Progress in copper-based supported heterogeneous electro-Fenton catalysts

As an advanced oxidation technology (AOPs), electro-Fenton (EF) has been widely used in wastewater treatment, especially in the removal of emerging pollutants. Extremely low pH requirement and additional sludge management for the homogeneous electro-Fenton technology necessitate the development of heterogeneous electro-Fenton (HEF) reactions that utilize solid catalysts that can be recovered and reused. In addition to the use of iron-containing solid substrates as catalysts, in recent years, copper-based HEF catalysts have become a hot topic in HEF research due to their high catalytic oxidation ability and good stability. The copper-based HEF catalyst exhibits better performance than the iron-based catalyst in alkaline and neutral environments. Supporting copper-based catalysts on carriers with high specific surface area and porous structure is an effective strategy to improve the activity and stability of catalysts. In this paper, the copper-based catalysts applied in HEF technology are classified and introduced according to different spatial positions and carriers. The great potential of machine learning in catalyst design and application is analyzed. Finally, the commonly used reactors in HEF technology are summarized. This paper provides a direction for the further development of efficient, stable and green HEF catalysts, and also provides guidance for the development of HEF technology.