Tailoring Plasmonic Sensitivity through Functional MXene–MOF Hybrids for High-Performance PIERS Detection of Pharmaceutical Molecules

Abstract

Photo-induced enhanced Raman spectroscopy (PIERS) offers ultrasensitive molecular detection by exploiting localized surface plasmon resonance (LSPR). However, conventional Au/Ag PIERS substrates suffer from nanoparticle aggregation, poor molecular confinement, and limited reproducibility. Herein, we design two distinct plasmonic MXene–MOF hybrids based on titanium carbide Ti3C2Tx (Tx=-OH, -F) to overcome these limitations. In the first system, Au nanoparticles were anchored onto a thiol‐functionalized UiO‐66 framework (denoted as Ti3C2/UiO‐66‐SH2@Au) through robust Au–S bonding, while the second employed Ag nanoparticles stabilized on an amine‐functionalized UiO‐66 (Ti3C2/UiO‐66‐NH2@Ag) via Ag–N coordination. The resultant Ti3C2/UiO‐66‐SH2@Au hybrid serves as efficient PIERS substrates for detecting pharmaceutical analytes such as acetaminophen and acetylsalicylic acid, where the porous MOF networks facilitate analyte adsorption and preconcentration, where the conductive MXene enables effective charge‐transfer coupling between molecular vibrations and plasmonic excitations. The Ti3C2/UiO‐66‐SH2@Au exhibits a significantly stronger Raman enhancement, attributed to synergistic hot‐spot generation, favourable Fermi‐level alignment, and strong molecule-metal interactions. Nevertheless, the Ti3C2/UiO‐66‐NH2@Ag displays weaker enhancement due to suboptimal host-guest and interfacial electronic coupling. To further elucidate the interfacial charge-transfer mechanism, density functional theory (DFT) calculations reveal that the Au–S interface exhibits stronger electronic coupling and enhanced charge redistribution than the Ag–N interface, with charge density difference maps confirming pronounced electron localization at the Au–S boundary, consistent with the experimentally observed superior plasmonic enhancement in Ti3C2/UiO‐66‐SH2@Au. This study demonstrates that hybrid MOFs can be harnessed to precisely tune plasmonic sensitivity, establishing a materials‐driven pathway toward next‐generation porous PIERS platforms for chemical and pharmaceutical sensing.