Chemical and Optoelectronic Control of Ti3C2Tx MXene Work Function Values via Covalently-Tethered Electron Withdrawing or Electron Donating Organic Monolayers

We functionalized Ti3C2Tx MXene surfaces with organosilanes to modify the interfacial electronic configuration and work function values. Modifications included reaction with trimethoxy(3,3,3-trifluoropropyl)silane to yield a terminal electron-withdrawing group. Modification to yield a terminal electron donating character relative to nonderivatized MXene utilized (3-aminopropyl)trimethoxysilane (APTMS). X-ray photoelectron spectroscopy (XPS) established successful derivatization of Ti3C2Tx MXene surfaces with each silane in a process that did not deleteriously oxidize the MXene material. Ultraviolet photoelectron spectroscopy (UPS) quantified work-function values for resulting derivatized Ti3C2Tx thin films. Ultraviolet photoelectron spectroscopy (UPS) established shifts in work function values of ~350–400 meV relative to nonderivatized Ti3C2Tx MXenes based on interfacial dipoles resulting from covalent organosilane attachment. We discuss these results in the context of EMI shielding, catalysis, chemical sensing, and energy applications.