Anodic water oxidation to H2O2 on Fe-doped ZnO for electro-Fenton wastewater purification

The pandemic COVID-19 and worsening micropollutant has speed up wastewater purification to develop the highly efficient advanced treatment such as electro-Fenton. Despite ZnO being recognized as a viable electrocatalyst for H2O2 electrosynthesis through the two-electron water oxidation method, there is a dearth of information regarding the implementation of its resultant product. Here, we carefully investigate the Fe-doped ZnO electrode, the Faradaic efficiency of H2O2 electrogeneration at 3.2 V vs. RHE reach summit 78%, moreover it can retain current density of 10 mA cm(-2) for a minimum in 6 h. The electrocatalytic production of hydrogen peroxide can result in the generation of hydroxyl radicals (center dot OH) upon reaction with iron. This system, comprising of hydrogen peroxide and hydroxyl radicals, can be utilized for the treatment of contaminated water. Ofloxacin (OFX) is utilized as a representative micropollutant to evaluate degradation efficacy, whereby both the removal and mineralization rates of OFX are found to be satisfactory. The toxicity of OFX and its transformation products was evaluated by ECOSAR program. In addition, the electrode system can also be used for the removal of microbial contamination in water with a killing rate up to 99%. This method of electrochemical water oxidation to produce H2O2 offers a novel tactical for on-site advanced oxidation processes.

Automated summary

The COVID-19 pandemic has accelerated the development of wastewater purification technologies, such as electro-Fenton. Through careful investigation, we have found that a Fe-doped ZnO electrode can achieve a Faradaic efficiency of 78% for H2O2 electrogeneration at a voltage of 3.2 V vs. RHE, and maintain a current density of 10 mA cm(-2) for at least 6 hours. This electrocatalytic process can generate hydroxyl radicals, which can be used for the treatment of contaminated water. Additionally, this electrode system can effectively remove microbial contamination, with a killing rate of up to 99%.