Oxygen Vacancy-Engineered Ti-Mo-Ni Ternary Oxide Nanotubes as Binder-Free Supercapacitor Electrodes with Exceptional Potential Window

The charge storage performance of metal oxides as electrochemical supercapacitor electrodes is limited by their poor conductivity and limited operating potential window. Herein, we report on the oxygen-vacancy engineering of Ti-Mo-Ni-O nanotubes via hydrogen annealing to boost their capacitive performance. Hydrogen treatment of the nanotubes resulted in 110% increase in specific capacitance as compared to the air-annealed counterpart with excellent stability over 3700 cycles and an exceptional capacitance retention of 99%. The observed enhancement can be ascribed to the faradaic capacitance contribution from the several redox pairs of Nickel, Molybdenum, and Ti3+. This was further confirmed via the electrochemical impedance spectroscopy measurements, revealing a drastic decrease in the internal resistance upon hydrogen treatment. We hope our demonstrated two-step interfacial engineering opens a new strategy to design high performance electrode materials for advanced electrochemical supercapacitors.