It is shown that in nanoporous titanium dioxide films, sensitivity to atmospheric hydrogen exposure and electroforming can coexist and are interdependent. The devices work as conventional hydrogen sensors below a threshold electric field while above it, the well-known electroforming is observed. Offering hydrogen in this regime accelerates the electroforming process, and in addition to the usual reversible increase of the conductance in response to the hydrogen gas, an irreversible conductance decrease is superimposed. The behavior is interpreted in terms of a phenomenological model where current carrying, oxygen-deficient filaments with hydrogen-dependent conductivities form inside the TiO2 matrix.

2.
X.
Chen
and
S. S.
Mao
,
Chem. Rev.
107
,
2891
(
2007
).
3.
D. B.
Strukov
,
G. S.
Snider
,
D. R.
Stewart
, and
R. S.
Williams
,
Nature
453
,
80
(
2008
).
4.
J. J.
Yang
,
M. D.
Pickett
,
X.
Li
,
D. A. A.
Ohlberg
,
D. R.
Stewart
, and
R. S.
Williams
,
Nat. Nanotechnol.
3
,
429
(
2008
).
5.
D.-H.
Kwon
,
K. M.
Kim
,
J. H.
Jang
,
M. M.
Jeon
,
M. H.
Lee
,
G. H.
Kim
,
X.-S.
Li
,
G.-S.
Park
,
B.
Lee
,
S.
Han
,
M.
Kim
, and
C. S.
Hwang
,
Nat. Nanotechnol.
5
,
148
(
2010
).
6.
K.
Szot
,
M.
Rogala
,
W.
Speier
,
Z.
Klusek
,
A.
Beshehm
, and
R.
Waser
,
Nanotechnology
22
,
254001
(
2011
).
7.
N.
Yamamoto
,
S.
Tonomura
,
T.
Matsuoka
, and
H.
Tsubomura
,
Surf. Sci.
92
,
400
(
1980
).
8.
S. A.
Akbar
and
L. B.
Younkman
,
J. Electrochem. Soc.
144
,
1750
(
1997
).
9.
D. H.
Kim
,
Y.-S.
Shim
,
H. G.
Moon
,
H. J.
Chang
,
D.
Su
,
S. Y.
Kim
,
J.-S.
Kim
,
B. K.
Ju
,
S.-J.
Yoon
, and
H. W.
Jang
,
J. Phys. Chem. C
117
,
17824
(
2013
).
10.
M. D.
Pickett
,
G.
Medeiros-Ribeiro
, and
R. S.
Williams
,
Nat. Mater.
12
,
114
(
2013
).
11.
O. K.
Varghese
,
D.
Gong
,
M.
Paulose
,
K. G.
Ong
, and
C. A.
Grimes
,
Sens. Actuators, B
93
,
338
(
2003
).
12.
M.
Paulose
,
O. K.
Varghese
,
G. K.
Mor
,
C. A.
Grimes
, and
K. G.
Ong
,
Nanotechnology
17
,
398
(
2006
).
13.
M.
El-Achhab
,
A.
Erbe
,
G.
Koschek
,
R.
Hamouich
, and
K.
Schierbaum
,
Appl. Phys. A
116
,
2039
(
2014
).
14.
See supplemental material at http://dx.doi.org/10.1063/1.4917034 for details.
15.
S.
Wendt
,
R.
Schaub
,
J.
Matthiesen
,
E.
Vestergaard
,
E.
Wahlström
,
M.
Rasmussen
,
P.
Thostrup
,
L.
Molina
,
E.
Laegsgaard
,
I.
Stensgaard
,
B.
Hammer
, and
F.
Besenbacher
,
Surf. Sci.
598
,
226
(
2005
).
16.
J. J.
Yang
,
F.
Miao
,
M. D.
Pickett
,
D. A. A.
Ohlberg
,
D. R.
Stewart
,
C. N.
Lau
, and
R. S.
Williams
,
Nanotechnology
20
,
215201
(
2009
).
17.
P.
Knauth
and
H. L.
Tuller
,
J. Appl. Phys.
85
,
897
(
1999
).
18.
L. A.
Harris
,
J. Electrochem. Soc.
127
,
2657
(
1980
).
19.
S.
Lee
,
J. S.
Lee
,
J.-B.
Park
,
Y. K.
Kyoung
,
M.-J.
Lee
, and
T. W.
Noh
,
APL Mater.
2
,
066103
(
2014
).
20.
R.
Münstermann
,
T.
Menke
,
R.
Dittmann
, and
R.
Waser
,
Adv. Mater.
22
,
4819
(
2010
).
21.
M.
Cerchez
,
H.
Langer
,
M. E.
Achhab
,
T.
Heinzel
,
D.
Ostermann
,
H.
Lüder
, and
D.
Ostermann
,
Appl. Phys. Lett.
103
,
033522
(
2013
).
22.
U.
Roland
,
T.
Braunschweig
, and
F.
Roessner
,
J. Mol. Catal. A: Chem.
127
,
61
(
1997
).
23.
U.
Aschauer
and
A.
Selloni
,
Phys. Chem. Chem. Phys.
14
,
16595
(
2012
).
24.
F.
Filippone
,
G.
Mattioli
,
P.
Alippi
, and
A. A.
Bonapasta
,
Phys. Rev. B
80
,
245203
(
2009
).
25.
T.
Bjørheim
,
S.
Stølen
, and
T.
Norby
,
Phys. Chem. Chem. Phys.
12
,
6817
(
2010
).
26.
D. A.
Panayotov
and
J. T.
Yates
,
Chem. Phys. Lett.
436
,
204
(
2007
).
27.
P. W.
Peacock
and
J.
Robertson
,
Appl. Phys. Lett.
83
,
2025
(
2003
).
28.
F.
Herklotz
,
E. V.
Lavrov
, and
J.
Weber
,
Phys. Rev. B
83
,
235202
(
2011
).
29.
P.
Kowalski
,
B.
Meyer
, and
D.
Marx
,
Phys. Rev. B
79
,
115410
(
2009
).
30.
M.
Islam
,
M.
Calatayud
, and
G.
Pachioni
,
J. Phys. Chem. C
115
,
6809
(
2011
).
31.
J. B.
Bates
,
J. C.
Wang
, and
R. A.
Robertson
,
Phys. Rev. B
19
,
4130
(
1979
).
32.

For (a), τA is also the recovery time after H2 is turned off. In Figs. 3(b) and 3(d), τA = 50 s was used. We chose σ1o=3.5×1012Sm,σ2o=6×1012Sm,σ3o=1013Sm, σA(cα)=2.0×1012Sm,σA(cβ)=2.2×1012Sm,σA(cγ)=2.6×1012Sm, σ2,Bo(cα)=4.7×1012Sm,σ2,Bo(cβ)=4.2×1012Sm, and σ2,Bo(cγ)=4.1×1012Sm.

33.
R. F.
Bartholomew
and
D. R.
Frankl
,
Phys. Rev.
187
,
828
(
1969
).
34.
Ö.
Cakabay
,
M.
ElAchhab
, and
K.
Schierbaum
,
Appl. Phys. A
118
,
1127
(
2015
).

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