2 Quantum Chemistry in Perovskite Fluoride and Hydride: Nanoscale. . .
49
2.5.1 Safety of Hydride Ion Conduction
In respect to hydride ion conduction, hydride ion-doped KMgF 3 perovskite can be
utilized for electrolyte of solid fuel cell, due to small activation energy and structural
stability at high temperature. If achieved, it could be called “solid fluoride fuel cell
(SFFC)”. However, we will face one big concern “hydrogen fluoride generation”.
Hydrogen fluoride molecule is very harmful for human. If ideal perovskite structure
is kept during hydride ion conduction, hydrogen fluoride is not produced. After
repeated use of SFFC, nonuniform distorted surface may be formed. For example,
hydrogen fluoride may be produced under electron withdrawing environment as
shown in Fig. 2.19. This point should be investigated in future experiment.
2.5.2 Safety of Hydrogen Molecule Production Combined
with Hydride Ion Conduction
Let us consider the special environment under applied voltage at high temperature.
KMgH 3 perovskite starts to be dissociated, whereas hydride ion still migrates within
remained solid part. It implies that hydrogen migration is accelerated by hydride ion
conduction in KMgH 3 perovskite (see Fig. 2.20). Thought the synergistic effect
on hydrogen molecule production sounds ideal, we must pay attention to rapid
hydrogen molecule production in the air. For safety, future experiment should be
performed using explosion-proof apparatus.
Fig. 2.19 The schematic
figure of hydrogen fluoride
production on nonuniform
distorted surface
Surface
H -
F -
HF
e -
Fig. 2.20 The schematic
figure of hydrogen molecule
releases on nonuniform
distorted surface
H -
Acceleration
Surface
Dissociation
H 2
H -
H -
Mg
Mg
49
2.5.1 Safety of Hydride Ion Conduction
In respect to hydride ion conduction, hydride ion-doped KMgF 3 perovskite can be
utilized for electrolyte of solid fuel cell, due to small activation energy and structural
stability at high temperature. If achieved, it could be called “solid fluoride fuel cell
(SFFC)”. However, we will face one big concern “hydrogen fluoride generation”.
Hydrogen fluoride molecule is very harmful for human. If ideal perovskite structure
is kept during hydride ion conduction, hydrogen fluoride is not produced. After
repeated use of SFFC, nonuniform distorted surface may be formed. For example,
hydrogen fluoride may be produced under electron withdrawing environment as
shown in Fig. 2.19. This point should be investigated in future experiment.
2.5.2 Safety of Hydrogen Molecule Production Combined
with Hydride Ion Conduction
Let us consider the special environment under applied voltage at high temperature.
KMgH 3 perovskite starts to be dissociated, whereas hydride ion still migrates within
remained solid part. It implies that hydrogen migration is accelerated by hydride ion
conduction in KMgH 3 perovskite (see Fig. 2.20). Thought the synergistic effect
on hydrogen molecule production sounds ideal, we must pay attention to rapid
hydrogen molecule production in the air. For safety, future experiment should be
performed using explosion-proof apparatus.
Fig. 2.19 The schematic
figure of hydrogen fluoride
production on nonuniform
distorted surface
Surface
H -
F -
HF
e -
Fig. 2.20 The schematic
figure of hydrogen molecule
releases on nonuniform
distorted surface
H -
Acceleration
Surface
Dissociation
H 2
H -
H -
Mg
Mg