Subband Gap Response of TiO2 and SrTiO3 Photoelectrodes

Abstract

The response of TiO2 and SrTiO3 photoelectrodes to subband gap light has been explored as a function of numerous variables, including intensity and wavelength of light, applied potential, temperature, and electrolyte composition. The photoresponse is shown to be linear with light intensity, to depend on the square root of the applied potential, to occur only for hv > 2.2 eV, and to be independent of temperature and electrolyte composition. These results suggest a bulk excitation process involving impurity and defect-related states in the gaps of these semiconductors. A qualitative model is presented to account for the main features of this excitation process and to provide a basis for suggesting future experiments.

Emergent Midgap Excitons in Large‐Size Freestanding 2D Strongly Correlated Perovskite Oxide Films

“…[21] The defect traps related to oxygen vacancies are ≈0.4 eV below the conduction bandedge. [22,23] Similar fitting results could be obtained for all transferred samples (Figure S2, Supporting Information).…”

“…The origin of the PL peaks and carrier dynamics could be understood based on the band diagram of SrTiO 3 with the in-gap defect states. [21][22][23]32] A schematic of radiative transitions is depicted in Figure 6, where E C is conduction band minimum and E V is valance band maximum; the indirect bandgap separated by them is 3.2 eV. By considering the intrinsic and extrinsic defect reactions, emission peaks are assigned to the interband transitions between in-gap energy states.…”

Photoelectrochemical properties of metal-cluster oxide compounds, A2Mo3O8 and (LiY)Mo3O8

“…However, in the present case of Zn=M%O s and MgaMo30 8, abrupt changes in slope have not been encountered as can be seen from figure 6. Possibly, the observed behaviour seen in figure 6 may indicate defect-related sub-band gap states extending from the band edges into the band gap as illustrated by the work of Butler et al (1981) and Salvador et al (1984) although the nature and origin of these states may differ for the present compounds. Since many d-band semiconductors exhibit predominantly indirect band gaps (e.g.…”

A light–heat synergism in the sub-bandgap photocatalytic response of pristine TiO2: a study of in situ diffusion reflectance and conductance

“…11 For undoped pristine TiO 2 materials, it has been found that they can respond to light with a photon energy lower than the band gap energy (E g ), i.e., the sub-bandgap (SBG) light response, although the efficiency is much lower than that of the superbandgap response. For example, it has been reported that photoelectrochemical (PEC) water oxidations can occur over pristine rutile TiO 2 anodes and SrTiO 3 under SBG light illuminations; 12,13 we recently saw that SBG light illumination can result in a relatively high PEC property over TiO 2 nanorod arrays. 14 The SBG light response might be dependent on the TiO 2 type.…”