Colloid electrostatic self-assembly synthesis of tin oxide/graphene nanocomposites for supercapacitors

Yankun Wanga,b,Yushan Liua,Jianmin Zhanga,*

a College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, China

b College of Chemistry and Environment, Henan Institute of Education, Zhengzhou 450046, China

*Corresponding author. E-mail:

Experimental section

Synthesis of graphene oxide. Graphene oxide (GO) was synthesized using the following modified Hummer’s method(Hummers Jr and Offeman 1958). Graphite (2 g) was mixed withconcentrated H2SO4(69 mL) and the mixture was stirred for 30 min within an ice bath. KMnO4(8 g) was added very slowly into the dark suspension and the reaction mixture was stirred and sonicated for another 15 min under a reaction temperature of 20 ◦C. Then the ice bath was removed, and the mixture was stirred at 35 ◦C overnight. Distilled water was added to the pasty solution under magnetic stirring and the color of the solution turned to yellowish brown. After another 2 h of vigorous stirring, H2O2(30wt %, 25 mL) was added and the color turned golden yellow immediately. The mixture was washed with HCl (5 %) for several times and then deionized water until the solution became acid free. The reaction mixture was filtered and dried under vacuum at 65 ◦C. The GO was obtained as a gray powder and used for the further experimental.

Synthesis of Sn(OH)4 colloid.Sn(OH)4 colloid solution was prepared using the method reported previously(Li et al. 2015). In a typical process, 2 g SnCl45H2O was dissolve in 200 ml deionized water to form a transparent solution, for the slowly hydrolyzed, the solution gradually transformed into ivory colloid after standing for 9 h under room temperatureand the Sn(OH)4 colloid suspension was obtained.

Fig. S1Construction of the coin capacitor

Fig. S2Zeta potential analyses of GO and Sn(OH)4 colloids

Fig. S3Photographs of GO, Sn(OH)4 colloidsuspension with Tyndall phenomenonand Sn(OH)4/GO precipitation.

Fig. S4TGA results ofrGO and SGNC.

Fig. S5XPS spectra of C 1s of the GO and SGNC.

Fig. S6 (a)N2 adsorption-desorption curves of SnO2;(b) the pore size distributions curveof SnO2.

Fig.S7EDS pattern of SGNC.

Fig. S8Nyquist plots of SGNC electrode before and after 3000th cycle.

References:

Hummers Jr WS, Offeman RE (1958) Preparation of graphitic oxide. J Am Chem Soc 80:1339–1339. doi:10.1021/ja01539a017

Li X, Wei J, Chai Y, Zhang S (2015) Carbon nanotubes/tin oxide nanocomposite-supported Pt catalysts for methanol electro-oxidation. J Colloid Interface Sci 450:74–81. doi:10.1016/j.jcis.2015.02.072

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