Co–Fe–P Nanosheet Arrays as a Highly Synergistic and Efficient Electrocatalyst for Oxygen Evolution Reaction

The rational design and synthesis of highly efficient electrocatalysts for oxygen evolution reaction (OER) is of critical importance to the large-scale production of hydrogen by water electrolysis. Here, we develop a bimetallic, synergistic, and highly efficient Co–Fe–P electrocatalyst for OER, by selecting a two-dimensional metal–organic framework (MOF) of Co-ZIF-L as the precursor. The Co–Fe–P electrocatalyst features pronounced synergistic effects induced by notable electron transfer from Co to Fe, and a large electrochemical active surface area achieved by organizing the synergistic Co–Fe–P into hierarchical nanosheet arrays with disordered grain boundaries. Such features facilitate the generation of abundant and efficiently exposed Co3+ sites for electrocatalytic OER and thus enable Co–Fe–P to deliver excellent activity (overpotential and Tafel slope as low as 240 mV and 36 mV dec–1, respectively, at a current density of 10 mA cm–2 in 1.0 M KOH solution). The Co–Fe–P electrocatalyst also shows great durability by steadily working for up to 24 h. Our work thus provides new insight into the development of highly efficient electrocatalysts based on nanoscale and/or electronic structure engineering.