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.
Highlights
As one of the green energy carriers, hydrogen is one of the attractive measures for solving the energy supply security and the greenhouse gas reduction because of its favorable energy density, renewability, and eco-friendly nature
Palladium (Pd) and its alloy or composite films are mostly utilized as sensitive components in optical fiber hydrogen sensors for the high sensitivity and selectivity of Pd to the hydrogen gas
Due to changes of the mechanical stress and optical constants triggered by the hydrogenation process of Pd films, optical hydrogen sensors based on various modulation methods have been reported, such as signal intensity [2], wavelength [3], interference path length [4], and polarization state [5]
Summary
As one of the green energy carriers, hydrogen is one of the attractive measures for solving the energy supply security and the greenhouse gas reduction because of its favorable energy density, renewability, and eco-friendly nature. An improved sensor response time to below one second achieved within the 0−40 mbar pressure range by utilizing 25 atom % Au alloy NPs. Other Pd nanostructures, such as single Pd-Au nanofocus [19] and single Pd nanowire [20], have been studied for their high sensitivity, but the weak modulation effects of the single nanostructure request expensive apparatus. Au-Pd core-shell nanocrystal film samples was measured This method is independent of precision equipment and apparatus (such as sputter coater, rotary evaporator, or atomic layer), and is easy to realize the light path system. It has presented a simple and promising means to fabricate a hydrogen optical fiber sensor with high performance and low cost
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