Unusual layer-by-layer growth of epitaxial oxide islands during Cu oxidation

Abstract

Elucidating metal oxide growth mechanisms is essential for precisely designing and fabricating nanostructured oxides with broad applications in energy and electronics. However, current epitaxial oxide growth methods are based on macroscopic empirical knowledge, lacking fundamental guidance at the nanoscale. Using correlated in situ environmental transmission electron microscopy, statistically-validated quantitative analysis, and density functional theory calculations, we show epitaxial Cu2O nano-island growth on Cu is layer-by-layer along Cu2O(110) planes, regardless of substrate orientation, contradicting classical models that predict multi-layer growth parallel to substrate surfaces. Growth kinetics show cubic relationships with time, indicating individual oxide monolayers follow Frank-van der Merwe growth whereas oxide islands follow Stranski-Krastanov growth. Cu sources for island growth transition from step edges to bulk substrates during oxidation, contrasting with classical corrosion theories which assume subsurface sources predominate. Our results resolve alternative epitaxial island growth mechanisms, improving the understanding of oxidation dynamics critical for advanced manufacturing at the nanoscale.

Computational Catalyst Design for Dry Reforming of Methane: A Review

“…Within the DFT framework, simulated relaxations resolve stable adsorption state energies, and transitional reaction or activation barriers are calculated by the nudged elastic band (NEB) or dimer method . Thermodynamic favorability in reactions is assessed by comparing the adsorption energies of the reactants and products to determine the initial (endothermic) or final (exothermic) reaction states . Kinetic favorability within a single process is determined by the reaction with the highest energetic barrier in that process or its rate-determining step (RDS) .…”

Visualizing the Nanoscale Oxygen and Cation Transport Mechanisms during the Early Stages of Oxidation of Fe–Cr–Ni Alloy Using In Situ Atom Probe Tomography

“…Understanding the oxidation mechanisms of solid materials and analyzing the resultant distribution of oxygen isotopes at nanoscale spatial resolution is pivotal to understanding of a wide variety of processes, including material degradation, [1][2][3][4][5] corrosion of engineered materials, [6][7][8] microorganism corrosion, [9] oxidation of anodes in solid oxide fuel cells, [10] and catalysis. [11,12] In geological sciences mapping 18 O in solid minerals tracer and an environmental reactor chamber attached to the APT system.…”

“…[17] Among the different methods used to study the oxidation mechanisms in solid materials, in situ environmental transmission electron microscopy (TEM) and in situ scanning tunneling microscopy are powerful for studying the atomic-scale structural changes associated with the early stages of oxidation. [1,3,5,18,19] However, these in situ techniques lack the sensitivity to distinguish individual oxygen isotopes. At the same time, nanosecondary ion mass spectrometry (SIMS) and other massspectrometry-based techniques, which are highly sensitive for oxygen isotopes, lack 3D sub-nanometer-scale spatial resolutions.…”

Quantifying Real-Time Sample Temperature Under the Gas Environment in the Transmission Electron Microscope Using a Novel MEMS Heater

“…In situ heating experiments inside an electron microscope, such as the transmission electron microscope (TEM), have been widely used to study dynamic processes of temperature-induced structural transitions, including phase transformation, melting/sublimation (Asoro et al, 2013; Li et al, 2019), high-temperature degradation (Divitini et al, 2016; Wang et al, 2020 b ), and precipitation (Chen et al, 2006; Liu et al, 2017). In recent years, the rapid development of environmental TEM (ETEM) has brought more possibilities for in situ heating experiments, especially in gas–solid reaction-related fields such as catalyst reaction (Hansen et al, 2002; Hofmann et al, 2007; Simonsen et al, 2010; Behrens et al, 2012; Baldi et al, 2014; Vendelbo et al, 2014; Panciera et al, 2015; Chi et al, 2020), nanostructure growth (Sharma & Iqbal, 2004; Kodambaka et al, 2007; Hudak et al, 2014; Rackauskas et al, 2014; Panciera et al, 2015), and corrosion (Zhou et al, 2012; Zou et al, 2017, 2018; Luo et al, 2018; Curnan et al, 2019; Li et al, 2020; Wang et al, 2020 a ). Accurate control and measurement of the real sample temperature under experiment conditions are critical for the understanding and interpretation of the experimental results.…”