Synthesis, structure, properties and applications of MXenes: Current status and perspectives

The family of MAX phases and their derivative MXenes are continuously growing in terms of both crystalline and composition varieties. In the last couple of years, several breakthroughs have been achieved that boosted the synthesis of novel MAX phases with ordered double transition metals and, consequently, the synthesis of novel MXenes with a higher chemical diversity and structural complexity, rarely seen in other families of two-dimensional (2D) materials. Considering the various elemental composition possibilities, surface functional tunability, various magnetic orders, and large spin–orbit coupling, MXenes can truly be considered as multifunctional materials that can be used to realize highly correlated phenomena. In addition, owing to their large surface area, hydrophilicity, adsorption ability, and high surface reactivity, MXenes have attracted attention for many applications, e.g., catalysts, ion batteries, gas storage media, and sensors. Given the fast progress of MXene-based science and technology, it is timely to update our current knowledge on various properties and possible applications. Since many theoretical predictions remain to be experimentally proven, here we mainly emphasize the physics and chemistry that can be observed in MXenes and discuss how these properties can be tuned or used for different applications.

Recent advances in MXenes: From fundamentals to applications

Half-metals and spin gapless semiconductors are promising candidates for spintronic applications due to the complete (100%) spin polarization of electrons around the Fermi level. Based on recent experimental and theoretical findings of graphene-like monolayer transition metal carbides and nitrides (also known as MXenes), we demonstrate from first-principles calculations that monolayer Ti2C and Ti2N exhibit nearly half-metallic ferromagnetism with the magnetic moments of 1.91 and 1.00 UB per formula unit, respectively, while monolayer V2C is a metal with instable antiferromagnetism, and monolayer V2N is a nonmagnetic metal. Interestingly, under a biaxial strain, there is a phase transition from nearly half-metal to truly half-metal, spin gapless semiconductor, and metal for monolayer Ti2C. Monolayer Ti2N is still a nearly half-metal under a proper biaxial strain. Large magnetic moments can be induced by the biaxial tensile and compressive strains for monolayer V2C and V2N, respectively. We also show that the structures of these four monolayer MXenes are stable according to the calculated formation energy and phonon spectrum. Our investigations suggest that, unlike monolayer graphene, monolayer MXenes Ti2C and Ti2N without vacancy, doping or external electric field exhibit intrinsic magnetism, especially the half-metallic ferromagnetism and spin gapless semiconductivity, which will stimulate further studies on possible spintronic applications for new two-dimensional materials of MXenes.

Monolayer MXenes: promising half-metals and spin gapless semiconductors

The family of MAX phases and their derivative MXenes are continuously growing in terms of both crystalline and composition varieties. In the last couple of years, several breakthroughs have been achieved that boosted the synthesis of novel MAX phases with ordered double transition metals and, consequently, the synthesis of novel MXenes with a higher chemical diversity and structural complexity, rarely seen in other families of two-dimensional (2D) materials. Considering the various elemental composition possibilities, surface functional tunability, various magnetic orders, and large spin$-$orbit coupling, MXenes can truly be considered as multifunctional materials that can be used to realize highly correlated phenomena. In addition, owing to their large surface area, hydrophilicity, adsorption ability, and high surface reactivity, MXenes have attracted attention for many applications, e.g., catalysts, ion batteries, gas storage media, and sensors. Given the fast progress of MXene-based science and technology, it is timely to update our current knowledge on various properties and possible applications. Since many theoretical predictions remain to be experimentally proven, here we mainly emphasize the physics and chemistry that can be observed in MXenes and discuss how these properties can be tuned or used for different applications.

Recent advances in MXenes: from fundamentals to applications

Presently, increasing attention is given to MXenes (MXs)presenting them as unique materials amongst 2-D materials. Nevertheless, prevailing studies have dwelt on properties of pure MXs, with very little attention paid to MXs and MXs-polymeric nanoarchitectures interfacial and surface behavior. Therefore, this review presents MXs-polymeric nanoarchitectures surface modification for different uses especially for storage (ECS) and energy conversion uses. Based on the interfacial and architectural behavior, emerging synthesis and applications of MXs surface modified nanoarchitectures for energy storage applications, and so on, are elucidated.

On interfacial and surface behavior of polymeric MXenes nanoarchitectures and applications

Energy storage properties of selectively functionalized Cr-group MXenes

The invention provides a ruthenium-silicon composite oxide-embedded nickel base active electrode material and a preparation method thereof An insert of an active material is a ruthenium-silicon composite oxide; the average particle size is 12 nm; and the mole ratio of Si to Si+Ru is 018-022:1 According to the preparation method of the ruthenium-silicon composite oxide-embedded nickel base active electrode material, a composite electroplating method is adopted for synchronously depositing nickel and the ruthenium-silicon composite oxide to obtain the ruthenium-silicon composite oxide-embedded nickel base active electrode material The material is excellent in hydrogen evolution activity; and the preparation method is simple, high in operability, easy in raw material obtaining and low incost

Ruthenium-silicon composite oxide-embedded nickel base active electrode material and preparation method thereof

The invention provides a nickel-based active electrode material in which ruthenium-zirconium composite oxide is implanted and a preparing method of the nickel-based active electrode material. The implanted body of the active material is ruthenium-zirconium composite oxide, the average particle size is 12 nm, and the Zr:Zr+Ru molar ratio is 0.16-0.20:1. According to the preparing method of the nickel-based active electrode material in which ruthenium-zirconium composite oxide is implanted, a composite electroplating method is adopted, nickel and ruthenium-zirconium composite oxide are depositedat the same time, and the nickel-based active electrode material in which the ruthenium-zirconium composite oxide is implanted is obtained. The material has excellent hydrogen evolution activity, thepreparing method is simple, operability is high, raw materials are easy to obtain, and cost is low.

Nickel-based active electrode material in which ruthenium-zirconium composite oxide is implanted and preparing method of nickel-based active electrode material

Wang Qifan

Papers

Energy storage properties of selectively functionalized Cr-group MXenes

Ruthenium-silicon composite oxide-embedded nickel base active electrode material and preparation method thereof

Nickel-based active electrode material in which ruthenium-zirconium composite oxide is implanted and preparing method of nickel-based active electrode material