Hydrogen peroxide as sustainable fuel: Electrocatalysts for production with a solar cell and decomposition with a fuel cell

Article abstract of DOI:10.1039/c0cc01797c

Hydrogen peroxide was electrochemically produced by reducing oxygen in an aqueous solution with [Co(TCPP)] as a catalyst and photovoltaic solar cell operating at 0.5 V. Hydrogen peroxide thus produced is utilized as a fuel for a one-compartment fuel cell with Ag-Pb alloy nanoparticles as the cathode.

Full text of DOI:10.1039/c0cc01797c

View Article Online / Journal Homepage / Table of Contents for this issue
COMMUNICATION
www.rsc.org/chemcomm | ChemComm
Hydrogen peroxide as sustainable fuel: electrocatalysts for production
with a solar cell and decomposition with a fuel cellw
a
a
b
ac
Yusuke Yamada,* Yurie Fukunishi, Shin-ichi Yamazaki and Shunichi Fukuzumi*
Received 9th June 2010, Accepted 11th August 2010
DOI: 10.1039/c0cc01797c
Hydrogen peroxide was electrochemically produced by reducing
oxygen in an aqueous solution with [Co(TCPP)] as a catalyst
and photovoltaic solar cell operating at 0.5 V. Hydrogen peroxide
thus produced is utilized as a fuel for a one-compartment fuel cell
with Ag–Pb alloy nanoparticles as the cathode.
oxygen and water. However, such a combination of produc-
tion of H with a solar cell and decomposition with a fuel
2
O
2
cell has yet to be reported.
2 2
We report herein a combination of H O production by the
electrocatalytic reduction of O in air with electrical power
2
generated by a photovoltaic solar cell and power generation
An oil-based society includes insistent problems owing to not
with an H
electrocatalysts for O
chemical structures of the Co porphyrins used are depicted in
2 2
O fuel cell. Cobalt porphyrins have been used as
7
–12
only CO
2
but also harmful chemicals such as NO
x
, SO
x
2
reduction to produce H
2
O
2
.
The
and particulate matter in the emission gas from an internal-
combustion engine. In order to attain really clean air, a
1
3
Scheme 1. In order to improve the performance of an H
fuel cell, a cathode composed of Ag and Ag–Pb alloy nano-
particles was employed. Compared with an H fuel cell
2 2
O
1
hydrogen-based society has been pursued for several decades.
A critical problem of hydrogen as an alternative fuel is on its
2
storage and portability. The hydrogen-based society is really
2 2
O
5
using an Ag plate as a cathode, the open circuit potential was
improved with comparable current density, resulting in higher
power density.
far from real before we develop a new compound, which can
store hydrogen in high volumetric density and release it at an
ambient condition for portable uses.
Electrocatalytic O
H-type cell with an agar salt bridge. The thermodynamic
potential for the two-electron reduction of O at a given pH
reduction was carried out by using an
2
Hydrogen peroxide (H
because H can oxidize various chemicals selectively to
produce no waste chemicals but water.
energy carrier alternative to oil or hydrogen, because H
can be used in a fuel cell, in which the reactions occurring at
2 2
O ) has attracted many process chemists,
2
O
2
2
3
,4
2
H O
2
can be an
is 0.65 V. Cobalt porphyrins in Scheme 1 were mounted on
a glassy carbon electrode by a drop-casting method. The
prepared electrode catalyst was dipped in hydrosulfuric acid,
and Pt wire was put in the other side of the H-type cell.
2
O
2
5
,6
anode and cathode are given as follows:
2
Electrocatalytic O reduction current was recorded against
+
2 2 2
Anode: H O - O + 2H + 2e , 0.68 V
À
voltage vs. saturated calomel electrode (SCE) as displayed in
Fig. 1a. Oxygen reduction current was observed on all catalysts
but [Co(DPP)]. Among the Co porphyrins, [Co(TCPP)] showed
the highest onset potential of 0.3 V. The onset potential
observed on [Co(TPP)] was as same as that of [Co(TCPP)].
+
2 2 2
Cathode: H O + 2H + 2e - 2H O, 1.77 V
À
2 2 2 2
Total: 2H O - O + 2H O
[Co(OEP)] showed modest activity, the lower onset potential of
The maximum output potential theoretically achievable is 1.09 V,
which is comparable to those of a hydrogen fuel cell (1.23 V)
and a direct methanol fuel cell (1.21 V). However, the reported
0.1 V, compared to former two Co porphyrins.
5
power density has yet to be by far sufficient.
If we can produce H
abundant in air with a solar cell, and generate electrical
power by an efficient H O fuel cell, very ideal recyclable
2 2
O by the electrochemical reduction of
O
2
2
2
society would be realized because H O is liquid at room
2
2
temperature and the by-product after power generation are
a
Department of Material and Life Science,
Graduate School of Engineering,
Osaka University, Suita, Osaka 565-0871, Japan.
E-mail: yamada@chem.eng.osaka-u.ac.jp,
fukuzumi@chem.eng.osaka-u.ac.jp; Fax: +81-6-6879-7370;
Tel: +81-6-6879-7368
Research Institute for Ubiquitous Energy Devices,
National Institute of Advanced Industrial Science and Technology,
b
1
-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
c
Department of Bioinspired Science, Ewha Womans University, Seoul
20-750, Korea
1
w Electronic supplementary information (ESI) available: Experimental
details for catalyst preparation, for dynamic laser scattering, and CV
13
of H
2
O
2
over Ag–Pb nanoparticles. See DOI: 10.1039/c0cc01797c
Scheme 1 Co porphyrin catalysts for oxygen reduction.
7
334 Chem. Commun., 2010, 46, 7334–7336
This journal is c The Royal Society of Chemistry 2010

View Article Online
Fig. 1 (a) Electrocatalytic current at oxygen reduction. ~: [Co(DPP)]
K: [Co(OEP)] m: [Co(TPP)] ’: [Co(TCPP)]. (b) CV of [Co(TCPP)] at
À1
scan rate = 20 mV s (black; under air, blue; 3 mM H
O
2 2
, red; with
oxygen bubbling). The measurements were performed in 0.1 M hydro-
sulfuric acid at 25 1C. To prevent contamination of the coordinating
ion or ligands, ultrapure water was used in the experiments.
Fig. 2 TEM images of Ag or Ag–Pb alloy nanoparticles. (a) Ag
Fig. 1b compares CV curves of [Co(TCPP)] under three
different conditions. When oxygen gas was passed through a
solution during the CV measurements, two separated reduction
peaks were observed around 0 V and À0.3 V (red). When the
nanoparticles, (b) Ag–Pb alloy (Ag : Pb = 9 : 1), (c) Ag–Pb alloy
(
7 : 3) and (d) Ag–Pb alloy (Ag : Pb = 6 : 4).
of Ag–Pb alloy with the peaks assigned to Ag which is the core
part of the nanoparticles. In the range from 301 to 501 in 2y,
Ag nanoparticles provided two peaks at 38.11 and 44.21
assigned to Ag(111) and Ag(200), respectively (Fig. 3a).
Ag–Pb alloy catalysts provided additional two peaks around
41.51 and 35.21 as shown in Fig. 3b and c. The diffraction
pattern of Pb metal displayed in Fig. 3d showed no peaks at
41.51 and 35.21. These diffraction peaks were not assigned to
AgO and PbO. Thus, the two peaks appeared were assigned to
Ag–Pb alloy. The peaks were almost diminished for the alloy
of Ag : Pb = 6 : 4, indicating less alloy formation at high Pb
concentration. The Ag–Pb alloy nanoparticles were prepared
by the successive reduction process: Ag reduction and Pb
reduction in the presence of Ag seeds. Ag–Pb alloy was formed
on the surface of nanoparticles.
2 2
solution contained H O (3 mM), a reduction peak appeared
around À0.3 V predominantly (blue). Although another peak
appeared around 0 V, the current level was comparable to that
observed at the measurement under air (black). Thus, the first
reduction peak that appeared around 0 V corresponds to two
electron reduction of O
2
. When the applied potential is con-
trolled to around 0 V, H O should be formed selectively.
2
2
H O production by O reduction with the Co porphyrins was
2
2
2
performed at 0 V for 1 hour. The concentration of H O was
2
2
determined by the colorimetric titration with oxo[5,10,15,20-
14
tetra(4-pyridyl)porphyrinato]titanium(IV). The highest amount
À8
of H
2
O
2
of 3.4 Â 10 mol was achieved at [Co(TCPP)]. The
2 2
current efficiency for H O production was nearly 100% under
1
5
the present conditions.
Based on these results, [Co(TCPP)] and Pt wire electrodes
were connected to a conventional Si photovoltaic solar cell,
which generates electrical power of 0.5 V at 2.5 mA (see ESIw).
After 11 hours of running, the amount of H O produced
Fig. 4 shows the I–V and I–P curves of the constructed fuel
cells with a cathode of a glassy carbon electrode mounting Ag
nanoparticles or Ag–Pb alloy nanoparticles and an anode of
Au electrode. The current density was normalized by the
2
2
À5
reached 1.46 Â 10 mol. Although the catalytic behavior as
well as cell and electrode structures should be improved more
for better performance, H O was successfully achieved by the
2
2
reduction of molecular O
solar cell.
For construction of a one-compartment H
2
with a conventional photovoltaic
2 2
O fuel cell,
1
6
Ag–Pb alloy nanoparticles were employed, because higher
specific surface area is expected for Ag nanoparticles as
5
compared to an Ag plate, and also the addition of a foreign
2 2
element to Ag metal could improve the H O reduction
activity of Ag. Fig. 2 shows the TEM images of Ag and
Ag–Pb alloy nanoparticles. The shape of nanoparticles was
nearly spherical independent of their compositions. The average
diameter of Ag nanoparticles was 41 nm with the size distri-
buted from 13 nm to 75 nm. Similar average diameters of
Ag–Pb alloy were observed, 50 nm (Ag : Pb = 9 : 1), 34 nm
(
7 : 3) and 39 nm (6 : 4) respectively. The size distributions of
alloy particles were 26 nm to 88 nm (9 : 1), 15 to 73 nm (7 : 3)
and 14 to 77 nm (6 : 4).
Powder X-ray diffraction analysis of Ag–Pb alloy nano-
particles in Fig. 3 exhibited new peaks assigned to the formation
Fig. 3 X-Ray diffraction patterns of nanoparticles composed of
(a) Ag, (b) Ag–Pb alloy (9 : 1), (c) Ag–Pb alloy (6 : 4) and (d) Pb.
This journal is c The Royal Society of Chemistry 2010
Chem. Commun., 2010, 46, 7334–7336 7335

View Article Online
This work was supported by a Grant-in-Aid from the
Ministry of Education, Culture, Sports, Science, and Techno-
logy, Japan (No. 20108010 to S.F.) and KOSEF/MEST
through WCU project (R31-2008-000-10010-0). Y.Y. thanks
to the financial support from the Ogasawara Foundation for
the Promotion of Science and Engineering. We acknowledged
to Profs. Norimitsu Tohnai and Nobuyuki Zettsu for XRD
and TEM measurements.
Notes and references
1
(a) D. G. Nocera, Chem. Soc. Rev., 2009, 38, 13; (b) S. Fukuzumi,
Eur. J. Inorg. Chem., 2008, 1351.
2
(a) C. W. Hamilton, R. T. Baker, A. Staubitzc and I. Manners,
Chem. Soc. Rev., 2009, 38, 279; (b) H.-L. Jiang, S. K. Singh,
J.-M. Yan, X.-B. Zhang and Q. Xu, ChemSusChem, 2010, 3, 541.
I. Hermans, E. S. Spier, U. Neuenschwander, N. Turra and
A. Baiker, Top. Catal., 2009, 52, 1162.
3
Fig. 4 I–V and I–P curves of a one-compartment H
with Ag or Ag–Pb alloy cathode. (Au anode. 1N NaOH, 300 mM
. Black: Ag, green: Ag : Pb = 6 : 4, red: Ag : Pb = 7 : 3 and
2
O
2
fuel cell
4 (a) H. Egami, T. Oguma and T. Katsuki, J. Am. Chem. Soc., 2010,
132, 5886; (b) X. Chen, J. Zhang, X. Fu, M. Antonietti and
X. Wang, J. Am. Chem. Soc., 2009, 131, 11658.
2 2
H O
5
S. Yamazaki, Z. Siroma, H. Senoh, T. Ioroi, N. Fujiwara and
K. Yasuda, J. Power Sources, 2008, 178, 20.
blue: Ag : Pb = 9 : 1).
6
A borohydride–hydrogen peroxide fuel cell has been reported; see:
J. Wei, X. Wang, Y. Wang, J. Guo, P. He, S. Yang, N. Li, F. Pei
and Y. Wang, Energy Fuels, 2009, 23, 4037.
F. C. Anson, C. N. Shi and B. Steiger, Acc. Chem. Res., 1997, 30,
437.
B. Su, I. Hatay, A. Trojanek, Z. Samec, T. Khoury, C. P. Gros,
J. M. Barbe, A. Daina, P.-A. Carrupt and H. H. Girault, J. Am.
Chem. Soc., 2010, 132, 2655.
geometric surface area of the glassy carbon electrode. The plot
in black is the results obtained by Ag nanoparticles without Pb
addition. The higher power density, open circuit voltage and
short-circuit current were obtained when Ag–Pb alloys were
used as cathodes (Ag : Pb = 9 : 1 (blue), 7 : 3 (red), 6 : 4
7
8
(
green) in Fig. 4). The higher values were achieved on Ag–Pb
alloys with the ratios of 9 : 1 and 7 : 3. The open-circuit
9 (a) C. J. Chang, Y. Deng, D. G. Nocera, C. Shi, F. C. Anson and
C. K. Chang, Chem. Commun., 2000, 1355; (b) C. J. Chang,
Z. H. Loh, C. Shi, F. C. Anson and D. G. Nocera, J. Am. Chem.
Soc., 2004, 126, 10013.
potential of ca. 150 mV far from the theoretical potential
(
1.09 V) is ascribed to the overpotentials observed at the anode
and the cathode. The CV of H over the Ag–Pb alloy
exhibited the onset potential (ca. À0.08 V vs. SCE) for the
reduction far from the thermodynamic value (0.70 V) at
the given pH (Fig. S1 in ESIw).
In the present approach, H
and power generation by the direct H O fuel cell in basic
2
O
2
1
0 J. P. Collman, R. Boulatov and C. J. Sunderland, in The Porphyrin
Handbook, ed. K. M. Kadish, K. M. Smith and R. Guilard,
Academic Press, San Diego, 2003, vol. 11, p. 1.
2 2
H O
1
1 K. M. Kadish, L. Fremond, Z. Ou, J. Shao, C. Shi, F. C. Anson,
´
F. Burdet, C. P. Gros, J.-M. Barbe and R. Guilard, J. Am. Chem.
Soc., 2005, 125, 5625.
2
2
O is produced in acidic media
12 (a) K. M. Kadish, L. Fre
´
mond, J. Shen, P. Chen, K. Ohkubo,
2
2
S. Fukuzumi, M. E. Ojaimi, C. P. Gross, J.-M. Barbe and
R. Guilard, Inorg. Chem., 2009, 48, 2571; (b) S. Fukuzumi,
K. Okamoto, C. P. Gros and R. Guilard, J. Am. Chem. Soc.,
2004, 126, 10441.
3 Abbreviations of porphyrin ligands; TCPP: 5,10,15,20-tetraphenyl
porphinate, OEP: 2,3,7,8,12,13,17,18-octaethyl porphinate, TCPP:
5,10,15,20-tetra(4-carboxylphenyl) porphinate, DPP: 2,3,5,7,8,10,12,
13,15,17,18,20-dodecaphenylporphinate.
14 C. Matsubara, N. Kawamoto and K. Takamura, Analyst, 1992,
117, 1781.
media. In order to achieve a more efficient system, the media
conditions should be the same or similar for H O production
2
2
and power generation. For H
basic conditions, O reduction over a Pd-loaded catalyst under
2
mild conditions has been reported. For H O reduction in
2 2
O production in neutral to
1
2
1
7
2
acidic conditions, some metal complexes such as Prussian Blue
have been reported to show a certain activity although their
1
activity is not sufficient. In the next step it is required to
8
1
5 [Co(TPP)] also provided nearly the same amount of H
3.1 Â 10 mol, although the current efficiency was slightly smaller
(95%). [Co(OEP)] also exhibited high current efficiency of 100%,
2
O
2
,
improve either or both the catalysts for realizing a H -based
2
2
O
À8
1
9
society.
À8
however, the amount of H
2
O
2
was as low as 1.5 Â 10 mol.
In conclusion, we have demonstrated the potential use of
H O as an energy carrier alternative to oil or hydrogen. H O
2
1
6 Ag–Pb nanoparticles were prepared by reducing Pb ion with
formalin in the presence of Ag nanoparticles seeds and the molar
ratios of Ag to Pb were varied among 6 : 4, 7 : 3 and 9 : 1 (see
ESIw for preparations and characterization).
2
2
2
was produced by the electrocatalytic reduction of O in air
2
using a [Co(TCPP)]-modified electrode with the electric power
1
7 M. Sun, J. Zhang, Q. Zhang, Y. Wang and H. Wan, Chem.
2 2
generated by a photovoltaic solar cell. H O thus produced
Commun., 2009, 5174.
8 A. A. Karyakin, E. E. Karyakina and L. Gorton, Electrochem.
Commun., 1999, 1, 78.
was used as a fuel of a direct fuel cell, which has a very simple
one-compartment structure, to generate electric power.
1
Although the power density of an H
to be improved, combination of H
cell and power generation with an H
ideal sustainable energy conversion and preservation system.
2
O
2
fuel cell still needs
production with a solar
2
O fuel cell provides an
19 Cobalt corroles may be good candidates as an O
catalyst with a smaller overpotential; see: K. M. Kadish, J. Shen,
L. Fremond, P. Chen, M. E. Ojaimi, M. Chkounda, C. P. Gros,
2
reduction
2
O
2
´
2
J.-M. Barbe, K. Ohubo, S. Fukuzujmi and R. Guilard, Inorg.
Chem., 2008, 47, 6726.
7
336 Chem. Commun., 2010, 46, 7334–7336
This journal is c The Royal Society of Chemistry 2010