Deeply self-reconstructing CoFe(H3O)(PO4)2 to low-crystalline Fe0.5Co0.5OOH with Fe3+-O-Fe3+ motifs for oxygen evolution reaction

In this study, phosphate FeCo(H3O)(PO4)(2) nanosheet arrays (NAs) were synthesized using an electrochemical strategy. FeCo(H3O)(PO4)(2) NAs as precatalyst could undergo significant self-reconstruction, including leaching of phosphate anions and electro-oxidation of Co2+ during anodizing at the potential range of oxygen evolution reaction (OER) in 1 M KOH solution, eventually resulting in the formation of Fe0.5Co0.5OOH NAs with low crystallinity. The high content of Fe in Fe0.5Co0.5OOH NAs promoted the formation of active Fe3+-O-Fe3+ motifs that increased OER occurrence. Additionally, Fe incorporation increased the ratio of the reaction rate constants of oxygen evolution to Co3+/Co4+ (k(OER)/k(M,ox)) and enhanced the reaction order on the hydroxyl ion. These factors significantly contributed to the outstanding OER catalytic performances of Fe0.5Co0.5OOH NAs.

Automated summary

In this study, phosphate FeCo(H3O)(PO4)(2) nanosheet arrays were synthesized using an electrochemical strategy. It was found that FeCo(H3O)(PO4)(2) nanosheet arrays could undergo significant self-reconstruction under the conditions of oxygen evolution reaction (OER), resulting in the formation of Fe0.5Co0.5OOH nanosheet arrays with low crystallinity. The high Fe content in Fe0.5Co0.5OOH nanosheet arrays promoted the formation of active Fe3+-O-Fe3+ motifs and enhanced the reaction order on the hydroxyl ion, leading to outstanding OER catalytic performances.