Constructing a superhydrophobic free-standing cathode for highly efficient H2O2 production over a wide pH range

Abstract

In situ producing H₂O₂via a two-electron oxygen reduction reaction (2e⁻ ORR) pathway offers a promising approach for water purification and environmental remediation. However, it is still challenging to develop an efficient cathode for H₂O₂ production over a wide pH range. Here, a carbon fiber paper (CFP) self-supported Co–NC cathode (Co–NC/CFP) with adjustable hydrophilicity/hydrophobicity was designed, aimed at improving H₂O₂ generation and organic wastewater degradation efficiency. It was found that a polytetrafluoroethylene (PTFE)-treated Co–NC/CFP cathode (Co–NC/CFP–PTFE) showed superior H₂O₂ electrosynthesis performance over a wide pH range, undergoing a 50 h stability test with negligible decay. Combined spectroscopic results and contact angles reveal that the enhanced performance originates from the design of binder-free cathodes and triple-phase boundaries (TPBs), which ensures rapid electron transport and mitigates the H₂O₂ corrosion process. The integrated cathode fabricated device demonstrates a rapid organic dye degradation efficiency of 99.6% and high reusability. This work provides an avenue not only for designing and fabricating highly efficient free-standing cathodes for H₂O₂ electrosynthesis but also for improving the reusability of the cathode for sustainable wastewater treatment.