Stability of Plasmonic Mg-MgO Core–Shell Nanoparticles in Gas-Phase Oxidative Environments

Abstract

Magnesium is a recent addition to the plasmonic toolbox: nanomaterials that efficiently utilize photons' energy due to their ability to sustain localized surface plasmon resonances. Magnesium nanoparticles protected by a native oxide shell can efficiently absorb light across the solar spectrum, making them a promising photocatalytic material. However, their inherent reactivity toward oxidation may limit the number of reactions in which Mg-MgO can be used. Here, we investigate the stability of plasmonic Mg-MgO core−shell nanoplates under oxidative conditions. We demonstrate that the MgO shell stabilizes the metallic Mg core against oxidation in air at up to 400 °C. Furthermore, we show that the reactivity of Mg-MgO nanoplates with water vapor (3.5 vol % in N 2 ) decreases with temperature, with no oxidation of the Mg core detected from 200 to 400 °C. This work unravels the potential of Mg-MgO nanoparticles for a broad range of catalytic transformations occurring in oxidative environments.

Magnesium Nanoparticles for Surface-Enhanced Raman Scattering and Plasmon-Driven Catalysis

“…Colloidally synthesized Mg NPs have a native, self-limiting MgO layer that is protective in gas phase oxidative environments up to 400 °C but susceptible to water. , The incubation of Mg NPs with the Raman reporter molecules 4-MBA and 4-NBT − was thus performed in IPA to avoid degradation of Mg; ethanol and methanol could also be used but lead to poorer colloidal stability than IPA. NPs retain their metallic cores postincubation, as confirmed by the Mg bulk plasmon peak indicating metallic Mg, at ∼10.1 eV in STEM-EELS (Figures C,D and S3).…”