Alkali Metal Cation Incorporation in Conductive TiO₂ Nanoflakes with Improved Photoelectrochemical H₂ Generation

Abstract

In this research, we investigate the effect of alkali metal cations including Li, Na and Cs in hydrothermal solution on the morphology, stability, and photoactivity of nanostructured TiO 2 nanoflakes as a photoanode. The TiO 2 nanoflakes are formed through hydrothermal treatment of Ti foil in 1.0 M LiOH, NaOH or CsOH at 100°C for 3 h. By subsequent thermal reduction of the structure in an optimized Ar/H 2 environment, conductive TiO 2 nanoflakes were formed. The reduction treatment remarkably improves the photocurrent density of the TiO 2 nanoflakes and has the highest impact on the sample treated in the NaOH alkali solution. For the nanoflakes produced in NaOH alkali solution, the bandgap is shifted to a lower value and the structure shows the most stable morphology after thermal treatment compared to nanoflakes formed in other alkali solutions. Such reduced hydrothermally treated nanoflakes formed in NaOH can generate a photocurrent density of approximately 1 mA/cm À 2 vs. Ag/AgCl in 1.0 M KOH solution, which is six times higher than for pristine TiO 2 .[a] E.

Photoelectrochemical Water‐Splitting Using CuO‐Based Electrodes for Hydrogen Production: A Review

“…Low‐bandgap ceramic oxides such as TiO 2 , BiVO 4 , WO 3 , SnO 2 , Fe 2 O 3 , Cu 2 O, and CuO are considered among promising electrode materials for conducting half water‐splitting. [ 141,150–155 ] Figure illustrates the band edge position and the bandgap of some promising metal oxides that have attracted great attention during the past decade. These materials have specific conduction band (CB) and valence band (VB) edge potentials with different positions compared to water oxidation–reduction half potentials.…”

Intrinsically Ru-Doped Suboxide TiO2 Nanotubes for Enhanced Photoelectrocatalytic H2 Generation

“…From the samples’ CV curves in dark conditions, it is apparent that the area under the curve is dramatically increased for Ru-doped TNTs after Ar/H 2 treatment at 550 °C. This is due to nonfaradic processes that occurred at the surface of the electrode, increasing the active surface area and the number of active sites for the electrocatalytic process and improving the conductivity. ,, …”

“…This is due to nonfaradic processes that occurred at the surface of the electrode, increasing the active surface area and the number of active sites for the electrocatalytic process and improving the conductivity. 20,40,41 Figure 4f illustrates the impedance modulus of the pristine and Ru-doped TiO 2 nanotubes before and after hydrogenation treatment. The Bode diagram results indicate that both To further gain insight into the interplay between the photoactivity and the light absorption of Ru-doped TiO 2 under Ar/H 2 reduction, we prepared photoanodes at different reduction temperatures (500, 550, 600, and 650 °C).…”

Morphology-oriented urchin-like TiO2 nanostructures for enhanced photoelectrochemical water splitting

“…For TiO 2 nanotubes, for example, vast studies have been investigated to grow nanotubes with controlled length and thickness by changing the chemical composition of the electrochemical bath [25,26]. Recently, we have reported the growth of TiO 2 nano akes on Ti substrate in alkaline media including LiOH, NaOH and CsOH and investigated the PEC hydrogen generation of the resulted photoanodes [11]. Results showed that the nano akes produced in NaOH alkali solution shows the most stable morphology after thermal treatment and higher photoelectrochemical performance, compared to nano akes formed in other alkali solutions.…”