Recent Advances in Fabrication and Characterization of Graphene-Polymer Nanocomposites

Graphene has attracted considerable interest over recent years due to its intrinsic mechanical, thermal and electrical properties. Incorporation of small quantity of graphene fillers into polymer can create novel nanocomposites with im- proved structural and functional properties. This review introduced the recent progress in fabrication, properties and potential applications of graphene-polymer composites. Recent research clearly confirmed that graphene-polymer na-nocomposites are promising materials with applications ranging from transportation, biomedical systems, sensors, elec-trodes for solar cells and electromagnetic interference. In addition to graphene-polymer nanocomposites, this article also introduced the synergistic effects of hybrid graphene-carbon nanotubes (CNTs) on the properties of composites. Finally, some technical problems associated with the development of these nanocomposites are discussed.

Recent advancements in metal organic framework based electrodes for supercapacitors

Metal organic frameworks（MOFs） are considered as very promising candidates to build electrodes for electrochemical energy storage devices such as lithium ion batteries, fuel cells and supercapacitors, due to their diverse structure, adjustable aperture, large specific surface area and abundant active sites. Supercapacitor has been widely investigated in the past decades. Of critical importance in these devices is the electrode active materials, and this application has been intensively studied with the development of novel nanomaterials. In this review we summarize recent reports on MO Fs as electrode materials for super capacitors. Specifically,the synthesis of MOF materials for super capacitor electrodes and their performance in electrochemical energy storage are discussed. We aim to include supercapacitor electrode materials related to MOFs, such as carbon, metal and composite materials. It is proposed that MOFs play an important role in the development of a new generation of supercapacitor electrode materials. Finally, we discuss the current challenges in the field of supercapacitors, with a view towards how to address these challenges with the future development of MOFs and their derivatives.

Dynamical evolution of Ge quantum dots on Si(111):From island formation to high temperature decay

Heteroepitaxial growth is a process of profound fundamental importance as well as an avenue to realize nanostructures such as Ge/Si quantum dots(QDs),with appealing properties for applications in opto-and nanoelectronics.However,controlling the Ge/Si QD size,shape,and composition remains a major obstacle to their practical implementation.Here,Ge nanostructures on Si(111)were investigated in situ and in real-time by low energy electron microscopy(LEEM),enabling the observation of the transition from wetting layer formation to 3D island growth and decay.The island size,shape,and distribution depend strongly on the growth temperature.As the deposition temperature increases,the islands become larger and sparser,consistent with Brownian nucleation and capture dynamics.At 550◦C,two distinct Ge/Si nanostructures are formed with bright and dark appearances that correspond to flat,atoll-like and tall,faceted islands,respectively.During annealing,the faceted islands increase in size at the expense of the flat ones,indicating that the faceted islands are thermodynamically more stable.In contrast,triangular islands with uniform morphology are obtained from deposition at 600◦C,suggesting that the growth more closely follows the ideal shape.During annealing,the islands formed at 600◦C initially show no change in morphology and size and then rupture simultaneously,signaling a homogeneous chemical potential of the islands.These observations reveal the role of dynamics and energetics in the evolution of Ge/Si QDs,which can serve as a step towards the precise control over the Ge nanostructure size,shape,composition,and distribution on Si(111).