Gram-scale synthesis of highly doped chlorine graphene quantum dots: Synthesis and photoluminescence properties

Band-gap engineering of graphene-based nanomaterials has a huge influence on their optical and structural properties. Our contribution reports the successful gram-scale synthesis of highly chlorinated graphene quantum dots (Cl-GQDs) via a two-step preparation method. X-ray photoelectron spectroscopy (XPS) proved the successful doping of chlorine atoms into the as-prepared graphene oxide quantum dots (O-GQDs). Time-resolved fluorescence revealed a high decrease in the relaxation lifetime from 690 ps for O-GQDs to 5.3–4 ps for Cl-GQDs. Transmission electron microscopy (TEM) confirms that all nanoparticles are on the quantum scale (4–6 nm). The large blueshift in photoluminescence (PL) 150 nm from the original O-GQD (440 → 290 nm) supports the chlorination effect which enables tuning the band gap of O-GQD.