Ni-ferrite (NiFe2O4) is a promising reactive ceramics of the ferrite for the solar hydrogen production by a two-step water splitting process using concentrated solar energy. However, it should be pretreated before H2-generation reaction by grinding the Ni-ferrite sintered after the O2-releasing reaction to make a fine powder. If the Ni-ferrite and yttria stabilized zirconia (YSZ) form a solid solution between these oxides (YSZNiFe2O4 solid solution=YSZ(Ni,Fe)), it is expected that the two-step water splitting process with the Ni-ferrite system can proceed without treatment of the reduced product because of the high thermal stability of the YSZNiFe2O4 solid solution. The YSZNiFe2O4 solid solution was prepared by calcination of the mixture of the YSZ balls and NiFe2O4 powder at T=1823K for 1h, and its reactivity and thermal stability were examined for the two-step water splitting process. During the ten times repetition of the two-step water splitting reaction (T=1773K for O2-releasing, and 1473K for H2-generation) with the YSZNiFe2O4 solid solution using infrared imaging furnace, the reactivity for O2-releasing and H2-generation was kept constant. The molar ratio of the released O2 gas volume (the average O2 gas, 1.9cm3g) and the generated H2 gas volume (the average H2 gas, 3.8cm3g) was nearly 1:2, indicating that the water decomposition process via two steps proceeds. The X-ray diffractometry (XRD) measurement showed that the YSZ(Ni,Fe) keeps the YSZ phase structure during the ten times repetition of the two-step water splitting process. The successive H2 gas production by the two-step water splitting process was performed (ten times repetition of the two-step water splitting process). From comparative study on the reactivity and the thermal stability for the two-step water splitting reaction among the YSZNiFe2O4 solid solution, NiFe2O4 and ZnFe2O4, it is concluded that the YSZNiFe2O4 solid solution is superior to the others.

1.
Tamaura
,
Y.
,
Steinfeld
,
A.
,
Kuhn
,
P.
, and
Ehrensberger
,
K.
, 1995, “
Production of Solar Hydrogen by a Novel, 2-Step, Water-Splitting Thermochemical Cycle
,”
Energy
0360-5442,
20
(
4
), pp.
325
330
.
2.
Palumbo
,
R.
,
Lèdè
,
J.
,
Boutin
,
O.
,
Elorza–Ricart
,
E.
,
Steinfeld
,
A.
,
Moeller
,
S.
,
Weidenkaff
,
A.
,
Fletcher
,
E. A.
, and
Bielicki
,
J.
, 1998, “
The Production of Zn From ZnO in a Single Step High Temperature Solar Decomposition Process
,”
Chem. Eng. Sci.
0009-2509,
53
(
14
), pp.
2503
2517
.
3.
Kaneko
,
H.
,
Hasegawa
,
N.
,
Suzuki
,
A.
, and
Tamaura
,
Y.
, 2003, “
Two-Step Water Splitting for Solar H2 Production With Ni-Ferrite Using Concentrated Solar Heat
,”
The International Symposium on Reactivity of Solids
, Kyoto, Japan, Nov. 9–13, Paper No. C026.
4.
Kaneko
,
H.
,
Kodama
,
T.
,
Gokon
,
N.
,
Tamaura
,
Y.
,
Lovegrove
,
K.
, and
Luzzi
,
A.
, 2004, “
Decomposition of Zn-Ferrite for O2 Generation by Concentrated Solar Radiation
,”
Sol. Energy
0038-092X,
76
(
1–3
), pp.
317
322
.
5.
Tamaura
,
Y.
,
Uehara
,
R.
,
Hasegawa
,
N.
,
Kaneko
,
H.
, and
Aoki
,
H.
, 2004, “
Study on Solid-State Chemistry of the ZnO∕Fe3O4∕H2O System for H2 Production at 973–1073K
,”
Solid State Ionics
0167-2738,
172
(
1–4
), pp.
121
124
.
6.
Steinfeld
,
A.
, 2005, “
Solar Thermochemical Production of Hydrogen—A Review
,”
Sol. Energy
0038-092X,
78
(
5
), pp.
603
615
.
7.
Tamaura
,
Y.
, and
Kaneko
,
H.
, 2005, “
Oxygen-Releasing Step of ZnFe2O4∕(ZnO+Fe3O4)-System in Air Using Concentrated Solar Energy for Solar Hydrogen Production
,”
Sol. Energy
0038-092X,
78
(
5
), pp.
616
622
.
8.
Nakamura
,
T.
, 1977, “
Hydrogen Production From Water Utilizing Solar Heat at High Temperatures
,”
Sol. Energy
0038-092X,
19
(
5
), pp.
467
475
.
9.
Wilhelm
,
R. V.
, Jr.
, and
Howarth
,
D. S.
, 1979, “
Iron Oxide-Doped Yttria-Stabilized Zirconia Ceramic: Iron Solubility and Electrical Conductivity
,”
Am. Ceram. Soc. Bull.
0002-7812,
58
, pp.
228
232
.
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