Passivating Polycrystalline Copper with an Ultrathin Samarium Layer

Abstract

We report how a layer of samarium (Sm) with a thickness equivalent to ∼ 2 atoms (0.8 nm) deposited by thermal evaporation is remarkably effective at passivating polycrystalline copper (Cu) towards oxidation in ambient air. To monitor the rate of Cu oxidation in real time, slab‐like Cu films with a thickness of 9 nm were fabricated on glass modified with a layer of 3‐mercaptopropyl silatrane, which immobilises condensing Cu atoms by reaction with the thiol moiety, promoting slab‐like film formation at very low thickness. Upon exposure to ambient air the rate of increase in electrical resistance due to reaction with oxygen and water is slowed by more than an order of magnitude when the Cu film is capped with the ultra‐thin Sm layer. After 1 year the resistance increases by ∼30% as compared to ∼190% for Cu films without an ultra‐thin Sm layer. Photoelectron spectroscopy, atomic force microscopy and Kelvin probe measurements shed light on the underlying mechanism of passivation. Additionally, the ultra‐thin Sm layer is greatly lowering the work function of polycrystalline Cu films making this approach attractive for applications requiring a low work function electrode with high stability in air.This article is protected by copyright. All rights reserved.

Tuning the CO2 Hydrogenation Activity via Regulating the Strong Metal–Support Interactions of the Ni/Sm2O3 Catalyst

“…From the atomic resolution STEM image of Figure d, it is observed that the average thickness of the SMSI overlayer is 1.9 ± 0.2 nm. The amorphous Sm 2 O 3 layer can be associated with the inherent defects such as oxygen deficiency. − The higher work function of nickel (5.0–5.3 eV) compared to reducible oxide Sm 2 O 3 (2.7–2.8 eV) facilitates the electron transfer from Sm 2 O 3 to Ni within the Ni/Sm 2 O 3 system. , As proposed by Fu et al, this electron transfer drives the transport and migration of Sm 2 O 3 species over Ni nanoparticles, resulting in the formation of an encapsulating layer . Therefore, with annealing at H 2 /N 2 = 1:4, the surface of Ni nanoparticles would be covered with Sm 2 O 3 through a surface diffusion process.…”