Sustainable cathode design for electrochemical hydrogen peroxide generation using waste-derived carbon from invasive biomass

Abstract

In this work, carbonaceous materials were synthesized from Phragmites australis, an invasive reed species, through hydrothermal carbonization and NaOH chemical activation, and evaluated as electrocatalysts for hydrogen peroxide (H₂O₂) production. The electrochemical generation of H₂O₂ via the two-electron oxygen reduction reaction (2e-ORR) is gaining increasing interest as a green and decentralized approach for advanced water treatment. The impact of catalyst and polytetrafluoroethylene (PTFE) loadings on electrode performance was systematically evaluated, identifying an optimal 1:50 catalyst/PTFE ratio that achieved 438.2 mg L⁻¹ of H₂O₂ with a Faradaic efficiency of 70 %, a power consumption of 4.46 kWh kg⁻¹, and production yield of 2.43 mg h⁻¹cm^-² after 120 min (-0.9 V vs Ag/AgCl). Morphological analyses confirmed that the optimal ratio achieved the desired hydrophobicity (contact angle greater than 120º) and uniform material distribution, which facilitated efficient mass transport at the three-phase boundary. These results improve upon those previously obtained for the same waste biomass activated with KOH and pyrolysis, both in terms of H₂O₂ accumulation and FE. Furthermore, they demonstrated the high transformation potential of this invasive plant biomass compared to other studies on biomass-derived carbon materials, offering a sustainable route for future environmental technologies.