FeSe/FeSe2 Heterostructure as a Low‐Cost and High‐Performance Electrocatalyst for Oxygen Evolution Reaction

Abstract A key consensus of implementing large‐scale water splitting is developing highly efficient, durable, and earth‐abundant electrocatalysts for oxygen evolution reaction (OER). In recent years, the Fe‐based materials used in OER have attracted researchers’ great attention around the globe, and Fe has been identified as the OER active sites. In this study, we firstly synthesized the coral‐like FeSe/FeSe 2 heterostructure catalyst via a one‐pot solvothermal method. We demonstrated that different components of FeSe/FeSe 2 heterostructure can facilitate the electron transfer process of the system, where a high Fe charge state promotes OER performance, rendering the coral‐like FeSe/FeSe 2 heterostructure to be more promising Fe‐based electrocatalyst for oxygen evolution reaction in alkaline. As expected, the as‐prepared FeSe/FeSe 2 heterostructure with highly charged iron and negatively charged selenium species exhibited better OER performance and needed only an overpotential of 309 mV to achieve an anodic current density of 10 mA cm −2 . In addition, the catalyst had quick kinetics and good durability in alkaline medium. The present study would open up a potential avenue for the development of highly active non‐noble‐metal electrocatalysts.