Ti3C2Tx MXene Polymer Composites for Anticorrosion: An Overview and Perspective.

As the most studied two-dimensional (2D) material from the MXene family, Ti3C2Tx has constantly gained interest from academia and industry. Ti3C2Tx MXene has the highest electrical conductivity (up to 24,000 S cm-1) and one of the highest stiffness values with a Young's modulus of ∼ 334 GPa among water-dispersible conductive 2D materials. The negative surface charge of MXene helps to disperse it well in aqueous and other polar solvents. This solubility across a wide range of solvents, excellent interface interaction, tunable surface functionality, and stability with other organic/polymeric materials combined with the layered structure of Ti3C2Tx MXene make it a promising material for anticorrosion coatings. While there are many reviews on Ti3C2Tx MXene polymer composites for catalysis, flexible electronics, and energy storage, to our knowledge, no review has been published yet on MXenes' anticorrosion applications. In this brief report, we summarize the current progress and the development of Ti3C2Tx polymer composites for anticorrosion. We also provide an outlook and discussion on possible ways to improve the exploitation of Ti3C2Tx polymer composites as anticorrosive materials. Finally, we provide a perspective beyond Ti3C2Tx MXene composition for the development of future anticorrosion coatings.

The Ti3 AlC2 MAX Phase as an Efficient Catalyst for Oxidative Dehydrogenation of n-Butane.

Dehydrogenation or oxidative dehydrogenation (ODH) of alkanes to produce alkenes directly from natural gas/shale gas is gaining in importance. Ti3 AlC2 , a MAX phase, which hitherto had not been used in catalysis, efficiently catalyzes the ODH of n-butane to butenes and butadiene, which are important intermediates for the synthesis of polymers and other compounds. The catalyst, which combines both metallic and ceramic properties, is stable for at least 30 h on stream, even at low O2 :butane ratios, without suffering from coking. This material has neither lattice oxygens nor noble metals, yet a unique combination of numerous defects and a thin surface Ti1-y Aly O2-y/2 layer that is rich in oxygen vacancies makes it an active catalyst. Given the large number of compositions available, MAX phases may find applications in several heterogeneously catalyzed reactions.

Modification of the ZnO(0001)-Zn surface under reducing conditions.

The ZnO(0001)-Zn terminated crystal face was studied after reduction at high temperatures by combination of STM, STS, XPS and TDS. The clean ZnO(0001)-Zn surface exhibits triangular reconstruction in UHV, while after exposure to 10(-5) mbar H(2) at RT this reconstruction is lifted and a rough surface has formed. The roughness as well as the metallic character of the surface increased with the applied low-pressure reduction temperature up to 800 K. XPS revealed that exposure to 1 bar H(2) at RT led to the formation of OH groups; at higher temperatures progressive metallization of the ZnO surface was found to occur. Analysis of the thermal desorption results showed that huge amounts of H(2) dissolved into the ZnO crystal. The results obtained under these conditions were in good accordance with thermodynamic calculations. The experimental ratio between the absorbed amount of H(2) at RT and 800 K amounts to 1000. The ratio calculated from increasing diffusion coefficients with temperature only amounts to 6. This emphasizes the importance of ZnO as a H supplier by spillover, and proves that metallic Zn boosts dissociative adsorption of H(2). This surface modification of the ZnO structure during the reduction promotes an enhanced activity of the Cu/ZnO catalyst at elevated temperatures.