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Supporting Information
High Performance Asymmetric Supercapacitors:New NiOOH
Nanosheet/Graphene Hydrogels and Pure Graphene Hydrogels
School of Chemical and Biomedical Engineering, Nanyang Technological University,
Singapore 637459, Singapore
Figure S1. A digital photograph of hydrogels obtained in various solvents with
different DMF/H2O ratio.
Figure S2. XRD patterns of the pure NiOOH prepared in D6-H1 solvent via a similar
procedure as NiOOH/GS hydrogels except no GO was added.
Figure S3. TEM images of Ni/GS hydrogels (a, b) and Ni(OH)2/GS hydrogels (c, d)
produced by single solvothermal and hydrothermal reactions, respectively.
Figure S4. SEM images of pure NiOOH.
Figure S5. (a, b) The plots of v1/2 vs. i(V)/v1/2 used for calculating k1 and k2 at different
potentials.
According to power law relationship, i= aν for non-diffusion limited processes and
i= aν1/2 for diffusion limited processes. Thus, total current i (V) = k1ν+ k2ν1/2 and i (V)/
ν1/2 = k1ν1/2 + k2.[1-3] Current values at different potentials were calculated from cyclic
voltammogram at different scan rates of 1 to 10 mV s-1. Plots of i/ν1/2 vs. ν1/2 have been
drawn at different potentials and from the straight line obtained value of k1 (slope) and
k2 (intercept) are calculated.
Figure S6. Charge-discharge curves of T-NiOOH/GS.
Figure S7. (a) Nitrogen adsorption and desorption isotherms and (b) BJH pore size
distribution of freeze-dried GS hydrogels.
Figure S8. (a) The survey XPS spectra, (b) C1s spectra and (c) N1s spectra of freeze-
dried GS hydrogels.
Figure S9. (a) The charge-discharge curves and (b) the corresponding specific
capacitance of graphene hydrogels (H-GS) in a two-electrode system.
Figure S10. CV curves of H-NiOOH/GS and H-GS at 20 mV s-1.
References:
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[2] M. Sathiya, A.S. Prakash, K. Ramesha, J.M. Tarascon, A.K. Shukla, J. Am. Chem. Soc. 133 (2011)
16291-16299.
[3] V. Augustyn, J. Come, M.A. Lowe, J.W. Kim, P.-L. Taberna, S.H. Tolbert, H.D. Abruña, P. Simon,
B. Dunn, Nat Mater. 12 (2013) 518-522.