Dissolution-regrowth of hierarchical Fe-Dy oxide modulates the electronic structure of nickel-organic frameworks as highly active and stable water splitting electrocatalysts

As the kinetically sluggish oxygen evolution reaction (OER) is considered to be a bottleneck in overall water splitting, it is necessary to develop a highly active and stable electrocatalyst to overcome this issue. Herein, we successfully fabricated a three-dimensional iron-dysprosium oxide co-regulated in-situ formed MOF-Ni arrays on carbon cloth (FeDy@MOF-Ni/CC) through a facile two-step hydrothermal method. Electrochemical studies demonstrate that the designed FeDy@MOF-Ni/CC catalyst requires an overpotential of only 251 mV to reach 10 mA cm−2 with a small Tafel slope of 52.1 mV dec−1. Additionally, the stability declined by only 5.5% after 80 h of continuous testing in 1.0 M KOH. Furthermore, a cell voltage of only 1.57 V in the overall water splitting system is sufficient to achieve 10 mA cm−2; this value is far better than that of most previously reported catalysts. The excellent catalytic performance originates from the unique 3D rhombus-like structure, as well as coupling synergies of Fe-Dy-Ni species. The combination of lanthanide and transition metal species in the synthesis strategy may open entirely new possibilities with promising potential in the design of highly active OER electrocatalysts.