Atmospheric pressure plasma jet printing and in situ oxidation of Ti2C MXene for photocatalytic dye degradation

An innovative, low-power atmospheric pressure plasma jet (APPJ) approach has been developed for the in situ synthesis TiO 2 -Ti 2 C MXene heterostructures with enhanced light harvesting and photocatalytic properties. The one-step oxygen-plasma functionalization of Ti 2 C MXene enables the controlled formation of photoactive rutile TiO₂ nanoparticles on the MXene nanosheets, as confirmed by XRD and SEM. HRTEM further reveals the formation of plasma induced defect-rich TiO 2 on the Ti 2 C MXene substrate, which enhances photocatalytic performance through improved light absorption and charge separation. The introduction of vacancies and mixed oxidation states of Ti and C broadens the absorption spectrum and facilitates electron mobility. These structural modifications also increase the electronic density of states near the Fermi level, reducing electron-hole recombination and enabling more effective charge transfer. For the first time, we report a work function of 4.64 eV for Ti 2 C MXene, which can be correlated with enhanced photocatalytic activity. The combined effects of defect engineering, electronic-structure modulation, and intimate TiO 2 /MXene interfacial contact result in substantially improved photocatalytic activity. The optimized p MX05 heterostructure, produced after only 5 min of plasma exposure, achieved approximately 2.1-fold higher methylene blue degradation efficiency under UV irradiation than pristine Ti 2 C MXene, while exhibiting a 1.11-fold enhancement compared with commercial P25 TiO 2 . Overall, this scalable, single-step APPJ strategy provides an energy-efficient route for simultaneously oxidizing and functionalizing Ti 2 C MXene, offering a versatile platform for engineering advanced photocatalytic thin films and electrodes for environmental remediation and sustainable energy applications.