Bifunctional Electrocatalysts for Overall Water Splitting from an Iron/Nickel-Based Bimetallic Metal-Organic Framework/Dicyandiamide Composite

Pyrolysis of a bimetallic metal-organic framework (MIL-88-Fe/Ni)-dicyandiamide composite yield a Fe and Ni containing carbonaceous material, which is an efficient bifunctional electrocatalyst for overall water splitting. FeNi3 and NiFe2O4 are found as metallic and metal oxide compounds closely embedded in an N-doped carbon-carbon nanotube matrix. This hybrid catalyst (Fe-Ni@NC-CNTs) significantly promotes the charge transfer efficiency and restrains the corrosion of the metallic catalysts, which is shown in a high OER and HER activity with an overpotential of 274 and 202mV, respectively at 10mAcm(-2) in alkaline solution. When this bifunctional catalyst was further used for H-2 and O-2 production in an electrochemical water-splitting unit, it can operate in ambient conditions with a competitive gas production rate of 1.15 and 0.57Ls(-1) for hydrogen and oxygen, respectively, showing its potential for practical applications.