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A high performance poly(vinyl alcohol)/montmorillonite/poly(styrene sulfonic acid) (PVA/MMT/PSSA) proton-conducting composite membrane was fabricated by a solution casting method. The characteristic properties of these blend composite membranes were investigated by using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, methanol permeability measurement, and the AC impedance method. The ionic conductivities for the composite membranes are in the order of 10-3 S cm-1 at ambient temperature. There are two proton sources used on this novel composite membrane: the modified MMT fillers and PSSA polymer, both materials all contain the -SO3H group. Therefore, the ionic conductivity was greatly enhanced. The methanol permeabilities of PVA/MMT/PSSA composite membranes is of the order of 10-7 cm2 s-1. It is due to the excellent methanol barrier properties of the PVA polymer. The peak power densities of the air-breathing direct methanol fuel cells (DMFCs) with 1M, 2M, 4M CH3OH fuels were 14.22, 20.00, and 13.09 mW cm-2, respectively, at ambient conditions. The direct methanol fuel cell with this composite polymer membrane exhibited good electrochemical performance. The proposed PVA/MMT/PSSA composite membrane is therefore a potential candidate for future applications in DMFC. © 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Chu C.-S.,Ming Chi University of Technology
Applied Optics | Year: 2011

This paper presents a high-sensitivity oxygen sensor that comprises an optical fiber coated at one end with tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp)3]2+) and porous silica nanoparticles embedded in an n-octyltriethoxysilane (Octyl-triEOS)/ tetraethylorthosilane (TEOS) composite xerogel. The sensitivity of the optical oxygen sensor is quantified in terms of the ratio IN2=IO2 , where IN2 and IO2 represent the detected fluorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental results show that the oxygen sensor has a sensitivity of 26. The response time was 2 s when switching from pure nitrogen to pure oxygen, and 7:7 s when switching in the reverse direction. The experimental results show that compared to an oxygen sensor based on Ru(II) complex immobilized in the solgel matrix, the proposed optical fiber oxygen sensor has higher sensitivity. In addition to the increased surface area per unit mass of the sensing surface, the porous silica nanoparticles increase the sensitivity because a substantial number of aerial oxygen molecules penetrate the porous silica shell. The proposed optical sensor has the advantages of easy fabrication, low cost, fast response, and high sensitivity for oxygen monitoring using a cheap LED as a light source. © 2011 Optical Society of America. Source


Kuo C.-C.,Ming Chi University of Technology
Optics and Lasers in Engineering | Year: 2011

Excimer laser annealing (ELA) is frequently employed to fabricate low-temperature polycrystalline silicon films on glass substrate. The grain size and crystallinity of polycrystalline silicon films are significantly affected by the resolidification behavior during ELA. A real-time in situ time-resolved optical measurement system is developed to record the rapid phase transformation process during ELA. The average solidification velocity of liquid-Si is calculated from these optical spectra using MATLAB and Excel softwares. Field emission scanning electron microscopy images reveal maximum grain size of poly-Si films with a diameter of 1 μm, which is obtained in the complete melting regime of both frontside ELA and backside ELA. Recrystallization mechanisms of complete melting of Si thin films in frontside ELA and backside ELA are demonstrated. Resolidification scenarios of partial melting, near-complete melting and complete melting in frontside ELA and backside ELA are proposed. © 2011 Elsevier Ltd. All rights reserved. Source


Chu C.-S.,Ming Chi University of Technology
Journal of Luminescence | Year: 2013

A simple, low-cost technique for fabrication of high performance optical fiber oxygen sensor is described. An organically modified silicate (ORMOSIL) as a matrix for the fabrication of oxygen sensing film was produced. The technique is based on coating the end of an optical fiber with ormosil composite xerogel film sequestered with luminophore palladium (II) meso- tetrakis(pentafluorophenyl)porphyrin (PdTFPP) prepared by a sol-gel process. The composite xerogel studied is n-propyltrimethoxysilane (n-propyl-TriMOS)/ tetraethylorthosilane (TEOS)/n-Octyltriethoxysilane (Octyl-triEOS). Result shows that, expect for PdTFPP-doped n-propyl-TriMOS/TEOS/Octyl-triEOS composite xerogel shows a high sensitivity and linear Stern-Volmer relationship which indicates the homogenous environment of the luminophore. The sensitivity of the optical oxygen sensor is quantified in terms of the ratio IN2/I O2, where IN2and IO2represent the detected phosphorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental result reveals that the PdTFPP-doped n-propyl-TriMOS/TEOS/Octyl-triEOS oxygen sensor has sensitivity of I N2/I100O2=263. © 2012 Elsevier B.V. Source


Su C.-H.,Ming Chi University of Technology
Applied Energy | Year: 2013

Several homogeneous acid catalysts (nitric, sulfuric, and hydrochloric acids), were selected to investigate their recoverability and reusability for esterifying enzyme-hydrolyzed FFAs and methanol to produce biodiesel. Although all of the three catalysts drove the reaction at high yield, hydrochloric acid is the only recoverable and reusable catalyst, as indicated by partitioning data. Hence, esterifying FFAs and methanol was catalyzed using hydrochloric acid; and the reaction conversion, which was affected by the reaction conditions, was optimized using response surface methodology. A maximal reaction conversion of 98.19% was obtained at 76.67. °C, at a methanol/FFAs molar ratio of 7.92, a catalyst concentration of 0.54. M, and after a reaction time of 103.57. min. The catalyst could be reused at least five times to drive the reaction to a conversion of 97%. This study demonstrated that recoverable and reusable hydrochloric acid is promising for potential applications, including biodiesel production. © 2012 Elsevier Ltd. Source

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