Highly-efficient degradation of organic pollutants and synchronous electricity generation in a photocatalytic fuel cell based on the catalytic reactions of hydroxyl and chlorine radicals

Abstract

Organic compounds in wastewater are significant energy sources. Given this situation, a novel and high-performance photocatalytic fuel cell (PFC) integrated with NaOCl/Cu (II) was successfully constructed to effectively convert hazardous organics into clean energy. This designed system is comprised of nickel oxide (NiO)/TiO2 nanotubes (TNTs) photoanode and polyaniline (PANI)/multi-walled carbon nanotubes (MWCNTs) cathode. Compared to the single PFC, the combined system exhibited better performance. This coupled PFC/NaOCl/Cu (II) system enhanced the photocatalytic reaction and strengthened the reaction range of reactive species from the surface of electrodes to the whole liquid phase via generation of reactive chlorine radicals (Cl•, Cl2•–, ClO•) and reactive oxygen species (HO•, •O2–, HO2•). Hence, PFC/NaOCl/Cu (II) exhibited excellent cell efficiency, increasing the AB113 degradation by 48.1% and electrical power generation by 59.38% compared to the PFC system without adding NaOCl/Cu (II). The effects of the important operating parameters (initial pH, NaOCl/Cu (II), and concentration of substrate) on the PFC performance were investigated by response surface methodology (RSM). The results showed that the different model compounds could be used as fuel. The highest short circuit current density of 3.1 mA cm –2, and maximum power density of 1.12 mW cm–2 were obtained using citric acid as the substrate. This study provided an efficient approach to dispose of organic waste and to generate synchronous electrical power.