Prussian blue analogs derived nanostructured Mn/Fe bimetallic carbon materials for organic pollutants degradation via peroxymonosulfate activation

In this study, using Prussian blue analogs (Mn-Fe PBAs) as the precursors, Mn/Fe bimetal loaded N-doped carbon materials (Mn-Fe-CN) were obtained by pyrolysis followed by acid etching. The influences of calcination temperature and the molar ratio of Fe/Mn in precursor were investigated. Mn-Fe-CN obtained by calcining Mn-Fe PBAs precursors with Fe/Mn molar ratio of 0.5 at 700 °C exhibited high activity for degradation of rhodamine b (RhB) by activating peroxymonosulfate (PMS). Acid etching achieved higher catalytic activity by removing excessive agglomerated metals generated during pyrolysis process and exposing more catalytic active sites in the catalyst. Fe, Mn and N-doped carbon were the active sites of the catalyst. In the Mn-Fe-CN/PMS/ RhB system, there was a redox cycle between Fe and Mn with multivalent states. O2•− and 1O2 were found to be the major reactive oxygen species, while •OH, SO4•− and electron transfer between Mn-Fe-CN and PMS, RhB played the minor roles. This work could provide a reference for further development of high performance and environmentally friendly catalyst.