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Catalyst Design for the Electrochemical CO 2 Conversion Peter - - PowerPoint PPT Presentation

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6 th SCCER Symposium (HaE) Martigny 25/10/2017 Catalyst Design for the Electrochemical CO 2 Conversion Peter Broekmann Department of Chemistry and Biochemistry University of Bern, Switzerland 6 th SCCER Symposium (HaE) Martigny

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SLIDE 1

Catalyst Design for the

Electrochemical CO2 Conversion

Peter Broekmann

Department of Chemistry and Biochemistry University of Bern, Switzerland

6th SCCER Symposium (HaE)

Martigny – 25/10/2017

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SLIDE 2

Outline of the talk

  • Motivation and introduction
  • SCCER HaE Storage: WP4
  • Approach towards catalyst design
  • Cu foams as catalysts for C2 hydrocarbon formation

6th SCCER Symposium (HaE)

Martigny – 25/10/2017

  • Ag foams as catalysts for syn gas and methane production
  • OD-Cu dendrites as catalysts for alcohol production
  • Conclusions and outlook
  • Selected examples
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SLIDE 3

Introduction - Motivation The SCCER Heat and Electricity Storage WP4 : Catalytic and electrocatalytic CO2 conversion WP4

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SLIDE 4

Introduction - Motivation

Syn gas

(CO/H2)

Hydrocarbons

(CH4; C2H4)

Alcohols

(MetOH; EtOH; PrOH)

Formic Acid

(HCO2H) Taget: synthetic fuels and chemical feedstock

*By courtesey of Günter Schmidt (Siemens) *

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SLIDE 5

Introduction - Motivation

Syn gas

(CO/H2)

Hydrocarbons

(CH4; C2H4)

Alcohols

(MetOH; EtOH; PrOH)

Formic Acid

(HCO2H)

Target specific catalysts: (i) efficiency (ii) selectivity (iii) durability

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SLIDE 6

Introduction - Motivation

200µm

Metal foam catalyst

Cu-foam

  • Metal dendrites/foams
  • Cu, Sn, Ag, Pd
  • OD metal foams
  • Cu/CuxO
  • Sn/SnOx
  • (Ir/IrO2)
  • Supports
  • 2D Cu mesh
  • 3D Cu skeleton/sponge

NP-catalysts

Cu-NPs

  • Metal-oxide NPs
  • InOx (C-supported)
  • SnOx (C-supported)
  • Metal-alloy NPs
  • Cu (C-supported)
  • CuxAuy (C-supported)
  • CuxSny (C-supported)
  • Supports
  • Vulcan
  • rGrOx

Approaches towards catalyst design

Comparison

 ec-CO2RR activity  ec-CO2RR selectivity  Stability

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SLIDE 7

Introduction - Motivation

Materials of interest

Additive-assisted electrodeposition

Interconnect technology Power to gas/liquid

(CO2 to value)

CO2 ethylene

Cu electro-catalyst

CO2 formate

Sn electro-catalyst

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SLIDE 8

Cu foams as catalysts for ec-CO2RR

(hydrocarbons)

Metal foam deposition: working principle

Plating conditions

1.5 M H2SO4, 0.2 M CuSO4 J = -3 A/cm2

  • A. Dutta , M. Rahaman, N. C. Luedi, M. Mohos, P. Broekmann, ACS Catal. 6 (2016) 3804-3814
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SLIDE 9

5s 20s 40s 60s 80s

200µm 200µm 200µm 200µm 200µm

Plating conditions

1.5 M H2SO4, 0.2 M CuSO4 , J = -3 A/cm2, Additive package I

Increasing deposition time

Template/additive controlled deposition of high surface area Cu catalysts (foams)

Cu foams as catalysts for ec-CO2RR

(hydrocarbons)

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SLIDE 10

50 100 150 10 20 30 40 50 60

Pore diameter / µm Faradaic efficiency / %

CO

C2H4 C2H6 Total FE of C2 products

5s 80s

200µm 200µm

CO2 electrolysis conditions

1h electroylsis, CO2 sat. 0.5 M NaHCO3 E = -0.8 V vs RHE

Increasing deposition time

Product distribution of CO2RR on Cu foams

Cu foams as catalysts for ec-CO2RR

(hydrocarbons)

  • A. Dutta , M. Rahaman, N. C. Luedi, M. Mohos, P. Broekmann, ACS Catal. 6 (2016) 3804-3814
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SLIDE 11

Cu 3D skeleton 2D Cu mesh

Cu supports for CO2RR catalysts 2 mm

  • Replace the wafer substrate by3D Cu skeletons and 2D Cu meshes.
  • Translate the Cu foam catalysts to more realistic supports suitable for gas

flow approaches.

2 mm

Cu foams as catalysts for ec-CO2RR

(hydrocarbons)

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SLIDE 12
  • Transfer of the functional Cu foam on the 2D Cu mesh.
  • Activity towards C2-product formation

Increasing deposition time

2D Cu mesh support

Cu foams as catalysts for ec-CO2RR

(hydrocarbons)

3D Cu skeleton support

Increasing deposition time

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SLIDE 13
  • Presence of well-defined facets on the Cu foam.
  • Important for C-C coupling reations.

Cu foams as catalysts for ec-CO2RR

(hydrocarbons)

3D Cu skeleton support

  • 1.0
  • 0.9
  • 0.8
  • 0.7
  • 0.6

2 4 6 8 10 12 14

C2H

4 Faradaic Efficiency (%) E / V vs. RHE

2D Cu mesh (electroplolished) 20s deposition of Cu foam on 3D Cu skeleton

  • 1.0
  • 0.9
  • 0.8
  • 0.7
  • 0.6

2 4 6 8 10 12 14 16 18

C2H

6 Faradaic Efficiency (%) E / V vs. RHE

2D Cu mesh (electroplolished) 20s deposition of Cu foam on 3D Cu skeleton

Product analysis

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SLIDE 14

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

Additive-assisted metal foam deposition

50 µm 25µm

Primary porosity

(liquid/solid interface)

5 µm 2 µm

Secondary porosity (side-walls)

(gas/solid interface)

1 µm 200 nm

Ag (20s) Ag (20s) Ag (20s) Ag (20s) Ag (20s) Ag (20s)

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SLIDE 15

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

ec-CO2RR on Ag foam catalysts

50 µm

Primary porosity

(liquid/solid interface)

Ag (20s) Ag (20s)

  • 1.6
  • 1.4
  • 1.2
  • 1.0
  • 0.8
  • 0.6
  • 0.4

20 40 60 80 100

FE Ag foams-20s / % E / V vs. RHE

CO H2 CH4 C2H4 CO2 electrolysis conditions

1h electroylsis, CO2 sat. 0.5 M NaHCO3

Product selectivity

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SLIDE 16

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

50 µm

Primary porosity

(liquid/solid interface)

Ag (20s) Ag (20s)

  • 1.6
  • 1.4
  • 1.2
  • 1.0
  • 0.8
  • 0.6
  • 0.4

20 40 60 80 100

FE Ag foams-20s / % E / V vs. RHE

CO H2 CH4 C2H4

Product selectivity

 First ec-CO2RR catalyst beyond Cu suitable for hydrocarbon formation.  Morphology matters!!!

ec-CO2RR on Ag foam catalysts

5 µm

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SLIDE 17

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

50 µm

Primary porosity

(liquid/solid interface)

Ag (20s) Ag (20s)

Product selectivity

 First ec-CO2RR catalysts beyond Cu for hydrocarbon formation.  Morphology matters!!!

ec-CO2RR on Ag foam catalysts

  • 1.6
  • 1.4
  • 1.2
  • 1.0
  • 0.8
  • 0.6

10 20 30 40 50 60

E / V vs. RHE FE / %

Total Hydrocarbon (CH4 + C

2H 4)

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SLIDE 18

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

50 µm

Primary porosity

(liquid/solid interface)

Ag (20s) Ag (20s)

 Superior stability of the Ag foam catalyst for CO formation.

10 20 30 40 50 60 70

  • 2
  • 4
  • 6
  • 8
  • 10

j

Steady state geo / mA cm

  • 2

Time / hrs

Steady state current 20 40 60 80 100 FE H2 (%) FE of H2

FE CO (%)

FE of CO

Catalyst durability

(CO region at -0.8 V vs RHE)

ec-CO2RR on Ag foam catalysts

5 µm

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SLIDE 19

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

50 µm

Primary porosity

(liquid/solid interface)

Ag (20s) Ag (20s)

 Moderate stability of the Ag foam catalyst for CH4 formation.

Catalyst durability

(CH4 region at -1.5 V vs RHE)

ec-CO2RR on Ag foam catalysts

1 2 3 4 5 6 7 8 9

  • 100
  • 90
  • 80
  • 70
  • 60
  • 50
  • 40
  • 30
  • 20

Time / hrs

j

Steady state geo / mA cm

  • 2

20 40 60 80 100

FE CH4 FECO FE H2

 C1 hydrocarbon pathway is the origin for catalyst degradation. 5 µm

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SLIDE 20

30 60 90 120 150 180 210 240 20 40 60 80 100 120

  • 0.8 V
  • 1.5 V
  • 1.5 V
  • 1.5 V
  • 1.5 V

FECO FECH4

  • 0.8 V
  • 0.8 V
  • 0.8 V
  • 0.8 V

Time / min.

  • 1.5 V

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

50 µm

Primary porosity

(liquid/solid interface)

Ag (20s) Ag (20s)

 The robust Ag foam catalyst tolerates potential changes.

Catalyst durability

(CH4 region at -1.5 V vs RHE)

ec-CO2RR on Ag foam catalysts

5 µm

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SLIDE 21

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

Identical location (IL) HR-SEM inspection

10 µm 250 nm 100 nm 10 µm 250 nm 100 nm

as prepared post mortem

4h; -0.8 V vs RHE (CO region)  Ag foam catalst are inherently stable/tolerant against CO formation.  Primary and secondary porosity remains unaffectd by CO production.

ap (20s) ap (20s) ap (20s) pm (20s) pm (20s) pm (20s)

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SLIDE 22

Ag foams as catalysts for ec-CO2RR

(syn gas; CO/H2)

Identical location (IL) HR-SEM inspection

10 µm 500 nm 100 nm 10 µm 250 nm 100 nm

as prepared post mortem

4h; -1.5 V vs RHE (CH4 region)  Ag foam catalst are inherently unstable/intolerant against CH4 formation .  Primary porosity remains unaffectd by CO production.

ap (20s) ap (20s) ap (20s) pm (20s) pm (20s) pm (20s)

250 nm

ap (20s)

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SLIDE 23

OD-Cu dendrites as catalysts for ec-CO2RR

(hydrocarbons, alcohols)

Functionalization of Cu mesh supports

SEM SEM SEM SEM SEM SEM

Cu mesh Cu dendrite

  • M. Rahaman, A. Dutta , A, Zanetti, P. Broekmann, ACS Catal. (2017), in press
  • Step 1: electropolishing of the mesh support in phosphoric acid.

 Multi-step catalyst preparation

  • Step 2: Potentiostatic electrodeposition of dendritic Cu.
  • Step 3: Thermal annealing at 300° C for 1h.
  • Step 4: Reduction of the OD-Cu precursor under ec-CO2RR conditions
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SLIDE 24

OD-Cu dendrites as catalysts for ec-CO2RR

(hydrocarbons, alcohols)

Identical location (IL) HR-SEM inspection

as deposited

(step 2)

Oxide derived (OD)

(step 3)

(OD) post mortem

(step 4)

  • The active catalyst forms under operando conditions during ec-CO2RR.
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SLIDE 25

OD-Cu dendrites as catalysts for ec-CO2RR

(hydrocarbons, alcohols)

ec-CO2RR on OD-Cu dendrites

(OD) post mortem

(step 4)

  • OD-Cu dendrites show superior performance for C2 and C3 alcohol formation.
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SLIDE 26

OD-Cu dendrites as catalysts for ec-CO2RR

(hydrocarbons, alcohols)

ec-CO2RR on OD-Cu dendrites

OD Cu dendrite Cu mesh Cu dendrite

Kortlever et al., Phys. Chem. Lett. 2015, 6, 4073 Nie et al., Angew. Chem. Int. Ed. 2013, 52, 2459-2462

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SLIDE 27

6th SCCER Symposium (HaE)

Martigny – 25/10/2017

 Zn0.93Cu0.07 foam

Conclusions and outlook

  • Electrodeposition (e.g. metal foams) is a promising alternative for CO2RR

catalyst preparation to common NP synthesis.

Syn gas

(CO/H2)

Hydrocarbons

(CH4; C2H4)

Alcohols

(MetOH; EtOH; PrOH)

Formic Acid

(HCO2H)  Ag foam

  • 97% FECO, -0.8V
  • 83% FECO, -1.0V

 Cu foam

  • 55% FEC2, -0.8V

 OD Cu dendrites

  • 26% FEC2-alc., -1.0V

 Cu0.85Pd0.15 foam  Ag foam

  • 50% FECH4, -1.5V
  • 80% FEHCO2H, -0.2V
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SLIDE 28

6th SCCER Symposium (HaE)

Martigny – 25/10/2017

Acknowledgements

  • The CO2 group at UniBe:
  • A. Dutta, M. Rahaman, A. Zanetti, A. Rudnev, C. Morstein, N. Schlegel,
  • M. Mohos, N. Luedi, Kiran, Yuhui Hou, M. Galvezazquez, A. Kuzume
  • The funding agencies:
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SLIDE 29

Thank you for your

kind attention

6th SCCER Symposium (HaE)

Martigny – 25/10/2017