Highly efficient electro-generation of hydrogen peroxide using NCNT/NF/CNT air diffusion electrode for electro-Fenton degradation of p-nitrophenol

Abstract

To promote the in situ generation of hydrogen peroxide (H2O2) in electro-Fenton system, a new air diffusion electrode (ADE) was put forward in the present work using N-doped multi-walled carbon nanotubes (NCNT) as the catalyst layer, multi-walled carbon nanotubes (CNT) as the diffusion layer, and nickel foam (NF) as the supporting material, respectively. The catalyst layer in ADE was characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. Then the performances of H2O2 accumulation and p-nitrophenol (p-NP) degradation with the electrode (NCNT/ NF/CNT ADE) were investigated. The experimental results showed that H2O2 accumulation on the NCNT/NF/CNT ADE was greatly improved by the presence of N doping, and H2O2 accumulation concentration could reach 307 mg L-1 after 120 min at the current intensity of 100 mA. Moreover, the NCNT/NF/CNT ADE presented more effective performance on p-NP degradation than the CNT/NF/CNT ADE or the NF ADE. p-NP of initial 50 mg L-1 could be almost completely removed after 30 min, and the total organic carbon removal efficiency reached 62.61% after 120 min when 0.4 mM Fe2 was added into the system. The repeatability test suggested that the stability of the NCNT/NF/CNT ADE was very good.