A portable solar light-driven biophotoelectrocatalytic system for pollutant removal powered by photovoltaic cells

Photoelectrocatalytic (PEC) technology has been considered as one of the most efficient advanced oxidation processes for wastewater treatment, but the necessity of external electric power supply limits the portability of PEC system for on-field applications. Herein, a portable solar-powered biophotoelectrocatalytic system driven by photovoltaic (PV) cells was explored for degradation of pollutant by coupling BiVO₄/Fe₂O₃-deposited photoanode and horseradish peroxidase (HRP)-immobilized cathode. The integration of PV cells in this PEC device could not only avoid the necessary introduction of external electric power supply, but also improve the utilization of solar irradiation. The characterization of BiVO₄/Fe₂O₃ photoanode demonstrates that ultrathin Fe₂O₃ layer on BiVO₄ electrode could facilitate the holes transfer to the surface efficiently and thus avoid charge recombination. After HRP was immobilized on the cathode, the removal efficiency for 2,4-dichlorophenol (2,4-DCP) was obviously promoted, attributed to the efficient HRP-catalyzed oxidation reaction by in-situ generated H₂O₂ from PEC process. Under natural solar irradiation, the proposed portable biophotoelectrocatalytic device exhibited a satisfying removal efficiency of 92.0% for 100 ppm of 2,4-DCP after 3-h treatment. The intermediate products formed during the degradation process were identified by liquid chromatography-mass spectrometry, and possible 2,4-DCP degradation pathway was also proposed.