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

Abstract

The demand for H₂O₂, a highly efficient and green disinfectant, has been increasing worldwide in recent years. However, the conventional processes for H₂O₂ production are either energy-intensive or have high environmental impact. Herein, we propose 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 impact of key operational factors such as the applied voltage, pH, aeration rate, light intensity, thickness of the pTTh catalytic layer, and electrolyte nature and concentrations on H₂O₂ synthesis was 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 in darkness. Moreover, the BSPS system was successfully tested under natural illumination from sunlight for efficient synthesis of H₂O₂. Finally, a tertiary treatment process by further combining the BSPS system with the 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.