Supporting Information Tunable Photodeposition of MoS2 onto ...
Supporting Information
Tunable Photodeposition of MoS2 onto Composite of Reduced Graphene Oxide and CdS for Synergic Photocatalytic Hydrogen Generation Yuexiang Li,* Hao Wang and Shaoqin Peng Department of Chemistry, Nanchang University, Nanchang 330031, China E-mail: [email protected]
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Experimental Section 1. Preparation of Graphene Oxide (GO) GO was synthesized by a modified Hummers’ method. In a typical process, graphite powder (5.0 g) and NaNO3 (2.5 g) were added to 115 mL of concentrated H2SO4 in an ice bath, and then gradual addition of KMnO4 (15.0 g) was conducted under stirring. After 4 h stirring at 35 °C, 230 mL of distilled water was added to the mixture, and the resultant mixture was stirred at 98 °C for 15 min. It was further diluted to 700 mL and stirred for 30 min. 12 mL of 35 wt % H2O2 was introduced under stirring to terminate the reaction. GO powders were obtained by centrifugation, rinsing with water and acetone, and drying at 60 °C overnight. 2. Adsorption Amounts of MoS42- on CdS, rGO and rGO1.5/CdS Adsorption amounts of MoS42- on CdS and rGO1.5/CdS were determined under the similar condition for the photodeposition of MoS2. In brief, 0.080 g of the as-prepared CdS or rGO1.5/CdS powder was added into 87 mL of 15 vol % TEOA solution whose pH was adjusted to 7, 9, 11 or 12, and then dispersed in an ultrasonic bath for 30 min. Next, 13.0 mL of 1.0 mg·mL-1 (3.8×10-3 mol·L-1) (NH4)2MoS4 was introduced, the mixture was stirred for 2 h at room temperature in the dark, and then centrifuged. After that, the MoS42- concentration of the supernatant was measured on a spectrophotometer at 468 nm. The adsorption amount of MoS42- onto CdS or rGO1.5/CdS was calculated based on the concentration difference (∆C) before and after the mixing. Adsorption amount of MoS42- on rGO was measured by the same processes except using 1.0 mL of rGO suspension (1.2 mg mL-1) instead of its powder. The rGO suspension was obtained by ultrasonically dispersing the mixture of 30 mg rGO and 25 mL distilled water for 30 min. 3. Preparation of MoS2/GO and MoS2/rGO1.5/CdS 2
60 mg of GO and 97 mg of (NH4)2MoS4 were milled in a mortar for 30 min, and then the mixture was pyrolyzed at 350 oC under N2 atmosphere for 2 h to obtain MoS2/GO. For preparation of MoS2/rGO1.5/CdS, 12 mg of the MoS2/GO and 0.738 g of Cd(AC)2.2H2O were added to 80 mL of DMSO, and the other preparation conditions were the same as those for the preparation of rGO1.5/CdS.
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Supplementary Data
Figure S1 UV-vis absorption spectra of CdS and rGOx/CdS.
Figure S 2 IR spectra of rGO1.5/CdS/MoS2-11 and rGO1.5/CdS.
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Figure S3 Selective EDS analysis areas of rGO1.5/CdS/MoS2-7 (A) and rGO1.5/CdS/MoS2-9 (B) and rGO1.5/CdS/MoS2-11 (C).
The EDS analyses show that the Mo contents of the area 1 of the three samples decrease from the sample A to C [0.21(A), 0.13(B) and 0.02 at% (C)] with increasing the deposition pH, while those of the area 2 of the three samples increase [0.00 (A), 0.07(B) and 0.27 at% (C)].
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Figure S4 Effect of rGO content on the photocatalytic hydrogen evolution of rGOx/CdS/MoS2-11. The x values for the sample A, B, C and D are 0.5, 1.0, 1.5 and 2.5 wt%, respectively. Reaction conditions: catalyst, 50 mg; 10 vol % lactic acid solution (100 mL); light source, 350 W xenon lamp with a cutoff filter (λ≥420 nm, light intensity 34 mw·cm-1), 1 h irradiation.
Figure S5 Effect of the depositing time of MoS2 on the photocatalytic hydrogen evolution of rGO1.5/CdS/MoS2-11. Reaction conditions as in Figure S4.
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Tunable Photodeposition of MoS2 onto Composite of Reduced Graphene Oxide and CdS for Synergic Photocatalytic Hydrogen Generation Yuexiang Li,* Hao Wang and Shaoqin Peng Department of Chemistry, Nanchang University, Nanchang 330031, China E-mail: [email protected]
1
Experimental Section 1. Preparation of Graphene Oxide (GO) GO was synthesized by a modified Hummers’ method. In a typical process, graphite powder (5.0 g) and NaNO3 (2.5 g) were added to 115 mL of concentrated H2SO4 in an ice bath, and then gradual addition of KMnO4 (15.0 g) was conducted under stirring. After 4 h stirring at 35 °C, 230 mL of distilled water was added to the mixture, and the resultant mixture was stirred at 98 °C for 15 min. It was further diluted to 700 mL and stirred for 30 min. 12 mL of 35 wt % H2O2 was introduced under stirring to terminate the reaction. GO powders were obtained by centrifugation, rinsing with water and acetone, and drying at 60 °C overnight. 2. Adsorption Amounts of MoS42- on CdS, rGO and rGO1.5/CdS Adsorption amounts of MoS42- on CdS and rGO1.5/CdS were determined under the similar condition for the photodeposition of MoS2. In brief, 0.080 g of the as-prepared CdS or rGO1.5/CdS powder was added into 87 mL of 15 vol % TEOA solution whose pH was adjusted to 7, 9, 11 or 12, and then dispersed in an ultrasonic bath for 30 min. Next, 13.0 mL of 1.0 mg·mL-1 (3.8×10-3 mol·L-1) (NH4)2MoS4 was introduced, the mixture was stirred for 2 h at room temperature in the dark, and then centrifuged. After that, the MoS42- concentration of the supernatant was measured on a spectrophotometer at 468 nm. The adsorption amount of MoS42- onto CdS or rGO1.5/CdS was calculated based on the concentration difference (∆C) before and after the mixing. Adsorption amount of MoS42- on rGO was measured by the same processes except using 1.0 mL of rGO suspension (1.2 mg mL-1) instead of its powder. The rGO suspension was obtained by ultrasonically dispersing the mixture of 30 mg rGO and 25 mL distilled water for 30 min. 3. Preparation of MoS2/GO and MoS2/rGO1.5/CdS 2
60 mg of GO and 97 mg of (NH4)2MoS4 were milled in a mortar for 30 min, and then the mixture was pyrolyzed at 350 oC under N2 atmosphere for 2 h to obtain MoS2/GO. For preparation of MoS2/rGO1.5/CdS, 12 mg of the MoS2/GO and 0.738 g of Cd(AC)2.2H2O were added to 80 mL of DMSO, and the other preparation conditions were the same as those for the preparation of rGO1.5/CdS.
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Supplementary Data
Figure S1 UV-vis absorption spectra of CdS and rGOx/CdS.
Figure S 2 IR spectra of rGO1.5/CdS/MoS2-11 and rGO1.5/CdS.
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Figure S3 Selective EDS analysis areas of rGO1.5/CdS/MoS2-7 (A) and rGO1.5/CdS/MoS2-9 (B) and rGO1.5/CdS/MoS2-11 (C).
The EDS analyses show that the Mo contents of the area 1 of the three samples decrease from the sample A to C [0.21(A), 0.13(B) and 0.02 at% (C)] with increasing the deposition pH, while those of the area 2 of the three samples increase [0.00 (A), 0.07(B) and 0.27 at% (C)].
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Figure S4 Effect of rGO content on the photocatalytic hydrogen evolution of rGOx/CdS/MoS2-11. The x values for the sample A, B, C and D are 0.5, 1.0, 1.5 and 2.5 wt%, respectively. Reaction conditions: catalyst, 50 mg; 10 vol % lactic acid solution (100 mL); light source, 350 W xenon lamp with a cutoff filter (λ≥420 nm, light intensity 34 mw·cm-1), 1 h irradiation.
Figure S5 Effect of the depositing time of MoS2 on the photocatalytic hydrogen evolution of rGO1.5/CdS/MoS2-11. Reaction conditions as in Figure S4.
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