Electronic-ferry in metal element migration promoting deep activation of NiFe based phosphide for high efficient and stable oxygen evolution reaction

The design principle of high-efficient water electrolysis catalysis in oxygen evolution reaction (OER) has been primarily focused on the construction of multi-metal active centres. However, the spatial barrier between nonadjacent metal sites restricts the electron transfer, thus limits the activation and stability of active sites for improving the OER performance. Herein, a concept of electronic-ferry strategy by metal element migration in OER reconstruction is adopted to form dynamic electron-bridge between heterogeneous metal ions, which synchronously improves the OER kinetics and the corrosion resistance of metals centres. By designing layered NiCrP@NiFeP with concentration gradient, Cr element stepwise-release from the core part endows electron-ferry along the path of Ni2+-Cr4+/Ni3+-Cr6+ and Cr3+-Fe4+, achieving deep activated Ni(Fe)OOH layer with highly stable Fe sites in OER reconstruction process. The reconstructed NiCrP@NiFeP electrode shows 270 mV overpotential at 100 mA cm-2 current density with steady working more than 2600 h.