Nanocrystalline TiO/TiCT MXene composites with a tunable work function prepared using atmospheric pressure oxygen plasma.

Composites of TiO and TiCT MXene are of great interest because they combine superior TiO photocatalytic activity with excellent MXene conductivity. As these composites have conventionally been prepared using methods requiring high temperatures, a process for producing similar materials at reduced temperature could be beneficial for applications in flexible and printed electronics. Therefore, we used low-temperature dielectric barrier discharge to develop a method for forming crystalline TiO by treating TiCT MXene surfaces with high-power-density oxygen plasma comprising various energetic and reactive oxygen species, which oxidize MXene surfaces and form TiO nanoparticles on disordered graphitic carbon sheets within a few seconds.

Synthesis and Raman spectroscopy of a layered SiS phase at high pressures.

Dichalcogenides are known to exhibit layered solid phases, at ambient and high pressures, where 2D layers of chemically bonded formula units are held together by van der Waals forces. These materials are of great interest for solid-state sciences and technology, along with other 2D systems such as graphene and phosphorene. SiS is an archetypal model system of the most fundamental interest within this ensemble.

Creating new layered structures at high pressures: SiS.

Old and novel layered structures are attracting increasing attention for their physical, electronic, and frictional properties. SiS, isoelectronic to SiO, CO and CS, is a material whose phases known experimentally up to 6 GPa exhibit 1D chain-like, 2D layered and 3D tetrahedral structures. We present highly predictive ab initio calculations combined with evolutionary structure search and molecular dynamics simulations of the structural and electronic evolution of SiS up to 100 GPa.

Structural transformation between long and short-chain form of liquid sulfur from ab initio molecular dynamics.

We present results of ab initio molecular dynamics study of the structural transformation occurring in hot liquid sulfur under high pressure, which corresponds to the recently observed chain-breakage phenomenon and to the electronic transition reported earlier. The transformation is temperature-induced and separates two distinct polymeric forms of liquid sulfur: high-temperature form composed of short chain-like fragments with open endings and low-temperature form with very long chains. We offer a structural description of the two liquid forms in terms of chain lengths, cross-linking, and chain geometry and investigate several physical properties.

Transformation pathways in high-pressure solid nitrogen: from molecular N2 to polymeric cg-N.

The transformation pathway in high-pressure solid nitrogen from N2 molecular state to polymeric cg-N phase was investigated by means of ab initio molecular dynamics and metadynamics simulations. In our study, we observed a transformation mechanism starting from molecular Immm phase that initiated with formation of trans-cis chains. These chains further connected within layers and formed a chain-planar state, which we describe as a mixture of two crystalline structures--trans-cis chain phase and planar phase, both with Pnma symmetry.