The synergetic degradation of organic pollutants and removal of Cr(VI) in a multifunctional dual-chamber photocatalytic fuel cell with Ag@Fe2O3 cathode

Abstract Photocatalytic fuel cell (PFC) is a novel energy conversion device that can effectively convert light into chemical energy and then electrical energy, accompanied with the pollutant purification treatment by photocatalytic technology. In this study, the synergetic photocatalytic degradation of organic dye in anode and the reduction of heavy metal Cr(VI) in cathode are carried out in an improved dual-chamber PFC device with TiO2 and core–shell structured Ag@Fe2O3 nanoparticles as photoanode and cathode materials, respectively. Among different materials, Ag@Fe2O3 shows the highest catalytic activity to the reduction of Cr(VI) with an apparent kinetic constant of 0.058 min−1, even much better than commercial Pt foil (0.027 min−1). From morphology and electrical characterizations, the excellent electrical conductivity of noble metal Ag and suitable conduction band positions between TiO2 and Fe2O3 lead to a rapid and directional transfer of photoinduced electrons, and the variable valence of Fe(II)/(III) in iron oxide facilitates continuous catalytic reduction of Cr(VI) to Cr(III). Moreover, the addition of H2O2 into anode chamber can significantly accelerate the reactions and electricity output. The radical quenching tests prove that the existence of H2O2 can efficiently increase the production of photoinduced carriers, and more oxidizing species (such as O2− and OH) can be produced from the reactions between H2O2 and photoinduced holes or electrons.