Supporting Information

Transcription

1 Supporting Information MoSe2 embedded CNT-Reduced Graphene Oxide (rgo) Composite Microsphere with Superior Sodium Ion Storage and Electrocatalytic Hydrogen Evolution Performances Gi Dae Park, Jung Hyun Kim, Seung-Keun Park, and Yun Chan Kang* Address: Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul , Republic of Korea. *Corresponding author. yckang@korea.ac.kr (Yun Chan Kang, Fax: (+82) ) S-1

2 Figure S1. Schematic diagram of the spray pyrolysis system for MoO x -rgo-cnt, MoO x - rgo, and bare MoO 3 powders. S-2

3 Figure S2. Morphologies of a,b) MoO x -rgo-cnt, c,d) MoO x -rcnt, e,f) MoO x -rgo, and g,h) bare MoO 3 powders prepared by spray pyrolysis process.. S-3

4 Figure S3. XRD patterns of MoO x -rgo-cnt, MoSe 2 -CNT, MoO x -rgo, and bare MoO 3 powders prepared by spray pyrolysis process. S-4

5 Figure S4. HR-TEM images of the MoSe 2 -rgo-cnt composite powders. S-5

6 Figure S5. Morphologies of bare MoSe 2 powders prepared by spray pyrolysis process and subsequent one-step post-treatment. S-6

7 Figure S6. Morphologies of bare MoSe 2 powders prepared by spray pyrolysis process and subsequent one-step post-treatment. S-7

8 Figure S7. TG curves of MoSe 2 -rgo-cnt, MoSe 2 -rgo, and MoSe 2 -CNT powders prepared by spray pyrolysis process and subsequent one-step post-treatment. S-8

9 Figure S8. N 2 gas adsorption and desorption isotherms of MoSe 2 -rgo-cnt, MoSe 2 -rgo, and bare MoSe 2 powders prepared by spray pyrolysis process and subsequent one-step posttreatment. S-9

10 Figure S9. CV curves of a) MoSe 2 -rgo, b) MoSe 2 -CNT, c) bare MoSe 2, and d) rgo-cnt, powders prepared by spray pyrolysis process and subsequent one-step post-treatment. S-10

11 Figure S10. Morphologies of MoSe2-rGO-CNT, MoSe2-rGO, and bare MoSe2 powders observed after 200 cycles at a current density of 0.3 A g-1 by SIB measurements: a,b) MoSe2rGO-CNT, c,d) MoSe2-rGO, and e,f) bare MoSe2. S-11

12 Figure S11. Morphologies of MoSe2-rGO-CNT powders observed after 1000 cycles from 0.0 to 0.3 V (vs. RHE) at a scan rate of 0.1 V s 1 by HER measurements. S-12

13 Figure S12. Time-dependent current density curve (i-t curve) under a constant overpotential of 260 mv vs. RHE. S-13

14 Table S1. Electrocatalytic performances of various nanostructured MoSe 2 materials in hydrogen evolution reaction reported in the previous literatures. Current density Preparation Tafel slope Morphology Electrolyte (ma cm -2 ) Ref. method (mv dec -1 ) *η = overpotential MoSe 2 porous microsphere Colloidal route 0.5 M H 2 SO (at η = 77 mv). S1 Carbon fiber aerogel supported fewlayered MoSe 2 Solvothermal method 0.5 M H 2 SO (at η = 104 mv). S2 nanosheets MoSe 2 /graphene nanosheets CVD 0.5 M H 2 SO (at η = 159 mv). S3 Ultrathin MoSe 2 nanosheets decorated on carbon fiber cloth Solvothermal method 0.5 M H 2 SO (at η = 182 mv). S4 CNT@MoSe 2 hybrid Solvothermal method 0.5 M H 2 SO (at η = 178 mv). S5 MoSe 2 /graphene Wet chemistry method 0.5 M H 2 SO (at η = 195 mv). S6 MoSe 2 nanofilm CVD 0.5 M H 2 SO (at η = 250 mv). S7 MoSe 2 x (x 0.47) nanosheets Colloidal synthesis 0.5 M H 2 SO (at η = 280 mv). S8 MoSe 2 embedded CNT-reduced graphene oxide Spray pyrolysis 0.5 M H 2 SO (at η = 234 mv). This work composite S-14

15 The contribution of rgo-cnt to the capacities of the MoSe 2 -rgo-cnt composite powders for sodium-ion storage was investigated. The rgo-cnt composite powders were prepared by selectively etching the MoO x by diluted hydrogen peroxide in the MoO x -rgo-cnt composite powders prepared by spray pyrolysis process. The rgo-cnt composite powders had similar morphology to that of the MoSe 2 -rgo-cnt composite powders as shown in Figures S13 and 1b. The initial discharge/charge curves and cycling performances of the two samples at a current density of 0.3 A g -1 are shown in Figure S13c and d, respectively. The initial discharge and charge capacities of the rgo-cnt composite powders were 677 and 265 ma h g -1, respectively, and their stabilized reversible discharge capacity measured at the 100 th cycle was 182 ma h g -1. The discharge capacity of the MoSe 2 -rgo-cnt composite powders for the 100 th cycle was 398 ma h g -1. Therefore, the contribution of rgo-cnt composite in the discharge capacity of the MoSe 2 -rgo-cnt composite powders was 13.4 %. Figure S13. (a, b) Morphologies of the rgo-cnt composite powders obtained by selectively etching the MoO x by diluted hydrogen peroxide in the MoO x -rgo-cnt composite powders and (c) initial discharge and charge curves and (d) cycling performances of the MoSe 2 -rgo- CNT and rgo-cnt composite powders. S-15

16 The gravimetric and areal capacities of the MoSe 2 -rgo-cnt composite at the active materials mass loadings of 1.4, 2.9, 6.2 and 9.6 mg cm -2 are shown in Figure S14. The electrode was prepared from a mixture containing 70 wt % of the active material, 20 wt % of Super P, and 10 wt % of sodium carboxymethyl cellulose binder. The initial areal discharge capacities of the MoSe 2 -rgo-cnt composite at the loading amounts of 1.4, 2.9, 6.2 and 9.6 mg cm -2 were 0.70, 1.28, 2.69 and 4.07 ma h cm -2, respectively, and their initial areal charge capacities were 0.53, 0.91, 1.94 and 2.93 ma h cm -2. After 50 cycles, the MoSe 2 -rgo-cnt composite at the loading amounts of 1.4, 2.9, 6.2 and 9.6 mg cm -2 delivered areal discharge capacities of 0.52, 1.01, 2.00 and 2.85 ma h cm -2, respectively. The MoSe 2 -rgo-cnt composite shows excellent areal capacities compared to those of the 2D-nanostructured materials as shown in Table S2. Figure. S14. (a) Gravimetric and (b) areal capacities of the MoSe 2 -rgo-cnt composite at the different active materials mass loadings on the electrode. S-16

17 Table S2. Areal capacity of various 2D-nanostructured materials in sodium ion batteries reported in the previous literatures. Morphology Porous hollow carbon spheres decorated with MoSe 2 nanosheets Preparation method Stőber reaction conditions Mass loding 1.0 mg cm -2 Reversible capacity / Current density Ref ma h cm S9 0.2 ma cm -2 Ultrathin MoSe 2 nanosheets anchored on MWCNT Hydrothermal 1.0 mg cm ma h cm S ma cm -2 Fullerene-like MoSe 2 nanoparticles-embedded CNT balls Spray pyrolysis 1.2 mg cm ma h cm S ma cm -2 Coaxial-cable MoSe 2 /C Hydrothermal 1.2 mg cm ma h cm S ma cm -2 Exfoliated MoS 2 Nanosheets Liquid phase exfoliation (LPE) technique mg cm ma h cm S ma cm -2 SnS Solvothermal 2.3 mg cm ma h cm S ma cm -2 SnO Heterostructure Hydrothermal 1.2 mg cm ma h cm S ma cm -2 MoSe 2 embedded CNTreduced graphene oxide composite Spray pyrolysis 9.6 mg cm ma h cm ma cm -2 This work S-17

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