Effect of applied potential on photocatalytic phenol degradation using nanocrystalline TiO sub(2) electrodes

• Published in: Applied catalysis. B, Environmental Environmental, 2010-01, Vol.93 (3-4), p.205-211
• Main Authors: Oliveira, Haroldo G, Nery, Daiane C, Longo, Claudia
• Format: Article
• Language: English
• ISSN: 0926-3373
• DOI: 10.1016/j.apcatb.2009.09.030

The activity of transparent and highly porous nanocrystalline TiO sub(2) electrodes for phenol degradation by heterogeneous photocatalysis was investigated. Electrochemical characterization, performed for electrodes with areas = 1.0 cm super(2), revealed that the capacitance values increased under irradiation. Electrodes with areas = 9.0 cm super(2) were used for remediation of 10 mL of an aqueous solution containing 50 mg L super(-1) of phenol. Irradiated by a solar simulator, removal of 48% of total organic carbon was achieved after 3 h. The efficiency was significantly enhanced for electrochemically assisted photocatalysis; the average mineralization was 78% after 3 h and was almost complete after 6 h for a TiO sub(2) electrode externally connected to a Pt counter-electrode and biased at +0.7 or +1.1 V with a potentiostat, or by a series connection to a solar cell. Phenol degradation exhibited pseudo-first-order kinetics, and application of the bias potential increased the rate constant from 0.21 to 0.47 h super(-1). Applying a potential bias to the TiO sub(2) electrode minimizes the recombination of photogenerated charge carriers and enhances the photocatalytic activity towards organic pollutant degradation.