Graphene Quantum Dots Derived from Carbon Fibers

TLDR

Graphene quantum dots are nanometer‑scale graphene fragments with remarkable optical and electronic properties, yet their conventional synthesis via nanolithography or chemical breakdown of graphene oxide is multistep and tedious. This study demonstrates that acid treatment and chemical exfoliation of inexpensive pitch‑based carbon fibers can produce graphene quantum dots in scalable quantities. The process breaks down the fibers’ stacked graphitic domains, yielding GQDs whose photoluminescence can be tuned by adjusting size through process parameters. The resulting 1–4 nm, 1–3 layer GQDs exhibit zigzag edges, stable nanosecond photoluminescence, biocompatibility, low toxicity, and high water solubility, making them excellent high‑contrast bioimaging and biosensing probes.

Abstract

Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating optical and electronic properties. These have been synthesized either by nanolithography or from starting materials such as graphene oxide (GO) by the chemical breakdown of their extended planar structure, both of which are multistep tedious processes. Here, we report that during the acid treatment and chemical exfoliation of traditional pitch-based carbon fibers, that are both cheap and commercially available, the stacked graphitic submicrometer domains of the fibers are easily broken down, leading to the creation of GQDs with different size distribution in scalable amounts. The as-produced GQDs, in the size range of 1-4 nm, show two-dimensional morphology, most of which present zigzag edge structure, and are 1-3 atomic layers thick. The photoluminescence of the GQDs can be tailored through varying the size of the GQDs by changing process parameters. Due to the luminescence stability, nanosecond lifetime, biocompatibility, low toxicity, and high water solubility, these GQDs are demonstrated to be excellent probes for high contrast bioimaging and biosensing applications.