Solid State Phenomena Vol. 317

Abstract: This study reported the preparation and characterization of gel polymer electrolyte (GPE) using poly (vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP), lithium perchlorate (LiClO₄) and 1-butyl-3-metilimmidazoliumhexafluorophosphate [PF₆]. The GPE were prepared by solution casting technique. [Bmim] [PF₆] ionic liquid is used as an additive for the purpose of increasing the ionic conductivity of GPE. Morphological analysis showed that the electrolyte gel polymer sample had a smooth and flat surface with the addition of [Bmim] [PF₆] and no phase separation effect was observed. This shows the compatibility between PVdF-HFP and [Bmim] [PF₆]. ATR-FTIR analysis showed that C-F bond related peaks experienced peak changes in terms of intensity and peak shifting. This proves the interaction of the imidazolium ion with the fluorine atom through the formation of coordinate bonds. Ionic conductivity analysis showed that PVdF-HFP-[Bmim][PF₆] samples reached a maximum room temperature ionic conductivity value of 2.44 × 10^-4 S cm^-1 at 60 wt.% [Bmim] [PF6]. When 20 wt.% of LiClO₄ added to the system, the ionic conductivity increased one magnitude order to 2.20 × 10^-3 S cm^-1.

Abstract: The cost of conventional membrane, Nafion® used in the current proton exchange membrane fuel cell (PEMFC) is high. Thus different alternatives are being proposed as an option of Nafion® membrane in PEMFC application. In this study, poly(vinyl alcohol)/ N-methylene phosphonic chitosan/ 2-hydroxyethylammonium formate (PVA/NMPC/2-HEAF) proton exchange membrane was prepared using the solution casting technique. The effects of 2-HEAF concentrations (0 – 20 wt.%) on crosslinked and non-crosslinked PVA/NMPC/2-HEAF membrane were studied. The characterizations of PVA/NMPC/2-HEAF membrane were done by Fourier transformation infrared spectroscopy (ATR-FTIR), water uptake test, ion exchange capacity (IEC) analysis and electrochemical impedance spectroscopy (EIS). The crosslinkages (-O-CH₂-O-) formed using formaldehyde crosslinking agent were confirmed through the formation of new peak by –CH₂- stretching at around 2863 cm^-1 and the increased intensity of C-O stretching absorption. Crosslinked PVA/NMPC/5 wt.% 2-HEAF membrane showed the highest percentage of water uptake and IEC value. The EIS result agrees with the water uptake and IEC analysis where crosslinked PVA/NMPC/5 wt.% 2-HEAF showed the highest ionic conductivity of 5.44 × 10^-5 S cm^-1. This is due to the plasticization effect of 2-HEAF that softened the polymer chains and which it also provided more charge carriers to increase the ion mobility in the membrane.

Abstract: NiO nanoparticle was synthesized by a sol-gel method with three different pH values namely pH=1, 7 and 11, and then calcined at temperature of 450 ᵒC. The influence of different pH values on the physical properties of NiO nanoparticles were investigated by a particle size analyzer (PSA), field emission scanning electron microscope (FESEM) and X-ray diffractometer (XRD). Structural analysis confirmed that a cubic structure of NiO nanoparticle was obtained without any secondary phase for NiO powders prepared with pH=1, while the peak of secondary phase (Ni) appeared for NiO powders prepared with pH= 7 and 11. Morphological observation showed that the NiO nanoparticles prepared with pH=7 and 11 tend to form more agglomerates compared to one prepared with pH=1. The average diameter of NiO nanoparticles with pH 1, 7 and 11 were approximately in the range of 19-26 nm, 21-28 nm, and 24-30 nm, respectively. NiO powder that was synthesized with pH=1 was further used to prepare composite anode of NiO Nps-BaCe_0.54Zr_0.36Y_0.1O_2.95 (BCZY) powder. Unfortunately a composite of NiO Nps-BaCeO₃-BaZrO₃ was obtained instead of BCZY and governed by agglomerates with size in the range of 70-300 nm.

Abstract: One of the challenges in fabricating organic semiconductor thin film is to produce bettermolecular ordering that compromise its electronic properties. Molecular ordering of amorphous thin film can be improved in many ways. Here, high molecular weight polylactic acid (PLA) is introduced as binding matrix to promote 3'''-didodecyl-2,2':5',2'':5'',2'''-quaterthiophene (4T) film’s homogeinity across indium tin oxide (ITO) surface. Molecular ordering of the spin coated biodegradable PLA and 4T blend film processed at ambient atmosphere was studied using two vibrational spectroscopy methods. The complementary analysis of infrared absorption spectrum and Raman spectrum had identified several vibrational modes contributed by thiophene rings and alkyl functional groups. The Raman analysis implied there is a slight change of thiophene ringsʼ molecular orientation due to compressive stress after introduction of polymer. Microscopic characteristics of oligothiophenes especially at the π-π conjugated backbones contained crucial information in order to exploit the oligothiophene as flexible electronics devices.

Abstract: Zinc oxide (ZnO) nanorods is widely investigated due to its high photoelectrochemical conversion performance. Further enhancement may be afforded by introducing a metal chalcogenide sensitization layer such as zinc selenide (ZnSe). In this study, ZnO nanorods were electrodeposited with ZnSe at potential range from -0.5 V to -0.9 V vs Ag/AgCl reference electrode. Structural, morphological and optical properties of ZnSe electrodeposited were investigated as a function applied potential by using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). ZnSe electrodeposited for 15 minutes at -0.7 V showed crystallite size of 20.13 nm with the lowest band gap energy of 2.97 eV. The existence of ZnSe particles with the size of 41.8 nm were proven by FESEM images, after ZnSe particles were electrodeposited onto ZnO nanorods that have an average diameter of 62.6 nm and length of 1.6 µm. The photocurrent density generated by samples were measured in a three-electrodes cell incorporated with halogen lamp. The photocurrent generated increased between -0.5 V to -0.7 V before dropped at higher applied potential due to hydrogen evolution process which affected the thin film quality, ultimately affecting photoconversion performance. The highest photocurrent density of 0.2621 mAcm^-2 was recorded for samples prepared at -0.7 V vs Ag/AgCl.

Abstract: The effect of various target to substrate distance on the physical properties of sputtered Gd-doped ZnO thin films were investigated. The thin films with three distances between a target to substrate ranged from 12.0, 13.5 and 15.0 cm were deposited by a dual-target sputtering method. All the thin film properties were characterized using x-ray diffraction, atomic force microscope, energy dispersive x-ray analysis and ultra-violet visible spectrophotometer. The sharp and intense peak of (002) was observed for a sample with the target to substrate distance of 13.5 cm which indicated good crystallinity as compared to other samples. Gd incorporations of 3 at% in ZnO films were further confirmed via the energy dispersive x-ray analysis. AFM images revealed that the surface topology Gd-doped ZnO thin film have a smooth and uniform surface. The transmittance was above 90 % and slightly decrease with the increase of target to substrate distance. The bandgap value was static at 3.14 eV for all the 12.0, 13.5 and 15.0 cm of various target to substrate distances.

Abstract: Tin oxide (SnO₂) thin film is a form of modification of semiconductor material in nanosize. The thin film study aims to analyze the effect of triple doping (Aluminum, Indium, and Fluorine) on the optical properties of SnO₂: (Al + In + F) thin films. Aluminum, Indium, and Fluorine as doping SnO₂ with a mass percentage of 0, 5, 10, 15, 20, and 25% of the total thin-film material. The addition of Al, In, and F doping causes the thin film to change optical properties, namely the transmittance and absorbance values ​​changing. The transmittance value is 67.50, 73.00, 82.30, 87.30, 94.6, and 99.80 which is at a wavelength of 350 nm for the lowest to the highest doping percentage, respectively. The absorbance value increased with increasing doping percentage at 300 nm wavelength of 0.52, 0.76, 0.97, 1.05, 1.23, and 1.29 for 0, 5, 10, 15, 20, and 25% doping percentages, respectively. The absorbance value is then used to find the gap energy of the SnO₂: (Al + In + F) thin film of the lowest doping percentage to the highest level i.e. 3.60, 3.55, 3.51, 3.47, 3.42, and 3.41 eV. Thin-film activation energy also decreased with values of 2.27, 2.04, 1.85, 1.78, 1.72, and 1.51 eV, respectively for an increasing percentage of doping. The thin-film SnO₂: (Al + In + F) which experiences a gap energy reduction and activation energy makes the thin film more conductive because electron mobility from the valence band to the conduction band requires less energy and faster electron movement as a result of the addition of doping.

Abstract: Polyaniline (PANI) thin films were successfully prepared from an aqueous electrolyte bath containing aniline and sulphuric acid (H₂SO₄) using electrodeposition method. The present study demonstrates that the properties of PANI thin film depends on the variation of pH and aniline concentration in prepared precursor. The optical and structural of PANI thin films were characterized using UV-Visible spectrometer (UV-Vis), X-ray diffraction spectrometer (XRD), Fourier Transform Infra-Red spectrometer (FTIR) and Raman spectrometer. PANI layer grown at pH 2.00 displayed green colour layer which denoted as emeraldine base (half oxidized state of PANI) while at pH 3.80 the colour of PANI layer was yellow representing the leucoemeraldine base (fully reduced state of PANI). Result obtained from FTIR confirmed the footprint of PANI and Raman spectrometer confirmed the half oxidized emeraldine base of PANI. Optical analysis using UV-Vis demonstrated the smallest energy band gap, E_g of PANI is 3.54 eV for sample with 0.50 M aniline concentration and pH 2.00. The trend shows that the bandgap of PANI is increased as the pH increased from 2.00 to 3.80. XRD result showed that all the deposited PANI layers were amorphous. Full characterization of this material is providing some information on PANI behavior due to pH and concentration in the prepared precursor.

Abstract: In this study, mild steel was treated with SDBS:ZnSO₄ compound by immersing the mild steel substrates in a SDBS:ZnSO₄ bath of varying pH. The effect of bath solution pH and immersion time on the corrosion protection properties of SDBS:ZnSO₄ pre-treated mild steel in sodium chloride solution was investigated using electrochemical impedance spectroscopy (EIS) and polarization measurements. From the EIS results, it was found that the inhibition efficiency provided by the pre-treatment was significantly affected by the pH of the bath solution, where inhibition was highest at pH 6. This is due to the formation of a good protective layer on mild steel substrate caused by the deposition of zinc hydroxide/oxide and SDBS compound. Increasing the immersion time from 1 h to 24 h increased the inhibition efficiency. From the polarization measurements, the current density was significantly reduced, and the shift to a more positive corrosion potential value indicated a higher protection layer was formed on the metal surface during more prolonged immersion. It has been found that longer pre-treatment immersion time allows a denser protective layer formed, which prevented the diffusion of water towards the mild steel substrate that can lead to corrosion.

Abstract: In this study, poly(m-aminophenol) (PMAP) coating was electrochemically synthesized by cyclic voltammetry (CV) on mild steel surface to investigate the effects of its barrier protection within the scope of its electrochemical impedance towards further oxidation of the mild steel substrates. The developed PMAP coating were characterized by Fourier Transform Infrared (FTIR) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). The barrier resistance ability of PMAP coating towards corrosion of mild steel was determined in 0.5 M aqueous sodium chloride solution (NaCl) at various immersion times by the electrochemical impedance spectroscopy (EIS). The barrier properties were interpreted through impedance measurement using Nyquist and Bode plots. Equivalent electrical circuit models derived from the plots were employed to describe the coating barrier behaviour and performance. Data obtained showed that, the oxidation peak of PMAP coating were observed at potential +1.0 V (Ag/AgCl). The micrograph of FESEM indicates the formation of a dense and continous PMAP coatings. In FTIR analyses, the presence of peak around 1082 cm^-1 ascribed to C–O–C etheric linkage which supported the formation of electro polymerized PMAP coating on mild steel surface. EIS measurement revealed that, PMAP coatings experienced a significant drop in total impedance values with time followed by the development of an electrochemical reactions on coating/metal interface, which indicates the gradual degradation of the barrier resistance ability of the PMAP coatings.