Table 1. Elemental analysis, electrical conductivity and zeta potential of VC, GO, rGO and S-rGO.

Sample	C (wt.%)	O (wt.%)	H (wt.%)	N (wt.%)	S (wt.%)	σ (S·cm−1)	ζ(mV)
VC	98.50	1.24	<0.10	<0.10	<0.10	2.1	−24.8
GO	52.65	43.17	4.08	<0.10	<0.10	2.4 × 10−4	−27.6
rGO	85.74	13.06	1.20	<0.10	<0.10	5.2	−10.4
S-rGO	74.63	15.42	2.52	2.26	5.17	4.3	−64.2