Impact of thermally reducing temperature on graphene oxide thin films and microsupercapacitor performance

Maphiri, Vusani M.; Bakhoum, Daba T.; Sarr, Samba; Sylla, Ndeye Fatou; Rutavi, Gift; Manyala, Ncholu I.

Impact of thermally reducing temperature on graphene oxide thin films and microsupercapacitor performance

Maphiri, Vusani M.; Bakhoum, Daba T.; Sarr, Samba; Sylla, Ndeye Fatou; Rutavi, Gift; Manyala, Ncholu I.

Date: 2022-06-28

Abstract:

In this work, a thermally reduced graphene oxide (TRGO) thin film on microscopic glass was prepared using spray coating and atmospheric pressure chemical vapour deposition. The structure of TRGO was analysed using X-ray diffraction (XRD) spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, and ultraviolet–visible spectroscopy (UV-Vis) suggesting a decrease in oxygen functional groups (OFGs), leading to the restacking, change in colour, and transparency of the graphene sheets. Raman spectrum deconvolution detailed the film’s parameters, such as the crystallite size, degree of defect, degree of amorphousness, and type of defect. The electrochemical performance of the microsupercapacitor ( -SC) showed a rectangular cyclic voltammetry shape, which was maintained at a high scan rate, revealing phenomenal electric double-layer capacitor (EDLC) behaviour. The power law and Trasatti’s analysis indicated that low-temperature TRGO -SC is dominated by diffusion-controlled behaviour, while higher temperature TRGO -SC is dominated by surface-controlled behaviour.

Description:

SUPPLEMENTARY MATERIALS : FIGURE S1: The digital images showing the appearance (colour) of the prepared thin film on MSG, FIGURE S2: The XRD patterns of (a) GO and (b)–(f) TRGO-100 to TRGO-500, plotted together with the diffraction pattern of the microscopic glass under the same conditions, TABLE S1: Sample ID, interplanar distance and carbon content, FIGURE S3: (a) Interspace distance and (b) C/O ratio as a function for graphite, GO and TRGO-100, TRGO-200, TRGO-300, TRGO-400 and TRGO-500, FIGURE S4: SEM images of (a) graphite, (b) GO, (c) TRGO-300 and (d) TRGO-500, FIGURE S5: The AFM micrograph of (a) GO and (b)–(f) TRGO-100 to TRGO-500; and (g) corresponding height colour scale, FIGURE S6: The FTIR of graphite, MSG, GO and TRGO samples, TABLE S2: Roughness parameter of the prepared GO/TRGO thin film, FIGURE S7: (a) Absorbance and (b) transmittance of microscope glass, FIGURE S8: Raman spectra of graphite, GO and TRGO-100–TRGO-500, FIGURE S9: Digital image of -SC, TABLE S3: Dimensions and parameters of -SC, FIGURE S10: (a)–(d) CV curves of TRGO 200–TRGO 500, TABLE S4: The areal capacitance determined from the CV curve, FIGURE S11: log I versus log v curves for the anodic and cathodic currents at (a) TRGO-200, (b) TRGO-300, (c) TRGO-400 and (d) TRGO-500 reducing temperatures, respectively, FIGURE S12: Trasatti’s method for the TRGO micro-supercapacitors: (a,c,e,g) inverse capacitance as a function of square root of scan rate and (b,d,f,h) capacitance as a function of inverse square root of scan rate, TABLE S5: Sample ID, maximum total capacitance, maximum EDL capacitance and maximum pseudocapacitance, FIGURE S13: (a)–(d) GCD curves of TRGO 200–TRGO 500, TABLE S6: The areal capacitance determined from the GCD curve, FIGURE S14: (a) Area capacitance as a function of reducing temperature at various current densities, (b)–(e) the capacitance retention and capacitance columbic efficiency of the TRGO sample and (f) EIS Nyquist plot at high frequency region, TABLE S7: Sample ID, resistance electrolyte plus charge transfer resistance (Re + Rct), Warburg coefficient (sw) and ion diffusion coefficient (D), FIGURE S15: The frequency dependence of the Re C and Im C for (a)–(b) TRGO-200 to TRGO-500 and FIGURE S16: The relationship between Re Z and w0.5 at low frequencies for TRGO samples [60].

DATA AVAILABILITY STATEMENT : Data is contained within the article or supplementary material.

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