Fe-doped CoP core–shell structure with open cages as efficient electrocatalyst for oxygen evolution

Developing a facile approach based on transition metal-based Prussian blue (PB) and its analogues (PBAs) with core–shell nanostructure is a very promising choice for constructing cost-effective electrocatalysts for oxygen evolution reaction (OER). Herein, a bimetallic core–shell structure with open cages of Fe-doped CoP (Fe-CoP cage) has been synthesized using CoFe-PBA cage-4 as precursor through a facile hydrothermal method and following phosphating process. Interestingly, there is an open hole in each face center of Fe-CoP cage, which suggests the more exposure of active sites for OER. Electrochemical measurements show that Fe-CoP cage can afford a current density of 10 mA cm−2 at a low overpotential (300 mV), which is better than that of RuO2. The excellent performance can be attributed to Fe doping composition and unique open-cage core–shell structure. The synergistic effect derived from bimetallic active for OER has been discussed. And its great catalytic stability has been evaluated via 1000 cycles of CV and chronoamperometry measurement. This work provides a potential method to design multiple transitional metal-doping electrocatalysts with complex framework derived from PBAs for water splitting.