Treatment of Organic Pollutants Using a Solar Energy Driven Photo-Oxidation Device

Two of the main problems of society in the near future are the access to clean water and energy. In particular, organic pollutants can be a major health threat. Within available methods, a trade-off can be established between the pollutant treatment price and the final pollutant concentration that can be achieved. In this paper, a water treatment device is proposed in order to decouple these two variables. It consists of a BiVO4 photoanode combined with a thin film silicon solar cell. BiVO4 is an earth-abundant material with a bandgap energy of 2.4 eV. Here, its good catalytic properties are shown for the degradation of phenol and chloroform when combined with an external bias voltage of 1 V versus Ag/AgCl. In addition, to cover the voltage needs, an a-Si:H/nc-Si:H solar cell has been coupled with the BiVO4 photoanode. This solar cell has been specifically designed to work under the transmitted spectrum of BiVO4, with thicknesses of 300 and 2000 nm for the top and bottom cell, respectively. This device has successfully been fabricated, and tested for removal of organic contaminants from an aqueous solution, performing even better than the BiVO4 photoanode alone with a similar external bias voltage applied.