Researchers have demonstrated the experimental realization of the first all-carbon optical diode that is ready for scalable integration along with being inherently broadband in operation with no restrictions on polarization or phase-matching criteria. As they show, harnessing the optical properties of graphene-based materials offers an opportunity to create the all-photonic analogs of diodes, transistors, and photonic logic gates that will one day enable construction of the first all-photonic computer.
A three-dimensional crumpled graphene-encapsulated nickel sulfide electrode is reported as a superior high-energy lithium storage material. Compared with an electrode without crumpled graphene encapsulation, the optimized electrode yields significant improvements, especially in the cycling stability and rate capability. This enhanced performance is attributed to the 3D framework providing high continuous electron pathway and more free space for charge and mass transfer, and the stabilizing effect of the crumpled graphene based stretchy shell.
Ever since its discovery in 2004, graphene has been considered a relatively stable, high surface area platform to anchor nanostructured catalyst materials for various electrochemical and photocatalytic applications. The emergence of solution-based graphene in the form of graphene oxide has enabled new wet-chemistry approaches to the creation of graphene-based nanocomposites. A new study raises questions about the long-term stability of reduced graphene oxide in an aqueous environment where hydroxyl radicals can be present as part of the photocatalytic reaction cycle.
Transparent conductive coatings pervade modern technology. They are a critical component of optoelectronic devices such as smartphone and tablet displays as well as solar cells. The search for novel transparent electrode materials with good stability, high transparency and excellent conductivity is driven by the required trade-off between transparency and conductivity. In new work, researchers now have simultaneously increased the conductivity and transparency of ultra thin graphite by lithium intercalation.
Researchers have developed a new separation membrane with 2D layered transition metal dichalcogenides (tungsten disulfide) for size-selective separation of small molecules of about 3 nm. The as-prepared WS2 membranes exhibit 5 times higher water permeance than graphene oxide membranes with similar rejection. To further improve the water permeance, they team employed ultrathin metal hydroxide nanostrands to create more fluidic channels while keeping the rejection rate of specific molecules unchanged.
A growing body of medical nanotechnology research deals with the development of antibacterial applications, ranging from nanotechnology-based approaches for diagnosing superbugs to antimicrobial surface coatings and wound treatment with antibacterial nanomaterials. Especially silver nanomaterials have been used effectively against different bacteria, fungi and viruses but also carbon nanomaterials like nanotubes and graphene. In new work, researchers have now designed an antibacterial system combining graphene quantum dots with a low dose of a common medical reagent, hydrogen peroxide H2O2.
Renewable and high-capacity energy systems like fuel cells and metal-air batteries are key components in any scenario on future energy systems free of fossil fuels. The performance of fuel cells largely depends on the oxygen reduction reaction - the process that breaks the bonds of the oxygen molecules - which is substantially affected by the activity of the cathode catalyst. Researchers have now demonstrated the synthesis of a novel N-doped graphene/single-walled carbon nanotube hybrid material by a facile and cost-favorable one-step CVD method.
Over the past few years, researchers have developed numerous methods for synthesizing graphene. The synthesis of high-quality graphene is usually prepared by a complex and costly process - epitaxial growth on transition metal surfaces via chemical vapor deposition using high-purity hydrocarbons as precursors. In new work, researchers demonstrate graphene synthesis by liquid precursor deposition, a process that may give access to a wider range of substrate materials for graphene growth.