Molecular Dynamics Simulation of Bismuth Telluride Exfoliation Mechanisms in Different Ionic Liquid Solvents

Appraising the potency of small molecule inhibitors and their graphene surface-mediated organizational attributes on uric acid-melamine clusters

Uric acid (UA) and melamine (MM) crystallization in humans is associated with adverse medical conditions, including the germination of kidney stones, because of their low solubility. The growth of kidney stones, usually formed on renal papillary facades, is accomplished on the matrix-coated surface by the aggregation of preformed crystals or secondary crystal nucleation. Therefore, the effects of inhibitors such as theobromine (TB) and allopurinol (AP) on MM-UA aggregation are investigated by employing classical molecular dynamics simulations on a graphene surface. This impersonates the exact essence of the precipitation of kidney stones. The interaction between MM-UA is very intense and, thus, large clusters are formed on the surface. The presence of TB and AP will, however, substantially inhibit their aggregation. TB and AP significantly impede UA aggregation in particular. Therefore, lower order UA clusters are formed. These smaller UA clusters then pull a lower number of MM towards themselves, resulting in a smaller order UA-MM cluster. MM and UA aggregation on a 2D graphene surface is found to be spontaneous. There is no difference in these molecules' adsorption with a change in the force field parameters (i.e., GAFF and OPLS-AA) for graphene. Moreover, the greater the surface area of graphene, the more molecules are absorbed. The solute-surface van der Waals interaction energy plays a driving force in the adsorption of solute molecules on the surface. In addition, interactions like hydrogen bonding and π-stacking over the graphene surface involve binding all like molecules. These aggregated solute molecules strongly attract more like molecules until all solute molecules are adsorbed on the graphene surface, as estimated by enhanced sampling. The molecular origin of graphene exfoliation by MM is also described here. The present work helps to design novel kidney stone inhibitors.

Disentangling the liquid phase exfoliation of two-dimensional materials: an "in silico" perspective

Liquid Phase Exfoliation (LPE) is one of the most successful synthetic roots for the preparation of two-dimensional (2D) materials from their bulk counterparts. In recent years, significant progress has been accomplished for the development and modification of LPE techniques. However, precise identification of the hierarchical steps of the molecular mechanism of LPE remains to some extent elusive. Additionally, the a priori choice of suitable solvents for successful exfoliation and dispersion of various layered materials poses a challenge for both academia and industry. Computational methods, particularly Molecular Dynamics (MD) simulations with classical force-fields have contributed a great deal towards the understanding of the underlying mechanism of LPE, providing remarkable insights into the molecular-level details of the solvent-material interactions at the nanoscale and predicting "good" and "bad" solvents for exfoliation as well as stabilization of the dispersed state. With an intention to build up a unified understanding, in this perspective article, we summarize the recent advancements of molecular simulation techniques employed to decipher the mechanism of LPE, pointing out the key features of molecular interactions and identifying several thermodynamic parameters governing the phenomena. In addition, we outline the necessary characteristics of solvent molecules, essential for their use as "good" solvents towards LPE. Also, we highlight the limitations of simulation methods for the modelling of LPE. We believe that this article will be beneficial for the selection of solvents for the synthesis of novel 2D materials via LPE and will also provide a comprehensive view to computational material scientists towards the development of novel simulation protocols for investigating and analysing such complex molecular events.

Solution-Based Synthesis and Processing of Metal Chalcogenides for Thermoelectric Applications

Metal chalcogenide materials are current mainstream thermoelectric materials with high conversion efficiency. This review provides an overview of the scalable solution-based methods for controllable synthesis of various nanostructured and thin-film metal chalcogenides, as well as their properties for thermoelectric applications. Furthermore, the state-of-art ink-based processing method for fabrication of thermoelectric generators based on metal chalcogenides is briefly introduced. Finally, the perspective on this field with regard to material production and device development is also commented upon.

Exfoliation of crystals

The review is concerned with progress in methods for exfoliation of crystals, from mechanical exfoliation using sticky tape to modern techniques involving sonication-assisted exfoliation, shear exfoliation in liquids using intercalating agents and stabilizers, direct liquid exfoliation and cosolvent exfoliation. The potential of methods of osmotic swelling in water and in organic dispersion media with constant and variable chemical composition of nanosheets, chemical and electrochemical intercalation, exfoliation by hydrazine (including versions resulting in changes in the chemical composition of nanosheets), ionic liquids and supercritical fluids is discussed. Methods for size sorting of nanosheets by density-gradient and cascade centrifugation and the possibility of nanosheet size control are analyzed.

The bibliography includes 136 references.