Photoelectrochemical Hydrogen Generation and Concomitant Organic Dye Oxidation under TiO2 Nanotube

Abstract

Highly ordered TiO2 nanotube has been widely employed as photoanode for degradation of organic compounds oxidation during photoelectrochemical process, but its capacity to form hydrogen is not explored. The present work describes the degradation of reactive black 5 dye used as a model of organic pollutant at TiO2 nanotube electrode and concomitant generation of hydrogen at the cathode. A two compartment cell (25mL each compartment) with 0.1 mol L-1 Na2SO4 medium was used and the TiO2 nanotube was photoactivated with UV light using 150W Xe-Arc lamp (Oriel) under bias potential. All photoelectrochemical measurements were carried out in a potenciostat Autolab PGSTAT 302 using a Pt gauze as cathode and as reference electrode a Ag/AgCl. Dye degradation was monitored by spectrophotometric and TOC measurements and hydrogen generation monitored by volume and gas chromatography analysis. The influence of parameters like concentration, pH of the cathode and anode and applied potential was investigated. Using the best experimental conditions of 5x10-5 M dye in 0.1 M Na2SO4 M pH 6, E= 1.0 V and UV irradiation it was obtained 100% of color removal and 72% of TOC removal. Simultaneously was 44% of hydrogen efficiency after 2 h of photoelectrolysis.