Novel Sb-doped SnO2 ceramic anode coated with a photoactive BiPO4 layer for the photoelectrochemical degradation of an emerging pollutant

Abstract

In the present work, a study about the electrochemical and photoelectrochemical degradation of an emerging pollutant using an Sb-doped SnO2 anode coated with a photocatalytic layer of BiPO4 has been performed. The electrochemical characterization of the material was carried out by means of linear sweep voltammetry, light-pulsed chronoamperometry and electrochemical impedance spectroscopy. These studies confirmed that the material is photoactive at intermediate potential values (around 2.5 V), and that the charge transfer resistance decreases in the presence of light.A positive effect of the illuminated area on the degradation degree of norfloxacin was observed: at 15.50 mA cm−2, the degradation rate was 83.37% in the absence of light, 92.24% with an illuminated area of 5.7 cm2, and it increased up to 98.82% with an illuminated area of 11.4 cm2. The kinetics of the process were evaluated, and the by-products of the degradation were identified by ion chromatography and HPLC. In the case of the mineralization degree, the effect of light is less significant, especially at higher current densities. The specific energy consumption of the process was lower in the photoelectrochemical experiments as compared to the experiments in dark conditions. At intermediate current densities (15.50 mA cm−2) a decrease in energy consumption of 53% was achieved by illuminating the electrode.