Metal–Organic Framework Hybrid‐Assisted Formation of Co3O4/Co‐Fe Oxide Double‐Shelled Nanoboxes for Enhanced Oxygen Evolution

Rational design of complex metal–organic framework (MOF) hybrid precursors offers a great opportunity to construct various functional nanostructures. Here, a novel MOF‐hybrid‐assisted strategy to synthesize Co3O4/Co‐Fe oxide double‐shelled nanoboxes is reported. In the first step, zeolitic imidazolate framework‐67 (ZIF‐67, a Co‐based MOF)/Co‐Fe Prussian blue analogue (PBA) yolk–shell nanocubes are formed via a facile anion‐exchange reaction between ZIF‐67 nanocube precursors and [Fe(CN)6]3− ions at room temperature. Subsequently, an annealing treatment is applied to prepare Co3O4/Co‐Fe oxide double‐shelled nanoboxes. Owing to the structural and compositional benefits, the as‐derived Co3O4/Co‐Fe oxide double‐shelled nanoboxes exhibit enhanced electrocatalytic performance for oxygen evolution reaction in alkaline solution. Yolk–shelled zeolitic imidazolate framework‐67 (ZIF‐67)/Co‐Fe Prussian blue analogue nanocubes are synthesized via an anion‐exchange reaction between ZIF‐67 nanocubes and [Fe(CN)6]3− ions. After thermal treatment in air, the complex metal–organic framework hybrid precursors are transformed into double‐shelled Co3O4/Co‐Fe oxide nanoboxes, which exhibit enhanced performance as an electrocatalyst for the oxygen evolution reaction.