Modern-day electronics or communication technology would not exist without electron microscopy, and the same can be said for many other types of technology. Beyond imaging, the focused beam of electrons is also used for analysis of the chemical composition, the crystal structure, and many other useful things. In new work, researchers have proposed to use graphene as a two-dimensional vacuum chamber, and build a two-dimensional electron microscope, where the electrons fly from the electron gun to the target without ever leaving the graphene sheet.
Inspired by the unique optical and electronic property of graphene, two-dimensional layered materials - as well as their hybrids - have been intensively investigated in recent years, driven by their potential applications for nanoelectronics. The broad spectrum of atomic layered crystals includes transition metal dichalcogenides (TMDs), semiconducting dichalcogenides, monoatomic buckled crystals, such as black phosphorous (BP), and diatomic hexagonal boron nitride, etc. Tihis article examines the recent advancement of flexible 2D electronic devices based on TMDs and BP.
Several research projects are working on reinventing the contact lens as a smart electronic device that, for instance, works as a self-powered biosensor for various point-of-care monitoring and wireless biomedical sensing. n addition to sensors, researchers are devising numerous applications for smart contact lenses, ranging from drug delivery systems to protection from electromagnetic wave damage. An application closer to contact lenses' original function, graphene can change the focal length of a polymeric soft contact lens in order to adjust near- and farsightedness.
Access to accurate surface energy values of graphene is not only of fundamental interest, but provides a useful reference for anyone involved in research on graphene properties, (surface) modifications, and the implementation of graphene in devices. New research demonstrates the successful application of the graphene surface force balance (g-SFB) to directly measure the surface energy of pure graphene. This work is of fundamental interest to a broad community and will aid the advancement of fundamental measurements of 2D and other nanomaterials.
Despite their potential, the practical use of Li-O2 batteries is seriously limited by the corrosion of Li metal by ambient water vapor from air. One way to circumvent this issue is to use an oxygen selective membrane that allows only oxygen into the battery while stopping or slowing water vapor intake. The membrane must be mechanically robust and yet sufficiently thin and light so as to not increase deadweight of the battery. Researchers now have discovered a way to make the thinnest possible oxygen selective membrane using graphene.
Photodetectors with a spectral response from the ultraviolet (UV) to visible light have significant importance in modern industrial and scientific applications such as imaging, communication, environmental monitoring and day and nighttime surveillance. Compared to other materials, the photo-current conversions of two-dimensional transition metal dichalcogenides such as MoS2 nanosheets are impressive, making them great candidates for next-generation visible light photodetectors. Researchers have now developed a facile and low-cost solution processing strategy to fabricate mechanically flexible 2D organic-inorganic hybrid thin-film photodetectors on a conventional filter paper.
Next-generation electronics will be based on two-dimensional semiconductors, which have a significantly higher resistance than conventional silicon-based electronics. This development is significantly limited by the high contact resistance between the metal electrode and the 2D semiconductor. To minimize the energy dissipation and improve the device performance, it is critical to reduce the contact resistance. Researchers have now shown that MXenes, a class of 2D metal carbides or nitrides, can achieve low contact resistance with 2D semiconductors.
Researchers have demonstrated that nanoengineered SnO anodes suppress volume change and prolong sodium ion battery cycle life. Sodium ion batteries are promising alternative to lithium ion batteries, particularly for home based and grid level storage solutions. Tin monoxide has been demonstrated to have excellent physical and chemical properties and has a large theoretical capacity as battery anode, for instance for sodium ion batteries. Unfortunately, though, it also exhibits large volume change during the sodiation and lithiation process, which makes it unsuitable as a high-performing anode material.