Photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid on TiO2 films under UVA and UVB irradiation

TA McMurray, JA Byrne, PSM Dunlop, ET McAdams

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Titanium dioxide (TiO2) photocatalysis is a possible alternative/complementary technology for water purification. Attempts to increase the overall efficiency of the process include using higher energy UV to gain better quantum efficiency and electrochemically assisting the process by the application of an external electrical potential. In this work, nanocrystalline TiO2 films, prepared on borosilicate glass and indium-doped tin oxide (ITO) borosilicate glass, were used to investigate the photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid under UVA and UVB irradiation. The experiments were carried out in a stirred tank reactor with high mass transfer characteristics. The rate of formic acid oxidation under UVB irradiation was 30% greater as compared to UVA irradiation. A maximum Phi(app) of 9% was obtained under UVA irradiation in 100% O-2 under open circuit or +1.0 V (SCE) applied potential. A maximum Phi(app) of 20.3% was obtained under UVB irradiation with 100% O-2 using TiO2 on borosilicate glass. Phi(app) was 19% for +1.0 V, 100% O-2, using TiO2 on ITO borosilicate glass under UVB irradiation. The increase in oxidation rates and Phi(app) with UVB irradiation are due to the higher extinction coefficient of TiO2 at shorter wavelengths and/or the promotion of conduction band electrons to higher more stable states, thus reducing the rate of recombination of charge carriers. The use of a UVB source as compared to a UVA source results in a significant increase in the rate of oxidation and increased apparent quantum yields, however, a cost analysis of the process would be required to determine the economic viability of employing UVB sources. Electrochemically assisted photocatalysis may prove beneficial in large-scale reactors where mass transfer limitations exist.
LanguageEnglish
Pages723
JournalJournal of Applied Electrochemistry
Volume35
Issue number7-8
DOIs
Publication statusPublished - 2005

Fingerprint

formic acid
Formic acid
Irradiation
Borosilicate glass
Oxidation
Application programs
Indium
Photocatalysis
Tin oxides
Mass transfer
Quantum yield
Conduction bands
Charge carriers
Quantum efficiency
Titanium dioxide
Purification

Cite this

@article{237c7e2747504e7590b92f5a96d16a5b,
title = "Photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid on TiO2 films under UVA and UVB irradiation",
abstract = "Titanium dioxide (TiO2) photocatalysis is a possible alternative/complementary technology for water purification. Attempts to increase the overall efficiency of the process include using higher energy UV to gain better quantum efficiency and electrochemically assisting the process by the application of an external electrical potential. In this work, nanocrystalline TiO2 films, prepared on borosilicate glass and indium-doped tin oxide (ITO) borosilicate glass, were used to investigate the photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid under UVA and UVB irradiation. The experiments were carried out in a stirred tank reactor with high mass transfer characteristics. The rate of formic acid oxidation under UVB irradiation was 30{\%} greater as compared to UVA irradiation. A maximum Phi(app) of 9{\%} was obtained under UVA irradiation in 100{\%} O-2 under open circuit or +1.0 V (SCE) applied potential. A maximum Phi(app) of 20.3{\%} was obtained under UVB irradiation with 100{\%} O-2 using TiO2 on borosilicate glass. Phi(app) was 19{\%} for +1.0 V, 100{\%} O-2, using TiO2 on ITO borosilicate glass under UVB irradiation. The increase in oxidation rates and Phi(app) with UVB irradiation are due to the higher extinction coefficient of TiO2 at shorter wavelengths and/or the promotion of conduction band electrons to higher more stable states, thus reducing the rate of recombination of charge carriers. The use of a UVB source as compared to a UVA source results in a significant increase in the rate of oxidation and increased apparent quantum yields, however, a cost analysis of the process would be required to determine the economic viability of employing UVB sources. Electrochemically assisted photocatalysis may prove beneficial in large-scale reactors where mass transfer limitations exist.",
author = "TA McMurray and JA Byrne and PSM Dunlop and ET McAdams",
year = "2005",
doi = "10.1007/s10800-005-1397-1",
language = "English",
volume = "35",
pages = "723",
journal = "Journal of Applied Electrochemistry",
issn = "0021-891X",
number = "7-8",

}

TY - JOUR

T1 - Photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid on TiO2 films under UVA and UVB irradiation

AU - McMurray, TA

AU - Byrne, JA

AU - Dunlop, PSM

AU - McAdams, ET

PY - 2005

Y1 - 2005

N2 - Titanium dioxide (TiO2) photocatalysis is a possible alternative/complementary technology for water purification. Attempts to increase the overall efficiency of the process include using higher energy UV to gain better quantum efficiency and electrochemically assisting the process by the application of an external electrical potential. In this work, nanocrystalline TiO2 films, prepared on borosilicate glass and indium-doped tin oxide (ITO) borosilicate glass, were used to investigate the photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid under UVA and UVB irradiation. The experiments were carried out in a stirred tank reactor with high mass transfer characteristics. The rate of formic acid oxidation under UVB irradiation was 30% greater as compared to UVA irradiation. A maximum Phi(app) of 9% was obtained under UVA irradiation in 100% O-2 under open circuit or +1.0 V (SCE) applied potential. A maximum Phi(app) of 20.3% was obtained under UVB irradiation with 100% O-2 using TiO2 on borosilicate glass. Phi(app) was 19% for +1.0 V, 100% O-2, using TiO2 on ITO borosilicate glass under UVB irradiation. The increase in oxidation rates and Phi(app) with UVB irradiation are due to the higher extinction coefficient of TiO2 at shorter wavelengths and/or the promotion of conduction band electrons to higher more stable states, thus reducing the rate of recombination of charge carriers. The use of a UVB source as compared to a UVA source results in a significant increase in the rate of oxidation and increased apparent quantum yields, however, a cost analysis of the process would be required to determine the economic viability of employing UVB sources. Electrochemically assisted photocatalysis may prove beneficial in large-scale reactors where mass transfer limitations exist.

AB - Titanium dioxide (TiO2) photocatalysis is a possible alternative/complementary technology for water purification. Attempts to increase the overall efficiency of the process include using higher energy UV to gain better quantum efficiency and electrochemically assisting the process by the application of an external electrical potential. In this work, nanocrystalline TiO2 films, prepared on borosilicate glass and indium-doped tin oxide (ITO) borosilicate glass, were used to investigate the photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid under UVA and UVB irradiation. The experiments were carried out in a stirred tank reactor with high mass transfer characteristics. The rate of formic acid oxidation under UVB irradiation was 30% greater as compared to UVA irradiation. A maximum Phi(app) of 9% was obtained under UVA irradiation in 100% O-2 under open circuit or +1.0 V (SCE) applied potential. A maximum Phi(app) of 20.3% was obtained under UVB irradiation with 100% O-2 using TiO2 on borosilicate glass. Phi(app) was 19% for +1.0 V, 100% O-2, using TiO2 on ITO borosilicate glass under UVB irradiation. The increase in oxidation rates and Phi(app) with UVB irradiation are due to the higher extinction coefficient of TiO2 at shorter wavelengths and/or the promotion of conduction band electrons to higher more stable states, thus reducing the rate of recombination of charge carriers. The use of a UVB source as compared to a UVA source results in a significant increase in the rate of oxidation and increased apparent quantum yields, however, a cost analysis of the process would be required to determine the economic viability of employing UVB sources. Electrochemically assisted photocatalysis may prove beneficial in large-scale reactors where mass transfer limitations exist.

U2 - 10.1007/s10800-005-1397-1

DO - 10.1007/s10800-005-1397-1

M3 - Article

VL - 35

SP - 723

JO - Journal of Applied Electrochemistry

T2 - Journal of Applied Electrochemistry

JF - Journal of Applied Electrochemistry

SN - 0021-891X

IS - 7-8

ER -