Dual role of N-doped graphene film as a cathode material for anodic organic oxidation and persulfate production and as a planar carbocatalyst for non-electrochemical persulfate activation

Abstract

In this study, a large-area N-doped graphene film (NG/NF) was fabricated on a nickel foam (NF) substrate via thermal chemical vapor deposition along with the flow of gaseous C₂H₄/NH₃ mixtures. It was demonstrated to enable the sequential process of anodic organic oxidation followed by non-electrochemical activation of anodically formed persulfate. NG-20/NF exhibited the highest electrical conductivity owing to the presence of a pyridinic-N dopant. It thus substantially outperformed the undoped graphene film (G/NF) and NF in initiating anodic oxidation reactions, that is, oxidative organic degradation and conversion of SO₄²⁻ into persulfate. NG-20/NF performed non-radical persulfate activation, achieving constant treatment efficiency, regardless of whether electric current was applied. A marginal reduction in treatment performance occurred in the electrochemical system using NG/NF during recurring cycles of separate switch-on and -off periods. Accordingly, the dual role of NG/NF as the cathode in paired redox reactions and as the carbocatalyst in persulfate activation was shown.