Kinetic Analysis of Multi-Channel Hydrogen Reactions on Plasmonic Based Au-GdC Thin Film Nanocomposites

The reaction kinetics of hydrogen on gold nanoparticles (AuNP) embedded in gadolinium doped ceria has been studied in an oxygen-free environment through the time dependent analysis of the localized surface plasmon resonance (LSPR) peak of AuNPs. The change in LSPR peak position over time during gas exposure is extracted from the absorbance spectra and is used as the sensing signal. The signal transduction is proposed to be a combination of charge exchange from hydrogen dissociation on AuNP surface to form the intermediate Au-hydride species and atomic hydrogen spillover to the GdC matrix. The reaction kinetics study carried out at 500°C for 5 to 20% H2 in N2 showed a linear relation between the rate of reaction and "P" _("H" _2)^(1⁄2), indicating that H2 dissociative adsorption is the rate limiting step for the initial sensing response. A subsequent spillover type mechanism induces a secondary red shift of the plasmon peak position. From an Arrhenius analysis the activation energy determined for hydrogen ...