Electrochemical catalytic mechanism of N-doped electrode for in-situ generation of OH in metal-free EAOPs to degrade organic pollutants

Abstract

• The rapid and convenient method of electrochemical deposition method was used to load PANI on GF. • The main N-functional groups are the active centers for producing and activating H 2 O 2 into OH. • The new cathode overcomes the secondary pollution coming from the traditional EF reaction metal catalyst. High-performance electrochemical advanced oxidation process (EAOPs) using a carbon cathode is a promising environmental protection technology for environmental remediation. The development of a stable and effective cathode is the research focus of this process. In the course of this research, a composite cathode of polyaniline modified graphite felt (PANI/x-GF) synthesized by electrodeposition was introduced. This electrode synthesizes H 2 O 2 in situ through the nitrogen base doped with PANI and activates it into OH radical. Herein, by means of density functional theory (DFT) computations, the effect of various types and sites of nitrogen atoms on electrocatalytic activity was investigated based on characterization and electrochemical examinations. It was revealed that pyridinic N and graphitic N in PANI/6-GF and electron transfer of GF increased the electrocatalytic activity and selectivity for two-electron ORR activity about the H 2 O 2 generation. The main N-functional groups are the active centers of producing and activating H 2 O 2 and entering OH free radicals in situ, and the conversion rate of the modified cathode to OH free radicals is as high as 93%. Due to the improved ORR performance, the degradation of bisphenol A using the in-situ metal-free EAOPs system has been significantly enhanced and the PANI/6-GF showed good stability. These results show that PANI/6-GF composite cathode has great advantages, and is expected to be used as the cathode of metal-free EAOPs system to remove organic pollutants in wastewater.