Pyridine N of N/Co-co-doped graphite gas diffusion electrode facilitating the efficient production of hydroxyl radicals in the electro-peroxone process

Abstract

The electro-peroxone (E-peroxone) process combines ozone (O3) and hydrogen peroxide (H2O2) produced by an oxygen reduction reaction (ORR) pathway to generate super-active hydroxyl radical (·OH), which is considered to be a promising new advanced oxidation technology. Here, a N/Co-co-doped graphite gas diffusion electrode (Co-NG GDE) has been prepared by a simple mixed calcination method and applied in the E-peroxone system. Somewhat surprisingly, the Co-NG GDE exhibited the highest degradation efficiency for phenol and oxalate, though it performed the worst in the ORR to H2O2. The characterization test and experimental results have shown that Co-NG GDE produces abundant O2.– that can replace H2O2 to react with O3 to form super-active ·OH, which is due to the higher pyridine-N content of it. This work circumvents the limitation of H2O2 as the main intermediate in the traditional E-peroxone process by altering the main reaction pathway of the E-peroxone process and brings some new enlightenment to the research and development of this methodology.