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.

No abstract

Current metal-free catalysts for hydrogen evolution reaction (HER) are mainly carbon-based. In this work, HER catalytic activity on two dimensional (2D) boron sheets (α and β12) are explored using periodic density functional theory. Using the binding free energy of H (ΔGH*) as the descriptor, we found that both α and β12 sheets present superior activity, with ΔGH* being close to zero. It is expected that 2D boron sheets would be a promising metal-free catalyst in electrolysis of water and may offer novel thoughts for the design of new catalysts for other reactions.

No abstract