Electro-catalysis of ORR and OERon surfaces

Jan RossmeislCAMD

Technical University of Denmark

CASE CASE -- CAtalysisCAtalysis for for SustainableSustainable EnergyEnergy

2009 DTU2009 DTU

From Sun to Fuel

New idea ?Poul la Cour, Askov school for popular education for adults ~1891-1908

1000 l/h H2 ~1.3kW www.poullacour.dk

Electricity

H2O½O2+H2

Electrochemical Energy Conversion

η = 60 – 70 %

Electric energyElectric energy Chemical energy HChemical energy H22 Electric energyElectric energy

η = 40 – 60 %

H2O ½O2+H2 ½O2+H2 H2O

Fuel cell and electrolysis

Oxygen electrode:½O2+2H++2e- H2O

½O2+H2 H2O+electricity

Hydrogen electrode:H2 2H++2e-

The oxygen electrode problemFuel Cell ORR on Pt:

½O2+2H++2e- H2O

Electrolysis OER on IrO2:

H2O ½O2+2H++2e-

Gasteiger, Kocha, Sompalli, Wagner, Applied Catalysis B: Environmental, 56 (2005) 9-35.

Marshall, Tsypkin, Børresen, Hagen, Tunold, Mater. Chem. Phys. 94 (2005) 226–232.

Sabatier volcano

• The activity is a tradeoff between a not too strong and a not too weak binding at the catalyst

Activity

Reactivity

Too weakToo strong

Electrochemical environment

AnodeCathode

+

-

-

Electrolyte +

+

+

+ -

-

-

-

+

Computational SHEChemical potential of H+(aq)+e-

H2O(l) OH*+½H2(g)1. Get E with DFT2. Zero point energy and

entropy: G0 =Ew+Ezpe-TS0

H2O(l) OH*+H+(aq)+e-

1/2H2(g)H+(aq)+e-

1. SHE Convention:G(U=0) = 0

2. Potential:G(U) = -eU-kTln(aH+)

Thermo-chemistry only

Nørskov, Rossmeisl, Logadottir, Lindqvist, Kitchin, Bligaard Jónsson, J. Phys. Chem. B, 108, (2004)

Binding energy

½½HH22

H*H*HH+++e+e--

--eUeU∆∆GG

Field effects

Rossmeisl, Nørskov, Taylor, Janik, Neurock. J. Phys. Chem. B 110, (2006), 21833-21839

Karlberg, Rossmeisl, Nørskov, PCCP, 9 (2007) 5158

Surface structure Pt 111

Bondarenko, Stephens, Hansen, Pérez-Alonsoa, Tripkovic, Johansson, Rossmeisl, Nørskov, Chorkendorff 2010

Wakisaka, H. Suzuki, S. Mitsui, H. Uchida, M. Watanabe. Langmuir 25 (2009) 1897-1900

OH-coverageH2O↔OH*+H++e-

ΘOH=1/3 1/(1+ exp((ΔGOH-eU)/kT))

Pt3Ni

Pt

Rossmeisl, Karlberg, Jaramillo, Nørskov. Faraday Discussions 140, (2008) 337-346

Stamenkovic, Fowler, Mun, Wang, Ross, Lucas and Markovic, Science, 2007, 315, 493-497

Charge transfer reactions

O2+OH+2H2O

H++e- H++e-

H++e- H++e-

ORR intermediates along the direct mechanism

H+

e-

H+ H+H+

- - -e- e- e-

OER intermediates along the direct mechanism

0

1.23

1.2072

Perfect catalyst

∆G4 ∆G3 ∆G2 ∆G1

0

1.23

2.5283

Weaker binding of OH and stronger binding of OOH

Pt (111)

∆G4 ∆G3 ∆G2 ∆G1

Scaling relations

Rossmeisl, Logadottir, Nørskov, Chemical Physics, 319, (2005), 178Abild-Perdersen, Greeley, Studt, Rossmeisl, Munter, Moses, Skularson, Bligaard, Nørskov. PRL, 99, (2007) 016105

ΔG1ΔG4

OO OO HH

ORR

ΔG1

Ni PtNi Pt Au

Strong binding Weak binding

η

Pd Ag

Sabatier VolcanoRossmeisl,Karlberg,Jaramillo,NørskovFaradayDiscussions 140, (2008) 337-346

∆G1∆G4

∆G3

∆G2OER

Dissolution potential

CRC Handbook of Chemistry and Physics, CRC Press, New York, 1996http://databases.fysik.dtu.dk/hlsPT/surface/

The ORR volcano

Stamenkovic, Fowler, Mun, Wang, Ross, Lucas and Markovic, Science, 2007, 315, 493-497Stamenkovic, Moon, Mayrhofer, Ross, Markovic, Rossmeisl, Greeley, Nørskov, Angewandte, 2006, 45, 2897

Zhang, Vukmirovic, Xu, Mavrikakis and Adzic, Angewandte, 2005, 44, 2132-2125

Screening of Pt3X and Pd3X alloys

Greeley, Stephens, Bondarenko, Johansson, Hansen, Jaramillo, Rossmeisl, Chorkendorff, Nørskov. Nature Chem 1, 552-556, (2009)

The ORR volcano

Stamenkovic, Fowler, Mun, Wang, Ross, Lucas and Markovic, Science, 2007, 315, 493-497Stamenkovic, Moon, Mayrhofer, Ross, Markovic, Rossmeisl, Greeley, Nørskov, Angewandte, 2006, 45, 2897

Zhang, Vukmirovic, Xu, Mavrikakis and Adzic, Angewandte, 2005, 44, 2132-2125

Greeley, Stephens, Bondarenko, Johansson, Hansen, Jaramillo, Rossmeisl, Chorkendorff, Nørskov. Nature Chem 1, 552-556, (2009)

How to weaken ΔEOH

Cu/Pt (111) near surface alloy (NSA)Knudsen et al JACS 2007;Andersson et al, JACS 2009.

Subsurface Cu

Stephens, Bondarenko,Perez-Alonso, Calle-Vallejo, Bech, Johansson, Jepsen, Frydendal, Knudsen, Rossmeisl, Chorkendorff,

accepted in JACS 2011.

ORR

ΔG1

Ni PtPt

Strong binding Weak binding

η

Better than optimal?Rossmeisl,Karlberg,Jaramillo,NørskovFaradayDiscussions 140, (2008) 337-346

∆G1∆G4

∆G3

∆G2 OER

Oxygen Evolution RuO2

+2H2O(l) +H2O(l)+½H2 +H2O(l)+H2(g) +3/2H2(g) +O2(g)+ 2H2(g)

Gwater=0.0 eV GHO=1.32 eV GO=2.71 eV GHOO=4.31eV GO2=4.92 eV

Scaling relations

Weak bindingStrong binding

Metals

Oxides

EOH(EO)

CusCus sitesite Hollow siteHollow site

Binding Site Geometry

Optimal Optimal binding site binding site on metalson metalsOntopOntopbinding site binding site on metalson metalsOntopOntop site site binding on binding on oxidesoxides

E. Fernandez, P.G. Moses, A. Toftelund, H.A. Hansen, J.I. Martinez, F. Abild-Pedersen, J. Kleis, B. Hinnemann, J. Rossmeisl, T. Bligaard, J.K. Nørskov. Angewandte Chemie International Edition DOI: 10.1002/anie.200705739

Slope ~ number of bondsIntercept ~ binding site

Oxide volcano

Strong binding

J. Rossmeisl, Z.-W. Qu, H. Zhu, G.-J. Kroes and J.K. Nørskov,.J. Electroanalytical Chem 607, (2007), 83-89

Strong binding Weak binding

Rutile oxides Metals

ORRORR

OEROER

Weak binding

H. Dau, C. Limberg, T. Reier, M. Risch, S. Roggan, P. Strasser, Chemcatchem 2010, 2, 724.

Universal scaling EEOOHOOH=E=EOHOH + 3.2 + 3.2 0.2 0.2 eVeV

MetalsMetalsOxidesOxides

Man, Su, Calle-Vallejo, Hansen, Martinez, Inoglu, Kitchin, Nørskov, Rossmeisl ChemCatChemChemCatChem accepted 2011accepted 2011

M. Koper in press 20102010

Limitation

HH22OO

HO*HO*

HOO*HOO*OO22O*O*

OER Volcano

∆∆GG33 S. Trasatti. Electrochimica Acta. 29, (1984), 1503.

OER Volcano

∆∆GG33 Bockris, Otagawa, J. Electrochem Soc 131,(1984)

Molecular catalysts?

F. Calle-Vallejo, José I. Martínez, and J. Rossmeisl 2011

Looks like oxides

OO22

2H2O

HO*HO*O*O*

HOO*HOO*

Fundamental problem?Inspired by J. Messinger’s slides

∆∆GG

HH+++e+e--

HH+++e+e--

HH+++e+e--

HH+++e+e--

2H2H22O(l)O(l)

OO22(g)(g)

HOHO--((aqaq))

HOOHOO--((aqaq))HOOH(aqHOOH(aq))

2H2H22O(l)O(l)

3.34 3.34 eVeV

3.53 3.53 eVeV

Implications on ORRmake the smallest step big

Implications on OERmake the biggest step small

Summary• Both OER and ORR is in the end limited by OH-

OOH scaling• It cannot be tuned (beyond optimal) by catalyst

design.• This is also true for N2 and CO2 reduction

Routes forward• Either: Two-electron oxidation?• Or: We need something that stabilizes OOH

relative to OH – 3-D design of the active site?

3D structures

--++

--++

Oxygen evolving center

J. Rossmeisl, K. Dimitrievski, P. Siegbahn, J.K. Nørskov. Phys. Chem. C. 111 (2007), 18821

Two electron reactions~ No overpotential

ClCl22+2e+2e--

ClCl--+Cl+Cl*+e*+e--

2Cl2Cl--∆∆GG

At 1.36 VAt 1.36 V

Different reaction mechanisms

H.A. Hansen, I.C. Man, F. Studt, F.Abild-Pedersen, T. Bligaard,J. RossmeislPCCPPCCP 1212 (2010) 283(2010) 283--290290