Solar-powered enzymatic-photoelectrocatalytic system constructed with three-dimensional dual photoelectrodes for highly efficient purification of coking wastewater

The coupling of photoelectrocatalysis (PEC) and enzymatic catalysis was explored for efficient treatment of practical phenol-containing coking wastewater outdoors. The developed enzymatic-photoelectrocatalytic (EPEC) system consisted of three-dimensional dual photoelectrodes fabricated with carbon fiber cloth (CFC), namely a CFC-supported WO 3 photoanode with oxygen vacancies and a CFC-supported Au-BiOBr photocathode with immobilized horseradish peroxidase (HRP). The experimental results and computational fluid dynamics study revealed that dual CFC-based photoelectrodes with three-dimensional network structures could optimize the fluid diffusion on the electrode surface and enhance the efficiency of pollutant degradation. Further investigation indicated that the introduction of oxygen vacancies promoted the PEC oxidation activity of the WO 3 photoanode while the Au nanoparticles modification was favorable to improving the immobilization of HRP and PEC generation of H 2 O 2 on BiOBr photocathode. Moreover, photovoltaic (PV) cells were integrated in the EPEC system to provide applied potential and promote the utilization of solar irradiation. The mineralization rate of coking wastewater reached 88.5% using the PV-integrated EPEC system driven by natural solar energy, which demonstrated potential for treating actual industrial wastewater.