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

摘要

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 degrees C, lower than typical ALD reaction temperatures for these metal oxides. The ultrathin coatings (up to similar 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.