Anomalous reverse mechanical polarization switching in negative piezoelectric CuInPS.

van der Waals ferroelectric CuInPS (CIPS) has drawn significant attention not only because of its unique properties but also owing to its technological potential for nanoelectronics. Mechanical polarization switching provides a new approach to modulating polarization states through flexoelectricity. This approach is particularly favourable for CIPS to avoid surface damage under an electric field due to the coupling between polarization switching and ionic motion.

Broken-gap energy alignment in two-dimensional van der Waals heterostructures for multifunctional tunnel diodes.

Two-dimensional (2D) materials are promising platforms for future nanoelectronic technologies as they provide the building blocks for atomically thin devices, including switches, amplifiers, and oscillators. When 2D materials are layered on top of each other, forming van der Waals heterostructures (vdWHs), they can provide unique properties not possessed by the individual layers. Here we consider the vdWHs HfS/MoTe, HfS/WTe, 1T-HfS/WTe, TiS/WSe, TiS/ZnO, and TiSe/WTe as potential Esaki (or tunnel) diodes that can be incorporated into electronic devices.

Surface chemistry altering electronic behaviour of liquid metal-derived tin oxide nanosheets.

Possessing excellent electronic properties and high chemical stability, semiconducting n-type two-dimensional (2D) tin dioxide (SnO) nanosheets have been featured in sensing and electrocatalysis applications recently. Derived from non-layered crystal structures, 2D SnO has abundant unsaturated dangling bonds existing at the surface, providing interfacial activity. How the surface chemistry alters the electronic properties of 2D SnO nanomaterials remains unexplored.

Defect-Free, Few-Atomic-Layer Thin ZnO Nanosheets with Superior Excitonic Properties for Optoelectronic Devices.

Two-dimensional (2D) wide bandgap materials are gaining significant interest for next-generation optoelectronic devices. However, fabricating electronic-grade 2D nanosheets from non-van der Waals (n-vdW) oxide semiconductors poses a great challenge due to their stronger interlayer coupling compared with vdW crystals. This strong coupling typically introduces defects during exfoliation, impairing the optoelectronic properties.

Use of Perfluorochemicals in Li-Air Batteries: A Critical Review.

As lithium-ion (Li-ion) batteries approach their theoretical limits, alternative energy storage systems that can power technology with greater energy demands must be realized. Li-metal batteries, particularly Li-air batteries (LABs), are considered a promising energy storage candidate due to their inherent lightweight and energy-dense properties. Unfortunately, LAB practicality remains hindered by inadequate oxygen solubility and diffusion rates within the electrolyte, both which are fundamental for LAB operation.

Repairing and Preventing Photooxidation of Few-Layer Black Phosphorus with β-Carotene.

Few-layer black phosphorus (FLBP), a technologically important 2D material, faces a major hurdle to consumer applications: spontaneous degradation under ambient conditions. Blocking the direct exposure of FLBP to the environment has remained the key strategy to enhance its stability, but this can also limit its utility. In this paper, a more ambitious approach to handling FLBP is reported where not only is FLBP oxidation blocked, but it is also repaired postoxidation.

Ferroelectric van der Waals heterostructures of CuInPSfor non-volatile memory device applications.

Two-dimensional (2D) ferroelectric materials are providing promising platforms for creating future nano- and opto-electronics. Here we propose new hybrid van der Waals heterostructures, in which the 2D ferroelectric material CuInPS(CIPS) is layered on a 2D semiconductor for near-infrared (NIR) memory device applications. Using density functional theory, we show that the band gap of the hybrid bilayers formed with CIPS can be tuned and that the optical and electronic properties can be successfully modulated via ferroelectric switching.

Improving sensing of formaldehyde using ZnO nanostructures with surface-adsorbed oxygen.

Detection of pollutant gases, such as formaldehyde (HCHO), in our homes and surrounding environment is of high importance for our health and safety. The effect of surface defects and specifically pre-adsorbed oxygen on the gas sensing reaction of HCHO with ZnO nanostructures is largely unknown. Using density functional theory, nonequilibrium Green's function method and molecular dynamics (AIMD) simulations, we show that the presence of surface oxygen has two key roles in the sensitivity of ZnO towards HCHO: (1) it leads to the presence of charge trap states, which vanish upon the adsorption of HCHO, and (2) it facilitates the dissociative chemisorption of HCHO on the surface.

Electric Control of Exchange Bias Effect in FePS-FeGeTe van der Waals Heterostructures.

Manipulating the exchange bias (EB) effect using an electronic gate is a significant goal in spintronics. The emergence of van der Waals (vdW) magnetic heterostructures has provided improved means to study interlayer magnetic coupling, but to date, these heterostructures have not exhibited electrical gate-controlled EB effects. Here, we report electrically controllable EB effects in a vdW heterostructure, FePS-FeGeTe.

Electrochemical Stability of Zinc and Copper Surfaces in Protic Ionic Liquids.

Ionic liquids are versatile solvents that can be tailored through modification of the cation and anion species. Relatively little is known about the corrosive properties of protic ionic liquids. In this study, we have explored the corrosion of both zinc and copper within a series of protic ionic liquids consisting of alkylammonium or alkanolammonium cations paired with nitrate or carboxylate anions along with three aprotic imidazolium ionic liquids for comparison.

Surface Functionalization of WS Nanosheets with Alkyl Chains for Enhancement of Dispersion Stability and Tribological Properties.

Tungsten disulfide (WS) exhibits intriguing tribological properties and has been explored as an excellent lubricious material in thin-film and solid lubricants. However, the poor dispersibility of WS has been a major challenge for its utilization in liquid lubricant applications. Herein, a top-down integrated approach is presented to synthesize oxygenated WS (WS-O) nanosheets strong acid-mediated oxidation and ultrasound-assisted exfoliation.

Tuning the Schottky barrier height in a multiferroic InSe/FeGeTe van der Waals heterojunction.

The ferroelectric material InSe is currently of significant interest due to its built-in polarisation characteristics that can significantly modulate its electronic properties. Here we employ density functional theory to determine the transport characteristics at the metal-semiconductor interface of the two-dimensional multiferroic InSe/FeGeTe heterojunction. We show a significant tuning of the Schottky barrier height as a result of the change in the intrinsic polarisation state of InSe: the switching in the electric polarisation of InSe results in the switching of the nature of the Schottky barrier, from being n-type to p-type, and is accompanied by a change in the spin polarisation of the electrons.

Nicotine Sensors for Wearable Battery-Free Monitoring of Vaping.

Nicotine, an addictive substance in tobacco products and electronic cigarettes (e-cigs), is recognized for increasing the risk of cardiovascular and respiratory disorders. Careful real-time monitoring of nicotine exposure is critical in alleviating the potential health impacts of not just smokers but also those exposed to second-hand and third-hand smoke. Monitoring of nicotine requires suitable sensing material to detect nicotine selectively and testing under free-living conditions in the standard environment.

Zero valence iron nanocube decoration of graphitic nanoplatelets.

Graphitic nanoplatelets (GNPs) have been treated using an ultrasonicated ozonolysis procedure to produce stable aqueous dispersions that facilitate deposition of thin films using electrophoretic deposition. The thin GNP films were then coated with zero valence (ZV) iron nanocubes using a pulsed electrodeposition technique. Characterization of the ZV-iron coating with deposition time revealed that the changing magnetic character of the ferromagnetic-graphitic hybrid material was related to the nucleation density and growth of the ZV-iron nanocubes.

Fluorinated Boron-Based Anions for Higher Voltage Li Metal Battery Electrolytes.

Lithium metal batteries (LMBs) require an electrolyte with high ionic conductivity as well as high thermal and electrochemical stability that can maintain a stable solid electrolyte interphase (SEI) layer on the lithium metal anode surface. The borate anions tetrakis(trifluoromethyl)borate ([B(CF)]), pentafluoroethyltrifluoroborate ([(CF)BF]), and pentafluoroethyldifluorocyanoborate ([(CF)BF(CN)]) have shown excellent physicochemical properties and electrochemical stability windows; however, the suitability of these anions as high-voltage LMB electrolytes components that can stabilise the Li anode is yet to be determined. In this work, density functional theory calculations show high reductive stability limits and low anion-cation interaction strengths for Li[B(CF)], Li[(CF)BF], and Li[(CF)BF(CN)] that surpass popular sulfonamide salts.

Spectroscopic and Computational Study of Boronium Ionic Liquids and Electrolytes.

Boronium cation-based ionic liquids (ILs) have demonstrated high thermal stability and a >5.8 V electrochemical stability window. Additionally, IL-based electrolytes containing the salt LiTFSI have shown stable cycling against the Li metal anode, the "Holy grail" of rechargeable lithium batteries.

Broad-Spectrum Solvent-free Layered Black Phosphorus as a Rapid Action Antimicrobial.

Antimicrobial resistance has rendered many conventional therapeutic measures, such as antibiotics, ineffective. This makes the treatment of infections from pathogenic micro-organisms a major growing health, social, and economic challenge. Recently, nanomaterials, including two-dimensional (2D) materials, have attracted scientific interest as potential antimicrobial agents.

Fully Light-Controlled Memory and Neuromorphic Computation in Layered Black Phosphorus.

Imprinting vision as memory is a core attribute of human cognitive learning. Fundamental to artificial intelligence systems are bioinspired neuromorphic vision components for the visible and invisible segments of the electromagnetic spectrum. Realization of a single imaging unit with a combination of in-built memory and signal processing capability is imperative to deploy efficient brain-like vision systems.

Liquid-Metal Synthesized Ultrathin SnS Layers for High-Performance Broadband Photodetectors.

Atomically thin materials face an ongoing challenge of scalability, hampering practical deployment despite their fascinating properties. Tin monosulfide (SnS), a low-cost, naturally abundant layered material with a tunable bandgap, displays properties of superior carrier mobility and large absorption coefficient at atomic thicknesses, making it attractive for electronics and optoelectronics. However, the lack of successful synthesis techniques to prepare large-area and stoichiometric atomically thin SnS layers (mainly due to the strong interlayer interactions) has prevented exploration of these properties for versatile applications.

Structural-Defect-Mediated Grafting of Alkylamine on Few-Layer MoS and Its Potential for Enhancement of Tribological Properties.

Two-dimensional transition-metal dichalcogenides possess inherent structural characteristics that can be harnessed for enhancement of tribological properties by making them dispersible in lube media. Here, we present a hydrothermal approach to preparing MoS nanosheets comprising 4-10 molecular lamellae. A structural-defect-mediated route for grafting of octadecylamine (ODA) on MoS nanosheets is outlined.

Electrically Activated UV-A Filters Based on Electrochromic MoO.

Chromism-based optical filters is a niche field of research, due to there being only a handful of electrochromic materials. Typically, electrochromic transition metal oxides such as MoO and WO are utilized in applications such as smart windows and electrochromic devices (ECD). Herein, we report MoO-based electrically activated ultraviolet (UV) filters.

Development of Stable Boron Nitride Nanotube and Hexagonal Boron Nitride Dispersions for Electrophoretic Deposition.

Boron nitride nanotubes (BNNTs) represent a relatively new class of materials that provides alternative electrical and thermal properties to the carbon analogue. The high chemical and thermal stability and large band gap combined with high electrical resistance make BNNTs desirable in several thin-film applications. In this study, stable BNNT and hexagonal boron nitride (hBN) particle dispersions have been developed using environmentally friendly advanced oxidation processing (AOP) that can be further modified for electrophoretic deposition (EPD) to produce thin films.

Differential Work-Function Enabled Bifunctional Switching in Strontium Titanate Flexible Resistive Memories.

Multifunctional electronic memories capable of demonstrating both analog and digital switching on-demand are extremely attractive for miniaturization of electronics without significant drain on energy consumption. Simultaneously translating functionality onto mechanically conformable platforms will further enhance their suitability. Here, we demonstrate the ability to engineer multifunctionality in strontium titanate (STO)-based resistive random-access memories (ReRAM) on a flexible polyimide platform.

Theoretical insight on the origin of anelasticity in zinc oxide nanowires.

Anelasticity of nanowires has recently attracted attention as an interesting property for high efficiency mechanical damping materials. While the mechanism of anelasticity has so far been analysed using continuum mechanical models based on defect diffusion, the mechanisms behind anelasticity have not yet been determined on an atomic level. Such information is needed in order to be able to design and synthesise new nanomaterials having desired mechanical properties.

Adsorption of toxic gases on silicene/Ag(111).

Silicene is a two-dimensional nanomaterial, composed of Si atoms arranged into a buckled honeycomb network. It has become of great interest in recent years due to its remarkable properties such as its natural compatibility with current silicon-based technology. Due to its extreme thinness on the nanoscale, and large lateral dimensions, it has potential applications in gas sensing, gas storage and components in modern electronic devices.