Oxygen-Evolution Catalysts Based on Iron-Mediated Nickel Metal–Organic Frameworks

Metal–organic frameworks (MOFs) based oxygen-evolution reaction (OER) catalyst is an emerging class of highly porous materials that have become increasingly attractive to develop a highly active and stable OER catalyst for overall water splitting. However, it suffers from poor conductivity and inadequate active sites. Herein, we have developed a series of hierarchical Fe-mediated Ni-based metal–organic frameworks (Fe x Ni 1– x -MOF) by an adjustable hydrolysis strategy, where the Ni-MOF is used as a template that is decorated with NiOOH active sites. Although Ni-MOF is dissociated during the ion exchange process, the structural integrity is kept for Fe x Ni 1– x -MOF as confirmed by the electron micrographs. Moreover, the optimized Fe 0.38 Ni 0.62 -MOF catalyst not only exhibits a remarkable OER catalytic performance with a low overpotential of 190 mV at 10 mA cm –2 but also shows a small Tafel slope of 58.3 mV dec –1 and stability. The excellent OER electrocatalytic activity can be attributed to the unique 3D flower-like structure decorated with NiOOH active sites induced by Fe 3+ species. This novel methodology expands a new way for the construction of highly efficient alkaline catalytic materials.