High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties.

For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000 °C show a maximum boron concentration of 6.04 ± 1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448 F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment.

Graphene oxide nanosheet wrapped white-emissive conjugated polymer nanoparticles.

We have demonstrated the preparation of white-emissive conjugated polymer nanoparticles wrapped with graphene oxide (GO) nanosheets. Highly stable, GO-wrapped, poly(9,9-di-n-octylfluorenyl-2,7-diyl) nanoparticles (GO-PFO NPs) with diameters in the range 30-150 nm were successfully obtained by utilizing the GO nanosheets as an interface stabilizer in an emulsification process. The synthesized GO-PFO NPs exhibited unique white-emitting photoluminescence with a characteristic green-emissive broad band above 500 nm, which was distinct from the photoluminescent behavior of PFO NPs without GO. This green emission was deduced to originate from the presence of the GO nanosheet shell surrounding the PFO NPs, rather than from luminescence of GO itself or formation of keto defects in the PFO chain. PL decay analysis showed that the GO-wrapped PFO NPs had a longer luminescence lifetime in comparison to PFO NPs without GO, and highly efficient energy transfer to lower energy state induced by the GO occurred.