Variable-temperature Raman spectroscopic study of the hydrogen sensing mechanism in Pt-WO3 nanowire film

Abstract

Two special properties of Pt coated WO3 (Pt-WO3) nanowire film for sensing hydrogen gas flow in air are reported in this paper, including the large relative resistance change (close to 100%) and the dependence of the millisecond-scale response time on operating temperature. A variable-temperature Raman spectroscopic system is applied to record the structural changes of WO3 nanowires in situ during the input of H2 gas at different operating temperatures. Furthermore, based on the experimental results, two combined models are proposed to be responsible for the hydrogen sensing mechanism in Pt-WO3 nanowire film.

Mechanistic Understanding of Efficient Polyethylene Hydrocracking over Two‐Dimensional Platinum‐Anchored Tungsten Trioxide

“…Moreover, a 3 cm À 1 shift of WÀ O stretching vibrations (at 699, 796 cm À 1 ) was observed in the Raman spectra (Figure 4g), indicating a length change for the WÀ O bonds. [39,40] This might be contributed by the dissociated H that migrated to the WO 3 , most likely by a hydrogen spillover effect, [37,41,42] reducing W 6 + to W 5 + [43] (Figure 4e). Stronger absorption at 500-800 nm in the UV/ Vis diffuse reflectance spectra (Figure 4h) after hydrogenation is attributed to chemisorbed H. [25] The hydrogen transfer over Pt/WO 3 was also supported by the smaller optical band gap (E g ) (calculated via Tauc's formula) of hydrogenated Pt/WO 3 (ca.…”

“…As inferred from the negligible H 2 binding capability of unloaded WO 3 compared to Pt/WO 3 (detected by H 2 À TPD, Figure S8), hydrogen dissociation predominantly took place on Pt sites, which is consistent with previous studies. [37][38][39] We next compared the XPS, Raman, and UV/Vis diffuse reflectance spectra of 2D Pt/WO 3 before and after the hydrogenation. It was found that the relative percentage of W 5 + increased from 17 % to 22 % after hydrogenation (see XPS results in Figure 4e and Table S4) and surface oxygen species were consumed (Figure 4f).…”

Mechanism of Interfacial Molecular Interactions Reveals the Intrinsic Factors for the Highly Enhanced Sensing Performance of Ag-Loaded Co3O4

“…25 In parallel, in situ Raman spectroscopy can track the structural evolutions of sensing material during gas sensing. 26 1d,e). The small nanoparticle showed a lattice distance of 0.24 nm, corresponding to the (111) crystal plane of the metallic Ag (Figure 1f).…”

Sinter-free inkjet-printed PEDOT:PSS/WO3/PEDOT:PSS flexible valency change memory

“…Recently, tungsten trioxide (WO 3 ), which is one of the binary TMO materials, has attracted significant attention for application in ReRAM devices [11][12][13][14][15][16][17][18][19][20] . WO 3 is a n-type, wide-bandgap semiconductor with an electronic bandgap (E g ) reported between 2.6 and 3.2 eV depending upon the crystallinity [12], which could be tailored according to the requirements by controlling the size of the nanoparticles; it decreases with size due to the quantum confinement effect [13].…”

“…Additionally, it is an important electrochromic material being transparent for most part of the visible spectrum. Its optical transmittance can be modulated by the presence of reducing gases (N 2 ) [14], external electrical stimulus [15] and heat [16]. Furthermore, it could be utilized as a photocatalytic [17], thermoelectric [18,19], and even ferroelectric material in ε-WO 3 form [19].…”