Mesoporous TiO2 as a nanostructured inorganic polymer thin film applied for a wide range ammonia concentration analyzer based on photoelectrochemical reaction

Mesoporous TiO2 as a nanostructured inorganic polymer thin film was applied for a wide range ammonia concentration analyzer in combination with an O2-reducing Pt cathode based on photocurrent generation from ammonia induced by UV-light irradiation. Various structured sensor units were fabricated comprised of a TiO2 photoanode, a Pt cathode, and an ultraviolet light-emitting diode (UV-LED) light source, and the photocurrent behavior was investigated as a function of ammonia concentration in water under stirring. Among the sensor units fabricated, the Type 4 sensor for which both the electrode surfaces are located perpendicular to the stirring direction gave the best characteristics, which was interpreted by the effective supply of ammonia and O2 onto the electrode surfaces. It was successfully demonstrated that this new type ammonia concentration analyzer gives a linear correlation of photocurrents against logarithmic ammonia concentration in the wide range of five orders of magnitude from 1 mM to nearly 10 M. Copyright © 2011 John Wiley & Sons, Ltd.