Nafion/silicon oxide/phosphotungstic acid nanocomposite membrane with enhanced proton conductivity.

Nafion-silicon oxide (SiO2)-phosphotungstic acid (PWA) composite membrane has been synthesized to improve Nafion based proton exchange membrane fuel cell (PEMFC) performance. The objective of the study is to fabricate Nafion-SiO2-PWA nanocomposite membrane using sol–gel reaction. The composite is composed of the mixture of Nafion solution, tetra ethoxy orthosilane (TEOS) and PWA solution. The mixed solution was casted at certain temperature until transparent membrane is obtained. Peaks of SiO2 and PWA in the infrared spectra revealed that both inorganic and organic components are present in the modified Nafion based nanocomposite membrane. Analysis with fuel cell test station showed that higher current density was produced by nanocomposite membrane (82mAcm−2 at 0.6V for NS15W) than with the Nafion membrane (30mAcm−2 at 0.2 V) at 90 ◦C and 40% relative humidity. The internal resistance was seen to increase with the inorganic content. The internal resistances of the commercial Nafion (N112), NS10W, NS15W and NS20W are 6.33, 4.84, 1.33 and 3.6�cm2, respectively and their Tafel constants are 93.4, 84.4, 11.25 and 26.6 mV, respectively. While the nanocomposite membrane results were shown to be better than the commercial Nafion, the overall performances are comparable to those in the open literature

ELECTROCHEMICAL PROPERTIES IMPROVEMENT OF PROTON EXCHANGE MEMBRANE FUEL CELL (PEMFC) USING NANOCOMPOSITE ELECTROLYTE MEMBRANE.

Nafion-Silica oxide (SiO2)-Phosphotungstic acid (PWA) composite membrane have been synthesized using solution phase sol-gel method. The effect of the weight ratio of Nafion:SiO2:PWA to the electrochemical properties of composite membrane when applies as electrolyte in the PEMFC was investigated using Fuel Cell Test System (FCTS) at temperature of range of 80 – 90 oC and 40% relative humidity (RH). The weight ratio of the composite membrane samples varied in the range of 100:2.88:1.15, 100:4.33:1.73 and 100:5.76:2.30 and designated as NS10W, NS15W and NS20W, respectively. The aim of the experiment was to insert the inorganic hygroscopic and high conductivity filler like PWA and SiO2 in the Nafion matrix to order to improve the water retention, proton conductivity (σ), hydrogen crossover (β), and thermal stability in addition to increase PEMFC performance at elevated temperature and low RH condition. The result showed when appropriately embeded in the Nafion cluster, the hydrated PWA and SiO2 were endowed in the composite membrane with their high proton conductivity, while retaining the desirable mechanical properties of the polymer film. The water uptake rate and the conductivity of the composite membranes was enhanced with the increase in SiO2 and PWA weight content, after which it is reduced when the ratio of Nafion:SiO2:PWA became 100:4.33:1.73. However, the conductivity of all the composite membranes were higher compare to the Nafion membrane at cell operation condition of 80 – 90 oC and 40% RH. While hydrogen crossover through the composite is lower than Nafion 112 membrane. This study indicated that Nafion-SiO2-PWA composite membrane can be a viable substitute for Nafion for PEMFC which showed good conductivity comparable to Nafion 112 at temperature nearing 100 oC, bearing in mind that Nafion-SiO2-PWA composite membranes have better thermal stability

Gravimetrical, theoretical, and surface morphological investigations of corrosion inhibition effect of 4-(benzoimidazole-2-yl) pyridine on mild steel in hydrochloric acid

The corrosion inhibition efficiency of the novel pyridine namely, 4-(Benzoimidazole-2-yl)pyridine has been studied for mild steel in a 1 M hydrochloric acid environment by utilizing gravimetrical techniques. The synthesized inhibitor exhibits a significant inhibitive efficiency of 93.8% at 0.005 M. The adsorption isotherm of the investigated inhibitor on mild steel surface obeys the Langmuir isotherm. Surface morphology investigated by utilizing scanning electron microscopy (SEM) demonstrates a smooth metal surface with the addition of 4-(Benzoimidazole-2-yl)pyridine in a hydrochloric acid environment. Quantum chemical calculations using density functional theory (DFT) have been used to investigate the molecular structure and behavior of 4-(Benzoimidazole-2-yl) pyridine as a corrosion inhibitor. Different parameters have been calculated using DFT, such as energies of highest occupied molecular orbital and lowest occupied molecular orbital (EHOMO and ELUMO), energy gap (∆E), and dipole moment (μ). These parameters were important to elucidate the behavior of the investigated molecule as a corrosion inhibitor in acidic solution and also suggest the mechanism of inhibition

Preface

Applied Mechanics and Materials174-177

Preface

Applied Mechanics and Materials166-169