Photoelectrochemical Characterization of Hydrogenated TiO₂ Nanotubes as Photoanodes for Sensing Applications

Abstract

In this work, hydrogenated TiO2 nanotubes (H-TNTs) electrodes were successfully fabricated via the anodization of a titanium sheet followed by a hydrogenation process. Oxygen vacancies were induced in the crystalline structure of TiO2 nanotubes (TNTs) as shallow donors that enhance the electronic conductivity of the TNTs. This improvement in the electronic conductivity and photoelectrocatalytic (PEC) performance was confirmed and evaluated by a photoelectrochemical characterization. Most importantly, the H-TNTs electrode was able to degrade potassium hydrogen phthalate (strong adsorbent) and glucose (weak adsorbent) indiscriminately. The corresponding photocurrents at the H-TNTs were 2-fold greater than that of the TNTs samples for the same concentrations of the organic compounds. This suggests that the H-TNTs electrode can be a promising sensor for the PEC determination of individual organic compounds or as an aggregative parameter of organic compounds (e.g., chemical oxygen demand).

Enhanced photoelectrochemical performance of the hierarchical micro/nano-structured TiO2 mesoporous spheres with oxygen vacancies via hydrogenation

“…S2B, ESI †). Their Ti2p3/2 and Ti2p1/2 peaks are15 centered at the binding energies of 458.6 eV and 464.3 eV, which is consistent with the characteristic of Ti 4+ in TiO 2 36. It is not surprised that no Ti 3+ is present at the particle surface because of its instability in air 36.…”

“…In conclusion, the hydrogenated TiO 2 mesoporous spheres with hierarchical structure consisting of primary nanoparticles with ∼ 15 15 nm in diameter and secondary colloidal spheres with 500-550 nm in diameter, have been prepared via a facile template-free strategy and subsequently hydrogen treatment. The obtained HMTiO 2 exhibits an enhanced photocatalytic performance, which might be predominantly attributed to the introduction of 20 hierarchical mesoporous structure besides Ov.…”

“…Nevertheless, a qualitative comparison of carrier densities between HM-TiO 2 and M-TiO 2 15 was reasonable because of their similar nanostructure. The increased donor density is due to the introduction of Ov, which functions as shallow electron donor, thus improving the electrical conductivities of TiO 2 and enhancing the separation efficiency of the photogenerated electron-hole pairs.…”

“…25 To address these issues mentioned above, the hierarchical 10 micro/nano-structured design with mesopores may be an alternative, as suggested by Rolison, underlying "the Importance of Nothing and the Unimportance of Periodicity" in catalytic nanoarchitectures, where "nothing" is the porosity at the nanoscale. 26 Such multilevel architectures, combining the 15 advantages of nanoscale and microscale particles, enable materials a wealth of optimized properties. [27][28][29] For instance, this hierarchical structure can simultaneously provide abundant catalytic active sites, electronic conducting framework and mass transport accessible porosity.…”

Dual modification of TiO 2 nanorods for selective photoelectrochemical detection of organic compounds

“…These in turn could significantly improve electrical conductivity and cause red-shift of light absorption resulting in better PEC performance [22][23][24]. Hydrogenated TiO2 has a higher sensitivity and wider linear range for the determination of collective organic compounds due to its decreased intrinsic electrochemical resistance in the UV region [25].…”