Study of basic biopolymer as proton membrane for fuel cell systems

Synthesis of Porous Proton Ion Conducting Solid Polymer Blend Electrolytes Based on PVA: CS Polymers: Structural, Morphological and Electrochemical Properties

In this study, porous cationic hydrogen (H+) conducting polymer blend electrolytes with an amorphous structure were prepared using a casting technique. Poly(vinyl alcohol) (PVA), chitosan (CS), and NH4SCN were used as raw materials. The peak broadening and drop in intensity of the X-ray diffraction (XRD) pattern of the electrolyte systems established the growth of the amorphous phase. The porous structure is associated with the amorphous nature, which was visualized through the field-emission scanning electron microscope (FESEM) images. The enhancement of DC ionic conductivity with increasing salt content was observed up to 40 wt.% of the added salt. The dielectric and electric modulus results were helpful in understanding the ionic conductivity behavior. The transfer number measurement (TNM) technique was used to determine the ion (tion) and electron (telec) transference numbers. The high electrochemical stability up to 2.25 V was recorded using the linear sweep voltammetry (LSV) technique.

Review of Chitosan-Based Polymers as Proton Exchange Membranes and Roles of Chitosan-Supported Ionic Liquids

Perfluorosulphonic acid-based membranes such as Nafion are widely used in fuel cell applications. However, these membranes have several drawbacks, including high expense, non-eco-friendliness, and low proton conductivity under anhydrous conditions. Biopolymer-based membranes, such as chitosan (CS), cellulose, and carrageenan, are popular. They have been introduced and are being studied as alternative materials for enhancing fuel cell performance, because they are environmentally friendly and economical. Modifications that will enhance the proton conductivity of biopolymer-based membranes have been performed. Ionic liquids, which are good electrolytes, are studied for their potential to improve the ionic conductivity and thermal stability of fuel cell applications. This review summarizes the development and evolution of CS biopolymer-based membranes and ionic liquids in fuel cell applications over the past decade. It also focuses on the improved performances of fuel cell applications using biopolymer-based membranes and ionic liquids as promising clean energy.

From an organic ligand to a metal–organic coordination polymer, and to a metal–organic coordination polymer–cocrystal composite: a continuous promotion of the proton conductivity of crystalline materials

A new strategy was proposed to increase proton conductivities in metal–organic coordination polymers (MOCPs) commencing from organic ligands, i.e. coordination inducement and MOCP–cocrystal composite formation.

Recent advances in application of chitosan in fuel cells

Fuel cells are electrochemical devices which convert chemical energy into electrical energy. Fuel cells have attracted attention due to their potential as a promising alternative to traditional power sources. More recently, efficient and environmentally benign biopolymer “chitosan” have been extensively investigated as a novel material for its application in fuel cells. This biopolymer can be used in both membrane electrolyte and electrode in various fuel cells such as alkaline polymer electrolyte fuel cells, direct methanol fuel cells and biofuel cells. This review provides an overview of main available fuel cells following by application of chitosan as novel biopolymer in fuel cells technology. Recent achievements are included and recommendations are also given for areas of future research.

An Investigation of Chitosan-Grafted-Poly(vinyl alcohol) as an Electrolyte Membrane

The membrane of chitosan-grafted-poly(vinyl alcohol)/poly(vinyl alcohol) (CS-g-PVA/PVA) was investigated along with chitosan (CS), PVA, CS/PVA, and Nafion 117 membranes for transport properties of water and methanol, mechanical properties, and ionic conductivity. The ionic conductivity,σ, of the crosslinked CS-g-PVA/PVA membrane was about 4.37 mS cm−1and the methanol permeability,PS, was1.8×10−7 cm2s−1. These gave the selectivity,σ/PS, of 23.95 mS·s·cm−3compared with 16.35 mS·s·cm−3of Nafion 117 membrane. The conductivity of the crosslinked CS-g-PVA/PVA membrane was greater than others including Nafion 117 when the membranes were saturated with methanol solution of which concentration was greater than 20%. This fact and that the mechanical properties of the wet crosslinked CS-g-PVA/PVA membrane were comparable to those of other membranes made it a promising material to be used as an electrolyte membrane in a direct methanol fuel cell.

Chitosan biopolymer for fuel cell applications

Fuel cell is an electrochemical device which converts chemical energy stored in a fuel into electrical energy. Fuel cells have been receiving attention due to its potential applicability as a good alternative power source. Recently, cost-effective and eco-friendly biopolymer chitosan has been extensively studied as a material for membrane electrolytes and electrodes in low to intermediate temperature hydrogen polymer electrolyte fuel cell, direct methanol fuel cell, alkaline fuel cell, and biofuel cell. This paper reviews structure and property of chitosan with respect to its applications in fuel cells. Recent achievements and prospect of its applications have also been included.

Electrical Switching in Thin Films of Nandi Flame Seed Cuticles

Current-voltage () characteristics of Nandi flame seed cuticles (NFSCs) have been studied as a function of irradiation, annealing, and poling temperature. The cuticles showed memory and threshold switching. Threshold voltage was about 5 V which is almost five times higher than observed in synthetic polymers. The threshold voltage increased to 6–8 V after irradiation and annealing depending on the duration of annealing or irradiation. After switching, conductivity increased by an order of . In reverse bias, increase of current was observed and the memory hysteresis loop was at higher conductivity than at the time of switching. Switching effect was minimized at a poling temperature of 370 K. Formation of semiquinones and quinoid radicals from phenolic compounds may have contributed to electrical switching and hysteresis effect.