title: Networks of ultrasmall Pd/Cr nanowires as high performance hydrogen sensors.
abstract: The newly developed hydrogen sensor, based on a network of ultrasmall pure palladium nanowires sputter-deposited on a filtration membrane, takes advantage of single palladium nanowires' characteristics of high speed and sensitivity while eliminating their nanofabrication obstacles. However, this new type of sensor, like the single palladium nanowires, cannot distinguish hydrogen concentrations above 3%, thus limiting the potential applications of the sensor. This study reports hydrogen sensors based on a network of ultrasmall Cr-buffered Pd (Pd/Cr) nanowires on a filtration membrane. These sensors not only are able to outperform their pure Pd counterparts in speed and durability but also allow hydrogen detection at concentrations up to 100%. The new networks consist of a thin layer of palladium deposited on top of a Cr adhesion layer 1-3 nm thick. Although the Cr layer is insensitive to hydrogen, it enables the formation of a network of continuous Pd/Cr nanowires with thicknesses of the Pd layer as thin as 2 nm. The improved performance of the Pd/Cr sensors can be attributed to the increased surface area to volume ratio and to the confinement-induced suppression of the phase transition from Pd/H solid solution (α-phase) to Pd hydride (β-phase).
authors.affiliation: Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Xiao-Qiao
authors.initials: XQ
authors.lastname: Zeng
authors.forename: Yong-Lei
authors.initials: YL
authors.lastname: Wang
authors.forename: Henry
authors.initials: H
authors.lastname: Deng
authors.forename: Michael L
authors.initials: ML
authors.lastname: Latimer
authors.forename: Zhi-Li
authors.initials: ZL
authors.lastname: Xiao
authors.forename: John
authors.initials: J
authors.lastname: Pearson
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Hsien-Hau
authors.initials: HH
authors.lastname: Wang
authors.forename: Ulrich
authors.initials: U
authors.lastname: Welp
authors.forename: George W
authors.initials: GW
authors.lastname: Crabtree
authors.forename: Wai-Kwong
authors.initials: WK
authors.lastname: Kwok