Lithium-sulfur (Li-S) batteries, which employ sulfur as cathode and metallic lithium as anode materials, have been extensively studied as promising alternatives to the widely used lithium-ion batteries because - theoretically - they can render 3-6 times higher energy density. In practice, though, it has proven challenging to approach that theoretical value. Specifically, the rapid capacity fading, low Coulombic efficiency, and irreversible loss of active materials have impeded large-scale commercial use of Li-S batteries. Researchers now have shown that trapping lithium polysulfide species on (nanoscale) host materials is an effective way to overcome these challenges.
The scaling up of nanomaterials in the broader context of materials science and engineering is the topic of a Perspective article, where the authors construct a roadmap for assembling nanoscale building blocks into bulk nanostructured materials, and define some of the critical challenges and goals. Two-dimenisonal sheets are uniquely well-suited in this roadmap for constructing dense, bulk-sized samples with scalable material performance or interesting emergent properties. But no matter what structures are used, when nanostructures with better-than-bulk material performances are used in bulk form, it is critical that those extraordinary nanoscale properties can be scaled to the macroscopic level.
Hierarchical porous carbon/graphene (HPC/HPG) materials have been intensively investigated over the past decades. These materials are demonstrated as promising electrode materials for various systems, such as lithium-ion batteries, lithium-sulfur batteries, supercapacitors, and fuel cells, with a remarkable capacity, high efficiency, long stability, and excellent rate capability. Researchers have now proposed the employment of hierarchical porous calcium oxide (CaO) particles as effective catalytic template for the facile CVD growth of graphene.
Due to the high concentration of silica in rice husks, most of the present research focuses on the preparation of silicon-based materials, which exhibit broad applications in the fields of adsorption, catalysis, energy storage, etc. There is also a large amount of organic components in rice husks, which is typically wasted in the preparation of these silica materials. Researchers now have developed an advanced method for the comprehensive use of rice husks. They fabricated high quality graphene quantum dots from the organic components of rice husks, and simultaneously obtained mesoporous silica nanoparticles with a high surface area from the inorganic content.
A scientist has discovered a previously unknown three-dimensional nanostructure consisting of graphene sheets. Graphene is a single monolayer of carbon atoms forming a hexagonal two-dimensional crystal lattice. The discovered nanostructure is a multilayer system of parallel hollow channels with quadrangular cross-section extending along the surface. The discovered nanostructure looked so extraordinary that it took some time to understand what it actually was. The structure was dramatically different from whatever had previously been observed on graphite.
Adding to the options for wirelessly powering implants from outside the body, researchers are proposing a light-driven powering device using near infrared rays (nIR). Flashing light impulses, which are absorbed by the device, induce temperature fluctuation, thus generating voltage/current pulses which can be used for charging a battery or biological stimulations. This flexible and compact device can generate electrical pulses with controllable amplitude and width when remotely irradiated by nIR. Not only can it supply power to implantable bioelectronics, but it also provides adjustable electrical pulses for nerve stimulation.
The complexity of the microenvironment of a biological cell is influenced by many factors, including surface topography and chemistry; matrix stiffness; mechanical stress; molecular liquid composition and other physiochemical parameters. However, most artificial biointerfaces are developed based on just a single chemical or physical factor to direct cell behaviors. The functions performed by these artificial biointerfaces are far simpler than those performed in the natural cell microenvironment. In an effort to more closely mimic a cell's natural environment, researchers have fabricated an antibody modified reduced graphene oxide platform and used it to significantly improve the efficiency for capturing circulating tumor cells.
Given the huge economic incentives, corrosion prevention and protection is a major business. The advanced materials that are being developed and used in modern industries require increasingly sophisticated coatings for improved performance and durability. Take for example the case of microbially induced corrosion (MIC) - one of the lesser understood forms of corrosion where micro-organisms manifest metallic surfaces and induce substantial damage that often goes unnoticed until there is a loss in the component functionality. New research features graphene as a promising novel surface coating that can be used to minimize metallic corrosion under harsh microbial conditions.