The nature and effects of rhodium and antimony dopants on the electronic structure of TiO₂: towards design of Z-scheme photocatalysts

Abstract

The nature and effects of rhodium and antimony doping in TiO2 have been investigated using X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Extended X-ray Absorption Fine Structure (EXAFS), X-ray Absorption Near Edge Structure (XANES) and diffuse reflectance spectroscopy.

Structure and magnetism of the Rh4+-containing perovskite oxides La0.5Sr0.5Mn0.5Rh0.5O3and La0.5Sr0.5Fe0.5Rh0.5O3

“…4a, these values indicate an oxidation state of Rh 4+ . 24,25 Fe 2p spectra (Fig. S2, ESI †) exhibit a well resolved Fe 2p 3/2 component centred at BE = 710.1 eV (FWHM = 3.44 eV) and a Fe 2p 1/2 component centred at BE = 723.3 eV (FWHM = 4.65 eV), consistent with Fe 3+ .…”

Phase quantification by X-ray photoemission valence band analysis applied to mixed phase TiO2 powders

“…Alternatively, the offset between the VBM and the Fermi Level, referenced at the zero point on the binding energy scale can be measured to determine changes in n/p type doping or to establish the workfunction of the surface. 14 The spectral shape of the valence band is a reflection of the energy distribution of the density of filled states, which itself is dependent on the atomic structure. Hence valence band shapes can be calculated from a theoretical partial density of states.…”

Hollow Sr/Rh-codoped TiO2 photocatalyst for efficient sunlight-driven organic compound degradation

“…Using the O 1s of rutile-TiO 2 alone as a reference (Table SI-1 †), the O 1s peak (at 529.3 eV) of Rh-TiO 2 -900 exhibited a negative shi in comparison to that of pristine rutile-TiO 2 (at 529.6 eV), which originated from the introduction of partially lled Rh 4+ states within the band gap. 13 This may cause the downward shiing of Fermi level towards the valence band, which may decrease energy bands along with the reduction potential of photogenerated electrons and induce a negative impact on the photoactivity. 13,34,35 In contrast, a strong positive shi in O 1s peak was observed (at 529.9 eV) for hollow Sr/Rh-TiO 2 -900 in comparison to rutile-TiO 2 alone and Rh-TiO 2 -900, for which the O 1s peaks were centered at 529.9 and 530.5 eV.…”

“…13 This may cause the downward shiing of Fermi level towards the valence band, which may decrease energy bands along with the reduction potential of photogenerated electrons and induce a negative impact on the photoactivity. 13,34,35 In contrast, a strong positive shi in O 1s peak was observed (at 529.9 eV) for hollow Sr/Rh-TiO 2 -900 in comparison to rutile-TiO 2 alone and Rh-TiO 2 -900, for which the O 1s peaks were centered at 529.9 and 530.5 eV. The increased binding energy of O 1s in hollow Sr/Rh-TiO 2 -900 could be assigned to the lling of Rh 3+ states within the band gap, which caused the upward shiing of Fermi level towards the conduction band, which increase the energy bands along with the reduction potential of photogenerated electrons and has a positive impact on the photocatalytic activity.…”

“…SI 1. † 6,13 Therefore, controlling the oxidation state of Rh in Rh-doped TiO 2 is critical to the photocatalytic enhancement of TiO 2 .…”