Fig. 1

(A) FTIR spectra of GO (a)、RGO (b)、SiW11Ni (c) and SiW11Ni-RGO (d); (B) XRD pattern of SiW11Ni

Fig. 2

SEM images of RGO (A), SiW11Ni (B) and SiW11Ni-RGO (C)

Fig. 3

Cyclic voltammetric (CV) curves (Scan rate, 0.1 V·s-1) of bare GCE, RGO/GCE, SiW11Ni/GCE and SiW11Ni-RGO/GCE in 0.1 mol·L-1 KCl solution containing 5 mmol·L-1 K3[Fe(CN)6]

Fig. 4

Nyquist plots (Amplitude, ±5 mV; Frequency, from 0.1 Hz to 10 kHz) of different modified electrodes in 0.1 mol·L-1 KCl solution containing 5 mmol·L-1 [Fe(CN)6]3-/4-

Fig. 5

CV curves of different modified electrodes for 40 μmol·L-1 DA at 0.1 V·s-1 scan rate in 0.1 mol·L-1 PBS (pH = 7.5)

Fig. 6

CV curves of SiW11Ni-RGO/GCE for different concentrations of DA (0, 20, 35, 80 μmol·L-1) in 0.1 mol·L-1 PBS (pH = 7.5)

Fig. 7

Effects of (A) molar ratio in RGO:SiW11Ni and (B) the load of SiW11Ni-RGO on peak currents for redox reaction of DA

Fig. 8

(A) CV curves of SiW11Ni-RGO/GCE for 30 μmol·L-1 DA at 0.1 V·s-1 scan rate in pH of 8.0 to 6.0; (B) Effect of solution pH on peak currents for redox reaction of DA

Fig. 9

(A) CV curves of SiW11Ni-RGO/GCE for 40 μmol·L-1 DA in 0.1 mol·L-1 PBS (pH = 7.5) at different scan rates: from 0.05 to 1 V·s-1; (B) the calibration plots of redox peak current versus scan rate

Fig. 10

(A) CV curves of SiW11Ni-RGO/GCE for different concentrations of DA (10 ~ 80 μmol·L-1) in 0.1 mol·L-1 PBS (pH = 7.5); (B) the calibration plots of redox peak current versus DA concentration

Tab. 1

Comparison of DA detection with different electrochemical sensors

Fig. 11

Effect of substances that often coexist with equal amounts of DA on detection of DA by SiW11Ni-RGO/GCE

Fig. 12

Stability performance of the modified electrode (SiW11Ni-RGO/GCE) within 15 days