Electrochemical Transformation of Metal Organic Framework into Ultrathin Metal Hydroxide-(oxy)hydroxide Nanosheets for Alkaline Water Oxidation

Electrochemical water oxidation requires a highly active electrocatalyst system with improved catalytic activity, high mechanical stability, and strong catalyst–support interactions. In this respect, a unique and facile method has been developed for the synthesis of ultrathin Fe–Co(OH)2–Co(O)x(OH)y nanosheets from self-supported Prussian blue analogues by chronoamperometric method. High electrochemical surface area, improved electronic conductivity, enhanced mechanical stability, and atomic level thickness (∼3 nm) of the self-supported ultrathin nanosheets provided the boost for alkaline water oxidation. The ultrathin Fe–Co(OH)2–Co(O)x(OH)y nanosheets demonstrated 10 mA cm–2 current density at only 250 mV overpotential for alkaline water oxidation. The ultrathin nanosheets also showed 24 h continuous oxygen evolution under chronoamperometric condition without losing the initial activity.