Hydrogen sensor based on palladium nanowire array

In this work palladium nanowire arrays have been studied for hydrogen gas sensing applications at room temperature. These parallel arrays of Pd nanowires were fabricated by electrode position from an aqueous plating solution onto an HOPG surface. The nanowires were then transferred onto a polymer film and silver electrical contact pads were fabricated by shadow masking. The morphology of the nanowires was analyzed using atomic force microscope (AFM) and the diameter of the observed nanowires was measured to be approximately 250 nm. Scanning electron microscope (SEM) images revealed that the nanowires fabricated by this procedure were mostly parallel and continuous. Experimental results indicated that the sensors are highly sensitive to Hydrogen, showing a two-order change in conductance. SEM images showed that the nanowires contain nanogaps in absence of H₂. On, exposure to H₂ palladium absorbed hydrogen resulting in the expansion of Pd grains. This expansion results in the closing of the nanogaps.