Über die Adsorption in Lösungen

Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

A decade after the first report, the family of two-dimensional (2D) carbides and nitrides (MXenes) includes structures with three, five, seven, or nine layers of atoms in an ordered or solid solution form. Dozens of MXene compositions have been produced, resulting in MXenes with mixed surface terminations. MXenes have shown useful and tunable electronic, optical, mechanical, and electrochemical properties, leading to applications ranging from optoelectronics, electromagnetic interference shielding, and wireless antennas to energy storage, catalysis, sensing, and medicine. Here we present a forward-looking review of the field of MXenes. We discuss the challenges to be addressed and outline research directions that will deepen the fundamental understanding of the properties of MXenes and enable their hybridization with other 2D materials in various emerging technologies.

The world of two-dimensional carbides and nitrides (MXenes)

2D transition metal carbides, carbonitrides, and nitrides, known as MXenes, are a rapidly growing family of 2D materials with close to 30 members experimentally synthesized, and dozens more studied theoretically. They exhibit outstanding electronic, optical, mechanical, and thermal properties with versatile transition metal and surface chemistries. They have shown promise in many applications, such as energy storage, electromagnetic interference shielding, transparent electrodes, sensors, catalysis, photothermal therapy, etc. The high electronic conductivity and wide range of optical absorption properties of MXenes are the key to their success in the aforementioned applications. However, relatively little is currently known about their fundamental electronic and optical properties, limiting their use to their full potential. Here, MXenes' electronic and optical properties from both theoretical and experimental perspectives, as well as applications related to those properties, are discussed, providing a guide for researchers who are exploring those properties of MXenes.

Electronic and Optical Properties of 2D Transition Metal Carbides and Nitrides (MXenes).

Two-dimensional transition metal carbides and nitrides known as MXenes, with a general formula of Mn+1Xn (n = 1–3), integrate the advantages of metallic conductive transition metals with large groups of carbides, nitrides, or carbonitrides. They have led to a burgeoning research interest in biomedical applications due to their ultrathin structure and fascinating physiochemical (electronic, optical, magnetic, etc.) properties. In this review, we summarize recent advances in biomedical applications for MXenes. We first introduce the preparation methods and surface modifications with respect to MXenes. Their unique properties are then elaborated. Thirdly, we highlight their various biomedical applications, such as with biosensors, antibacterial materials, bioimaging probes, therapeutics, and theranostics. In the end, the current challenges and new opportunities for MXenes in regard to their biomedical applications are also discussed.

Two-dimensional transition metal carbides and nitrides (MXenes) for biomedical applications.

We report on the synthesis, characterization, and application of Ti2N (MXene), a two-dimensional transition metal nitride of M2X type. Synthesis of nitride-based MXenes (Mn+1Nn) is difficult due to their higher formation energy from Mn+1ANn and poor stability of Mn+1Nn layers in the etchant employed, typically HF. Herein, the selective etching of Al from ternary layered transition metal nitride Ti2AlN (MAX) and intercalation were achieved by immersing the powder in a mixture of potassium fluoride and hydrochloric acid. The multilayered Ti2NTx (T is the surface termination) obtained was sonicated in DMSO and centrifuged to obtain few-layered Ti2NTx. MXene formation was verified, and the material was completely characterized by Raman spectroscopy, XRD, XPS, FESEM-EDS, TEM, STM, and AFM techniques. Surface-enhanced Raman scattering (SERS) activity of the synthesized Ti2NTx was investigated by fabricating paper, silicon, and glass-based SERS substrates. A Raman enhancement factor of 1012 was demonstrated usin...

Two-Dimensional Titanium Nitride (Ti2N) MXene: Synthesis, Characterization, and Potential Application as Surface-Enhanced Raman Scattering Substrate

A series of differently crosslinked polyacrylamide chelating resins were prepared, using N,N′-methylene-bis-acrylamide as the crosslinking agent. The crosslinked resins were functionalized by the reaction with ethylene diamine to get amino group capacities varying from 4.2 to 1.1 mequiv/g. The maximum adsorption capacities of the lightly crosslinked resin for Fe3+, Fe2+, Ni2+, and Cu2+ are 3.62, 4.22, 1.48, and 1.67 mequiv/g, respectively. The adsorbed metal ions can be quantitatively desorbed. The adsorption rate and the influence of pH on the adsorption of metal ions were examined. The resins can be used for the separation between different metal ions as well as the ions in different valence states (e.g., Fe3+ and Fe2+). The resin is amenable for continuous process and can be regenerated several times.

Synthesis of a polyacrylamide chelating resin and applications in metal ion extractions

An overview on the spectrum of sensitizers: The heart of Dye Sensitized Solar Cells

Borosiloxane oligomers, which give ceramic residue in the range of 64–75% (at 900 °C in inert atmosphere), were synthesized through the condensation of boric acid with phenyltrimethoxysilane (PTMOS) and phenyltriethoxysilane in diglyme both in the presence and absence of hydrochloric acid as catalyst. The effect of concentration of the reactants and reaction time on the processability, yield and thermal stability of the product obtained was studied. The oligomers obtained are soluble in common organic solvents and were characterized by FT-IR and NMR spectroscopy, GPC and TGA. The ceramic conversion of one of the oligomers was carried out by heat treatment at 900, 1,500 and 1,650 °C in inert atmosphere. XRD studies reveal that the ceramic formed at 1,500 °C is amorphous and undergoes crystallization to β-SiC when heat treated at 1,650 °C.

Benny K. George

Papers

Two-Dimensional Titanium Nitride (Ti2N) MXene: Synthesis, Characterization, and Potential Application as Surface-Enhanced Raman Scattering Substrate

Synthesis of a polyacrylamide chelating resin and applications in metal ion extractions

An overview on the spectrum of sensitizers: The heart of Dye Sensitized Solar Cells

Synthesis, Characterization and Ceramic Conversion Studies of Borosiloxane Oligomers from Phenyltrialkoxysilanes

Synthesis and characterization of a novel copper chromite catalyst for the thermal decomposition of ammonium perchlorate