Mechanical characterisation of the protective Al2O3 scale in Cr2AlC MAX phases

: A new kind of two-dimensional (2D) materials MXene (early transition metal carbides, nitrides and carbonitrides) is obtained by selective etching the A element from the MAX phases. MXene exhibits both the metallic conductivity and the hydrophilic nature due to its metal layer structure and hydroxyl or oxygen terminated surfaces. This review provides an overview of the MXene used in the electrolytes and electrodes for the fuel cells and water splitting. MXene with functional groups termination could construct ion channels that significantly benefits to the ion conductivity through the electrolyte. The metal supported by MXene interaction offers electronic, compositional, and geometric effects that could enhance the catalytic activity and stability. MXene have already shown promising performance for fuel cells and water electrolysis. Herein, the etching and intercalation methods of MXene in recent years are summarized. The applications of MXene for fuel cells electrolyte, catalyst and water splitting catalyst are revealed to provide more brief idea for MXene used as new energy materials.

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Oxidation mechanism of MAX phases (Ti3AlC2 powders) with and without Sn doping

Corrosion Science ◽

10.1016/j.corsci.2020.109197 ◽

2021 ◽

Vol 180 ◽

pp. 109197

Author(s):

Chunyu Guo ◽

Enhui Wang ◽

Shuize Wang ◽

Xinmei Hou ◽

Zhijun He ◽

...

Keyword(s):

Oxidation Mechanism ◽

Max Phases ◽

Sn Doping

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Laser-excited elastic guided waves reveal the complex mechanics of nanoporous silicon

Nature Communications ◽

10.1038/s41467-021-23398-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Marc Thelen ◽

Nicolas Bochud ◽

Manuel Brinker ◽

Claire Prada ◽

Patrick Huber

Keyword(s):

Guided Waves ◽

Laser Ultrasonics ◽

Bulk Silicon ◽

Nanoporous Silicon ◽

Stiffness Reduction ◽

Mechanical Characterisation ◽

Isotropic Elasticity ◽

On Chip ◽

Non Destructive

AbstractNanoporosity in silicon leads to completely new functionalities of this mainstream semiconductor. A difficult to assess mechanics has however significantly limited its application in fields ranging from nanofluidics and biosensorics to drug delivery, energy storage and photonics. Here, we present a study on laser-excited elastic guided waves detected contactless and non-destructively in dry and liquid-infused single-crystalline porous silicon. These experiments reveal that the self-organised formation of 100 billions of parallel nanopores per square centimetre cross section results in a nearly isotropic elasticity perpendicular to the pore axes and an 80% effective stiffness reduction, altogether leading to significant deviations from the cubic anisotropy observed in bulk silicon. Our thorough assessment of the wafer-scale mechanics of nanoporous silicon provides the base for predictive applications in robust on-chip devices and evidences that recent breakthroughs in laser ultrasonics open up entirely new frontiers for in-situ, non-destructive mechanical characterisation of dry and liquid-functionalised porous materials.

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Advances in MXene Films: Synthesis, Assembly, and Applications

Transactions of Tianjin University ◽

10.1007/s12209-021-00282-y ◽

2021 ◽

Author(s):

Xiaohua Li ◽

Feitian Ran ◽

Fan Yang ◽

Jun Long ◽

Lu Shao

Keyword(s):

Spin Coating ◽

Reaction Mechanisms ◽

Membrane Separation ◽

Synthesis Methods ◽

Metal Carbides ◽

Max Phases ◽

Practical Applications ◽

Coating Methods ◽

And Performance ◽

Important Form

AbstractA growing family of two-dimensional (2D) transition metal carbides or nitrides, known as MXenes, have received increasing attention because of their unique properties, such as metallic conductivity and good hydrophilicity. The studies on MXenes have been widely pursued, given the composition diversity of the parent MAX phases. This review focuses on MXene films, an important form of MXene-based materials for practical applications. We summarized the synthesis methods of MXenes, focusing on emerging synthesis strategies and reaction mechanisms. The advanced assembly technologies of MXene films, including vacuum-assisted filtration, spin-coating methods, and several other approaches, were then highlighted. Finally, recent progress in the applications of MXene films in electrochemical energy storage, membrane separation, electromagnetic shielding fields, and burgeoning areas, as well as the correlation between compositions, architecture, and performance, was discussed.

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Synthesis of high quality 2D carbide MXene flakes using a highly purified MAX precursor for ink applications

Nanoscale Advances ◽

10.1039/d0na00398k ◽

2021 ◽

Author(s):

Shi-Hyun Seok ◽

Seungjun Choo ◽

Jinsung Kwak ◽

Hyejin Ju ◽

Ju-Hyoung Han ◽

...

Keyword(s):

Raw Materials ◽

High Quality ◽

Max Phases ◽

Painting Process ◽

Manufacturing Techniques

A method of pelletizing raw materials was used to tackle unwarranted variations in MXene products depending on the parent MAX phases, manufacturing techniques, and preparation parameters, enabling a direct painting process on various surfaces for ink applications.

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Mechanical Characterisation and Shrinkage of Thermoactivated Recycled Cement Concrete

Applied Sciences ◽

10.3390/app11062454 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2454

Author(s):

Sofia Real ◽

José Alexandre Bogas ◽

Ana Carriço ◽

Susana Hu

Keyword(s):

Mechanical Strength ◽

Elasticity Modulus ◽

Ultrasonic Pulse Velocity ◽

Ultrasonic Pulse ◽

Pulse Velocity ◽

Cement Concrete ◽

Supplementary Cementitious Material ◽

Mechanical Characterisation ◽

Shrinkage Behaviour ◽

Binder Ratio

This paper investigates the mechanical and shrinkage behaviour of concrete with recycled cement (RC) thermoactivated from waste cement paste and waste concrete. Overall, compared to ordinary Portland cement (OPC), for the same water/binder ratio, the mechanical strength and ultrasonic pulse velocity were not significantly influenced by the incorporation of RC. The elasticity modulus decreased with the addition of RC and the shrinkage tended to increase at high RC content. The incorporation of up to 15% RC allowed the production of workable concrete with identical shrinkage and similar to higher mechanical strength than concrete with only OPC. RC proved to be a very promising more eco-efficient supplementary cementitious material.

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