(FeMnCe)-co-doped MOF-74 with significantly improved performance for overall water splitting.

Developing inexpensive electrocatalysts with high activity and stability is of great value for overall water splitting. In this work, we designed a series of 3d-4f (FeMnCe)-trimetallic MOF-74 with different ratios of 3d- and 4f-metal centers. Among them, FeMnCe-MOF-74/NF exhibited the best electrocatalytic performance for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in an alkaline solution. It only requires a low overpotential of 281 mV@100 mA cm for OER and 186 mV@-10 mA cm for HER in 1 M KOH. With FeMnCe-MOF-74/NF as the anode and cathode in the overall water splitting system, only 1.65 V is needed to deliver a current density of 10 mA cm. In particular, for the as-fabricated FeMnCe-MOF-74/NF||Pt/C cell unit, only 1.40 V is needed to achieve 10 mA cm. Therefore, the successful design of 3d-4f mixed-metallic MOF-74 provides a new viewpoint to develop highly efficient non-precious metal electrocatalysts.