Carboxylated graphene oxide–Mn2O3 nanorod composites for their electrochemical characteristics

Abstract

Carboxylated-graphene-Mn 2 O 3 (G-COOMn) nanocomposites were grown as Mn 2 O 3 nanowires on graphene sheets by a one-step thermal method using graphene oxide-COOH (G-COOH) and Mn(NO 3 ) 2 .Graphene oxide (G) was prepared by the Hummers method by using graphite flakes as a starting material. G-COOH sheets were synthesized using G and chloroacetic acid (Cl-CH 2 -COOH). G, G-COOH, and G-COOMn were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, 13 C-nuclear magnetic resonance, and Raman spectroscopy. The electrochemical properties of the fabricated G-COOMn supercapacitor were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests. The obtained results showed that the asymmetric supercapacitor had electrochemical capacitance performance within the potential range 0-0.7 V. The supercapacitor delivered a specific capacitance of $300 F g À1 at a current density of 50 mA cm À2 . The method used in this work provides an easy and straightforward approach for depositing Mn 2 O 3 nanowires on graphene sheets and may be readily extended to the preparation of other classes of hybrids based on G sheets for use in specific technological applications.

Electrochemical Supercapacitors from Diamond

“…SEM images of MnO 2 films coated on diamond with a deposited masses of (a, d) 2.0, (b, e) 24 and (c, f) 26 µg cm -2 at (a, b, c) low and (d, e, f) high magnifications.Manganese is known to possess several oxidation states that show correspondingly different redox activity, and hence different capacitance [50][51][52]. The oxidation states can be estimated from the splitting widths of the Mn 3s and Mn 2p peaks, as well as the binding energy (BE) of the Mn 2p 3/2 peak in the XPS spectra of MnO 2 films, as shown in literature [53][54][55].…”

Facile fabrication of coaxial-cable like Mn 2 O 3 nanofiber by electrospinning: Application as electrode material for supercapacitor

“…It is obvious that all of the CV curves exhibit two significant redox peaks, suggesting that the specific capacitance primarily originate from the pseudocapacitive capacitance based on a redox mechanism, which is very different from that of electrical double layer capacitors that usually produce a CV curve close to an ideal rectangular shape. Moreover, for most MnO x electrodes in neutral electrolyte, the CV curves usually exhibit rectangular shapes and no clear redox peaks can be found [38,39] to the OH − chemisorption/intercalation into Mn 2 O 3 structure according to the following equation [40] :…”

“…Unfortunately, Mn 2 O 3 particles, due to lower specific surface area, contains lower number of electroactive sites, and the irregular pores induce random scattering of OH − , which enhance the diffusion resistance and decrease the diffusion kinetics of these ions inside the sample. It should be stressed that most researches combine MnO x with carbon materials to improve their performance in the previous works [3,38,43] . However, the content of MnO x in the composite is low (less than 50%).…”

High Electrochemical Capacitance by Chemically Grafting Polyaniline Chains onto an Aniline‐Functionalized Graphene Oxide/TiO2 Nanotubes/Titanium Electrode

“…Carboxylated GO containing carboxylic acid groups was prepared according to Ref. . For obtaining an aqueous suspension of GO (10 mL) with concentration of 2 mg mL −1 , GO was diluted in deionized water and then it was sonicated for 1 h to obtain a clear aqueous suspension.…”

“…Carboxylated GO containing carboxylic acid groups was prepared according to Ref. [11].F or obtaining an aqueous suspension of GO (10 mL) with concentration of 2mgmL À1 ,G Ow as diluted in deionized water and then it was sonicated for 1h to obtain ac lear aqueous suspension. Thec ompounds of chloroacetic acid (2.0 g) and NaOH (2.4 g) were added to the obtained GO suspension, and the mixture was sonicated for 2h for the conversion of the ÀOH groups into the ÀCOOH groups to obtain GOÀCOOH.…”