Graphene quantum dots (GQDs) which are nanofragments of graphene with an average size between 2 and 50 nm have attracted much attention due to their outstanding properties such as high conductivity, high surface area, and good solubility in various solvents. GQDs combine the quantum confinement and edges effects and the properties of graphene. Therefore, GQDs offers a broad range of applications in various fields (medicine, energy conversion, and energy storage devices). This review will present the recent research based on the introduction of GQDs in batteries, supercapacitors, and micro‐supercapacitors as electrodes materials or mixed with an active material as an auxiliary agent. Tables, discussed on selected examples, summarize the electrochemical performances and finally, challenges and perspectives are recalled for the subsequent optimization strategy of electrode materials. This review is expected to appeal a broad interest on functional GQDs materials and promote the further development of high‐performance energy storage device.

Here, we demonstrate for the first time a strategy to self-assemble ZnO nanoparticles (NP) on a large area by a facile one-step process. First, rough and random ZnO nanocrystals (NC), were produced by free-stabilizing aqueous synthesis. Therefore, a post thermal treatment at various temperatures ranging from 80 to 800 °C was necessary to obtain size-tunable and photoluminescent crystalline NP. The fabricated NP had both efficient UV photoluminescence and photocatalytic activity by photo-degradation of Methylene Blue (MB) dye. The annealed NP showed an absorption blue shift in the UV region with decreasing size. This shift was attributed to high quantum confinement effect since ZnO NP diameter reached values lower than the Bohr radius of ZnO (~2.7 nm). The photocatalytic activity displayed dependency on the particle’s size, number, and crystallinity. Subsequently, the NP were self-assembled inside poly(methyl methacrylate) (PMMA) nanoholes. Subsequently, large area substrate of homogenous properties ZnO NP was obtained. Moreover, the synthesis facility, photoemission and photocatalytic properties of ZnO NP could be a new insight into the realization of high performance and low cost UV laser devices.