Preparation of N_x−Fe/Fe₃C/KVO₃ composites by heat treatment for high‐performance electrocatalytic oxygen evolution

Abstract

Cementite (Fe3C) as a special iron‐carbon alloy has excellent electrical conductivity, while its electron‐rich iron‐carbon bonds provide potential electrocatalytic oxygen evolution performance. In this work, novel Nx−Fe/Fe3C/KVO3 composites were obtained by simple heat treatment using K−V−Fe Prussian blue analogues (PBAs) nanocubes as precursors. The residual nitrogen after heat treatment using Prussian blue can introduce new C−N active sites, which can further improve the OER performance of these composites. The KVO3 can also synergize with Nx−Fe/Fe3C, thus requiring an overpotential of 359.9 mV to reach a current density of 10 mA ⋅ cm−2 at a sweep rate of 2 mV ⋅ s−1. Moreover, the Tafel slope of these electrocatalysts is only 32.9 mV ⋅ dec−1, indicating its high‐speed OER reaction kinetic process. This work provides a new idea for constructing Fe3C composite with other materials and will promote the development of non‐noble metal electrocatalysts for oxygen evolution.