(Invited) Mechanical Suppression of Electron Transfer in Subnanometer Confinement between MXene Layers

Ion adsorption and electron transfer are the primary charge storage mechanisms in porous electrodes. Desolvation/solvation of ions in subnanometer confinement may alter the balance between those two processes. For 2D materials like MXenes, there is a continuous change in interlayer spacing as ions are transported and stored between the layers. However, little is known about the effect of the mechanical constraint (pressure) on electrochemistry in confinement. In this work, the ion transportation process in between mechanically constrained MXene layers is monitored by combining in-situ UV-vis spectroscopy, in-situ optical spectroscopy, and in-situ XRD characterization. Compared with spray-coated Ti 3 C 2 T x films, physically constrained Ti 3 C 2 T x film with a constant interlayer spacing exhibited exceptional capabilities in suppressing redox reactions. Notably, this property of faradaic suppression under mechanical strain led to the application of MXene-based electrochemical cells as high-pressure electrochemical sensors.