Nitro-oxidized carboxylated cellulose nanofiber based nanopapers and their PEM fuel cell performance

The fuel cell is the best alternative to compensate for today's energy demand, but the high cost of fabrication of membranes (e.g., Nafion) hampers the widespread commercialization. Plant-derived nanocellulose is renewable, most abundant, and biocompatible with high strength and tunable surface chemistry. Here we have demonstrated the jute derived-nitro-oxidized carboxycellulose nanofibers (NOCNFs) as a viable and sustainable substitute for synthetic ionomer membranes used in proton exchange fuel cells (PEFCs). NOCNFs were obtained in two functionalities: carboxylate and carboxylic acid which were then transformed into nanopaper I and II, respectively. This is the first report where NOCNFs with two different functionalities were tested in PEFCs. The results indicated that nanopaper II performed better than nanopaper I with a high proton conductivity of 14.2 mS cm⁻¹ and power density of 19.1 mW cm⁻² at high temperature (80 °C) operation in PEFCs, along with excellent durability even for 24 h of operation.