OCNTs encapsulating Fe-Co PBA as efficient chainmail-like electrocatalyst for enhanced heterogeneous electro-Fenton reaction

Preparing heterogeneous electro-Fenton (HEF) catalysts without sacrificing activity towards the two-electron (2e−) oxygen reduction reaction (ORR) is a challenge, since Fenton-like active sites consist mainly of transition metals that prefer the 4e− ORR pathway. In this study, oxidized carbon nanotubes (OCNTs), which are promising ORR catalysts for the 2e− ORR, were uniformly attached to the surface of Prussian blue analogue (PBA) microcubes, forming a unique chainmail-like catalyst (OCNTs/PBA). 50 mg/L of sulfamethazine (SMZ) was completely removed within 30 min over OCNTs/PBA HEF process, with the first-order kinetic constant increased by 287.2 % compared with that PBA alone. To reveal the mechanism behind the enhanced catalytic activity, several possible interactions between the OCNTs and PBA were proposed and investigated further. This study not only offers a facile method to prepare a chainmail-like HEF catalyst, but also provides valuable insights into the rational design of HEF electrocatalysts with dual Fenton-like and ORR activity.