Photoelectrochemical characterisation of thermal and particulate titanium dioxide electrodes

Abstract

The photoelectrocatalytic performance of thermal and particulate TiO 2 films on Ti electrode substrates has been studied by photovoltammetry and bulk photoelectrolysis. The thermal TiO 2 film electrodes were prepared by Ti annealing in air at 700°C and 500°C while the particulate electrodes were prepared from dispersions of Degussa P-25 TiO 2 deposited onto Ti substrates and subsequently sintered at 700°C and 500°C. The photocurrent in the absence and presence of the model organic species of oxalate as well as its photooxidation rate depends on coating surface area, type (thermal or particulate) and crystallographic form (anatase or rutile). A method is proposed to account for surface area variations by normalising the data with respect to the electroactive surface area of the TiO 2 electrodes, as estimated by their surface electrochemistry in the dark. The thermal electrodes show high photocurrents both in the absence and the presence of oxalate whereas the performance of particulate electrodes is significantly improved upon oxalate addition. Nevertheless, the efficiency of thermal 700°C TiO 2 for oxalate photooxidation during bulk photoelectrolysis is comparable to that of Degussa P-25 TiO 2 -coated electrodes.

Titania‐Coated Platinum Thin Films by MOCVD: Electrochemical and Photoelectrochemical Properties

“…6A) is featureless apart from a broad peak centered at about -0.65 V, which is attributed to the reduction of Ti IV to Ti III on the electrode surface. [47] This result is congruent with other literature reports concerning a variety of polycrystalline TiO 2 -coated electrodes, [15,[17][18][19]48,49] and reflects the behavior for a n-type semiconductor. [18,46] Photocurrents (i ph ) originated under UV illumination, as is evident in Figures 6B-C.…”

“…From the photocurrent onset method, [50] the flat band potential was estimated to be about -0.60 (± 0.03) V, which is very close to that reported previously for TiO 2 -coated electrodes in neutral aqueous solutions. [15,51,52] The trend of photocurrent as a function of the applied potential, and for various TiO 2 film thicknesses, is displayed in Figure 8. It can be seen that, in all cases, current density increases with the increase of applied potential and tends to a plateau at about 0.4 V. At this potential, therefore, photogenerated electrons on the Pt-TiO 2 electrodes can be effectively driven to the counter electrode, which is beneficial to charge separation.…”

Photoelectrochemical properties of MoO2 thin films

“…The quantitative measure of semiconductor photoelectrochemical properties is the incident photon-to-current efficiency (IPCE) [34]:…”

Effect of oxidisable substrates on the photoelectrocatalytic properties of thermally grown and particulate TiO2 layers

“…Palombari et al [4] reported the presence of rutile, whereas Mintsouli et al [13] found anatase; neither reported the diffraction patterns of Ti sample heated at 500°C. In the present study, anatase lines were absent, but the indication of the strongest rutile line (2H = 27.45°, 110) was evident, corroborating the findings of Palombari et al [4].…”

“…Mintsouli et al [13] recently reported the photoelectrochemical characterization of TiO 2 grown by thermal oxidation of Ti in air and particulate (Degussa P25) TiO 2 electrodes, which were heated at 500 and 700°C. It was found that photocurrent depends on coatings surface area and crystallographic form.…”