Search

Electrochemical exfoliation of graphite has recently attracted a big attention as a simple, fast and scalable method for the preparation of high quality graphene, but there are some drawbacks that hinder its application. Direct deposition is one of the most critical challenges that makes it difficult to deposit uniform, compact and large scale graphene thin films. This work develops a facile electrophoretic deposition route to fabricate exfoliated graphene (EG) film on Ag nanowires (NWs) networks with a controllable film thickness in nanometers scale. EG thin films are deposited with different applied potentials and times from an EG dispersion in N, N -dimethylformamide solvent. Since confirmed by light transmittance results, the increase in deposition time or applied potential lead to an increase in the number of deposited EG layers. The scanning electron microscopy results confirm the uniformity and compactness of EG films deposited on Ag NWs network. Furthermore, transparency and conductivity of Ag NWs films before and after the deposition of EG are investigated. It shows significant improvement in its performance, as a result, it leads to Ag NWs/EG hybrid films exhibiting a sheet resistance of R s = 30 Ω sq -1 , and 85% light transmittance, comparable to conventional transparent conductive oxide films.

Organic materials have been found to be promising candidates for low-temperature thermoelectric applications. In particular, poly (3-hexylthiophene) (P3HT) has been attracting great interest due to its desirable intrinsic properties, such as excellent solution processability, chemical and thermal stability, and high field-effect mobility. However, its poor electrical conductivity has limited its application as a thermoelectric material. It is therefore important to improve the electrical conductivity of P3HT layers. In this work, we studied how molecular weight (MW) influences the thermoelectric properties of P3HT films. The films were doped with lithium bis(trifluoromethane sulfonyl) imide salt (LiTFSI) and 4-tert butylpyridine (TBP). Various P3HT layers with different MWs ranging from 21 to 94 kDa were investigated. UV&ndash, Vis spectroscopy and atomic force microscopy (AFM) analysis were performed to investigate the morphology and structure features of thin films with different MWs. The electrical conductivity initially increased when the MW increased and then decreased at the highest MW, whereas the Seebeck coefficient had a trend of reducing as the MW grew. The maximum thermoelectric power factor (1.87 &mu, W/mK2) was obtained for MW of 77 kDa at 333 K. At this temperature, the electrical conductivity and Seebeck coefficient of this MW were 65.5 S/m and 169 &mu, V/K, respectively.

Porous network-like MnO2 thick films are successfully synthesized on a flexible stainless steel (SS) mesh using a simple and low-cost electrodeposition method followed by an electrochemical activation process. Morphology, chemical composition and crystal structure of the prepared electrodes before and after the activation process are determined and compared by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses. The results show that the implementation of the electrochemical activation process does not change the chemical composition and crystal structure of the films, but it influences the surface morphology of the MnO2 thick layer to a flaky nanostructure. Based on the electrochemical data analysis, the maximum specific capacitance of 1400 mF (381 F g-1) and 3700 mF (352 F g-1) are measured for small (2.6 cm2) and large (10 cm2) surface area electrodes, respectively. In addition, a flexible symmetric MnO2//MnO2 solid state supercapacitor shows a capacitance of 0.3 F with about 98% retention at different bending angles from 0° to 360°.