Ultrafast Pd/AAO Nanowell Hydrogen Sensor

Abstract

ABSTRACTAnodized aluminum oxide (AAO) membranes consist of highly uniform and aligned nanopores with pore diameters ranging between 10 and 200 nm. Based on these nanoporous materials, we developed a new AAO nanowell structure that was synthesized through short-term anodization of aluminum foil. The nanowell structure was made of shallow wells that were oriented in a hexagonally closed packed configuration with well diameter around 50 nm and depth less than 100 nm. The chemical composition was amorphous alumina on aluminum substrate. Thin palladium film was then fabricated on the surface of the as-synthesized AAO nanowell to prepare a Pd/AAO nanowell structure. These devices demonstrated unexpectedly high hydrogen sensitivity. The response time ranged from a few hundred milliseconds to a few seconds with hydrogen concentration between 1 and 0.05%. They also showed modest responses at hydrogen concentration as low as 5 ppm.