Hydrogen responses of ultrathin Pd films and nanowire networks with a Ti buffer layer

Abstract

We report on hydrogen responses of ultrathin films and nanowire networks of palladium on titanium buffered silicon substrates and filtration membranes, respectively. We found that in both systems signatures such as retarding responses and saturation of the resistance changes at high hydrogen concentrations associated with the transition from Pd/H solid solution to Pd hydride diminish with decreasing the thickness of the palladium layer from 7 to 2 nm. Our results not only reveal a new way to suppress the phase transition in Pd/H system but also provide an alternative approach to achieve fast and sensitive hydrogen sensors with a wide concentration detection range.

Nanostructures of Pd–Ni alloy deposited on carbon fibers for sensing hydrogen

“…After absorbing 1.5% hydrogen gas, the nanoparticle sensor spends more than 2000 s to recover to original baseline level in pure argon, but the recovery time of the nanofilm sensor is only less than 1000 s. In addition, as shown in Fig. 10 recovery time of the nanofilm sensor after exposure to 2% H 2 is about 500 s and recovery time of the nanoparticle sensor after exposure to 0.5% H 2 is about 980 s. The results are close to the re- sult obtained by Rahimi et al [36], but better than the result obtained by Zeng et al [3]. For sensing hydrogen gas with higher concentration (>3%), it takes two or three days to recover the baseline level for the nanoparticle with large diameter, and the recovery time of the nanofilm was less than 24 h.…”

“…2. In this article, to avoid interference of complex gas and study behaviors of Pd-Ni alloy nanofilm and nanoparticles in H 2 , we chose argon as the carrier gas like many researchers' choice [3,23,29]. The concentration of hydrogen in argon was adjusted from 0% to 10% (V/V) by blending commercially standard H 2 -Ar mixture with pure argon through a gas-blending system.…”

“…And then, introducing air into the sample chamber accelerates the recovery process. Taking the recently published works [3,37] and our experimental results, the probable reactions that take place during hydrogen exposure and recovery stages have been proposed:…”

“…For example, Pd nanofilms, nanowires and nanoparticles [1][2][3] have been widely applied in hydrogen sensors. Many methods have been applied to prepare of different nanostructures, including thermal evaporation [4], electroless technique [5], electrochemical step-edge decoration [6,7], self-assembly [8], sputter deposition [9], and so on.…”

Reliability of Sensors Based on Nanowire Networks With Either an Equilateral Triangle Lattice or a Hexagonal Lattice Structure

“…D UE to their large surface area to volume ratio and available space for making electrical contacts, individual nanowires have been widely considered as interconnects or sensing elements in nanodevices [1]- [3]. For example, hydrogen gas (H 2 ) sensors based on individual palladium (Pd) nanowires show much improved performance in speed, sensitivity, and ultralow power consumption in comparison to their counterparts based on palladium thin or thick films.…”