Effect of applied potential on photocatalytic phenol degradation using nanocrystalline TiO2 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
• Subjects: Catalysis; Chemistry; Colloidal state and disperse state; Electrochemistry; Exact sciences and technology; General and physical chemistry; Phenol; Photocatalysis; Photochemistry; Photoelectrocatalysis; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Porous materials; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TiO2
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2009.09.030

The activity of transparent and highly porous nanocrystalline TiO2 electrodes for phenol degradation by heterogeneous photocatalysis was investigated. Electrochemical characterization, performed for electrodes with areas=1.0cm2, revealed that the capacitance values increased under irradiation. Electrodes with areas=9.0cm2 were used for remediation of 10mL of an aqueous solution containing 50mgL−1 of phenol. Irradiated by a solar simulator, removal of 48% of total organic carbon was achieved after 3h. The efficiency was significantly enhanced for electrochemically assisted photocatalysis; the average mineralization was 78% after 3h and was almost complete after 6h for a TiO2 electrode externally connected to a Pt counter-electrode and biased at +0.7 or +1.1V 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 0.47h−1. Applying a potential bias to the TiO2 electrode minimizes the recombination of photogenerated charge carriers and enhances the photocatalytic activity towards organic pollutant degradation.