Interfacial Concentration Gradient as a Source of Anomalous Photoeffect in Photoelectrodes

Abstract

TiO2-nanostructured photoelectrodes generate a concentration differential at the electrolyte/electrode interface under certain pH conditions that produce the anomalous photoeffect (APE). Increased cathodic current due to enhanced electron transfer toward the interface is identified as a source of the APE.

Photoelectrochemical Methods for the Determination of the Flat-Band Potential in Semiconducting Photocatalysts: A Comparison Study

“…Note that the big difference between the results from anodic and cathodic CV curves is not for all studied photocatalysts (Table ), but in most cases approximation of anodic curves gives more adequate values of potential. This corresponds to the recommendation for avoiding anomalous photoeffect during the measurements. , …”

“…This corresponds to the recommendation for avoiding anomalous photoeffect during the measurements. 77,78 Similar to the MS method, the presence of methanol in the electrolyte has no substantial effect on the E FB values estimated by using the GB plots (Figure 5b). In this case, the flat-band potentials are slightly positive (by 0.06−0.12 V) than the corresponding values measured without methanol (Table 2).…”

“…This result may be due to an anomalous photoeffect because the cathode current can be amplified under irradiation, thus resulting in the intersection of dark/light CV curves in the cathode region. Thota et al have shown recently 77 that in situ generated electroactive species at the electrode/electrolyte interface can be a source of this anomalous photoelectric effect. Therefore, a significant difference between the results from the analysis of anodic and cathodic curves of CV can be observed in the GB method.…”

“…The data obtained using the GB method are rather difficult to interpret due to the possible shift of the cathode curve of CV during irradiation of the photoelectrode. The reasons for that can be related to the anomalous photoeffect, , as discussed above, or Faraday processes, which lead to a change in the structure of nanoparticles. However, for some semiconducting photocatalysts, this method gives similar results as other methods (see the results for TiO 2 –N, Bi 2 WO 6 , and CoO photocatalysts in Table ).…”

Dual Functionality of Surface States in Dictating Photocurrent Generation of Au Nanocluster-Sensitized TiO2 Electrodes

“…These screenprinted electrodes were then slowly sintered in air at 550 °C followed by post-treatment with TiCl 4 . Finally, the freshly prepared electrodes were immersed in the Au 18 (SG) 14 NC solution for varied durations (1,6,12,24, and 48 h) to achieve uniform sensitization. After sensitization, the photoanodes (Au 18 −TiO 2 ) were washed with deionized water and ethanol solution to remove loosely bound NCs.…”