Colouration process of colloidal tungsten oxide nanoparticles in the presence of hydrogen gas

• Published in: Applied surface science 2012-10, Vol.258 (24), p.10089-10094
• Main Authors: Tahmasebi Garavand, N., Ranjbar, M., Mahdavi, S.M., Iraji zad, A.
• Format: Article
• Language: English
• Subjects: Ablation; Bubbling; Colloiding; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Exposure; Gasochromic; Laser ablation; Light scattering; Nanoparticles; Optical absorption; Palladium; Physics; Surface chemistry; Tungsten oxide nanoparticles; Tungsten oxides
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.06.081

[Display omitted] ► Tungsten oxide nanoparticles were prepared by pulsed laser ablation (PLA). ► Hydrogen catalyst (Pd) was deposited on tungsten oxide nanoparticles surface. ► After exposing the colloidal nanoparticles to hydrogen gas coloration occurs. ► An absorption peaks (1.6eV) appeared at the initial moments of hydrogen exposing. ► Two other peaks (1.26, 1.97eV) become dominant at long hydrogen exposure times. In this study, tungsten oxide nanoparticles were fabricated by pulsed laser ablation (PLA) of tungsten target using the first harmonic of a Nd:YAG laser (1064nm) in deionized water. After ablation, a 0.2g/lit PdCl2 solution was added to activate the solution against the hydrogen gas. Dynamic light scattering and X-ray photoelectron spectroscopy were used to measure the average size and the surface chemical composition of the synthesized nanoparticles, respectively. The aim is to investigate the influence of hydrogen exposure time on colouration process of colloidal nanoparticles. According to optical measurements, hydrogen bubbling into the produced colloidal Pd–WO3 led to formation of several absorption peaks at ∼1.26, ∼1.6 and ∼1.97eV. We observed the appearance and growth of a peak at 1.6eV at the initial stages of hydrogen exposure. However, two other peaks became dominant at long exposure times. The coloration process is reversible in the presence of oxygen gas.