A yolk–shell structure construction for metal–organic frameworks toward an enhanced electrochemical water splitting catalysis

NiFe-based transition metal catalysts are widely used in electrocatalysis, especially in the field of water splitting, due to their excellent electrochemical performance. Herein, a simple method was designed to synthesize a Ni MOF based on nickel foam and it was modified with Fe. After the introduction of Fe, the resulting material exhibits an obvious yolk-shell structure, which greatly increases the specific surface area and facilitates the construction of active sites. At the same time, the synergy between Ni and Fe is conducive to optimizing the electronic structure and effectively improving the poor stability of the MOF. As a result, the synthesized Ni MOF-Fe-2 only needs an overpotential of 229 mV to achieve the OER at a current density of 10 mA cm-2, which is better than most reported transition metal-based electrocatalysts. To our surprise, it showed extraordinary stability under the voltage used for water splitting.