A solar responsive photocatalytic fuel cell with a heterostructured ZnFe2O4/TiO2-NTs photoanode and an air-breathing cathode

A solar responsive photocatalytic fuel cell (PFC) system comprising a heterostructured ZnFe2O4/TiO2-NTs photoanode and an air-breathing cathode was successfully constructed for simultaneous pollutant removal and power production. The as-prepared PFC system exhibited outstanding properties in solar light response, photocurrent activity and long-term stability. Different categories of organic compounds were used to study the cell performances. Results showed that the additions of carboxylic acids (acetate acid, succinic acid or citric acid) and azo dyes (methylene blue or fuchsin) dramatically improved the maximum power density (P-max) and the short-circuit current density (J(sc)) relative to that without organic substrate. The PFC with citric acid obtained the highest P-max and J(ac) values of 13.1 mu W/cm(2) and 63.1 mu A/cm(2), respectively, which were similar to 3.7 and similar to 1.9 times as much as that without substrate. For comparison, the additions of phenolic compounds (phenol or hydroquinone) and pharmaceutical products (oxytetracycline hydrochloride or tetracycline hydrochloride) resulted in a decrease of Pm.. Tetracycline hydrochloride obtained the lowest Pm and Js, values of 1.3 mu W/cm(2) and 11.4 mu A/cm(2), respectively, this phenomenon was attribute to the complicated molecular structure of tetracycline hydrochloride and some intermediates produced in photoelectrocatalytic degradation process, which restricted the photocurrent enhancement. The degradation experiment showed that 79.8% of methylene blue (20 mg/1) was decolorized in the PFC process in 6 h, which was much higher than that of photolysis and photocatalysis process. The reaction mechanism responsible for the enhanced photoelectrocatalytic performance of the as-established PFC system was also discussed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.