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

Abstract

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 TiÀ MoÀ NiÀ 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 Ti 3 +. 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.

Electrochemical Fabrication of Ternary Black Ti‐Mo‐Ni Oxide Nanotube Arrays for Enhanced Photoelectrochemical Water Oxidation

“…Remarkably, hydrogen reduced samples exhibit superior stability accompanied with enhancement in the photoactivity as well as conductivity for water oxidation, comparable to those of air counterparts. Figure e displays the stability of the 10 h‐ hydrogen treated sample in 1 M KOH under illumination at 0.7 V, manifesting a continuous and long‐term stability over ∼14,000 s. That could evidence the presence of favorable shallow defects which might justify for the higher photoresponse in the hydrogen treated species, verifying overall PEC enhancment . Accordingly, these results suggest that hydrogen annealing could be an effective and impressive pathway for improving the photoelectrochemical activity of the fabricated material.…”

“…Notwithstanding that XRD patterns of the anatase phase of fabricated Ti−Mo‐Ni mixed oxide NTs showed a small shift in the peak positions in the range of ∼0.2–0.3° compared to that of pure TiO 2 . This is expected and might be assigned to the differences in the lattice constants due to implanting other metals within the TiO 2 lattice structure . Obviously, both air‐ and H 2 ‐ treated species show a mixture of anatase and rutile phases; whereby the active TiO 2 anatase crystal structure with lower surface energy is the dominant phase with a small contribution from rutile one.…”

“…04–001–7847). Importantly, no separate peaks were reported for Mo and Ni oxides, suggesting that their ions may be incorporated into the TiO 2 crystal structure or might be present in small fractions compared to Ti counterpart . Notwithstanding that XRD patterns of the anatase phase of fabricated Ti−Mo‐Ni mixed oxide NTs showed a small shift in the peak positions in the range of ∼0.2–0.3° compared to that of pure TiO 2 .…”

A mesoporous ternary transition metal oxide nanoparticle composite for high-performance asymmetric supercapacitor devices with high specific energy

“…Note the small shift in the O 1s peak of the TMN NPs to higher binding energy compared to that of pure TiO 2 (530.8 eV). This shift may be attributed to the electronegativity discrepancies between the host atom and the inserted dopants (χ Ti =1.5, χ Mo =2.6, and χ Ni =1.9) [25][26][27] . The addition of Ni and Mo (with higher electronegativity) to Ti decreases the Ti electronic cloud, which in turn increases the binding energies of O 2and Ti 4+ .…”

Untapped potential of 2D charge density wave chalcogenides as negative supercapacitor electrode materials

“…8 Therefore, it is important to improve the energy density of supercapacitors, which can be realized by tuning the active electrode material, electrolyte, and separator. 10,11 Recently, 2D charge density wave (CDW) materials are proved to be very efficient functional materials in many applications such as sensors, spintronics, and energy conversion. 12 As typical CDW materials, 2D transition metal dichalcogenides (TMDs) exhibit fast charge carrier transport and high charge storage ability.…”