Supporting Information
Water Oxidation Catalysis using Amorphous Manganese Oxides, Octahedral Molecular Sieves (OMS-2) and Octahedral Layered (OL-1) Manganese Oxide Structures Aparna Iyer,§ Joselyn Del-Pilar,† Cecil K. King’ondu,§ Edward Kissel,§ Hector F. Garces,# Hui Huang,§ Abdelhamid M. El-Sawy,§ Prabir K. Dutta,*† Steven L. Suib.*§# §
Department of Chemistry and #Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA.
†
Department of Chemistry, Newman & Wolfrom Lab, 100 West 18th Ave., The Ohio State University, Columbus, Ohio 43210, USA.
Corresponding authors: 1) Prabir K. Dutta, Telephone number: (614)-292-4532, Fax: (614)-292-1685, Email:
[email protected]. 2) Steven L. Suib, Telephone number: (860)-486-2797, Fax: (860)-486-2981, Email:
[email protected].
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Table of Contents
Page
Thermogravimetric analysis of AMO, OMS-2 and OL-1 in air
S3
Mass spectrometric analysis of reaction mixtures containing O-18 labeled water and unlabeled water and AMO catalyst
S4
Infrared characterization of fresh and spent AMO catalysts collected after water oxidation reaction
S5
X-ray diffraction patterns of OMS-2 catalyst recovered after reaction
S6
X-ray diffraction patterns of AMO and OL-1 catalysts recovered after reaction
S7
EDX analysis of the spent AMO catalyst
S8
Percentage of dissolved Mn detected by AAS in reactant solutions after removal of catalysts
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S2
110 AMO
OMS-2
OL-1
Weight loss (%)
100
90
80
70
60 25
125
225
325
425
525
625
Temperature (° C)
Figure S1. Thermogravimetric analysis of AMO, OMS-2 and OL-1 in air.
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0.25
Signal ratio (m/z 34) / (m/z 32)
O34/O32 Actual ratio 0.2
O34/O32 Theoretical ratio
0.15 0.1 0.05 0 O-18 labeled water
Unlabeled water
Figure S2. Mass spectrometric analysis of gas samples collected from the headspace of reaction mixtures containing O-18 labeled water and unlabeled water. Catalyst used for this test was AMO in CAN system. The actual and theoretical [O34/O32] m/z signal ratios are close indicating water was the source of dioxygen.
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Absorbance (arbitary units)
(a)
519
437
Absorbance (arbitary units)
350
420 490 Wavenumber (cm-1)
560
420 490 Wavenumber (cm-1 )
560
420 490 Wavenumber (cm-1)
560
(b)
Absorbance (arbitary units)
350
(c)
350
Figure S3. Infrared spectra of (a) AMO before water oxidation reaction (b) AMO sample collected after reaction with CAN (c) AMO sample collected after reaction with Ru(bpy)32+.
S5
Intensity (arbitary units)
(b)
(a)
5
15
25
35
45
55
65
75
2 theta (degrees)
Figure S4. X-ray diffraction patterns of OMS-2 catalyst recovered after reaction. (a) Fresh OMS-2 catalyst and (b) spent OMS-2 catalyst recovered after water oxidation reaction with 0.25 M CAN as an oxidant.
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Intensity (arbitary units)
*
(d)
(c)
*
(b)
* 5
15
(a) 25
35
45
55
65
75
2 theta (degrees)
Figure S5. X-ray diffraction patterns of catalysts recovered after reaction. (a) Fresh AMO catalyst (b) spent AMO catalyst recovered after water oxidation reaction with 0.25 M CAN as an oxidant, (c) fresh OL-1 catalyst, and (d) spent OL-1 catalyst recovered after water oxidation reaction with 0.25 M CAN as an oxidant. * indicates peak from the glass sample holder.
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Table S1. EDX analysis of the spent AMO catalyst. Prior to EDX analysis, the catalyst sample was recovered and washed with distilled deionized water after water oxidation tests. Atomic weight percentage Sample
Spot Mn
K
Ce
Spent AMO catalyst*
1
91.891
2.717
5.392
after 1 wash cycle
2
93.762
2.09
4.148
3
92.511
2.456
5.034
Spent AMO catalyst
1
95.635
2.464
1.901
after 6 wash cycles
2
96.751
1.594
1.655
3
95.661
2.791
1.548
*The water oxidation test was carried out in 80 mL aqueous solution containing 35 mg of AMO catalyst and 0.25 M CAN.
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Table S2. Percentage of dissolved Mn detected by AAS in reactant solutions after removal of catalysts.
%Mn detected in solutionb Test conditions
a
AMO
OMS-2
OL-1
No oxidant
n.d.c
n.d.
n.d.
0.25 M CAN
0.9%
n.d.
n.d.
a
Water oxidation tests were carried out for 30 minutes in 80 mL aqueous solutions containing 35 mg catalyst and 0.25 M CAN.
b
% Mn = mg/L of Mn detected in the reaction filtrate *100 mg/L of Mn in the catalyst used for reaction
c
n.d. indicates not detected
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