Acid pretreatment of three-dimensional graphite cathodes enhances the hydrogen peroxide synthesis in bioelectrochemical systems.

Graphite is a potential catalyst for hydrogen peroxide (HO) synthesis in bioelectrochemical systems (BESs) because of its high performance and low cost. In this study, acidic pretreatment method was performed on raw graphite powder to optimize the performance of three-dimensional graphite cathode and increase the HO yield. Through this method, the production rate of HO increased by 46.9% after 20% nitric acid (HNO) pretreatment and reached up to 1.55 mg·L·h, while the chemical oxygen demand (COD) removal efficiency increased by 54%. The high micropore surface area of the acid-pretreated graphite cathode (23.32 m·g) enhanced the oxygen reduction reaction (ORR) in the electrode and subsequently increased the Faradic efficiency and maximum power density by 25% and 45%, respectively. Thus, this approach has potential for HO synthesis.