according to a typical procedure, wherein 82.9 mg of Vulcan carbon powder (XC-72R), 89.6 mg CoPc, and 374 ⁇ L Nafion perfluorinated resin solution were stirred and sonicated in a 35 mL absolute ethanol. Then, 10 mL of the ink was sprayed onto the gas diffusion layer (Freudenberg H23C3).
  • the Cu electrode was prepared through airbrushing the catalyst ink consisting of 30 mg of Cu nanoparticles, 2 mL of methanol, and 22.5 ⁇ L Nafion perfluorinated resin solution onto a conductive gas-diffusion layer with a Cu nanoparticle loading of 1 mg cm -2 .
  • the catalyst ink comprising 15 mg of CoPc@HC, 2 mL of methanol and 45 ⁇ L Nafion perfluorinated resin solution was sprayed onto the Cu electrode with a CoPc@HC loading of 0.5 mg cm -2 using airbrushing.
  • CoPc@HC/sCu electrode was prepared by spraying CoPc@HC catalyst ink onto the sputtered Cu layer.
  • CoPc@HC electrode was prepared by spraying CoPc@HC catalyst ink onto the gas diffusion layer (Freudenberg H23C3).
  • Material characterization [00185] The morphology of catalyst layers including the first catalyst layer and the second catalyst layer can be characterized by scanning electrode microscopy (SEM) and transmission electron microscopy (TEM) measurements. The structure of the catalyst layers can be characterized by X-ray powder diffractometer (XRD) and X-ray absorption spectroscopy (XAS) measurements. The metal content of the catalysts, such as Co, Cu can be determined by inductively coupled plasma- optical emission spectroscopy (ICP-OES).
  • ICP-OES inductively coupled plasma- optical emission spectroscopy
  • N, C, and optionally P and/or S, of the catalytic system can be determined by X-ray photoelectron spectroscopy (XPS) and energy- dispersive X-ray spectroscopy (EDS) measurements.
  • XPS X-ray photoelectron spectroscopy
  • EDS energy- dispersive X-ray spectroscopy
  • TEM transmission electron microscopy
  • EDS energy-dispersive X-ray spectroscopy
  • X-ray photoelectron spectroscopy (XPS) measurements were performed in an ECSA device (PHI 5700) with Al K ⁇ X-ray energy source (1486.6 eV) for excitation.
  • XPS X-ray absorption spectroscopy
  • measurements were carried out at the 9BM beamline of the Advanced Photon Source (APS, Argonne National Laboratory, Lemont, Illinois). The XAS data were processed using ATHENA and ARTEMIS software incorporated into a standard IFEFFIT package.
  • In situ Raman measurements were conducted in a Renishaw inVia Raman Microscope with a water immersion objective ( ⁇ 63), 785 nm laser) in a modified flow cell.
  • Electrochemical measurement [00193] Without specification, all the CO 2 RR and CORR measurements were carried out in an electrochemical flow cell setup by using an electrochemical station (Autolab PGSTAT302N) equipped with a current booster (Metrohm Autolab, 10 A).
  • 0.5 M phosphate buffer solution 0.5 M H 3 PO 4 , 0.5 M KH 2 PO 4
  • 2.5 M KCl 2.5 M KCl
  • the solution consisting of 0.5 M H 3 PO 4 and 0.5 M KH 2 PO 4 was used as the anolyte.
  • Ag/AgCl (3M KCl) and a Pt mesh were employed as the reference electrode and counter electrode, respectively.
  • the cation-exchange membrane (Nafion 117) was used as the membrane to separate the cathode and anode chambers.
  • Full-cell measurement was carried out in a slim flow cell setup, which consisted of an anolyte chamber, catholyte chamber, and gas flow chamber. All chambers were designed to ensure the proximity between cathode and anode electrodes to minimize the ohmic losses. The distances between the Nafion membrane and cathode electrode and the Nafion membrane and anode electrode were both about 5 mm.
  • 0.05 M H 2 SO4 with 2.5 M KCl was used as the catholyte and 0.05 M H 2 SO4 was used as the anolyte.
  • Titanium mesh-supported iridium oxide (IrOx/Ti mesh) was used as the anode electrode and was prepared by a previously reported dip coating and thermal decomposition method.
  • the gas products were analyzed using a gas chromatograph (PerkinElmer Clarus 600).
  • the liquid products were measured by 1 H NMR spectroscopy (600 MHz Agilent DD2 NMR Spectrometer) with dimethyl sulfoxide (DMSO) as the reference standard and deuterium oxide (D2O) as the lock solvent.
  • DMSO dimethyl sulfoxide
  • D2O deuterium oxide
  • SPCE single pass carbon efficiency
  • j the partial current density of a specific group of products from CO 2 reduction
  • N the electron transfer for every product molecule.
  • EE full-cell energy efficiency
  • the VASP (Vienna Ab initio Package) software was used to perform all Density functional theory (DFT) calculations with the spin polarization setting.
  • the core-valence interaction was calculated by the project augmented wave method (PAW), where the Cu(d 10 p 1 ), Co(d 8 s 1 ), O(s 2 p 4 ), C(s 2 p 2 ), N(s 2 p 3 ) electrons were treated as valence states, and the remaining electrons were seen as a core state.
  • the cut-off energy was set to 450 eV.
  • the exchange-correlation correction effect was described by the generalized gradient approximation (GGA) in the Perdew-Burke- Ernzerhof functional (PBE).
  • the (3 ⁇ 3) Cu(111) model consisted of four Cu atoms layers was built, in which the bottom two-atom layers were fixed to mimic bulk material and other atoms were relaxed. A charged water layer consisting of one protonated water molecule and five regular water molecules was considered to cover the Cu(111) surface. The vacuum space was about 15 ⁇ along the z-axis. The k-point mesh was set to (3 ⁇ 3 ⁇ 1).

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Abstract

La présente invention concerne un système catalytique de réaction de réduction de dioxyde de carbone (CO2RR) ayant une double fonction de catalyse pour l'électroréduction de CO2 en produits multi-carbonés, le système catalytique comprenant : une première couche de catalyseur comprenant un support et un premier catalyseur à base métallique qui est configuré pour entretenir une réduction de CO2 en CO, le premier catalyseur à base métallique étant dispersé atomiquement sur le support ; et une seconde couche de catalyseur comprenant un second catalyseur à base métallique qui est configuré pour entretenir des mécanismes de couplage C-C pour produire des produits multi-carbonés à partir de CO ; la première couche de catalyseur étant positionnée au-dessus de la seconde couche de catalyseur pour générer du CO entre la première couche de catalyseur et la seconde couche de catalyseur.
PCT/EP2024/052203 2023-02-02 2024-01-30 Électroréduction de co2 dans des conditions acides à l'aide d'un catalyseur ayant une double génération de co et une fonction de couplage c-c WO2024160799A1 (fr)

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US20210115577A1 (en) 2019-10-22 2021-04-22 University Of Cincinnati Gas Diffusion Electrodes with Segmented Catalyst Layers for CO2 Reduction
WO2021075638A1 (fr) 2019-10-15 2021-04-22 서울대학교산학협력단 Structure de catalyseur pour la réduction électrochimique de co2 et son procédé de production

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