An overview of contemporary developments and the application of graphene-based materials in anticorrosive coatings

Although graphene and graphene-based materials (GBMs) offer a wide range of possible applications, interest in their use as barrier layers or as reinforcements in coatings for the mitigation of corrosion has grown during the past decade. Because of its unique two-dimensional nanostructure and exceptional physicochemical characteristics, graphene has gotten a lot of attention as an anti-corrosion material. This enthusiasm is largely driven by the requirement to integrate more features, improve anti-corrosion effectiveness, and eventually prolong the service duration of metallic components. As barriers against metal corrosion, graphene nanosheets can be applied singly or in combination to create thin films, layered frameworks, or composites. Concurrently, over the past few years, significant advancements have been made in the establishment of scalable production methods for graphene and materials based on graphene. Since there is currently a wide variety of graphene material with various morphologies and characteristics, it is even more important that the production approach and the intended application be properly matched. This review gathers the most recent data and aims to give the reader a comprehensive overview of the most recent developments in the use of graphene and GBMs in various anti-corrosion strategies. The structure-property correlation and anticorrosion techniques in these systems are given special consideration. The current article offers a critical examination of this topic as well, stressing the areas that require more research.

Locally spontaneous dynamic oxygen migration on biphenylene: a DFT study

The dynamic oxygen migration at the interface of carbon allotropes dominated by the periodic hexagonal rings, including graphene and carbon nanotubes, has opened up a new avenue to realize dynamic covalent materials. However, for the carbon materials with hybrid carbon rings, such as biphenylene, whether the dynamic oxygen migration at its interface can still be found remains unknown. Using both density functional theory calculations and machine-learning-based molecular dynamics (MLMD) simulations, we found that the oxygen migration departing away from the four-membered carbon (C₄) ring is hindered, and the oxygen atom prefers to spontaneously migrate toward/around the C₄ ring. This locally spontaneous dynamic oxygen migration on the biphenylene is attributed to a high barrier of about 1.5 eV for the former process and a relatively low barrier of about 0.3 eV for the latter one, originating from the enhanced activity of the C-O bond near/around the C₄ ring due to the hybrid carbon ring structure. Moreover, the locally spontaneous dynamic oxygen migration is further confirmed by MLMD simulations. This work sheds light on the potential of biphenylene as a catalyst for spatially controlled energy conversion and provides the guidance for realizing the dynamic covalent interface at other carbon-based or two-dimensional materials.

Growth Kinetics and Atomistic Mechanisms of Native Oxidation of ZrSxSe2-x and MoS2 Crystals

A thorough understanding of native oxides is essential for designing semiconductor devices. Here, we report a study of the rate and mechanisms of spontaneous oxidation of bulk single crystals of ZrS_xSe_2-x alloys and MoS₂. ZrS_xSe_2-x alloys oxidize rapidly, and the oxidation rate increases with Se content. Oxidation of basal surfaces is initiated by favorable O₂ adsorption and proceeds by a mechanism of Zr-O bond switching, that collapses the van der Waals gaps, and is facilitated by progressive redox transitions of the chalcogen. The rate-limiting process is the formation and out-diffusion of SO₂. In contrast, MoS₂ basal surfaces are stable due to unfavorable oxygen adsorption. Our results provide insight and quantitative guidance for designing and processing semiconductor devices based on ZrS_xSe_2-x and MoS₂ and identify the atomistic-scale mechanisms of bonding and phase transformations in layered materials with competing anions.