Preparation and Characterization of a Novel Sulfonated Titanium Oxide Incorporated Chitosan Nanocomposite Membranes for Fuel Cell Application

In this study, nano-TiO₂ sulfonated with 1,3-propane sultone (STiO₂) was incorporated into the chitosan (CS) matrix for the preparation of CS/STiO₂ nanocomposite membranes for fuel cell applications. The grafting of sulfonic acid (–SO₃H) groups was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis and energy-dispersive X-ray spectroscopy. The physicochemical properties of these prepared membranes, such as water uptake, swelling ratio, thermal and mechanical stability, ion exchange capacity and proton conductivity, were determined. The proton conducting groups on the surface of nano-TiO₂ can form continuous proton conducting pathways along the CS/STiO₂ interface and thus improve the proton conductivity of CS/STiO₂ nanocomposite membranes. The CS/STiO₂ nanocomposite membrane with 5 wt% of sulfonated TiO₂ showed a proton conductivity (0.035 S·cm⁻¹) equal to that of commercial Nafion 117 membrane (0.033 S·cm⁻¹). The thermal and mechanical stability of the nanocomposite membranes were improved because the interfacial interaction between the -SO₃H group of TiO₂ and the –NH₂ group of CS can restrict the mobility of CS chains to enhance the thermal and mechanical stability of the nanocomposite membranes. These CS/STiO₂ nanocomposite membranes have promising applications in proton exchange membrane fuel cells.

Synthesis and characterization of chitosan-coated titanate nanotubes: towards a new safe nanocarrier

Chitosan-coated titanate nanotubes as promising new nanocarriers: two different approaches, two different behaviors.

Titanate nanotubes for reinforcement of a poly(ethylene oxide)/chitosan polymer matrix

Soft polyethylene oxide (PEO)/chitosan mixtures, reinforced with hard titanate nanotubes (TiNTs) by co-precipitation from aqueous solution, have been used to produce compact coatings by the 'drop-cast' method, using water soluble PEO polymer and stable, aqueous colloidal solutions of TiNTs. The effects of the nanotube concentration and their length on the hardness and modulus of the prepared composite have been studied using nanoindentation and nanoscratch techniques. The uniformity of TiNT dispersion within the polymer matrix has been studied using transmission electron microscopy (TEM). A remarkable increase in hardness and reduced Young's modulus of the composites, compared to pure polymer blends, has been observed at a TiNT concentration of 25 wt %. The short (up to 30 min) ultrasound treatment of aqueous solutions containing polymers and a colloidal TiNT mixture prior to drop casting has resulted in some improvements in both hardness and reduced Young's modulus of dry composite films, probably due to a better dispersion of ceramic nanotubes within the matrix. However, further (more than 1 h) treatment of the mixture with ultrasound resulted in a deterioration of the mechanical properties of the composite accompanied by a shortening of the nanotubes, as observed by the TEM.

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.