Fe-Based Electrocatalysts for Oxygen Evolution Reaction: Progress and Perspectives

Electrocatalytic oxygen evolution reaction (OER) is a core reaction responsible for converting renewable electricity into storable fuels; yet, it is kinetically challenging, because of the complex proton-coupled multielectron transfer process. Transition-metal-based electrocatalysts, which provide the possibility for the realization of low-cost, high-activity, and stable OER in alkaline solution, therefore have attracted significant research interest in recent years. A fundamental understanding of composition-structure-activity relationships for these electrocatalysts is essential to guide the design of practical electrocatalysts for industrial applications. With more advanced ex situ and in situ techniques to determine the active sites, there has been increasing evidence revealing the critical role of Fe in the high performance of Fe-containing transition metal-based electrocatalysts. Here, we present a critical review of recent progress in Fe-containing electrocatalysts for OER, highlighting the significant role of Fe in enhancing the OER activity. We outline the historical development of the Fe-containing electrocatalysts, summarize the conflicting viewpoints on catalytic active sites, and offer guidelines for more rigorous identification. The synthesis techniques and the major challenges in improving the intrinsic catalytic activity and stability are discussed. Finally, a perspective regarding emerging issues yet to be explored for developing OER electrocatalysts for practical applications are also provided.