Ab initioatomistic thermodynamics study of the early stages of Cu(100) oxidation

Abstract

Using an ab initio atomistic thermodynamics framework, we identify the stable surface structures during the early stages of Cu(100) oxidation at finite temperature and pressure conditions. We predict the clean surface, the 0.25 monolayer oxygen-covered surface, and the missing-row reconstruction as thermodynamically stable structures in range of 100-1000 K and 10 −15 -10 5 atm, consistent with previous experimental and theoretical results. We also investigate the thermodynamic stabilities of possible precursors to Cu 2 O formation including missing-row reconstruction structures that include extra on-or subsurface oxygen atoms as well as boundary phases formed from two missing-row nanodomains. While these structures are not predicted to be thermodynamically stable for oxygen chemical potentials below the nucleation limit of Cu 2 O, they are likely to exist due to kinetic hindrance.

Calculations of oxide formation on low-index Cu surfaces

“…The Cu(100) 0.25 ML, Cu(100)-MRR, and Cu 2 O (Cu 2 O(111) surface is the most stable among low-index Cu 2 O surfaces) 58 are located on the convex hull, in agreement with the previous reports. 19,24,59 The Cu(100)-c(2 ⇥ 2) 0.5 ML structure, however, which was not shown in the phase diagrams of the previous work, 19,24 is found on our hull. According to the same slope of the 0.25 ML and c(2 ⇥ 2) 0.5 ML, the c(2 ⇥ 2) 0.5 ML can be observed while 0.25 ML cannot under a certain oxygen partial pressure because of the lack of a controlled O/Cu ratio.…”

“…Based on x-ray photoelectron spectroscopy (XPS), x-ray induced Auger electron spectroscopy (XAES), and scanning tunneling microscopy (STM) characterization of Cu(100) oxidation, it was understood that subsurface oxidation leads to the growth of disordered Cu 2 O. 22,23 Based upon the observed oxidation of the Cu(100) surface, [24][25][26][27][28] it is believed that the nucleation of Cu 2 O on the Cu(110) surface is also initiated by subsurface oxygen. 29,30 Although there are fewer studies of the Cu(111) surface, STM measurements suggest a) X. Lian and P. Xiao contributed equally to this work.…”

Surface-Step-Induced Oscillatory Oxide Growth

“…These Cu facets are oxide-free and ideal for in-situ TEM observations of oxidation. Within the range of temperature and pressure employed in the study, only Cu 2 O is expected to form [4,5], which was also confirmed by in-situ electron energy loss spectroscopy analysis (see Supplemental Material [6]). The DFT calculations were performed using the Vienna abinitio simulation package (VASP) [7,8].…”

Step-Edge Directed Metal Oxidation

“…An estimated 137 quadrillion (10 15 ) Joule of energy are lost yearly due to high-temperature corrosion problems 6 . Although the oxidation reaction of metal surfaces is highly complicated, different elementary processes, many of which are coupled, are involved from the onset of reaction.One good example for the metal oxidation study is the low-miller index surfaces of copper [7][8][9][10][11][12][13] . Recent studies using modern electron microscopy (EM) have revealed that the initial stages of Cu oxidation bear a striking resemblance to heteroepitaxial film growth where interfacial strain is the key factor in thin film growth and determines the shape of the oxide nano-island [14][15][16][17][18][19] .…”