Reliability and selectivity of H₂ sensors composed of Pd Film nanogaps on an elastomeric substrate

H₂ sensors composed of Pd films of 10 nm thickness were prepared on a compliant poly(dimethylsiloxane) (PDMS) substrate, using a combination of an initial H₂ concentration of 0.5% and mechanical elongation of the samples by 50% of their original length. The initial feed of hydrogen gas was controlled for the PDMS/Pd films, and then an on-off switching response was measured with H₂ concentrations ranging from 0.01% to 0.5%. The Pd films exhibited a nanogap width of less than 50 nm. The sensors exhibited slightly degraded sensing performances in humidified H₂ in a N₂ environment, whereas their performance, in terms of their saturation current, showed little variation in an ambient atmosphere. This may be the result of a retarding effect caused by water adsorption on the Pd film surface, which decreases the number of active sites available for H₂ adsorption. The sensor was exposed to several toxic gases such as CO, NO, NO₂, and NH₃, after a single cycle of H₂ exposure. The nanogaps in the multi-nanogap structure exhibited selective reactivity with H₂ but showed no response to the other gases to which they were exposed or no resulting degradation.