Tunable charge transport in Ti2CTx MXene flakes and printed thin films: a route to designing high-performance MXene devices

Ti-based MXene inks offer metallic conductivity for printed electronics, but oxidation can substantially alter their charge transport. Here, we investigate thickness-dependent oxidation and its impact on transport in Ti 2 CT x , the thinnest Ti-based MXene, from individual flakes to spray-coated thin films. Monolayer flakes become insulating through extensive oxidation, whereas bilayer and thicker flakes retain finite conductivity because surface oxidation shields the metallic inner layers. Temperature-, gate-voltage-, and magnetic-field-dependent measurements of back-gated devices reveal oxidation-dependent transport, ranging from variable-range hopping in spray-coated films to behaviour approaching the metal–insulator transition in the least-oxidised multilayer flakes. Single-flake and printed-film conductivities exceed 300 S cm -1 and 10 S cm -1 , respectively. These findings link thickness-dependent oxidation to charge transport across length scales and establish design principles for air-sensitive MXene devices with tunable electronic properties through control of insulating barriers within metallic networks.