Three-Layer PdO/CuWO4/CuO System for Hydrogen Gas Sensing with Reduced Humidity Interference

Abstract

The growing hydrogen industry is stimulating an ongoing search for new materials not only for hydrogen production or storage but also for hydrogen sensing. These materials have to be sensitive to hydrogen, but additionally, their synthesis should be compatible with the microcircuit industry to enable seamless integration into various devices. In addition, the interference of air humidity remains an issue for hydrogen sensing materials. We approach these challenges using conventional reactive sputter deposition. Using three consequential processes, we synthesized multilayer structures. A basic two-layer system composed of a base layer of cupric oxide (CuO) overlayered with a nanostructured copper tungstate (CuWO4) exhibits higher sensitivity than individual materials. This is explained by the formation of microscopic heterojunctions. The addition of a third layer of palladium oxide (PdO) in forms of thin film and particles resulted in a reduction in humidity interference. As a result, a sensing three-layer system working at 150 °C with an equalized response in dry/humid air was developed.

Preparation and Hydrogen-Sensitive Property of WO3/Graphene/Pd Ternary Composite

“…It can be found that Pd element was mainly metallic Pd 0 located at 335.3 and 340.55 eV. Additionally, there were other peaks of oxidized Pd 2+ located at 336.6 and 341.85 eV and Pd 4+ located at 338.2 and 343.45 eV [32]. This also corresponds to the XRD spectra.…”

“…It can be found that Pd element was mainly metallic Pd 0 located at 335.3 an 340.55 eV. Additionally, there were other peaks of oxidized Pd 2+ located at 336.6 and 341.8 eV and Pd 4+ located at 338.2 and 343.45 eV [32]. This also corresponds to the XRD spectr A small amount of oxidized Pd came from the partial oxidation of surface atoms of P nanoparticles by air due to their high activity.…”

Exploring the Redox Properties of the Low-Miller Index Surfaces of Copper Tungstate (CuWO4): Evaluating the Impact of the Environmental Conditions on the Water Splitting and Carbon Dioxide Reduction Processes

“…The morphologies of the CuWO 4 nanocrystals in different environments, that is, under synthesis conditions, – the conditions for carbon dioxide reduction, ,, and the conditions for water splitting, – were determined based on the surface phase diagrams discussed in the previous sections. The Wulff morphologies were constructed using the atomic configuration with the lowest surface free energy for each surface, using the following relationships σ 1 d 1 = σ 2 d 2 = · · · = σ n d n = c , where σ and d represent the surface free energy and the distance from the center to the surface of the crystal.…”

Gas Sensing Properties of CuWO4@WO3 n-n Heterojunction Prepared by Direct Hydrolysis of Mesitylcopper (I) on WO3·2H2O Nanoleaves

“…The sensor exhibited a three times higher response towards n-butanol as compared to the sensitive layer composed of pristine WO 3 . Kumar [20] proposes CuWO 4 /WO 3-x films, prepared by reactive magnetron sputtering, for hydrogen sensing and proves its enhanced performance towards this gas as compared to pristine CuO and WO 3 . Finally, Wang [21] studies the role of electron transfer behavior induced by CO chemisorption on visible-light-driven CO conversion over WO 3 and CuWO 4 /WO 3 in order to explain its higher gas sensing performance.…”