Centrifugal Deposited Au-Pd Core-Shell Nanoparticle Film for Room-Temperature Optical Detection of Hydrogen Gas

Abstract

In the present work, centrifugal deposited Au-Pd core-shell nanoparticle (NP) film was proposed for the room-temperature optical detection of hydrogen gas. The size dimension of 44, 48, 54, and 62 nm Au-Pd core-shell nanocubes with 40 nm Au core were synthesized following a solution-based seed-mediated growth method. Compared to a pure Pd NP, this core-shell structure with an inert Au core could decrease the H diffusion length in the Pd shell. Through a modified centrifugal deposition process, continues film samples with different core-shell NPs were deposited on 10 mm diameter quartz substrates. Under various hydrogen concentration conditions, the optical response properties of these samples were characterized by an intensity-based optical fiber bundle sensor. Experimental results show that the continues film that was composed of 62 nm Au-Pd core-shell NPs has achieved a stable and repeatable reflectance response with low zero drift in the range of 4 to 0.1% hydrogen after a stress relaxation mechanism at first few loading/unloading cycles. Because of the short H diffusion length due to the thinner Pd shell, the film sample composed of 44 nm Au-Pd NPs has achieved a dramatically decreased response/recovery time to 4 s/30 s. The experiments present the promising prospect of this simple method to fabricate optical hydrogen sensors with controllable high sensitivity and response rate at low cost.

Recent Advances in Palladium Nanoparticles-Based Hydrogen Sensors for Leak Detection

“…Typically, an experiment is performed by measuring the change in optical properties (transmittance, absorbance, reflectance, etc.) of the sensing material when switching from the carrier or recovery gas to H 2 enriched environment in a cyclic manner inside a gas chamber [10,11,12,15,90,95]. A light source is used to illuminate the sensing sample and the optical response of this latter within a set environment in the gas chamber is recorded by a photodetector.…”

“…In several cases, α to β phase transition during Pd-hydride formation is an important parameter in the detection mechanism [10]. This arises from the fact that the optical constants of the palladium hydride evolve from α to β phase and therefore its optical properties [12].…”

“…As reported by many authors [10,12,15,90,95], another key parameter is the synthesis process of the Pd NPs because it influences the morphology, structure and organization of the Pd NPs which result in specific optical properties upon sample exposure to hydrogen. In this context, for example, Corso et al [15], Kracker et al [90], and Isaac et al [95] reported an initial hydrogenation-dehydrogenation cycle in order to stabilize the sensing Pd NPs samples.…”

“…Here, the sensing sample is composed of a Si-based substrate coated by Pd NPs. With this configuration, several authors also used bimetallic Au/Pd NPs to take advantage of the well-defined plasmonic resonance of Au [10,11,95]. Therefore, this section will first focus on the use of Pd NPs for this kind of sensor, and then the use of bimetallic Au/Pd NPs will also be addressed.…”

“…To determine the efficiency of the hydrogen leak detection by the device, the sensor response time, chemical sensitivity and detection range parameters are particularly relevant. The response time is generally defined as the needed time to reach 90% of the signal maximum from the introduction of hydrogen in the sensor environment [1,6,7,8,9,10,11,12]. Accompanying the response time, the recovery time is commonly defined as the time needed to lower the signal maximum of 90%.…”