Fast, Sensitive Hydrogen Gas Detection Using Single Palladium Nanowires That Resist Fracture

Two types of pure palladium (Pd) nanowires, differentiated by microstructure, were electrodeposited: (1) nanocrystalline Pd nanowires (grain diameter approximate to 5 nm, henceforth nc5-Pd) and (2) nanocrystalline Pd nanowires with a grain diameter of 15 nm (nc15-Pd). These nanowires were evaluated for the detection of hydrogen gas (H-2). Despite their fundamental similarities, the behavior of these nanowires upon exposure to H-2 was dramatically and reproducibly different: nc5-Pd nanowires spontaneously fractured upon exposure to H-2 above 1-2%. Fractured nanowires continued to function as sensors for H-2 concentrations above 2%, actuated by the volume change associated with the alpha to beta phase transition of PdHx, ncl5-Pd nanowires, in contrast, withstood repeated exposures to H2 UP to 10% without fracturing. nc15-Pd nanowires showed a rapid (2 s at 10%) increase in resistance in the presence of H2 and a response that scaled smoothly with [H-2] spanning 5 orders of magnitude down to 2 ppm.