Fig. 1

The schematic illustration of the fabrication processes for the flexible OMC/G/Ni electrode. a) the CVD process for the preparation of graphene wrapped Ni foam (G/Ni); b) the deposition of resol-F127 monomicelles on the surface of G/Ni; c) the carbonization of the monomicelle/G/Ni composite to produce OMC/G/Ni.

Fig. S1.

A) and B) SEM images of G/Ni with different magnifications. C) and D) SEM images of OMC/Ni with different magnifications.

Fig. 2

Morphology and structure characterization of OMC/G/Ni. A-D) SEM images of OMC/G/Ni with different magnifications. E) and F) TEM images of OMC/G composites (after the etching of Ni foam) with different magnifications.

Fig. S2.

SEM images of the OMC layer over the surface of OMC/G/Ni.

Fig. S3.

The N2 adsorption and desorption profile of OMC/G/Ni.

Fig. S4.

A) Raman spectra of OMC/Ni, G/Ni, OMC/G/Ni; B) XRD patterns of OMC/Ni, G/Ni, OMC/G/Ni; C) the magnified XRD patterns of OMC/Ni and OMC/G/Ni from 20 to 34o (2θ).

Fig. 3

A) CV curves of G/Ni, OMC/Ni and OMC/G/Ni in PBS (pH = 7.4, 0.1 mol·L-1) containing DA (100 μmol·L-1) at a scan rate of 50 mV·s-1. B) The plots of capacitive current (Ianodic-Icathodic) versus scan rate.

Fig. S5

Nyquist plots of G/Ni, OMC/Ni, OMC/G/Ni obtained in PBS (0.1 mol·L-1) containing KCl (0.1 mol·L-1) and K3[Fe(CN)6] (5 mmol·L-1) from 105 to 10-1 Hz at an amplitude of 5 mV.

Fig. 4

A) CV curves of the OMC/G/Ni electrode in PBS (0.1 mol·L-1, pH = 7.4) with DA (50 μmol·L-1) at different scan rates: 20, 30, 40, 50, 75, 100, 125, 150, 175 and 200 mV·s-1. B) The fitting lines for the anodic and catholic peak currents versus scan rate.

Fig. 5

A) DPV curves of OMC/G/Ni in PBS (0.1 mol·L-1, pH = 7.4) solution with the DA concentrations in the range of 0 ~ 30 μmol·L-1. B) Magnified DPV curves with the DA concentrations of 0, 0.05, 0.15, 0.3, 0.5, and 1.0 μmol·L-1. C) Calibration plot of the peak current to DA concentration. D) The amperometric (i-t) curve of OMC/G/Ni upon addition of DA at 0.2 V. Inset: Magnified i-t curve upon the addition of DA at 0.05, 0.2 and 0.5 μmol·L-1. E) Calibration plot of i-t current to the DA concentration. F) Amperometric responses of OMC/G/Ni with the successive injections of DA, Glucose, UA, NaCl, AA, DA and DA (All the concentrations of the added analytes are 10 μmol·L-1 in the resulting PBS).

Fig. S6

The high-resolution XPS C 1s spectra of OMC/G/Ni. The peaks at 284.9, 284.4, 286.6, 287.6 and 288.7 eV can be attributed to the C-C, C=C, C-O, C=O, and O=C-O groups in the OMC/G/Ni electrode. The atomic percentages of these groups are 22.8% (C-C), 70.7% (C=C), 4.0% (C-O), 0.5% (C=O) and 2.0% (O-C=O), respectively.

Fig. S7

The CV curves of five independent OMC/G/Ni electrodes (Sample 1-5) in PBS (0.1 mol·L-1) containing DA (50 μmol·L-1).

Fig. 6

Stability tests of the OMC/G/Ni electrode. A) CV profiles for 100 scanning cycles at a scan rate of 50 mV·s-1; B) Current responses every other day in PBS (0.1 mol·L-1, pH = 7.4) with DA (50 μmol·L-1). C) CV curves under different bent states; D) Photograph showing the slightly bent electrode.

Fig. S8

The photos of OMC/G/Ni electrode under A) normal and B) sharply bent states.

Tab. S1

The electrochemical DA detection performances of OMC/G/Ni and the recently reported flexible electrodes

Tab. S2

The sensing performances of the OMC/G/Ni based sensor towards DA in human serum samples (n = 3)