The synergic generation of CO3•- and O2•- radicals in a novel photocatalytic fuel cell for efficient oxidation of carbonate-containing wastewater and simultaneous electricity production

The treatment of refractory wastewater and energy utilization are challenging environmental issues. Carbonate as the most common anion abounds in the aquatic environment. Here, we proposed a novel method to degrade carbonate-containing wastewater and simultaneous electricity generation via the combined oxidation of CO3 center dot- and O-2(center dot-) radicals. The CO3 center dot- radical was produced by the photoelectrode of TiO2/Si photovoltaic cell with the rear Si photovoltaic cell providing external bias, and the O-2(center dot-) radical was produced from the generation of H2O2 on a gas diffusion electrode (GDE), and they were both further enhanced from the activation reaction of H2O2 with HCO3- electrolyte. The result showed that a high degradation ratio of 91.97 % was achieved in 120 min for a typical refractory organics of rhodamine b (RhB), which is more than double of that in traditional system by using Pt black as cathode and SO42- as electrolyte. In addition, this system could achieve electricity production with a 28.9 % increase when adding RhB. Moreover, the mechanism of efficient degradation and electricity generation were also studied. The proposed system provides a novel way for organics efficient degradation and simultaneous electricity production in carbonate-containing wastewater.