Interfacial Atom‐Substitution Engineered Transition‐Metal Hydroxide Nanofibers with High‐Valence Fe for Efficient Electrochemical Water Oxidation

Abstract Developing low‐cost electrocatalysts for efficient and robust oxygen evolution reaction (OER) is the key for scalable water electrolysis, for instance, NiFe‐based materials. Decorating NiFe catalysts with other transition metals offers a new path to boost their catalytic activities but often suffers from the low controllability of the electronic structures of the NiFe catalytic centers. Here, we report an interfacial atom‐substitution strategy to synthesize an electrocatalytic oxygen‐evolving NiFeV nanofiber to boost the activity of NiFe centers. The electronic structure analyses suggest that the NiFeV nanofiber exhibits abundant high‐valence Fe via a charge transfer from Fe to V. The NiFeV nanofiber supported on a carbon cloth shows a low overpotential of 181 mV at 10 mA cm −2 , along with long‐term stability (>20 h) at 100 mA cm −2 . The reported substitutional growth strategy offers an effective and new pathway for the design of efficient and durable non‐noble metal‐based OER catalysts.