supplementary information - royal society of chemistry · 2011. 10. 10. · s2 measurements. the...

S1

Supplementary Information

Stability of Pt(II)-based H2-evolving catalysts

against H2 in aqueous solution

Kosei Yamauchi,a Shigeyuki Masaoka,

a,b,c and Ken Sakai*

a,d

a Department of Chemistry, Faculty of Science, Kyushu University, Hakozaki 6-10-1,

Higashi-ku, Fukuoka 812-8581, Japan. Fax: +81-92-642-2596; Tel: +81-92-642-2596;

E-mail: [email protected]

b Institute for Molecular Science, Higashiyama 5-1, Myodaiji, Okazaki 444-8787, Japan.

c PRESTO, Japan Science and Technology Agency (JST), Honcho 4-1-8, Kawaguchi,

Saitama, 332-0012, Japan.

d International Research Center for Molecular Systems (IRCMS), Kyushu University.

Experimental Section

Chemicals.

cis-PtCl2(NH3)2 and K2PtCl4 (Tanaka Kikinzoku Kogyo) were used as received.

PtCl2(dcbpy) (dcbpy = 4,4'-dicarboxy-2,2'-bipyridine),1 [PtCl(terpy)]Cl·2H2O (terpy =

2,2';6',2"-terpyridine),2 and PtCl2(en) (en = ethylenediamine)

3 were synthesized as

previously described.

Electronic Supplementary Material (ESI) for Dalton TransactionsThis journal is © The Royal Society of Chemistry 2011

S2

Measurements.

The time-course UV-vis absorption spectroscopy of Pt(II) complex under 1 atm of

H2 gas.

The time-course of UV-vis absorption spectra of each Pt(II) complex under 1 atm of

H2 gas were recorded using Shimadzu UV-2450SIM and UV-2550 spectrophotometers.

The solution of each Pt(II) complex was first degassed by three cycles of freeze-pump-

thaw treatment using the custom-made cell (see below). Next, the gas phase in the cell

was filled with 1 atm of H2 gas by using a balloon having a volume of at least 1 L.

During each experiment, the solution was continuously stirred with a magnetic stirrer

bar. The cell was thoroughly washed with aqua regia prior to each experiment to avoid

the factor arising from the presence of colloidal platinum, which might be depositted

over the inner surface of the cell.

A custom-made cell used for the experiments in Figs. 1, 2, S9, S10 and S11.


S3

Energy dispersive X-ray spectroscopy (EDX).

The energy dispersive X-ray spectrum of the solid deposited was measured on a

Shimadzu EDX-720 spectrometer using a Rh target. The measurement was carried out

in helium atmosphere in order to avoid X-ray emissions being absorbed by air. The

quantitative analysis of the elements involved in the bulk samples were determined by

use of the fundamental parameter (FP) method implemented in this setup, without

preparing any standard materials. The FP method is considered as a powerful method in

giving somewhat reliable results.

X-ray photoelectron spectroscopy (XPS).

An X-ray photoelectron spectrum was measured on a Shimadzu ESCA-3400 at a

vacuum pressure less than 1 × 10-5

Pa in the analysis chamber. A standard Mg Kα

excitation source (1253.6 eV) was used in the measurement. The sample was placed on

a carbon tape. Deconvolution was carried out using CasaXPS4 in which a Shirley type

background was employed.

References.

[1] H, Ozawa, M. Haga, K. Sakai, J. Am. Chem. Soc. 2006, 128, 4926-4927.

[2] M. Howe-Grant, S. J. Lippard, Inorg. Synth. 1980, 20, 101-105.

[3] F. Basolo, J. C. Bailar, B. R. Tarr, J. Am. Chem. Soc. 1950, 72, 2433-2438.

[4] CasaXPS Version 2.3.15, Casa Software Ltd., Teignmouth TQ14 8DE, United

Kingdom.


S4

0

0.5

1

1.5

2

2.5

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)

(a) right after dissolution(0.1 M NaCl)

(b) after 15 h of (a)

Fig. S1 (a) UV-vis absorption spectrum of 0.1 mM PtCl2(dcbpy) (1) in an aqueous

acetate buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0) containing 0.1

M NaCl at 20 °C. The time spent for the dissolution of the complex was ca. 30 min. (b)

UV-vis absorption spectrum of the solution after standing the solution (b) over 15 h at

20 °C.


S5

0

0.5

1

1.5

2

2.5

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)



Fig. S2 (a) UV-vis absorption spectrum of 0.1 mM [PtCl(terpy)]Cl·2H2O (2) in an

aqueous acetate buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0)

containing 0.1 M NaCl at 20 °C. The time spent for the dissolution of the complex was

ca. 15 min. (b) UV-vis absorption spectrum of the solution after standing the solution (b)

over 15 h at 20 °C.


S6

0

0.005

0.01

0.015

0.02

0.025

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)



Fig. S3 (a) UV-vis absorption spectrum of 0.1 mM cis-PtCl2(en) (3) in an aqueous acetate

buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0) containing 0.1 M NaCl

at 20 °C. (b) UV-vis absorption spectrum of the solution after standing the solution (b)

over 15 h at 20 °C.


S7

0

0.005

0.01

0.015

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)



Fig. S4 (a) UV-vis absorption spectrum of 0.1 mM cis-PtCl2(NH3)2 (4) in an aqueous


M NaCl at 20 °C. (b) UV-vis absorption spectrum of the solution after standing the

solution (a) over 15 h at 20 °C.


S8

0

0.5

1

1.5

2

2.5

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)


(b) right after dissolution(without NaCl)

(c) after 90 min of (b)

Fig. S5 (a) UV-vis absorption spectrum of 0.1 mM PtCl2(dcbpy) (1) in an aqueous


M NaCl at 20 °C. The time spent for the dissolution of the complex was ca. 30 min. (b)

UV-vis absorption spectrum of 0.1 mM PtCl2(dcbpy) (1) in an aqueous acetate buffer

solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0) at 20 °C. The time spent for

the dissolution of the complex was ca. 30 min. (c) UV-vis absorption spectrum of the

solution after standing the solution (b) over 90 min at 20 °C.


S9

0

0.5

1

1.5

2

2.5

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)



(c) after 2 min of (b)

(d) after 10 min of (b)

(e) after 30 min of (b)

Fig. S6 (a) UV-vis absorption spectrum of 0.1 mM [PtCl(terpy)]Cl·2H2O (2) in an

aqueous acetate buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0)

containing 0.1 M NaCl at 20 °C. The time spent for the dissolution of the complex was

ca. 15 min. (b) UV-vis absorption spectrum of 0.1 mM [PtCl(terpy)]Cl·2H2O (2) in an

aqueous acetate buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0) at

20 °C. (c)-(e) UV-vis absorption spectra of the solution after standing the solution (b)

over 2 min for (c), 10 min for (d), and 30 min for (e) at 20 °C.


S10

0

0.005

0.01

0.015

0.02

0.025

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)



(c) after 15 h of (b)

Fig. S7 (a) UV-vis absorption spectrum of 0.1 mM cis-PtCl2(en) (3) in an aqueous acetate

buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0) containing 0.1 M NaCl

at 20 °C. (b) UV-vis absorption spectrum of 0.1 mM cis-PtCl2(en) (3) in an aqueous

acetate buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0) at 20 °C. (c)

UV-vis absorption spectrum of the solution after standing the solution (b) over 15 h at

20 °C.


S11

0

0.005

0.01

0.015

0.02

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)



(c) after 15 h of (b)



M NaCl at 20 °C. (b) UV-vis absorption spectrum of 0.1 mM cis-PtCl2(NH3)2 (4) in an

aqueous acetate buffer solution (0.03 M CH3COOH, 0.07 M CH3COONa; pH 5.0) at

20 °C. (c) UV-vis absorption spectrum of the solution after standing the solution (b) over

15 h at 20 °C.


S12

0

0.5

1

1.5

2

2.5

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)

0 h

1 h

3 h

5 h

0.7

0.8

0.9

1

1.1

1.2

0 1 2 3 4 5Absorbance at 328 nm

Time (h)

Fig. S9 The time-course of UV-vis absorption spectra of 0.1 mM [PtCl(terpy)]Cl·2H2O (2)

under 1 atm of H2 gas in an aqueous acetate buffer solution (0.03 M CH3COOH, 0.07 M

CH3COONa; pH 5.0) containing 0.1 M NaCl at 20 °C. The inset shows the change in

absorbance at 328 nm. The solution was first degassed by three cycles of freeze-pump-thaw

treatment.


S13

0

0.05

0.1

0.15

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)

(a) 0 h

(b) 1 h

(c) 3 h

(d) 5 h

(e) filtrate of (d)0

0.02

0.04

0 1 2 3 4 5

Absorbance at 600 nm

Time (h)

Fig. S10 (a)-(d) The time-course of UV-vis absorption spectra of 1.0 mM cis-

PtCl2(NH3)2 (4) under 1 atm of H2 gas in an aqueous acetate buffer solution (0.03 M

CH3COOH, 0.07 M CH3COONa; pH 5.0) containing 0.1 M NaCl at 20 °C. (e) The UV-

vis absorption spectrum of the filtrate of the solution used for (d), where the solution

was filtered by a syringe filter with a pore diameter of 0.45 μm. The inset shows the

change in absorbance at 600 nm. The solution was first degassed by three cycles of

freeze-pump-thaw treatment.


S14

0

0.02

0.04

0.06

0.08

0.1

0.12

250 300 350 400 450 500 550 600 650 700 750 800

Absorbance

Wavelength (nm)

(a) 0 h

(b) 1 h

(c) 3 h

(d) 5 h

(e) filtrate of (d)

0

0.05

0 1 2 3 4 5

Absorbance at 800 nm

Time (h)

Fig. S11 (a)-(d) The time-course of UV-vis absorption spectra of 1.0 mM K2PtCl4

under 1 atm of H2 gas in an aqueous acetate buffer solution (0.03 M CH3COOH, 0.07

M CH3COONa; pH 5.0) containing 0.1 M NaCl at 20 °C. (e) The UV-vis absorption

spectrum of the filtrate of the solution used for (d), where the solution was filtered by a

syringe filter with a pore diameter of 0.45 μm. The inset shows the change in

absorbance at 800 nm.


S15

666768697071727374757677787980

Intensity

Binding Energy (eV)

Pt 4f5/2

Pt 4f7/2

Fig. S12 X-ray photoelectron spectrum for the Pt species in the solid particles produced

in the experiment for cis-PtCl2(NH3)2 (4). The Pt 4f7/2 and 4f5/2 binding energies are

respectively determined as 71.0 and 74.3 eV, where those for Pt metal were reported to be

71.2 and 74.5 eV (C. D. Wagner, W. M. Riggs, L. E. Davis, J. F. Moulder, G. E.

Muilenberg, Eds.; Handbook of X-ray Photoelectron Spectroscopy, Perkin-Elmer

Corp.: Eden Prairie, MN, 1979.).


S16

0

0.005

0.01

0.015

250 300 350 400 450 500 550 600

Absorbance

Wavelength (nm)

(a) before bubbling

(b) after bubbling over 5 h



M NaCl at 20 °C. (b) UV-vis absorption spectrum of the solution after continuously

bubbling the solution (a) with 504 ppm of H2 gas (10 mL/min) over 5 h at 20 °C.


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