Ni(OH)2NiOOH 2D-nanosheets tailored with FeOOH nanorods: A synergy of morphological engineering towards bifunctional overall water splitting

Oxygen evolution reaction (OER) is the bottleneck for effective overall water splitting owing to its sluggish reaction kinetics. Metal oxyhydroxides are a significant class of electrocatalysts that demonstrate remarkable activity and stability toward the oxygen evolution reaction. A facile one-pot hydrothermal synthesis is demonstrated in this study to obtain the heterostructured NiFe-oxyhydroxide electrocatalyst. FeOOH nanorods are decked over the 2D Ni(OH)2NiOOH nanosheets to form the Ni(OH)2NiOOH/FeOOH heterostructure. The prepared Ni(OH)2NiOOH/FeOOH electrocatalyst demands a minimal OER overpotential of 209 mV to reach a current density of 10 mA cm−2, which is relatively smaller than the commercial RuO2. Moreover, the NiFe-oxyhydroxide also exhibits remarkable activity towards hydrogen evolution reaction by demanding a minimal overpotential of 118 mV that is relatively lower than the commercial Pt/C to obtain a current density of 10 mA cm−2. With the implication of prepared Ni(OH)2NiOOH/FeOOH both as anode and cathode, the fabricated electrolyzer demonstrates a minimal cell voltage of 1.52 V to attain a current density of 10 mA cm−2 and displays an extended stability for a period of 50 h.