As a new class of fluorescent carbon materials, graphene quantum dots (GQDs) have attracted tremendous attention due to their outstanding properties and potential applications in biological, optoelectronic, and energy-related fields. Herein, top-down and bottom-up strategies for the fabrication of GQDs, mainly containing oxidative cleavage, the hydrothermal or solvothermal method, the ultrasonic-assisted or microwave-assisted process, electrochemical oxidation, controllable synthesis, and carbonization from small molecules or polymers, are discussed. Different methods are presented in order to study their characteristics and their influence on the final properties of the GQDs. The respective advantages and disadvantages of the methods are introduced. With regard to some important or novel methods, the mechanisms are proposed for reference. Moreover, recent exciting progresses on the applications of GQD, such as sensors, bio-imaging, drug carriers, and solar cells are highlighted. Finally, a brief outlook is given, pointing out the issues still to be settled for further development. We believe that new preparation methods and properties of GQDs will be found, and GQDs will play more important roles in novel devices and various applications.

We have developed a facile route to synthesize GQDs with high PL emission by using starch as a precursor for the first time, and they are successfully applied in cell imaging.

Graphene (graphene) is a new type of two-dimensional inorganic nanomaterial developed in recent years. It can be used as an ideal inorganic nanofiller for the preparation of polymer nanocomposites because of its high mechanical strength, excellent electrical conductivity and plentiful availability (from graphite). In this review, the preparation methods of graphene/polymer nanocomposites, including solution blending, melt blending and in situ polymerization, are introduced in order to study the relationship between these methods and the final characteristics and properties. Each method has an influence on the final characteristics and properties of the nanocomposites. The advantages and disadvantages of these methods are discussed. In addition, a variety of nanocomposites with different properties, such as mechanical properties, electronic conductivity, thermal conductivity and thermal properties, are summarized comprehensively. The potential applications of these nanocomposites in conductive materials, electromagnetic shielding materials, photocatalytic materials and so on, are briefly presented. This review demonstrates that polymer/graphene nanocomposites exhibit superior comprehensive performance and will be applied in the fields of new materials and novel devices. Future research directions of the nanocomposites are also presented.

Essentially, the performance of single-atom catalysts (SACs) has been strongly affected by their supports. Herein, the structural, electronic, and catalytic properties of single-iron catalysts over defective graphene have been investigated under the scheme of density functional theory for the oxygen reduction reaction. Graphene with single and double vacancies offers the excellent capacity to anchor single iron, forming Fe−N 3 and Fe− N 4 bonding networks. Among these concept catalysts, Fe−N 4 located at double vacancies offers the highest catalytic activity with an overpotential of 0.81 V via the HOOH dissociation pathway, which allows Fe/DVG-N 4 to be regarded as available, low-cost, and high-efficiency catalyst.

Biomarkers are important biochemical indicators, which could be used for identification, early diagnosis and monitoring of diseases during the course of treatment. However, biomarker diagnosis has some shortcomings such as requiring a large amount of samples, long test time and high cost, which seriously influences the correctness and timely treatment to patients. Here, a relatively fast and efficient plasmonic hot spot-localized surface imprinting of Ag spheres using biomarker template immobilization and hydrogel copolymerization is described. The technique takes a fine control of the imprinting process at the nanometre scale and provides a biosensor with high sensitivity. Proof of the opinion is established by detection of biomarker using surface-enhanced Raman scattering (SERS) spectroscopy. This work represents a valuable step towards SERS with biomarkers for cost-saving and time-saving diagnostic assay. It is expected that the new surface imprinted hydrogel plasmonic material can drive possibilities in advancing application of biomarkers in plasmonic biosensors.