First Combined Electron Paramagnetic Resonance and FT-IR Spectroscopic Evidence for Reversible O2 Adsorption on In2O3–x Nanoparticles

• Published in: Journal of physical chemistry. C Vol. 117; no. 40; pp. 20722 - 20729
• Main Authors: Siedl, Nicolas, Gügel, Philipp, Diwald, Oliver
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 10.10.2013
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Materials science; Nanoscale materials and structures: fabrication and characterization; Other topics in nanoscale materials and structures; Physics; Solid surfaces and solid-solid interfaces; Surface and interface electron states; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Conduction bands; Temperature dependence; Electronic properties; Fourier transform spectroscopy; Pressure effects; Conduction electron; Nanostructures; Sensor materials; Nanoparticles; Adsorption; Electron paramagnetic resonance; Absorption spectra; Nanostructured materials
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp4069834

Adsorption-induced electronic property changes determine the performance of nanostructured transparent conductive oxides and sensor materials. For the study of O2 adsorption on electron rich In2O3–x nanoparticles we used transmission FT-IR spectroscopy in combination with electron paramagnetic resonance (EPR). The reversible emergence and annihilation of conduction band electrons is subject to O2 adsorption and was tracked at different oxygen pressures via IR active Drude absorptions. Corresponding results were related to EPR measurements that were performed under identical experimental conditions. For the first time we identified a weak adsorption complex between O2 and the surface of In2O3–x nanoparticles in the temperature range between T = 90 K and T = 298 K. Complementing and supporting our FT-IR observations, this evidence opens the way to study sensing relevant adsorption processes at room temperature with spectroscopy.