Highly oxidative debris (OD) was obtained by aqueous ammonia wash of as-prepared graphene oxide (GO) which composed of OD and lightly oxidative GO sheets. The magnetic properties of OD and GO were studied. The results showed that OD has a low magnetization of 0.16 emu/g, and the magnetization of GO can be increased from 0.38 to 0.42 emu/g by discarding low-magnetization OD. Thus, this study provided a reliable method to increase the magnetization of GO. Hydroxyl groups were proposed to be the magnetic source.

High-photoluminescence (PL) graphene quantum dots (GQDs) were synthesized by a simple one-pot hydrothermal process, then separated by dialysis bags of different molecular weights. Four separated GQDs of varying sizes were obtained and displayed different PL intensities. With the decreasing size of separated GQDs, the intensity of the emission peak becomes much stronger. Finally, the GQDs of the smallest size revealed the most energetic PL intensity in four separated GQDs. The PL energy of all the separated GQDs shifted slightly, supported by density functional theory calculations.