Electrochemical Sensing Platform Based on the Biomass-Derived

Microporous Carbons for Simultaneous Determination of Ascorbic

acid, Dopamine, and Uric acid

Wenjing Zhang a, §, Liu Liu a, §, Yangguang Li a , Dongyang Wang a, Heng Ma a, Hailong Ren a, Yulin

Shi a , Yajie Han a,*, Bang-Ce Ye a, b*

a Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and

Chemical Engineering, Shihezi University, Shihezi, 832003, China.b State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai,

200237, China.

§The authors contributed equally to this work.

*Corresponding authors

Yajie Han

E-mail: yaji1978@126.com

Bang-Ce Ye

E-mail: bcye@ecust.edu.cn

Figure S1. XPS survey spectra of ZnCl2-CF: (A) high-resolution C1s; (B) high-resolution N1s; (C) high-resolution O1s.

Table S1. Peak energy of XPS survey spectra.

Name Peak BE FWHM (eV) Area (P) CPS. eV Atomic (%) QC1s 284.71 1.34 194735.96 47.74 1O1s 532.78 2.57 31083.35 3.16 1C1s 284.71 1.33 185168.65 45.4 1N1s 400.63 2.04 6152.68 0.97 1O1s 532.75 2.67 26914.05 2.73 1

The high resolution fitted C 1s XPS spectrum of ZnCl2-CF can be deconvoluted into carbon peaks with different chemical environments (Fig. S1A). The peak located at 284.6, 285.0, 286, 288.4 eV is attributed to C=C, C−C, C−OH and HO−C=O groups, respectively (Fan et al. 2012; Gao et al. 2018). The deconvoluted N 1s show three different peaks revealing the presence of pyridinic N1 (398.2), pyrrolic N2 (399.9), graphitic N3 (401.2 eV) (Liu et al. 2013). Furthermore, the corresponding O1s peak (Fig. S1C) at 534 eV reveals oxygen with the assignment of C-OH (532.2 eV) and C-O-C (533.3 eV) (Chen et al. 2017; Li et al. 2015).

Figure S2. (A) DPVs of AA (100 µM), DA (500 µM) and UA (500 µM) at ZnCl 2-CF/GCE from PBS with different pH values range of 4.0–9.0; (B) Plots of the oxidation peak potentials for AA, DA and UA as function of solution pH; (C) Effects of solution pH values on peak currents of AA, DA and UA at ZnCl2-CF/GCE; (D) CVs of the ZnCl2-CF/GCE in 1.0 mM [Fe(CN)6]3−/4− + 0.1 M KCl solution at different scan rates of 10, 20, 40, 60, 80, 100, 120, 140, 160,180 and 200 mV s−1. The inset is the plots of peak current versus the square root of scan rate.

Figure S3. (A) The influence for AA (100 µM), DA (500 µM) and UA (500 µM) from following compounds (0.5 M): glycine, glutamic acid, glucose, lysine, K+; SO4

2−, Cl−, NO3−. (B) The reproducibility investigation of 10 successive experiments for determination of AA (100 µM), DA (500 µM), and UA (500 µM).

Table S2. The cyclic voltammetry (CV) data of different electrodes in 0.1 M PBS (pH 7.0) with AA, DA, and UA concentrations of 200 μM.

Analytes Bare GCE ZnCl2-CF/GCE

E / (mV) ΔEp I / (μA) E / (mV) ΔEp I / (μA)

AA -276419117

8.654 -264421119

26.760

DA 143 24.540 157 67.230

UA 260 23.180 276 57.790

Table S3. The differential pulse voltammetry (DPV) data of different electrodes in 0.1 M PBS (pH 7.0) with AA, DA, and UA concentrations of 200 μM.

Analytes Bare GCE ZnCl2-CF/GCE

E / (mV) ΔEp I / (μA) E / (mV) ΔEp I / (μA)

AA -36160128

33.810 -296424136

67.400

DA 124 59.920 128 98.700

UA 252 54.130 264 102.600

Table S4. The integral fitting data of “Origin Software”.

Analytes Bare GCE ZnCl2-CF/GCE

RSArea dx Area dx

AA 0.556 0.144 3.169 0.289 1.201DA 2.050 0.157 5.400 0.187 0.023

UA 1.317 0.126 4.615 0.153 0.086

RS=2 ( t2−t1 )(ω2+ω1 )

According to the formula in reference (Dvořák et al. 2015) and assisted by the "Origin software", the calculated data is listed in Table S4. the peak resolutions of AA, DA, and UA to be 1.201, 0.023, and 0.086, respectively. This effectively distinguishes the response currents of the three substances, reducing the inaccuracy caused by mutual interference. In order to study the electrochemical sensing characteristics of different electrodes, we used CV and DPV to verify separately. Comparison between Table 1 and Table 2 shows that the ZnCl2-CF modified electrode has a much larger current response than the bare electrode when detected by the two methods, but the peak current of the DPV increases more significantly and the peak potential difference is greater. Reports suggest higher sensitivity of the method and better resolution than when using CV (Yuan et al. 2012). Therefore, we use differential pulse voltammetry (DPV) for subsequent experiments.

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