A new nanocomposite material has shown promise in boosting fuel cell efficiency — an application that might find potential use in making better bio-electrical devices, implantable batteries and biosesors. The material — a polyelectrolyte membrane for direct methanol fuel cells (DMFC) — has been made by modifying chitosan1.
Despite being nontoxic and biodegradable, on prolonged use chitosan has drawbacks like swelling and leaching out of proton carrier. To overcome this, the researchers prepared nanostructured N-p-carboxy benzyl chitosan (NCBC)-silica-poly (vinyl alcohol) hybrid proton exchange membranes (PEMs) for DMFC. Sophisticated imaging of the membranes revealed nano-sized silica particles homogenously distributed within the polymer matrix. Presence of cracks and holes on the membrane surface indicated the dense nature of the membrane.
The presence of water in the membrane phase is a prerequisite for high membrane conductivity. Both NCBC and silica acted as binders for water in the membrane matrix due to inter- and intra-molecular interaction. Increase in NCBC-silica content also revved up the proton conductivity even at high temperature.
The nanocomposite is environmentally benign, says lead researcher Vinod K. Shahi from the Electro-Membrane Processes Division of Central Salt and Marine Chemicals Research Institute, Gujarat.