All chemicals in this work were of analytical grade and used as
received. In a typical experiment, 10 mmol sodium stannate
(Na2SnO3) was dissolved in 50 ml of 1 M glucose aqueous solutions.
The clear solution was obtained through ultrasonic dispersion for
1 h before being transferred to a Telflon-lined stainless steel
autoclave heated at 180 C for 4 h. The precipitates were harvested
by centrifugation and washed thoroughly with deionized water
and ethanol several times, respectively. After drying at 80 C
overnight, SnO2 powders and SnO2@C powders were obtained at
550 C for 4 h with a heating rate of 2 C min1 under air and argon
atmosphere, respectively. SnO2@C/Cu sample was synthesized as
follows. 250 mg SnO2@C powders were dissolved in 100 ml 8 mM
CuSO4 aqueous solution through ultrasonic dispersion for 1 h.
Afterward, 5 ml hydrazine hydrate (N2H4H2O) was dripped into
the solution slowly. SnO2@C/Cu powders were harvested after
centrifugation and dried at 80 C under vacuum.