Integration of Cobalt Metal–Organic Frameworks into an Interpenetrated Prussian Blue Analogue to Derive Dual Metal–Organic Framework-Assisted Cobalt Iron Derivatives for Enhancing Electrochemical Total Water Splitting

It is important to design a highly efficient, cost-effective, and stable bifunctional electrocatalyst for the overall water splitting process to produce both oxygen and hydrogen, which is considered as one of the most promising methods for alternative renewable sources. In this study, a highly porous dual metal–organic framework (MOF) based bimetallic cobalt–iron phosphide and oxide nanoarrays were developed on nickel foam by a two-step liquid phase deposition process followed by calcination and phosphatization. As-synthesized MOF bimetallic derivatives act as effective bifunctional catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). It is interesting to note that the optimized electrochemical efficiency for OER and HER was achieved by MOF CoFeP nanoarrays with an overpotential of 310 mV and 200 mV offering a current density of 50 mA·cm–2. In addition, an integrated water electrolyzer is developed using MOF CoFeP as an anode and cathode, requiring a cell voltage of 1.78 V to achieve a current density of 50 mA·cm–2 in an alkaline medium. Our findings suggest that the ligand exchange conversion of the interpenetrated MOF network into an abundant porous structure could have a powerful synergistic effect on the overall water splitting reaction in an alkaline medium.