Self-powered electrochemical synthesis of hydrogen peroxide from air and lignin

Abstract

Lignin, which is typically available as a by-product of pulping process and biomass biorefinery, is a sustainable feedstock for production of carbon fuels and materials. Here, we report a novel coupled electrochemical system to achieve efficient production of H2O2 with air as the oxygen source and lignin as a carbon-based catalyst precursor and electron donor (fuel). By using a direct lignin fuel cell (DLFC) to power a paired electrolytic cell, the endogenous electrons of lignin can be transferred to air, resulting in the formation of H2O2 via two-electron oxygen reduction reaction (2e-ORR). A facile and efficient approach to synthesizing B,O-doped carbonaceous catalyst was developed with lignin as a carbon precursor, achieving an H2O2 productivity of 11812 mmol g−1 h−1 and Faradaic efficiency of 95.7%. Moreover, by using [Fe(CN)6]3−/[Fe(CN)6]4− redox couple as the electron mediators for oxidation of lignin on anode instead of oxygen evolution reaction (OER), the energy consumption of the electrolytic cell could be decreased by 11.4%.The self-powered system could obtain 93.7% of total electron transfer efficiency and avoid using external electricity. Therefore, this work provides a novel technical route for lignin utilization and production of H2O2 and biomass-based chemicals in a sustainable way.