Chemical tailoring of CQD/PEDOT hybrid materials with silver, molybdenum, and iridium for ibuprofen sensing: a computational approach

The persistent occurrence of pharmaceutical contaminants such as ibuprofen in water sources poses environmental and health risks. This study explores the chemical modification of carbon quantum dot/poly(3,4-ethylenedioxythiophene) (CQD/PEDOT) nanocomposites with Ag, Ir, and Mo for ibuprofen sensing. First-principles calculations at the B3LYP-D3/LanL2DZ level of computation were employed to examine structural, electronic, and adsorption properties. Ibuprofen adsorption induced notable bond length changes, particularly in Mo@CQD/PEDOT, indicating enhanced surface reactivity. Metal doping narrowed the HOMO-LUMO gap from 2.478 eV (pristine) to 1.087-1.631 eV, increased work function values, and strengthened donor-acceptor interactions, thereby improving charge transfer. Adsorption energies followed Ir (-1.126) > Ag (-1.044) > Mo (-0.916) > pristine (-0.879 eV), consistent with electrophilicity indices and Gibbs free energies, which depict a thermodynamically favourable binding. Vibrational and NCI analyses confirmed doping-induced frequency shifts and enhanced noncovalent/covalent interactions. Molecular dynamics (MD) simulations showed stable adsorption and thermodynamic favorability, with Mo@CQD/PEDOT exhibiting the highest work function (3.997 eV) and Ir@CQD/PEDOT the strongest covalent coupling in aqueous solvation. These robust computations project metal doping to effectively tune the electronic structure and adsorption characteristics of CQD/PEDOT, enhancing its potential as a sensitive platform for ibuprofen detection in environmental and electrochemical applications.