Scaling of flat band potential and dielectric constant as a function of Ta concentration in Ta-TiO2 epitaxial films

Abstract

Electrochemical impedance spectroscopy measurements of pulsed laser deposited single crystal anatase TiO2 thin films with various concentrations of Ta substituting for Ti were carried out. The qualities of the films were characterized by X-ray diffraction and Rutherford back scattering-channeling measurements. UV-visible measurements show a systematic increase of the bandgap with Ta incorporation. Corresponding Mott-Schottky plot was applied to obtain a continuous shift of the flat band potential with increasing free charge carrier (provided by Ta) concentration. This was verified theoretically by ab initio calculation which shows that extra Ta d-electrons occupy Ti t2g orbital with increasing Ta concentration, thereby pushing up the Fermi level. The Mott-Schottky results were consistent when compared with Hall effect and temperature dependent resistivity measurements. From the measured deviation of carrier densities from Hall and Mott-Schottky measurements we have estimated the static dielectric constant of the TiO2 as a function of Ta incorporation, not possible from capacitive measurements

Collisional Electron Transfer Route between Homogeneous Porphyrin Dye and Catalytic TiO2/Re(I) Particles for CO2 Reduction

“…39 These potentials are significantly more negative than those reported for CH 3 CN in other literature studies. 43,46,47 If we take this value as E fb of the hybrid, the endergonic electron injection from ZnP into dry TiO 2 particles would be much slower. However, in the presence of proton sources (3−6 vol % water, 3 vol % TFE, or 16.7 vol % TEOA), substantial positive shifts of E fb occur as much as 0.12−0.45 V (see Figure 10 and Table 3).…”

Sol–gel preparation of pure and doped TiO2 films for the photocatalytic oxidation of ethanol in air

“…The band gap (Fig.6) of Nb and Ta doped TiO 2 , compared to non-doped TiO 2 (sample B), showed an absorption edge ( Table 2) shifted to higher energy and this is due to band filling effects (Moss-Burstein shift) [32,33]. Upon V doping the samples synthesized from alkoxide showed a red-shift whereas the ones from V 2 O 5 presented a blue-shift.…”

Nickel Nanoparticles Encapsulated in Nitrogen‐Doped Carbon Nanofibers as Excellent Bifunctional Catalyst for Hydrogen and Oxygen Evolution Processes

“…The flat band potentials of GCN, GCN−Ni@C and Ni@C−(N)CNF‐5 were determined as: −0.93 V vs. SCE, −0.66 V vs. SCE and −1.40 V vs. SCE, respectively. It reveals higher reducing ability of photogenerated electrons in Ni@C−(N)CNF‐5 in comparison to GCN and GCN−Ni@C. Moreover, the free charge carrier concentration in the samples was determined from the slope of the M−S plots [32] . The slope of the samples was in the following order GCN>GCN−Ni@C>Ni@C−(N)CNF‐5, revealing that free charge carrier density increased when GCN was modified with Ni nanoparticles and graphitic carbon (GCN−Ni@C) and was the highest after CVD‐growth of CNFs (Ni@C−(N)CNF‐5).…”