Comparison of surface plasmon resonance responses to dry/wet air for Ag, Cu, and Au/SiO_(2)

摘要

We investigated the optical absorption spectra of Ag-, Cu-, and Au-mesoporous SiO_(2) systems, respectively, after the samples were heated in dry air and in wet air. As expected, dry air at high temperature leads to the surface plasmon resonance (SPR) disappearance of Ag-SiO_(2) and Cu-SiO_(2) and a slight SPR increase of Au-SiO_(2). However, a small amount of water vapor in air induces a strong SPR appearance for both Ag- and Au-containing samples, indicating that water vapor plays an abnormal reduction effect on both Ag and Au species in mesoporous SiO_(2), despite the fact that it usually plays an oxidation role on Pt-group metals, but it cannot induce the SPR appearance for the Cu-containing sample under the same condition.