One-Step Synthesis of N-Doped Graphene Quantum Dots from Chitosan as a Sole Precursor Using Chemical Vapor Deposition

We present a simple, environment-friendly, and fast synthesis of nitrogen-doped graphene quantum dots (N-GQDs) on copper foil by chemical vapor deposition using exclusively chitosan, a cheap and nontoxic biopolymer, as a carbon and nitrogen precursor. We characterized the synthesized N-doped graphene quantum dots using Raman spectroscopy, XPS, AFM, HRTEM, and HRSEM and found them to be in the range 10-15 nm in diameter and 2-5 nm-thick with 4.2% of maximum nitrogen content. The proposed growth mechanism process includes three key steps: (1) decomposition of chitosan into nitrogen-containing compounds, (2) adsorption of reactive species (HCN) on the copper surface, and (3) nucleation to form N-doped graphene quantum dots. The synthesized N-GQDs exhibit photoluminescence (PL) emission in the visible band region, thus making them suitable for applications in nano-optoelectronics.