Influence of pH and annealing on the optical and electrochemical properties of cobalt (III) oxide (Co3O4) thin films

Obodo, Raphael M.; Nwanya, Assumpta C.; Ekwealor, A. B. C.; Ahmad, Ishaq; Zhao, Ting; Osuji, R. U.; Mâaza, M.; Ezema, Fabian I.

doi:10.1016/j.surfin.2019.05.006

Cited by 62 publications

(17 citation statements)

References 31 publications

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“…However, for 2:1/GO nanocomposite, it was observed that absorbance increased rapidly before the visible region to 0.20 to the visible region and remain steady throughout the changes in the electromagnetic spectrum. The DRS‐visible spectra plotted results indicate that oxygen‐based functional groups in GO are small while electronic conjugation between graphene and metal oxides were dominant, hence GO absorption peak not obvious …”

Section: Resultsmentioning

confidence: 95%

“…The DRS-visible spectra plotted results indicate that oxygen-based functional groups in GO are small while electronic conjugation between graphene and metal oxides were dominant, hence GO absorption peak not obvious. 32 Figure 5B shows the studies of optical band gap energies of NiO-ZnO/GO nanocomposites. We used the relationship between photon energy (hѵ) and optical absorption coefficient (α) for the direct allowed transition to obtain a graph in which the linear part was extrapolated to produce the energy band gap.…”

Section: Resultsmentioning

confidence: 99%

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Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

et al. 2020

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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 morphology and elemental composition were studied using a scanning electron microscopy and energy‐dispersive X‐ray spectroscopy, respectively. The electrochemical properties were examined using cyclic voltammetry in a 1.0 M solution of Na2SO4 electrolyte with a three‐electrode system. Moreover, the NiO‐ZnO/GO binary metal oxides nanocomposite based electrodes fabricated for supercapacitor delivered a high specific capacitance of 1690 F g−1 for 1:1/GO sample at a scan rate of 10 mV s−1 and has excellent conductivity due to reduced band gap energy range of 1.52‐1.79 eV and with electrodes resistance of 0.02 Ω. The absence of semicircle in the Nyquist plot denotes low charge transfer resistance of the electrodes. The highest energy densities obtained for 1:1/GO and 2:1/GO are 192 and 148 Wh kg−1, respectively, while the highest power density obtained for 1:1/GO and 2:1/GO are 8.46 and 7.42 W kg−1, respectively. Our study paves way for a facile, affordable, nontoxic, and fast way to synthesis binary transition metal oxides/GO‐based electrodes material for high‐performance supercapacitor.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

et al. 2020

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“…The band gap energy plots of MnO 2 –NiO–ZnO@GO thin films were estimated from the vis‐DRS reflectance measurements using Equation ) 35 presented in Figure 5B.

italicαhv = k {(hv - E_{g})}^{n},

where the optical band gap energy is ( E g ), photon energy is hѵ , k is constant while n = 0.5. Our plots of ( αhν ) 2 verse ( hν ) presented in Figure 4B presented a direct graph, which suggests that MnO 2 –NiO–ZnO@GO thin films exercised direct allowed band gap energy.…”

Section: Resultsmentioning

confidence: 99%

Transformation of GO to rGO due to 8.0 MeV carbon (C++) ions irradiation and characteristics performance on MnO ₂ –NiO–ZnO @ GO electrode

et al. 2020

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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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“…Nucleation is an important stage in the formation of nanoparticles, and pH as an effective factor contributes to the creation of primary nuclei. Therefore, based on previous study, in which the effect of pH on the synthesis of Co 3 O 4 nanoparticles was investigated, in this study, pH of 10 was selected as optimal pH. At the same time, due to the formation of Co (OH) 3 , the solutions turned blue.…”

Section: Methodsmentioning

confidence: 99%

Microwave‐associate synthesis of Co₃O₄ nanoparticles as an effcient nanocatalyst for the synthesis of arylidene barbituric and Meldrum's acid derivatives in green media

Yahyazadehfar

Sheikhhosseini

Ahmadi

et al. 2019

Applied Organom Chemis

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In this study, Co3O4 nanocatalysts were constructed in environmentally appropriate conditions using controlled, effective, and facile microwave method. The final nanostructures were characterized by SEM, XRD, and TEM analyses. The products had a small size distribution, homogeneous morphology, and crystallographic structures associated with the formation of Co3O4 nanostructures. Moreover, EDS mapping analysis confirmed the existence of Co and O elements in the final structure, and the magnetic properties of the samples were investigated by VSM. The application of this nanostructure in a catalytic process was further examined, and the results suggested that it could be used as a novel candidate for the synthesis of arylidene barbituric and Meldrum,s acid through Knoevenagel condensation of aldehydes by barbituric and Meldrum,s acid in aqueous media. The high yield of these nanocatalysts would be justified by the nature of the nanostructure as well as the experimental procedure developed in this study, which affected the physicochemical features of the products.

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Influence of pH and annealing on the optical and electrochemical properties of cobalt (III) oxide (Co3O4) thin films

Cited by 62 publications

References 31 publications

Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

Transformation of GO to rGO due to 8.0 MeV carbon (C++) ions irradiation and characteristics performance on MnO ₂ –NiO–ZnO @ GO electrode

Microwave‐associate synthesis of Co₃O₄ nanoparticles as an effcient nanocatalyst for the synthesis of arylidene barbituric and Meldrum's acid derivatives in green media

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Influence of pH and annealing on the optical and electrochemical properties of cobalt (III) oxide (Co3O4) thin films

Cited by 62 publications

References 31 publications

Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

Conjugated NiO‐ZnO/GO nanocomposite powder for applications in supercapacitor electrodes material

Transformation of GO to rGO due to 8.0 MeV carbon (C++) ions irradiation and characteristics performance on MnO 2 –NiO–ZnO @ GO electrode

Microwave‐associate synthesis of Co3O4 nanoparticles as an effcient nanocatalyst for the synthesis of arylidene barbituric and Meldrum's acid derivatives in green media

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Transformation of GO to rGO due to 8.0 MeV carbon (C++) ions irradiation and characteristics performance on MnO ₂ –NiO–ZnO @ GO electrode

Microwave‐associate synthesis of Co₃O₄ nanoparticles as an effcient nanocatalyst for the synthesis of arylidene barbituric and Meldrum's acid derivatives in green media