A self-sustaining monolithic photoelectrocatalytic/photovoltaic system based on a WO3/BiVO4 photoanode and Si PVC for efficiently producing clean energy from refractory organics degradation

Abstract

A novel self-sustaining monolithic photoelectrocatalytic/photovoltaic (SMPP) system is constructed with a FTO-glass-based WO3/BiVO4 photoanode, which was prepared by coating BiVO4on WO3 nanoplate array using simple wet chemical methods, a rear Si photovoltaic cell (PVC) and a counter Pt-black/Pt cathode. The optimum SMPP system shows an efficient and stable degradation of tetracycline hydrochloride with a rate constant 0.75 h−1, and yields an open circuit voltage 1.35 V, a short circuit current 2900 μA cm−2, a power density 1112 μW cm−2, which is nearly 14 times that of theultimate conventional photocatalytic fuel cell to date, and a hydrogen generation rate 52.6 μmol h−1 cm−2. This outstanding performance should be due to the efficient electron/hole separation and light exploitation, because, under stimulated sunlight illumination, the front WO3/BiVO4 photoanode absorbs short-wavelength photons and generates electron/hole pairs, in which the photogenerated holes can oxidize organics, while the rear Si PVC captures the transmitting longer-wavelength photons to generate photovoltage that drives photogenerated electrons to the cathode for reducing H+ to H2 and generating electricity in the external-circuit. The results also demonstrate that various refractory organics can be efficiently decomposed along with the production of electricity and hydrogen by the SMPP system. This work provides a more efficient way to dispose organics and simultaneously produce clean energy than conventional technologies and serves well as a promising technology for wastewater recycling.