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(H 3 O)(PO 4 ) 2 nanosheet arrays (NAs) were synthesized using an electrochemical strategy. FeCo(H 3 O)(PO 4 ) 2 NAs as precatalyst could undergo significant self-reconstruction, including leaching of phosphate anions and electro-oxidation of Co 2+ during anodizing at the potential range of oxygen evolution reaction (OER) in 1 M KOH solution, eventually resulting in the formation of Fe 0.5 Co 0.5 OOH NAs with low crystallinity . The high content of Fe in Fe 0.5 Co 0.5 OOH NAs promoted the formation of active Fe 3+ –O–Fe 3+ motifs that increased OER occurrence. Additionally, Fe incorporation increased the ratio of the reaction rate constants of oxygen evolution to Co 3+ /Co 4+ (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 Fe 0.5 Co 0.5 OOH NAs.