Slow Morphological Change of Perfluorinated Ionomer as Deduced From 1H NMR Spectra of Confined Water

The behaviour of water molecules confined in the perfluorinated ionomer membrane, which is widely used for polymer electrolyte fuel cells, was investigated by 1H NMR spectroscopy. The 1H NMR spectra of water molecules confined in the membrane presented characteristic features depending on temperature and hydrated conditions. On the basis of the observations of the variations in the 1H NMR signals, it was deduced that the polymer underwent very slow conversions among distinct morphologies depending on temperatures and humidified conditions below 348 K. A plausible scheme of the local conversion of the states of the water molecules associated with the morphological changes of the polymer was proposed

Estimation of water contents of polymer electrolytes by 1H NMR spectroscopy

Water molecules confined in perfluorinated ionomer membranes which are widely used for polymer electrolyte fuel cells, presented apparently a single 1H NMR peak in hydrated states because of the rapid exchange among the water molecules at the distinct segments of the polymer. The peak shifted to the lower field with decreasing the water content due to the decrease of the fraction of the bulk water molecules which present a peak at higher field. The chemical shifts were found to be well correlated with the peak area. The water peak for MEA (Membrane Electrode Assembly) showed also similar behaviors to the membranes. From the relationship between the chemical shift and the peak area of the confined water peak we demonstrated the potential that the chemical shift could be utilized to estimate the water content in the hydrated membranes and MEA

The Effect of Platinum Deposition on the Water Photo-Reduction at p-Cu2O Semiconductor Electrodes with Visible Light Irradiation

The surface of a p-Cu2O semiconductor photoelectrode was modifi ed by electrodeposition of Pt nanoparticles and analyzed by XRD, SEM, XPS, and EIS (electrochemical impedance spectrometry) methods besides photocurrent measurements. The XRD, SEM, and XPS analyses showed the fabrication of Cu2O fi lm and the deposition of Pt particles. On the electrodeposition of Pt nanoparticles, cathodic photocurrent was enhanced. The EIS analysis suggested that Pt nanoparticles enhance the charge transfer process to the solution

Studies on the effects of Cd ion sources and chelating reagents on atomic layer Cds deposition by successive ionic layer adsorption and reaction (SILAR) method

CdS thin films were fabricated on an ITO-covered glass substrate by successive ionic layer adsorption and reaction (SILAR) method under various conditions. By changing Cd ion sources, chelating reagents, and pH, the obtained films were evaluated by their thickness, crystallinity, crystallite size, surface roughness, and elemental composition. CdCl2 and triethanolamine were found to provide the most well crystallized thick film among six Cd salts and six chelating reagents. In the present study, no marked effect of pH on the film quality was observed compared to the effect of the difference in the counter ions. The effects of counter ions, chelating reagents, and pH could be explained by the discussion in terms of the stability constant of Cd2+ for these chemical species and SH-

Preparation of ZnO by a nearby vaporizing chemical vapor deposition method

ZnO films were prepared by a nearby vaporizing chemical vapor deposition (CVD) method using bis(2,4-pentanedionato)zinc as a source material. The deposition rate increased exponentially from 0.58 to 147 nm min-1 with increasing substrate temperature. The highest preferred orientation to c-axis was obtained under the conditions that the distance between substrate and source surface (D) was 5.0 mm and the substrate temperature (Ts) was 300 °C. When we used a sapphire (0001) substrate, an epitaxial ZnO film could be deposited on this condition

Electrochemical evaluation of the roles of chelating reagents in Cd ion adsorption on CdS surface for the successive ionic layer adsorption and reaction (SILAR) deposition

We evaluated the effect of the chelating reagents in the SILAR (successive ionic layer adsorption and reaction) process by monitoring the formation of one layer of CdS on S surface of the CdS layers prepared by successive UPD (under potential deposition) method. Anodic stripping voltammetry was adopted to measure the amount of CdS deposited on Au substrate. Among the chelating reagents examined, the under of the ability to enhance the depusitiun by dipping was cysteine > (None) > mercaptoethylamine > triethanolamine >> ethylenediamine. Considering the stability constant of the chelating reagents to Cd ions, the present experimental result showed that tight binding of Cd atoms to the surface S atoms is an important step in the deposition of CdS by SILAR method

Enhanced Photoelectrocatalytic Activity of FTO/WO3/BiVO4 Electrode by Modified With Gold Nanoparticles for Water Oxidation Under Visible Light Irradiation

Gold nanoparticles were successfully deposited on FTO/WO3/BiVO4 electrode surface by means of electrolysis of AuCl4 - ions. The composite films were characterized by SEM, XPS and XRD techniques. An increase in photocurrent and a negative shift of onset potential for water oxidation were observed upon modification of the electrode surface with the Au particles. The electrochemical impedance spectroscopy was used to confirm the acceleration of charge transfer process by Au deposition at the electrode surface. The photocurrent action spectrum did not correlate with the plasmonic absorbance of Au nanoparticles at 560 nm, suggesting that the Au nanoparticles increased charge separation without undergoing a plasmon resonance effect under visible light irradiation