Confining CoFe Alloy Nanocubes Within N-Doped Carbon Shells via Pyrolysis of Phenolic Resin-Coated Etched Prussian Blue Analogs for Efficient Oxygen Evolution

Constructing core–shell structured carbon-coated alloy nanoparticles represents an effective strategy to enhance the electrocatalytic performance. In this work, CoFe-based Prussian blue analogs (PBAs) with hollow structures are firstly coated with phenolic resin via the in situ polymerization method. A subsequent carbonization treatment yields N-doped carbon-encapsulated CoFe alloy nanocubes (denoted as CoFe-NC@C). The carbon shell suppresses the structural collapse and particle aggregation of CoFe nanocubes while enhancing the electrical conductivity, thereby facilitating fast reaction kinetics. Meanwhile, the etching-induced hierarchical pore structure increases the specific surface area with a Brunauer–Emmett–Teller (BET) value of 57 m2 g−1, which exposes more accessible active sites and facilitates mass transport. Owing to the synergistic effect between the two components, the CoFe-NC@C catalyst exhibits an outstanding oxygen evolution reaction (OER) performance in an alkaline electrolyte, achieving a low overpotential of 278 mV (vs. RHE) at a current density of 10 mA cm−2 along with superb durability. This work demonstrates that the OER performance of PBA-derived alloys can be boosted through an integrated strategy of etching and carbon coating.