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

Abstract

Point defects play important and crucial roles in the design of high performance photocatalysts. We report on the electrochemical fabrication of black TiÀ Mo-NiÀ O nanotubes as a promising electrode material for solar-assisted water splitting. The ternary TiÀ Mo-NiÀ O catalyst was annealed in hydrogen atmosphere to induce point defects in the material to enhance its conductivity, charge carriers density, and performance. The effect of annealing duration on the performance of ternary TiÀ Mo-NiÀ O nanotube films was investigated. The hydrogenannealed nanotubes showed enhanced optical characteristics in the visible spectrum, which can be related to the formation of defect states upon hydrogen annealing. The 10 h-annealed sample showed an exceptionally enhanced photocurrent density of ∼ 10 mA/cm 2 with a remarkable open-circuit voltage of ∼ À 1.0 V Ag/AgCl under AM 1.5G illumination. This improved photocurrent is in agreement with the obtained 75 % incidentphoton-to-current-conversion-efficiency (IPCE), confirming the improved photoactivity of the hydrogen-treated mixed oxide nanotubes.

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

“…31,34 The calculated specic capacitance was found to be 255.4 F g À1 , which is the highest among all titanium-based electrodes reported so far in the literature. 9,25,33 Additionally, the galvanic charge/discharge (GCD) data plotted in Fig. 4d reveal a semi-triangular shape owing to the effect of Ni and Mo with a specic capacitance of 198.6 F g À1 .…”

“…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+ .…”

“…This shi may be attributed to the electronegativity discrepancies between the host atom and the inserted dopants (c Ti ¼ 1.5, c Mo ¼ 2.6, and c Ni ¼ 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 2À and Ti 4+ . Additionally, the Mo 3d highresolution spectrum can be deconvoluted into two sub-peaks at 232.2 and 236 eV, characteristic of Mo 3d 5/2 and Mo 3d 3/2 , respectively.…”

Recent Developments in the Use of Heterogeneous Semiconductor Photocatalyst Based Materials for a Visible-Light-Induced Water-Splitting System—A Brief Review

“…During earlier stages of research, stoichiometric water splitting was not successful in a theoretical way because of several difficulties, the simultaneous, reverse process, unstable nature of photocatalyst, poor variation in selecting photocatalyst and co-catalyst materials, etc. However, significant advancement has been executed, and many complications and hurdles have been overcome [9][10][11][12][13][14][15]. In this context, substantial research efforts have been carried out to upsurge the STH efficiency of those solar-driven photocatalysts.…”

“…In order to efficiently transform solar photons into usable fuels, n-type semiconductor materials can absorb a major portion of the spectral area, with appropriate energy band levels, and lower overpotential to execute a water photoelectrolysis reactions are mandatory. Extensive research efforts have been completed to promote viable n-type semiconducting electrodes that have emerged as photoanodes [14,15].…”