O/F co-doped CNTs promoted graphite felt gas diffusion cathode for highly efficient and durable H2O2 evolution without aeration

Electrocatalytic reduction of O2 is an environmentally friendly method for H2O2 production. Design and fabrication of efficient non-metallic electrocatalytic gas diffusion cathode (GDC) with strong durability is highly desirable. Carbon nanotubes (CNTs) is a promising electrocatalytic material for 2-electron O2reduction but with unsatisfying electrocatalytic activity and stability. Hetero-atom doping of CNTs has been proved to promote its electrocatalytic selectivity for H2O2 generation, but the electrocatalytic performance of CNTs co-doped with two hetero-atoms and its synergy mechanisms need further investigation. Herein, O or F mono-doped and O/F co-doped CNTs with different O/F ratios were developed through one-step acidification and then used as the electrocatalysts on the graphite felt (GF) GDC for H2O2 generation. The electrocatalytic activity was greatly improved by the synergetic effects of O/F-containing functional groups on the surface of CNTs. The GF/CNTs-1:1 cathode with the highest contents of COOH and CFX (X ≥ 2) was found to be most efficient in H2O2electrogeneration at a wide pH range of 1–9. Further, with coating of polytetrafluoroethylene (PTFE) film, the GF/CNTs-1:1/PTFE-30 GDC exhibited extremely high activity and superior stability in 15 cycles without aeration, giving the maximum H2O2 yield of 263.2 mg·L−1in 1 h with little decline rate. The present study provides opportunities for developing highly efficient, cost effective, and durable metal-free electrocatalysts for H2O2 evolution.