Ion implanted MXene electrodes for selective VOC sensors

Robust means of MXene functionalization are needed to industrialize the huge research interest that these materials see. Although there have been many reports on functionalized MXenes used for vapor sensing, most have focused on non-uniform additives such as nanoparticles, polymers, graphene etc. resulting in outstanding results, however achieved with techniques difficult to reproduce consistently. In this work a new approach to MXene functionalization for VOC sensing is proposed - implantation of screen printed MXene films with selected metal ions. This approach is highly reproducible and uniform on its own, but also yields no metallic phases in the films leading to classical doping. Using X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy the processes taking place TiCT during implantation are explained. The ion distribution is modeled and measured using secondary ion mass spectrometry, as well as discuss the limitations of the technique. Finally, it is shown that by setting together an array of virgin and Ni, Cu and Pd-doped TiCT electrodes, it is possible to differentiate between 5 VOC and water in the operationally relevant range. This approach shows a blueprint for functionalization with other ions using implantation not only for sensing, but also for other MXene applications.