Supporting Information Novel Mn3O4 Micro-octahedra: Promising ...
Supporting Information Novel Mn3O4 Micro-octahedra: Promising Cataluminescence Sensing Material for Acetone Lichun Zhang,1 Qin Zhou,1 Zonghuai Liu,2 Xiandeng Hou,1,3 Yubao Li,3 Yi Lv*1 1: Key Laboratory of Green Chemistry & Technology, Ministry of Education; College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China 2: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education; School of Chemistry and Materials Science, Shaanxi Normal University, Xi’an 710062, China 3: Analytical & Testing Center, Sichuan University, Chengdu, Sichuan 610064, China
Average oxidation states. The average oxidation number (ZMna) of manganese was evaluated from the value of available oxygen, which was determined by the standard oxalic acid method as described elsewhere.[S1] The alkali metal and manganese contents were determined by atomic absorption spectrometry (trace components) and chemical analysis (major components) after the samples were dissolved in a mixed a mixed acidic solution.[32] According to the average oxidation number ZMna of manganese, the prepared hexagonal nanoplates have a chemical formula of Mn3O4.26 with an average oxidation state of manganese 2.84, quantifying as 87% Mn3O4 and 13% MnO2 by calculation, which is roughly consistent with the mixed Mn3O4-MnO2 manganese oxide system. These results are presented in Table S1.
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Table S1. Chemical composition of prepared Mn3O4 micro-octahedra and hexagonal nanoplates. ZMn Sample
Mn (mmol g-1)
O (mmol g-1)
a
Formula 2.6
micro-octahedra
9.20
12.22
5
Mn3O3.99 2.8
hexagonal nanoplates
9.23
13.15
4
Mn3O4.26
[ZMna] The average oxidation state of manganese. Formation mechanism. Understanding the formation mechanism is important to realize the controllable synthesis of micro-nano materials. Up to now, a variety of formation mechanisms have been proposed for the formation of nanocrystals with different morphologies. A rolling and phase transformation mechanism has been proposed by Li and co-workers.[s2] In addition, other formation mechanisms, such as oriented attachment, capping-molecule-assisted and nucleationdissolution-anisotropic growth-recrystallization, have also been proposed.[s3,
s4]
The formation
mechanism of Mn3O4 micro-octahedra and hexagonal nanoplates is closely associated with the morphology change when KMnO4 is reduced in dodecylamine-Na2SO3-ethanol/dodecylamineethanol system. The morphology evolution of Mn3O4 micro-octahedra and hexagonal nanoplates was followed by SEM observation (Figure S1, S2), and this convinces us the “capping-moleculeassisted” and “nucleation-dissolution-anisotropic growth-recrystallization” mechanism. The morphology can be controllably tuned by adjusting hydrothermal treatment time and selecting suitable reducing agents, and this suggests that the Mn3O4 micro-otcahedra and hexagonal
23
nanoplates can be controllably synthesized by hydrothermal treatment of KMnO4 in the dodecylamine-Na2SO3-ethanol/dodecylamine-ethanol system.
Figure S1. The obtained Mn3O4 micro-octahedra samples at different hydrothermal conditions. (a) 180 ºC, 1 d; (b) 180 ºC, 1.5 d; (c)180 ºC, 2 d; and (d) 160 ºC, the mixture solution of 22 mL ethanol and 13 mL water instead of the 38 mL ethanol, 2 d.
24
Figure S2. The prepared manganese oxide hexagonal nanoplates samples at different hydrothermal times: (a) 3 h; (b) 6 h; (c) 12 h; and (d) 1 d.
Figure S3. XPS spectra of the prepared materials: (a) Mn3O4 micro-octahedra; and (b) hexagonal nanoplates.
The sensing conditions were optimized on Mn3O4 micro-octahedra by choosing proper temperature and carrier gas flow rate. Figure S4 and Figure S5 show the dynamic signals and the Signal/Noise ratios of acetone in the temperature range of 60-470 ºC, with an air flow rate in the range of 100-700 mL min-1. In terms of higher Signal/Noise ratio, 284 ºC and 500 mL min-1 air flow rate were selected for use.
25
250
9000
S/N
7500
CTL Intensity
200
150 S/N
CTL Intensity
6000
4500 100 3000 50 1500 0
0 100
0
200
300
400
500
Temperature (ºC)
Figure S4. The sensor based on Mn3O4 micro-octahedra responses towards 47.3 μg mL-1 acetone at different temperatures. The air flow rate: 500 mL min-1.
300
4000 200 S/N
Relative CTL Intensity
5000
3000 S/N
100
CTL Intensity
2000
1000
0 200
300
400
500
600
700
air flow (mL min-1)
Figure S5. The sensor based on Mn3O4 micro-octahedra responses towards 23.6 μg mL-1 acetone at different air flow rates. Temperature: 284 ºC.
26
103)
40
e d
30
a —1.6 μ g mL-1 b —7.9 μ g mL-1 c —23.6 μ g mL-1 d —157.6 μ g mL-1 e —262.7 μ g mL-1
Intensity (Counts,
×
20
10
c b a
0 10
20
30
40
Time (s)
Figure S6. Typical CTL spectra of response/recovery time at different acetone concentration (μg mL-1). The air flow rate: 500 mL min-1; and temperature: 284 ºC.
Figure S7. The relative sensor responses towards 52.2 μg mL-1 of selected VOCs. Sensing material: Mn3O4 micro-octahedra.
27
The tests for stability and durability of the sensor were carried out by sampling of acetone into the chamber every day at 284 ºC with the air flow rate at 500 mL min-1. After two months of use, no appreciable variations were detected. The RSD (n = 7) was 3.5% in a successive measurements.
Figure S8. Interference of water vapor with the determination of acetone by using the proposed CTL sensor. Relative CTL intensity of acetone and acetone-water solution (Vacetone: Vwater = 3:7). Air humidity: 67% at 18 ºC; air flow rate: 500 mL min-1; and working temperature: 284 ºC. References [s1] Methods for Determination of Active Oxygen in Manganese Ores; Japan Industrial Standard (JIS); Japanese Standards Association: 1969, M 8233. [s2] Y. Li, X. Wang, Chem. Eur. J. 2003, 9, 300-306. [s3] F. Cheng, J. Zhao, W. Song, C. Li, H. Ma, J. Chen, P. Shen, Inorg. Chem. 2006, 45, 20382044. [s4] H. Zhang, D. Yang, D. Li, X. Ma, S. Li, D. Que, Cryst. Growth Des. 2005, 5, 547-550.
28
Average oxidation states. The average oxidation number (ZMna) of manganese was evaluated from the value of available oxygen, which was determined by the standard oxalic acid method as described elsewhere.[S1] The alkali metal and manganese contents were determined by atomic absorption spectrometry (trace components) and chemical analysis (major components) after the samples were dissolved in a mixed a mixed acidic solution.[32] According to the average oxidation number ZMna of manganese, the prepared hexagonal nanoplates have a chemical formula of Mn3O4.26 with an average oxidation state of manganese 2.84, quantifying as 87% Mn3O4 and 13% MnO2 by calculation, which is roughly consistent with the mixed Mn3O4-MnO2 manganese oxide system. These results are presented in Table S1.
22
Table S1. Chemical composition of prepared Mn3O4 micro-octahedra and hexagonal nanoplates. ZMn Sample
Mn (mmol g-1)
O (mmol g-1)
a
Formula 2.6
micro-octahedra
9.20
12.22
5
Mn3O3.99 2.8
hexagonal nanoplates
9.23
13.15
4
Mn3O4.26
[ZMna] The average oxidation state of manganese. Formation mechanism. Understanding the formation mechanism is important to realize the controllable synthesis of micro-nano materials. Up to now, a variety of formation mechanisms have been proposed for the formation of nanocrystals with different morphologies. A rolling and phase transformation mechanism has been proposed by Li and co-workers.[s2] In addition, other formation mechanisms, such as oriented attachment, capping-molecule-assisted and nucleationdissolution-anisotropic growth-recrystallization, have also been proposed.[s3,
s4]
The formation
mechanism of Mn3O4 micro-octahedra and hexagonal nanoplates is closely associated with the morphology change when KMnO4 is reduced in dodecylamine-Na2SO3-ethanol/dodecylamineethanol system. The morphology evolution of Mn3O4 micro-octahedra and hexagonal nanoplates was followed by SEM observation (Figure S1, S2), and this convinces us the “capping-moleculeassisted” and “nucleation-dissolution-anisotropic growth-recrystallization” mechanism. The morphology can be controllably tuned by adjusting hydrothermal treatment time and selecting suitable reducing agents, and this suggests that the Mn3O4 micro-otcahedra and hexagonal
23
nanoplates can be controllably synthesized by hydrothermal treatment of KMnO4 in the dodecylamine-Na2SO3-ethanol/dodecylamine-ethanol system.
Figure S1. The obtained Mn3O4 micro-octahedra samples at different hydrothermal conditions. (a) 180 ºC, 1 d; (b) 180 ºC, 1.5 d; (c)180 ºC, 2 d; and (d) 160 ºC, the mixture solution of 22 mL ethanol and 13 mL water instead of the 38 mL ethanol, 2 d.
24
Figure S2. The prepared manganese oxide hexagonal nanoplates samples at different hydrothermal times: (a) 3 h; (b) 6 h; (c) 12 h; and (d) 1 d.
Figure S3. XPS spectra of the prepared materials: (a) Mn3O4 micro-octahedra; and (b) hexagonal nanoplates.
The sensing conditions were optimized on Mn3O4 micro-octahedra by choosing proper temperature and carrier gas flow rate. Figure S4 and Figure S5 show the dynamic signals and the Signal/Noise ratios of acetone in the temperature range of 60-470 ºC, with an air flow rate in the range of 100-700 mL min-1. In terms of higher Signal/Noise ratio, 284 ºC and 500 mL min-1 air flow rate were selected for use.
25
250
9000
S/N
7500
CTL Intensity
200
150 S/N
CTL Intensity
6000
4500 100 3000 50 1500 0
0 100
0
200
300
400
500
Temperature (ºC)
Figure S4. The sensor based on Mn3O4 micro-octahedra responses towards 47.3 μg mL-1 acetone at different temperatures. The air flow rate: 500 mL min-1.
300
4000 200 S/N
Relative CTL Intensity
5000
3000 S/N
100
CTL Intensity
2000
1000
0 200
300
400
500
600
700
air flow (mL min-1)
Figure S5. The sensor based on Mn3O4 micro-octahedra responses towards 23.6 μg mL-1 acetone at different air flow rates. Temperature: 284 ºC.
26
103)
40
e d
30
a —1.6 μ g mL-1 b —7.9 μ g mL-1 c —23.6 μ g mL-1 d —157.6 μ g mL-1 e —262.7 μ g mL-1
Intensity (Counts,
×
20
10
c b a
0 10
20
30
40
Time (s)
Figure S6. Typical CTL spectra of response/recovery time at different acetone concentration (μg mL-1). The air flow rate: 500 mL min-1; and temperature: 284 ºC.
Figure S7. The relative sensor responses towards 52.2 μg mL-1 of selected VOCs. Sensing material: Mn3O4 micro-octahedra.
27
The tests for stability and durability of the sensor were carried out by sampling of acetone into the chamber every day at 284 ºC with the air flow rate at 500 mL min-1. After two months of use, no appreciable variations were detected. The RSD (n = 7) was 3.5% in a successive measurements.
Figure S8. Interference of water vapor with the determination of acetone by using the proposed CTL sensor. Relative CTL intensity of acetone and acetone-water solution (Vacetone: Vwater = 3:7). Air humidity: 67% at 18 ºC; air flow rate: 500 mL min-1; and working temperature: 284 ºC. References [s1] Methods for Determination of Active Oxygen in Manganese Ores; Japan Industrial Standard (JIS); Japanese Standards Association: 1969, M 8233. [s2] Y. Li, X. Wang, Chem. Eur. J. 2003, 9, 300-306. [s3] F. Cheng, J. Zhao, W. Song, C. Li, H. Ma, J. Chen, P. Shen, Inorg. Chem. 2006, 45, 20382044. [s4] H. Zhang, D. Yang, D. Li, X. Ma, S. Li, D. Que, Cryst. Growth Des. 2005, 5, 547-550.
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