Water oxidation by P25 TiO2 photoanodes in acidic solution.
In: Chemosphere, Jg. 271 (2021-05-15), S. N.PAG
academicJournal
Zugriff:
P25 TiO 2 photoanodes are used to photo-oxidise water in two different acids, 0.5 M H 2 SO 4 and 1 M HClO 4. In the former acid, the linear sweep voltammogram, LSV, appears to exhibit two photocurrent waves, whilst only one in the latter. In 0.5 M H 2 SO 4 , the recorded LSV coupled with a low faradaic efficiency (0.58) for the photooxidation of water to O 2 , f O2 , and a significant level of persulfate, f S2O8 = 0.12, shows that the electrochemical kinetics are not simply those for water oxidation. In 1 M HClO 4 , the LSV coupled with a high f O2 value (0.91) suggest that the photocurrent is due to water oxidation. Photo-induced absorption spectroscopy, PIAS, measurements made using the P25 TiO 2 photoanode reveal a steady state absorbance change, ΔAbs ss , associated with the steady-state concentration of surface accumulated holes, [h+] ss , which varies with: (i) monitoring wavelength, with a peak at ca. 500 nm, and (ii) applied potential, flattening off at ca. 0.7 V vs Ag/AgCl. PIAS measurements, coupled with concomitant transient photocurrent (TC) measurements, on the P25 TiO 2 photoanode polarised at 1.3 v vs Ag/AgCl, in 1 M HClO 4 , show that the oxidation of water is second order with respect the concentration of the surface-accumulated, photogenerated holes, [h+] ss , which have a calculated turnover frequency of 19 s−1, under 1 sun irradiation. This is the first reported example of the use of PIAS/TC to probe the photoelectrochemical kinetics exhibited by a mesoporous semiconductor photoanode derived from a powder, for water oxidation and the significance of such is discussed briefly. • First use of PIAS/TC to probe oxidation of water by a powder-based photoanode. • First use of P25 TiO 2 as a photoanode in this PIAS/TC study. • faradiac efficiency for water oxidation is ≪ 1 inH 2 SO 4 , but not HClO 4. • In HClO 4 , PIAS/TC shows photogenerated hole reaction order is 2. • TOF (19 s−1) very similar to that for flat dense TiO 2 films. [ABSTRACT FROM AUTHOR]
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Water oxidation by P25 TiO2 photoanodes in acidic solution.
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Autor/in / Beteiligte Person: | O'Rourke, Christopher ; Mills, Andrew |
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Zeitschrift: | Chemosphere, Jg. 271 (2021-05-15), S. N.PAG |
Veröffentlichung: | 2021 |
Medientyp: | academicJournal |
ISSN: | 0045-6535 (print) |
DOI: | 10.1016/j.chemosphere.2021.129847 |
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