Platinum Decorated Palladium Nanowires for Room-Temperature Hydrogen Detection

The use of hydrogen as an energy carrier will require low-cost, low-power hydrogen sensors. Toward this goal, penta-twinned palladium nanowires (Pd NWs) are synthesized and fabricated sensors from them by drop-casting. Pd NWs drop-cast onto an interdigitated electrode (IDE) gave a response of 0.3% to 1 vol.% H₂, with response and recovery times of 12 and 20 s, respectively. However, they exhibited a negative response (decreased resistance) at low H₂ concentrations. Pd NWs on a paper substrate provided a tenfold higher response to 1 vol.% H₂, with response and recovery times of 10 s each, but still exhibited negative response at low H₂ concentration. Exposing the Pd NW-on-paper sensor to ozone-generating UV light degraded the PVP used in Pd NW synthesis, eliminating the reverse sensing response, and providing a response of 5% to 1 vol.% H₂, with response and recovery times of 15 s. This allowed reliable H₂ detection down to 100 ppm H₂. Finally, coating the Pd NWs with a small amount of Pt (<5%) reduced the response and recovery times to 5 s by catalyzing H₂ dissociation. This work provides a path to low-cost sensors to enable the safe use of H₂ as an energy carrier.