| AVS 58th Annual International Symposium and Exhibition | |
| Nanometer-scale Science and Technology Division | Tuesday Sessions |
| Session NS-TuP |
| Session: | Nanometer-scale Science and Technology Division Poster Session |
| Presenter: | Nicholas Joy, University of Albany-SUNY |
| Authors: | N.A. Joy, University of Albany-SUNY M.I. Nandasiri, Western Michigan University T. Varga, Pacific Northwest National Laboratory V. Shutthanandan, Pacific Northwest National Laboratory W. Jiang, Pacific Northwest National Laboratory P. Nachimuthu, Pacific Northwest National Laboratory S.V.N.T. Kuchibhatla, Pacific Northwest National Laboratory S. Thevuthasan, Pacific Northwest National Laboratory M.A. Carpenter, University of Albany-SUNY |
| Correspondent: | Click to Email |
Au doped cerium oxide (CeO2) material system has exhibited high activity, good selectivity and stability for low-temperature catalytic reactions. Recently, highly dispersed Au nanoparticles supported on metal oxides including CeO2 have attracted a great deal of attention due to their high catalytic activity. Au nanoparticles are also promising candidates for plasmonic applications due to the sensitivity of their surface plasmon resonance (SPR) band to changes in the environment. In this study, we report the growth, characterization, and gas sensing properties of Au nanoparticles embedded in CeO2 as optical beacons for the detection of H2, CO and NO2 in harsh environment.
CeO2 thin films were grown on Al2O3(0001) by oxygen plasma-assisted molecular beam epitaxy (OPA-MBE). Following the MBE growth and in-situ characterization by reflection high energy electron diffraction (RHEED), as-grown CeO2 thin films were irradiated by 2.0 MeV Au2+ ions generated in a tandem accelerator with high fluence of 1× 1017 ions/cm2 at 600°C. Subsequently, Au implanted ceria films were annealed at 600°C for 10 hours in air to form well defined Au nanoclusters. As-grown, irradiated, and annealed CeO2 thin films were characterized by Rutherford backscattering spectrometry (RBS), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD) techniques. The streaky RHEED patterns from the as-grown films indicate the epitaxial growth of the CeO2 thin films. Glancing incidence XRD (GIXRD) pattern of the as-grown 300 nm thick ceria film indicates the presence of some polycrystalline material. Following the Au implantation at 600°C, GIXRD pattern shows the Au peaks and the reflections associated with ceria-alumina inter-mixing phase (CeAlO3) in addition to CeO2 peaks. It suggests the inter-diffusion of metal atoms at the ceria-alumina interface, which is possibly due to the bombardment of high energy Au2+ ions. RBS data of the Au-implanted CeO2 sample also confirmed the inter-diffusion of the metal atoms at the film/substrate interface. Furthermore, the broader x-ray rocking curve of the CeO2(111) reflection after Au implantation confirm the crystalline disorder of the CeO2 film caused by irradiation. Despite the inter-diffusion and poor crystalline quality, both CeO2 and Au crystallites are highly-oriented in (111) direction. After annealing and ex-situ characterization of Au/CeO2 sample, SPR analysis and gas exposure experiments were performed in a high temperature optical transmission cell. The ppm level gas exposure experiments with the Au/CeO2 sample has shown promising sensing characteristics towards the detection of H2, NO2 and CO in an air background at 500°C.