Enhanced oxidation resistance of active nanostructures via dynamic size effect

Abstract

A major challenge limiting the practical applications of nanomaterials is that the activities of nanostructures (NSs) increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Here, using FeO NSs as an example, we show to the contrary, that reducing the size of active NSs can drastically increase their oxidation resistance. A maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. Rather than being determined by the structure or electronic properties of active sites, the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. We find this dynamic size effect to govern the chemical properties of active NSs.

Tuning the activities of cuprous oxide nanostructures via the oxide-metal interaction

“…1). Their atomic structures, both on the surface and at the step edge, could be clearly identified by ES-STM images [27][28][29] (Fig. 1).…”

Origin of nanoscale heterogeneity in the surface oxide film protecting stainless steel against corrosion

“…For both type of morphologies, at least one side of the islands is oriented along one of the 〈011〉 directions of the substrate, indicating epitaxial relationships between the oxide island structures and the substrate. The triangular oxide islands likely consist of iron oxide as supported by XPS 9 and could correspond to (111)-oriented crystallites adopting structures of trigonal symmetry like those of FeO, 24 Fe 3 O 4 , 22,25 or γ-Fe 2 O 3 . 22 Since (0001)-oriented α-Fe 2 O 3 presents a hexagonal structure based on STM examinations, 22,26 this possibility is not retained at this stage.…”

Investigation of the Tribofilm Formation of HiPIMS Sputtered MoSx Thin Films in Different Environments by Raman Scattering

“…For the ball-on-disk experiments in N 2 and air atmospheres, in which the highest wear coefficients were measured, the wear of the MoS x films leads to particles whose sizes are assumed to be in the range of at least several micrometers (larger than the exciting laser wavelength). For such sizes of particles, also made from MoS 2 , the chemical reactivity, in particular, the tendency of oxidation decreases, since the small surface areas of the particles limit the rate of oxidation [30,31]. Additionally, the scattering probability may become enlarged, while the probability of absorbing visible light and, in turn, inducing heat may be reduced.…”