HYDROGEN IN METALS / METALHYDRIDESmh2014.salford.ac.uk/cms/resources/uploads/files/... · Ref.: E....

CONTENTS 1) Hydrogen interaction with surfaces 2) Hydrides 3) Stability and hydrogen density 4) Complex hydrides

HYDROGEN IN METALS / METALHYDRIDES Andreas Züttel

HYDROGEN DENSITY

0

50

100

150

200

0 10 20 30

Hy

dro

ge

n d

en

sit

y [

kg

/m3]

Hydrogen density [kg H2/ 100kg storage material] Andreas Züttel, Switzerland, 17.07.14

liq. hydro- carbons

comp. H2 gas

liq. H2

liq. natural gas

NH3

carbon hydrates

INTERACTION OF GASES WITH SURFACES

STHG Δ⋅−Δ=Δ

Ref: W. Göpel, B. Kühnemann, Z. Phys. Chem. N.F. 122 (1980), p. 75

CHEMISORPTION OF GASES ON METAL SURFACES

Ref: M. Henzler, W. Göpel, „Oberflächenphysik des Festkörpers�, Teubner Studienbücher Physik, B. G. Teubner Stuttgart 1991, p. 474

ΔEchem≈ 0.25 eV

LENNARD-JONES POTENTIAL

Ref.: J. E. Lennard-Jones, Trans. Faraday Soc. 28 (1932), pp. 333. L. Schlapbach, Chapter 1, L. Schlapbach (Ed.) in Intermetallic Compounds I, Springer Series Topics in Applied Physics, Vol. 63, Springer–Verlag, 1988, p. 10.

Andreas Züttel, Switzerland, 17.07.14 6

BINARY HYDRIDES

Ref.: Gottfried Brendel, �Kapitel: Hydride�, Ullmanns Encyklopädie der technischen Chemie, 4. neubearbeitete und erweiterte Auflage, Band 13 (1977), pp. 109-133, Verlag Chemie Weinheim New York

DISCOVERY OF HYDROGEN ABSORPTION IN METALS

Thomas GRAHAM, born Dec. 20, 1805, Glasgow, Scot., died Sept. 11, 1869, London, Eng.

British chemist often referred to as �the father of colloid chemistry.� Educated in Scotland, Graham persisted in becoming a chemist, though his father disap- proved and with- drew his support. He then made his living by writing and teaching. He was a professor at a school in Ed inburgh (1830–37) and a t University College, London (1837–55), and was master of the mint (1855–69). In his final paper he described palladium hydride, the first known instance of a solid compound formed from a metal and a gas.

Ref.: Thomas Graham„On the Occlusion of Hydrogen Gas by Metals“, Proc. Royal Soc. 16 (1868), pp. 422

8

HYDROGEN ABSORPTION IN METALS

Ph. Mauron, M. Bielmann, EMPA, Switzerland

9


0 sec (vacuum) 5 sec (8 bar H2) 8 sec (8 bar H2) 15 sec (8 bar H2)

20 sec (8 bar H2) 30 sec (7 bar H2) 45 sec (6 bar H2) 60 sec (5 bar H2)

ZrMn1.5

HYDROGEN IN AND ON PALLADIUM

THERMO DESORPTION SPECTROSCOPY

After exposing Pd(111) at 115 K to equal doses of H2 and D2 a much stronger desorption of α-H than α-D is observed apparently due to faster H than D absorption into α-states.

Only minor HD desorption was ob-served. Apparently the gas which was dosed second bypassed the chemi-sorption state.

α: chemisorbed hydrogen at the surface β: interstitial hydrogen

Ref.: G. E. Godowski, R. H. Stulen, T. E. Felter, J. Vac. Sci. Technology A5 (1987), pp. 1103

α

β

HYDROGEN IN AND ON PALLADIUM

Andreas Züttel, IfRES (2005) 12

THERMODYNAMICS OF HYDRIDES

ΔH0 = 2/n·ΔHf

M + n/2 H2

MHn

H2

ΔHf

M + n/2 H2 → MHn

( ) ( ) ( )!"#

$%

&Δ−Δ−Δ⋅=Δ 2

0000

22 HHnMHMHHn

H n

( ) ( ) ( )!"#

$%

&−−⋅=Δ 2

0000

22 HSnMSMHSn

S n

S0(MHn) ≈ S0(M) → ΔS0 ≈ -S0(H2) S0(H2) = 130 JK-1mol-1

ΔH

= 0 = 0

≈ 0

HYDROGEN IN METALS

Ref.: P. Nordlander, J. K. Norskov, and F. Besenbacher, J. Phys. F. Metal Phys. 16:9 (1986), pp. 1161-1171, J.K. Norskov and F. Besenbacher, J. of the Less-Common Metals 130 (1987), pp. 475-490

METAL

H

n

r

EFFECTIVE MEDIUM THEORY

Jens Norskov


HEAT OF SOLUTION

LATTICE GAS

The free energy F = U - T·S is

ln exp H o HHN NF kTkT

ε ε+" #= − −% &' (∑

N : total number of sites NH : number of H ε0 : H binding energy NHH : number of nearest neighbour H-pairs ε : H-H pair interaction energy

Ref. Ronald Griessen, VU Amsterdam, NL Hemmes H, Salomons E, Griessen R, Sänger P, Driessen A., Phys Rev B Condens Matter. (1989);39(15):10606-10613.

εε HHoH NNE +=

ε ε0

ISOTHERM

Ref. Ronald Griessen, VU Amsterdam, NL

00

ln)(

ln21

0

→→

⋅⋅≅⋅⋅⋅

H

H

cp

cTkTppTk

0)(1

ln 21 =−⋅⋅+

−⋅⋅ i

i

i cnccTk ε

bdis nTppTk εεε −⋅+⋅=⋅⋅ 00

2)(

ln

H

HbH c

ckTcnTppTk

−⋅⋅+−⋅⋅+=⋅⋅⋅1

ln)(

ln 21

00

21 εεε

ΔH ΔS ΔG

Solubility (Sieverts)

Plateau (Maxwell)

Coexistence curve

Ronald Griessen



α-Phase: Solid Solution MHx (0 < x < 0.1) H H, ΔV/V = k·cH

β-Phase: Hydride Phase MHx x = {1, 2, 3,…} H H

RHΔ

−

RSΔ

RS

TRH

pp 00

0

Δ+

⋅

Δ−=$$

%

&''(

)ln( )HcTk

pp lnln ⋅⋅=""#

$%%&

'

021 ( )HcTk

pp lnln ⋅⋅=""#

$%%&

'

021

STABILITY OF HYDRIDES: VAN’T HOFF PLOT

Tdec



ΔH0 = 2/n·(ΔHf,H - ΔHf,M)

x A + y B + n/2 H2

H2

ΔHf,M

x A + y B + n/2 H2 → AxBy + n/2 H2 → AxByHn

( ) ( ) ( )!"#

$%

&Δ−Δ−Δ⋅=Δ 2

0000

22 HHnBAHHBAHn

H yxnyx

( ) ( ) ( )!"#

$%

&−−⋅=Δ 2

0000

22 HSnBASHBASn

S yxnyx

S0(AxByHn) ≥ S0(AxBy) → (ΔS0( ≤(-S0(H2)( S0(H2) = 130 JK-1mol-1

AxByHn

AxBy + n/2 H2

ΔHf,H

ΔH


ELECTRONIC STRUCTURE

1) Lattice expansion reduces the band-width. 2) Attractive potential of the proton affects the metal states and leads to the metal-hydrogen band 5 to 8 eV below EF. 3) The H-H interaction results in new features in the lower part of the density of states for systems with more than one H atom per unit cell. 4) An upwards shift of EF results from the balance between the additional electrons brought in by hydrogen and the number of new states below EF. The balance between the ‘exothermic’ lowering of occupied states and the ‘endothermic’ upwards shift of EF d e t e r m i n e s t h e s t a b i l i t y o f t h e metalhydride.

Ref.: L. Schlapbach, F. Meli, and A. Züttel, Chap. 21: “Intermetallic Hydrides and their Applications” in Intermetallic Compounds: Vol. 2, Practice, J. H. Westbrook and R. L. Fleischer (1994) John Wiley & Sons Ltd.

Bandstructure of LaNi5 and LaNi5H7

BINDING ENERGY

Ref.: Hammer B; Norskov J K, “Why Gold is the Noblest of all the Metals”, Nature 376, (1995), pp. 238-240

Ener

gy

antibonding

bonding

EF noble metal

EF transition metal

Adsorbate level

H s

s, p

d EF

DoS

E


SEMI-EMPIRICAL MODEL FOR THE STABILITY The Local Band-Structure Model

a = 18.6 kJ·mol-1HÅ4eV-3/2

b = -90 kJ·mol-1H

bRWEaHj

4j +∑⋅⋅Δ⋅=Δ −

∞

Rj

Ref.: R. Griessen, Phys. Rev. B 38 (1988), pp.3690-3698 and V.L. Moruzzi, J. F. Janak, A.R. Williams, „Calculated Electronic Properties of Metals�, Pergamon, New York (1978)

ΔE

W

EMPIRICAL MODELS: STABILITY

1) Reversed stability (global) ΔH(ABnH2m) = ΔH(AHm) + ΔH(BnHm) - (1-F)·ΔH(ABn)

Miedema Model

Ref.: H.H. Van Mal, K.H.J. Buschow and A.R. Miedema, J. Less-Common Met. 35 (1974), pp. 65

2) Imaginary binary hydrides (local) AmBn + xH → (AmBnHx)

interstitial site ΔH([AaBb]H) = ΔH(AmHx·a/(a+b)) + ΔH(BnHx·b/(a+b))

binary hydrides Ref.: I. Jacob, J.M. Bloch, D. Shaltiel and D. Davidov, Solid State Comm. 35 (1980), pp. 155.


INTERSTITIAL SITES IN METAL HYDRIDES

HYDROGEN ON

TETRAHEDRAL SITES

HYDROGEN ON

OCTAHEDRAL SITES

Ref: J. J. Reilly, G. D. Sandrock, �Metallhydride als Wasserstoff-Speicher�, Spektrum der Wissenschaften (April 1980), pp. 53-59

Andreas Züttel, University of Fribourg, 15.12.2002 25

FAMILIES OF HYDRIDE FORMING INTERMETALLICS

Intermetallic Prototype Structure compound AB5 LaNi5 Haucke phases, hexagonal

AB2 ZrV2, ZrMn2, TiMn2 Laves phase, hexagonal or cubic

AB3 CeNi3, YFe3 hexagonal, PuNi3-typ

A2B7 Y2Ni7, Th2Fe7 hexagonal, Ce2Ni7-typ

A6B23 Y6Fe23 cubic, Th6Mn23-typ

AB TiFe, ZrNi cubic, CsCl- or CrB-typ

A2B Mg2Ni, Ti2Ni cubic, MoSi2- or Ti2Ni-typ

BODY CENTERED CUBIC SOLID SOLUTION ALLOYS BCC Alloys: Ti-V-Mn, Ti-V-Cr, Ti-V-Cr-Mn, and Ti-Cr-(Mo, Ru)

Ref.: E. Akiba and M. Okada, “Metallic Hydrides III: Body-Centered-Cubic Solid-Solution Alloys”, MRS BULLETIN/SEPTEMBER 2002 699-703

V VH VH2

Structure fcc & hcp bcc Site O T O T Number 1 2 3 6 Size 0.414 0.255 0.155 0.291

DENSITY OF STATES FOR HYDROGEN


DENSITY OF STATES FOR HYDROGEN

Ref.: I. Bakonyi, F. Mehner, A. Rapp, A. Cziraki, E. Toth-Kadar, V. Skumryev, R. Reisser, H. Kronmüller and R. Kirchheim , Zeitschrift für Metallkunde (1993)


EMPIRICAL MODELS: GEOMETRY

1) Size of interstitial site: r > 0.37 Å

Westlake criterion Ref.: D. G. Westlake, J. Less-Common Metals 91 (1983), pp.275-292

2) Distance between hydrogen atoms: d > 2.1 Å

Ref.: A. C. Switendick, Z. Phys. Chem. N.F. 117 (1979), pp. 89

Number of hydrogen atoms: Number of interstitial sites for which 1) and 2) applies.

ρV < 245 kg m-3


METAL HYDRIDES WITH SHORT H-H SEPARATIONS

RTInH1.333 (R = La, Ce, Pr, or Nd; T = Ni, Pd, or Pt)

Ref.: P. Vajeeston et al. Phys. Rev. B 67 (2003), 014101

charge transfer electron density

CATALYZED HYDROGEN ABSORPTION

H2

activated Complex

Desorption

Recombination Adsorption

Intercalation

Mobility

A. Züttel et al., �LiBH4 a new hydrogen storage material�, Journal of Power Sources 118 (2003), pp. 1–7 S. Orimo et al., "Dehydriding and rehydriding reactions of LiBH4", Journal of Alloys and Compounds 404-406 (2005), pp. 427-430

B. Bogdanovic, M. Schwickardi, �Ti-doped alkali metal aluminium hydrides as potential novel reversible hydrogen storage materials�, Journal of Alloys and Compounds 253, 1-9 (1997).

1996 - 1997

J. N. Huiberts, R. Griessen, J. H. Rector, R. J. Wijngaarden, J. P. Dekker, D. G. de Groot, N. J. Koeman, �Yttrium and lanthanum hydride films with switchable optical properties�, Nature 380, 231-234 (21 March 1996)

2003 - 2004 “LiBH2”

“LiBH3.6”

“LiBH3”

LiH

STABILITY OF HYDRIDES

ΔH0

Elements

Alloy

Hydride Complex

ΔHf

ΔHdec

Li[BH4]

LiH+B

Li7B6

Li + B + H2

-195

[kJ]

-90

-75 kJ/molH2 H2



ΔH0 = 2/(3n)·(ΔHf,C - ΔHf,P)

A + n B + 2n H2

H2

ΔHf,P

A + n B + 2n H2 → AHn + B + 3/2n H2 → A[BH4]n

[ ]( ) ( ) ( )!"#

$%

&Δ−Δ−Δ⋅=Δ 2

004

00

232 HHnAHHBHAHn

H nn

( ) ( ) ( )!"#

$%

&−−⋅=Δ 2

0000

22 HSnBASHBASn

S yxnyx

S0(A[BH4]n) < S0(AHn + B) → (ΔS0( > (-S0(H2)( S0(H2) = 130 JK-1mol-1

A[BH4]n

AHn + B + 3/2n H2

ΔHf,C

ΔH

DEVELOPMENT*OF*THE*HYDROGEN*DENSITY*

0

5

10

15

20

25

1850 1900 1950 2000 2050

Year

H/MH

[mas

s%]

Pd*Mg2NiH4*

NaAlH4*

LiBH4*NH3BH3*

CH4*

liquid*e.g.*Al[BH4]3*!" +"

Thomas"GRAHAM"

Shin!Ichi"ORIMO""""""""""""Andreas"ZÜTTEL"

Boris"BOGDANOVIC"


STABILITY OF BHn AND BHn-

Ref.: Puru Jena , Virginia Commonwealth University, Richmond, VA (to be published).

Gradient Corrected Density Functional Theory

Energy gain in adding a H atom BHn-1 + H → BHn

Puru Jena

ADSORPTION ENERGY

[ ] ( ) ( )2211 97 HM

disHH

disMM

disMH XXHHmolkJH −⋅+Δ+Δ⋅=⋅Δ −Pauling:

Absorption Energy: [ ] ( )21 194 HMdisMM

ads XXHmolkJH −⋅+Δ=⋅Δ −

Pauling electronegativity

Ref.: Linus Pauling, “THE PRINCIPLES DETERMINING THE STRUCTURE OF COMPLEX IONIC CRYSTALS“, Journal of the American Chemical Society, 1929 - pubs.acs.org

Linus Carl Pauling * 28. 2. 1901; † 19. 8. 1994 1954 Nobelprize for chemistry 1962 Nobelprize for peace


STABILITY OF COMPLEX HYDRIDES

M[BH4]n

M, B, nH2 ΔH

ΔHdis

M, B, H2

ΔHm

ΔHMH = ΔHMM + 194·(XM - XH)2 [kJ / mol H]

MHn + Bn + 3/2nH2

M[BH4]n

ΔHf0 = 247.4·XM - 421.2

[kJ / mol BH4]

ΔHdis = ΔHf0 - ΔHMH - ΔHm

Ref.: Y. Nakamori, K. Miwa, A. Ninomiya, H. Li, N. Ohba, S.-I. Towata, A. Züttel, and Shin-ichi Orimo, Physical Review B 74, 045126 (2006); Linus Pauling, �THE PRINCIPLES DETERMINING THE STRUCTURE OF COMPLEX IONIC CRYSTALS�, Journal of the American Chemical Society, 1929 - pubs.acs.org

Pauling

Miwa, Orimo

0

50

100

150

200

0 10 20 30

Hy

dro

ge

n d

en

sit

y [

kg

/m3

]

Hydrogen density [kg H2/ 100kg storage material] Andreas Züttel, Switzerland, 17.07.14

HYDROGEN DENSITY

carbon hydrates liq. hydro-

carbons

metal hydrides

comp. H2 gas

liq. H2

liq. natural gas

NH3

complex hydrides

physi- sorption

VCard: A. Züttel

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