Functionalized graphene quantum dots with distinctive solvent-driven emission and enhanced carbon monoxide sensing: A DFT study

The widespread efficacy of graphene in nanotechnology has allowed researchers over the years to merge its unique features with quantum confinement effects to unlock newer possibilities in multiple domains. In this work, we have tailored a two-dimensional graphene sheet to 8 distinctive achiral quantum dots and systematically explored their tunable electro-optical responses through surface functionalization with consequent applicability in gas sensing. Emergent traces of spin-splitting in shape-dependent zigzag edges highlight the possibility of metal-free magnetic behavior of graphene in ambient conditions. Absorption and fluorescence spectra have been critically explored with a diverse range of oscillator strengths in the presence of water as a solvent (TD-DFT/CAM-B3LYP/PCM model) revealing the underlying alluring optical signatures. The introduced charge anisotropy through doping of III-V group elements caters to significant dipole moments that attract health-hazardous polar gas molecules like carbon monoxide (CO) with strengthened sensitivity. • Pristine GQDs are tailored with point group symmetry CS representing achiral nature. • A thumb rule is developed on the occurrence of spin-splitting in specific zigzag geometries. • Presence of foreign atoms induce sizeable dipole moments up to 6.7 Debye. • Strong fluorescence peaks are explored with water being a solvent having larger oscillator strengths of f ∼ 2. • Significantly sensitive ( ∼ 92%) gas sensing on AlN@GQD is detected.