Abstract:Summary
The nanocomposite of NiO‐ZnO/graphene oxide (GO) was synthesized for applications in supercapacitor electrodes material. GO was produced using the modified Hummers' method, and the nanocomposite of NiO‐ZnO/GO was synthesized using the co‐precipitation method. Thin films of nanocomposite powder were deposited on quartzite (glass) and fluorine‐doped tin oxide substrates by a drop casting technique. X‐ray diffraction revealed the crystallographic information of NiO‐ZnO/GO nanocomposites. The surface morph… Show more
“…However, band gap can be tuned by combining different constituent transition metal oxides and addition of carbon derivatives, this suits nanocomposite for numerous applications like supercapacitors, photovoltaics, fuel cells, thermoelectric, photo catalysis etc. [30]…”
Hydrothermally synthesized electrodes of Co 3 O 4 @GO, MnO 2 @GO and Co 3 O 4 /MnO 2 @GO were produced for usages in supercapacitors. Graphene oxide (GO) was incorporated in the nanocomposites used for electrodes synthesis due to its great surface area and electrical conductivity. The synergistic alliance among these composites and GO enhance electrodes performance, life span and stability. The structural properties as obtained from the X-ray diffraction (XRD) results suggest that nanocomposites are crystalline in nature. The morphological studies indicated that the nanocomposites have platelet nanoparticles with some agglomerations. The energy bandgaps estimated for the Co 3 O 4 @GO, MnO 2 @GO and Co 3 O 4 /MnO 2 @GO are 2.38 eV, 2.05 eV and 2.33 eV respectively The electrochemical studies provided highest specific capacitance from CV using 10 mV/s scan rates and GCD using 1.0 A/g current density were 765, 1215, 1518 and 975, 1358, 1718 F/g for Co 3 O 4 @GO, MnO 2 @GO and Co 3 O 4 /MnO 2 @GO respectively. These results obviously indicate that composites perform better than single transition metal oxide and the addition of graphene oxide enhanced electrodes performance.
“…However, band gap can be tuned by combining different constituent transition metal oxides and addition of carbon derivatives, this suits nanocomposite for numerous applications like supercapacitors, photovoltaics, fuel cells, thermoelectric, photo catalysis etc. [30]…”
Hydrothermally synthesized electrodes of Co 3 O 4 @GO, MnO 2 @GO and Co 3 O 4 /MnO 2 @GO were produced for usages in supercapacitors. Graphene oxide (GO) was incorporated in the nanocomposites used for electrodes synthesis due to its great surface area and electrical conductivity. The synergistic alliance among these composites and GO enhance electrodes performance, life span and stability. The structural properties as obtained from the X-ray diffraction (XRD) results suggest that nanocomposites are crystalline in nature. The morphological studies indicated that the nanocomposites have platelet nanoparticles with some agglomerations. The energy bandgaps estimated for the Co 3 O 4 @GO, MnO 2 @GO and Co 3 O 4 /MnO 2 @GO are 2.38 eV, 2.05 eV and 2.33 eV respectively The electrochemical studies provided highest specific capacitance from CV using 10 mV/s scan rates and GCD using 1.0 A/g current density were 765, 1215, 1518 and 975, 1358, 1718 F/g for Co 3 O 4 @GO, MnO 2 @GO and Co 3 O 4 /MnO 2 @GO respectively. These results obviously indicate that composites perform better than single transition metal oxide and the addition of graphene oxide enhanced electrodes performance.
“…This spectacle behaviour may be credited to recrystallization that took place after receiving energy from the first radiation and increased temperature [2]. Equation 7 and 8 were employed to evaluate the energy (E d ) and power (P d ) densities respectively [36].…”
Section: Resultsmentioning
confidence: 99%
“…There is a voltage drop observed in the GCD plots, especially for a current density of 2.0 A/g, this occurs as a result of losses due to resistance offered by the supercapacitor. It normally possesses significant value after numerous charge and discharge cycles sometimes referred to ageing phenomena [36,37]. Results obtained from the cycling test disclose higher cycling stability, with 83.02 % capacitance retention after 5000 cycles.…”
Section: Study Of Co 3 O 4 à Cuoà Zno/go Electrodes Electrochemical Pmentioning
Combination of transition metal oxides and carbon derivatives have received a lot of interest in last two decades for electrochemical energy storage due to their small size and high specific surface area. The effects of carbon ion irradiation on the properties of the electrodes were examined. The structural properties as obtained from the X-ray diffraction (XRD) results suggest that irradiation of the nanocomposite enhances the crystallinity of the materials up to the optimal dose of 5.0 × 10 15 ions/cm 2. Beyond this dose, there was a reduction in the crystallinity occasioned by distortion and defects in the structure of the material. The morphological studies indicated that the nanocomposites have spherical nanoparticles with some agglomerations. The agglomerations as well the particle sizes reduced with increase in the radiation dosages. The energy bandgaps estimated for the Co 3 O 4 À CuOÀ ZnO@GO reduced as energy dosages increases. The highest specific capacitance obtained from cyclic voltammetry (CV) plots at 10 mV/s scan rate and galvanostatic charge-discharge (GCD) were 1950 and 2045 F/g at a radiation dose of 5.0 × 10 15 ions/cm 2. Results indicate that carbon ion irradiations, especially low doses enhance the characteristics performance of these electrodes while high doses induce deficiencies and disorder to the Co 3 O 4 À CuOÀ ZnO@GO electrodes. These results also indicate that radiation is a useful tool to enhance or damage properties of nanomaterials especially with low energy doses.
“…Similarly, for a current density of 2.0 A/g, specific capacitance obtained are 1945, 1520, 1308, 828 and 315 F/g for pristine, illuminated with 2.25 × 10 15 , 5.0 × 10 15 , 7.5 × 10 15 and 1.0 × 10 16 ions/cm 2 respectively. Equations ) and () were employed to evaluate the energy ( E d ) and power ( P d ) densities, respectively 44 …”
Summary
The effect of 8.0 MeV carbon ions (C++) radiations on features and performances of MnO2–NiO–ZnO@GO electrodes (thin films). MnO2–NiO–ZnO@GO thin films were produced using the hydrothermal technique. 8.0 MeV carbon ions (C++) with doses of 2.25 × 1015, 5.0 × 1015, 7.5 × 1015 and 1.0 × 1016 ions/cm2 were irradiated on MnO2–NiO–ZnO@GO thin films. The XRD spectra indicate crystalline nature of the films while SEM images show rod‐like structures. The XRD calculated crystallite sizes varied from 1.24 to 5.58 nm. Energy‐dispersive X‐ray spectroscopy, Proton induced X‐ray emission (PIXE) and Rutherford back scattering (RBS) analysis are used to evaluate the elemental compositions of samples. Optical studies show reduced bandgap energies of various oxides due to the addition of graphene oxide. The electrochemical studies obtained a specific capacitance of 1627 and 1960 F/g for electrodes illuminated with radiation doses of 5.0 × 1015 and 7.5 × 1015 ions/cm2, respectively. Results indicate that carbon ion irradiation with low doses improved the performances of the nanostructured thin films while radiation with high doses induces adverse disorder and flaw to the MnO2–NiO–ZnO@GO thin film properties. These results show that ion beam irradiation is a useful tool to enhance or damage the properties of nanostructured materials depending on the dosages radiation beamed on the material.
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