Novel bio-solar hybrid photoelectrochemical synthesis for selective hydrogen peroxide production

The demand for H₂O₂, a highly efficient and green disinfectant, has been rising worldwide in recent years. However, the conventional processes for H₂O₂ production are either energy-intensive or with high environmental impact. Herein, we proposed an innovative bio-solar hybrid photoelectrochemical synthesis (BSPS) system that couples microbial photoelectrochemical synthesis and polyterthiophene (pTTh)-based photocatalysis for efficient and selective synthesis of green H₂O₂. The impacts of the key operational factors such as the applied voltage, pH, aeration rate, light intensity, thickness of pTTh catalytic layer, and electrolyte nature and concentrations on the H₂O₂ synthesis were assessed. The BSPS system yielded a cumulative production of 232.5 mg L^-1 of H₂O₂ in 12 h under LED light irradiation, which is 6.1-fold the yield using a typical graphite plate electrode and 7.8-fold the yield when the system was run under darkness. Moreover, the BSPS system was successfully tested under natural sunlight illumination for efficient synthesis of H₂O₂. Finally, a tertiary treatment process by further combining the BSPS system with Fenton reaction enabled the rapid and complete removal of twenty micropollutants in wastewater. This work introduces an innovative and sustainable energy recycling strategy enabling H₂O₂ generation and subsequent efficient tertiary wastewater treatment.