Co‐Fe Prussian Blue Analogue Nanocubes as Efficient Bifunctional Electrocatalyst for Overall Water Electrolysis

ABSTRACT Designing efficient bifunctional electrocatalysts for both oxygen and hydrogen evolution reactions (OER and HER) is highly targetable to reach a better sustainable future, but still, it remains a significant challenge. In this work, we introduced a novel and thermally effective one‐step co‐precipitation method to prepare Co‐Fe bimetallic Prussian blue analogues (CF‐PBAs). Based on the reaction time duration (namely, 8,10,12, and 14 h), different PBA analogues were prepared. The CF‐PBA‐12 nanocubes demonstrate an impressive bifunctional catalytic activity, which requires overpotential only 261 and 121 mV for OER and HER reactions to reach 10 mA/cm 2 current density in 1 m KOH. In addition, the fabricated alkaline water electrolyser set‐up exhibits an efficient lower voltage of 1.61 V at 10 mA/cm 2 and maintains excellent durability over 166 h. The better catalytic activity stems from the nanocubes crystalline structure, porous morphology, and the presence of coordinatively unsaturated Co and Fe centres. These features collectively enhance the density of active sites, promote efficient charge and mass transport, and facilitate the in‐situ transformation into highly active Co/Fe‐based (oxy)hydroxide species during water splitting.