Electrogeneration of hydrogen peroxide using phosphorus-doped carbon nanotubes gas diffusion electrodes and its application in electro-Fenton

Hydrogen peroxide (H 2 O 2 ) is a powerful oxidant with a wide range of applications, for example, organic synthesis and wastewater treatment . The present work describes the phosphorus-doped multiwall carbon nanotubes (P-CNTs) catalyst for electrogeneration of H 2 O 2 in acidic and neutral medium using gas diffusion electrode. These P-CNTs are synthesized by a simple and efficient hydrothermal method . The structure and morphology are characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) respectively. The kinetics of the oxygen reduction reaction (ORR) is evaluated by the rotating disk electrode technique. The accumulation of H 2 O 2 reaches to 1291.3   mg/L after 60   min for P-CNTs gas diffusion electrode, while the CNTs gas diffusion electrode produces 415.9   mg/L of H 2 O 2 . The current efficiency for the formation of H 2 O 2 is 88.5% when using P-CNTs gas diffusion electrode, which is higher than 64.7% of CNT gas diffusion electrode in 60   min. The operational parameters for P-CNTs gas diffusion electrode such as cathodic potential, pH and O 2 flow rate are optimized systematically. Finally the P-CNTs gas diffusion electrode is experimentally confirmed to be efficient in the degradation of 200   mg/L metronidazole (MNZ) by electro-Fenton (EF) process at both acidic and neutral pH, indicating its potential for the treatment of refractory organic pollutants wastewaters.