Hydrogen Sensing and Detection

Soundarrajan, P.; Schweighardt, F.K.

doi:10.1201/9781420045772.ch15

Cited by 24 publications

(27 citation statements)

References 23 publications

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“…The considered structures of PdPc and PdPcF 16 with V oriented hydrogen molecule, which correspond to the largest interaction energies, were used as initial scenario for total geometry optimization to obtain the more accurate binding parameters of H 2 , which are presented in Table 2. The The resistance-based sensing mechanism of semiconducting sensors has been studied in the literature [41]. The commonly accepted mechanism is based on the variation of the surface electron depletion region due to the reaction between hydrogen and the chemisorbed oxygen on the surface.…”

Section: Theoretical Study Of Hydrogen Binding To Palladium Phthalocymentioning

confidence: 99%

Thin Films of Unsubstituted and Fluorinated Palladium Phthalocyanines: Structure and Sensor Response toward Ammonia and Hydrogen

et al. 2017

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In the present work, we study and compare the structure and sensing properties of thin films of unsubstituted palladium phthalocyanine (PdPc) and hexadecafluorosubstituted palladium phthalocyanine (PdPcF 16 ). Thin films of PdPc and PdPcF 16 were obtained by the method of organic molecular beam deposition and their structure was studied using UV-visible spectroscopy, X-ray diffraction and atomic force microscopy techniques. The electrical sensor response of PdPc films toward ammonia and hydrogen was investigated and compared with that of PdPcF 16 films. The nature of interaction between the phthalocyanines films and some gaseous analyte molecules has been clarified using Quantum chemical (DFT) calculations.

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Section: Theoretical Study Of Hydrogen Binding To Palladium Phthalocymentioning

confidence: 99%

Thin Films of Unsubstituted and Fluorinated Palladium Phthalocyanines: Structure and Sensor Response toward Ammonia and Hydrogen

et al. 2017

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“…The optimum Pd thickness for perfect absorption is around 7 nm and changes minimally along the spectrum with changing the SiO 2 thickness. The ultra-thin nature of the Pd metal allows faster H 2 uptake and more sensitivity in a sensing environment [25,26]. When the Pd is 7 nm, the reflection coefficient at the resonance wavelength λ ∼ 518 nm becomes ∼3 × 10 −6 to achieve perfect absorption, and the largest RIC value obtained at ∼518 nm is 2.93 × 10 4 [ Fig.…”

mentioning

confidence: 99%

Perfectly absorbing ultra thin interference coatings for hydrogen sensing

et al. 2016

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Here we numerically demonstrate a straightforward method for optical detection of hydrogen gas by means of absorption reduction and colorimetric indication. A perfectly absorbing metal-insulator-metal (MIM) thin film interference structure is constructed using a silver metal back reflector, silicon dioxide insulator, and palladium as the upper metal layer and hydrogen catalyst. The thickness of silicon dioxide allows the maximizing of the electric field intensity at the Air∕SiO 2 interface at the quarter wavelengths and enabling perfect absorption with the help of highly absorptive palladium thin film ∼7 nm. While the exposure of the MIM structure to H 2 moderately increases reflection, the relative intensity contrast due to formation of metal hydride is extensive. By modifying the insulator film thickness and hence the spectral absorption, the color is tuned and eyevisible results are obtained. Hydrogen H 2 sensing requires development of highly sensitive, reliable, and short response-time sensors due to its use in critical applications such as fuel-cells, pharmaceuticals, and petroleum and chemical production. Palladium (Pd) can absorb H 2 upon exposure and transform into palladium hydride PdH x , and the optical and electrical properties of Pd metal are changed by such transformation [1]. Recent advancements in plasmonic research and nanofabrication techniques led the development of surface and localized surface plasmon-based (LSPR) hydrogen sensors using Pd [2][3][4]. Nanoparticle or LSPR sensors show good potential for faster response times [5,6]. However, the broad spectral response of LSPR-based hydrogen sensors arises as an issue, which, later on, led the researchers to reduce the linewidth with the help of a whispering gallery mode cavity [7], and to develop highly sensitive hybrid sensors such as using Pd with a good plasmonic metal [8,9]. For example, Alivisatos and co-workers have demonstrated highly sensitive hydrogen sensors by placing Pd nanoparticles close to the sharp corners of nanoantennas [10].Such sensing mechanisms are based on probing of the scattering properties of nanoantenna-Pd nanoparticle structure, rather than the direct probing of scattering properties of Pd nanoparticles that shows small wavelength shifts upon hydrogen exposure. Other important plasmon-based hydrogen sensing mechanism is based on plasmonic-perfect absorbers [11][12][13], and single crystal Pd and its alloy-coated nanowires [14,15]. The motivation behind the absorbance-based sensors is to minimize the requirement for the bulky optical setups, expensive light sources, and spectrometers by only probing the scattered light intensity at perfect-absorption wavelength. Moreover, some of the recent studies report the visual detection of hydrogen by using thin film optical coatings to circumvent the problems of hydrogen sensors based on electrical readout [16,17]. Despite the demonstration of visual detection of H 2 , the thin film structure did not take full advantage of the lossy nature of Pd films. In this study, we demo...

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Section: Introductionmentioning

confidence: 97%

“…Among flammable gases such as gasoline, propane, ethane, methane, and propylene, H 2 has a larger flammability range (4-75%, v/v) [1]. Moreover, H 2 is the lightest of all elements and the smallest molecule, it has the greatest tendency to leak [1]. Hence, advanced H 2 sensors are critical for many safety applications in fields where hydrogen is present and the risk of hydrogen leaks exists, even at a few ppm [1,2].…”

Section: Introductionmentioning

confidence: 99%