Polyaniline–chitosan nanocomposite: High performance hydrogen sensor from new principle

A high selectivity and response towards hydrogen gas is realized with a composite of polyaniline nanofibers embedded in chitosan matrix. The enhanced response originated from the new sensing mechanism related with the composite nature of chitosan and polyaniline. Based on the high gas sensing performance through nanostructured resistive polyaniline nanofibers, the swelling of chitosan as the matrix distributing among the resistor network controls the hopping conduction between the nanofibers. This gate control of chitosan on the polyaniline conduction claims a new type of sensor mechanism resulting in a reverse polarity in conductivity change with respect to the conductivity change of polyaniline. The response-reversal can enhance the sensing response. Furthermore, the highly enhanced selectivity for hydrogen was also achieved through filtration action of chitosan for large size and polar molecules. We thus demonstrate a new material and structural design of solid state sensor for improvement in selectivity and response.