In Situ Synthesis of Mo and Ti-Dual Oxide-Incorporated Mo₂Ti₂C₃T_x MXene Electrode Using a Lewis Acid-Assisted Method for Pseudocapacitors

MXenes, a class of two-dimensional transition metal carbides and nitrides, hold great promise for electrochemical energy storage applications due to their exceptional electronic conductivity, tunable surface chemistry, and pseudocapacitive charge storage mechanisms. This study introduces a one-step approach to deposit Mo and Ti-dual oxide nanoparticles in situ onto Mo 2 Ti 2 C 3 T x MXene using the Lewis acid molten salt method (LAMS), meticulously optimizing annealing conditions. The incorporation of Mo and Ti dual oxide nanoparticles improves the pristine Mo 2 Ti 2 C 3 T x MXene by preventing collapse of the layered structure and restacking of MXene sheets. Both three-electrode and coin cell devices are assessed in an aqueous electrolyte, illustrating the favorable role of the nanoparticles acting as spacers. Remarkable outcomes include a specific capacity of 434 C g –1 at 5 mA cm –2, exceptional capacity retention of 94% after 5000 charge–discharge cycles at 50 mA cm –2, and a high gravimetric energy density of 52.5 W h kg –1 at a power density of 1442 W kg –1 in an aqueous 3 M KOH electrolyte. This research underscores the potential of double transition metal MXenes as energy storage electrodes and an eco-friendly mass synthesis route, contributing to sustainable advancements in energy storage technology.