Building up nanostructured layer-by-layer films combining reduced graphene oxide-manganese dioxide nanocomposite in supercapacitor electrodes

Supercapacitor Based on Nanostructured Multilayer Films Consisting of Polyelectrolyte/Graphene Oxide‐MnO2‐ZnO for Energy Storage Applications

“…By monitoring the band at 350–400 nm, which can be attributed to d–d transitions of MnO 2 , [ 31,32 ] one can note a gradual increase in absorbance spectra. Such increase, as shown in Figure 2b, suggests a regular deposition of the materials during the film fabrication as the number of bilayers increases on the ITO substrate [ 27,28 ] until achieving a final dark brown aspect as displayed in the inset. The film formation may be associated with the electrostatic interactions between protonated amine groups (NH 3 + ) of PAH (positively charged) with carboxylic‐acid‐functionalized groups (COO − ) of GO dispersion (negatively charged).…”

“…MnO2 nanostructures were synthesized using the method described by Chen et al [ 27 ] A mixture of 1.0 m MnSO 4 and 0.5 m KMnO 4 was stirred for 4 h at 70 °C. Afterward, the precipitate was washed with distilled water and ethanol to eliminate impurities, followed by vacuum dried at 110 °C for 5 h. The dried powder was heated to 300 °C, then acidified with 2.0 m H 2 SO 4 at 90 °C for 2 h. To finish, the product was washed with distilled water and dried under vacuum.…”

Graphene Oxide Layer-by-Layer Films for Sensors and Devices

“…Table 2. Position of the peaks observed in the FTIR spectra of PAH/GO LbL films deposited on CaF 2 substrates and the respective designations of the vibrational modes [18,22,[36][37][38][39]. AFM topographic images for different sample areas of the GO layer show that the film surface appears to be homogeneous with a Sq of 3.09 nm.…”

“…Table 2. Position of the peaks observed in the FTIR spectra of PAH/GO LbL films deposited on CaF2 substrates and the respective designations of the vibrational modes [18,22,[36][37][38][39]. Stretching at the C=C bond of the aromatic ring, the C=O vibrations in the ketone (GO) groups, the vibrations due to torsion at the N-H bonds in the primary amines and with the stretching vibrations of the carbonate groups.…”

“…Moreover, the LbL film deposition method is carried out using aqueous solutions, which from an environmental point of view makes this technique lower risk. In recent years, several LbL films based on GO have been prepared and characterized, having the development of devices and sensors in mind [17][18][19][20][21][22][23].…”