Atomic layer deposited conformal ceramic coatings for anti-corrosion of Ag nanoparticles

Abstract

The goal of this work is to explore atomic layer deposition (ALD) as a thin film coating technique to inhibit corrosion of metal nanoparticles, given the technique’s ability to form a conformal coating on high aspect ratio substrates. Various coating materials, including Al2O3, ZrO2, HfO2, and TiO2 of different thicknesses were coated on Ag nanoparticles (NPs) in a fluidized bed ALD reactor. To avoid sintering of Ag NPs during the ALD process, the reaction temperature was set to 100 °C, lower than typical ALD reaction temperatures for these metal oxides. The ultrathin coatings (up to ~10 nm thick) were conformally deposited on the surface of Ag NPs. During the corrosion tests in a neutral 3.5 wt% NaCl solution, the corrosion current density was lowered by more than one order of magnitude; in an acid 0.5 M H2SO4 solution, the stabilities of different thin coatings were compared. Ultraviolet–visible spectra of coated Ag NPs showed retention of surface plasmonic resonance.