Core‐Shell Engineering of ZIF‐67@N‐Doped Hollow Carbon Spheres via Diffusion Strategy for Enhanced Oxygen Evolution Reaction

Abstract Metal‐organic frameworks (MOFs) serve as versatile precursors for creating long‐lasting electrocatalysts. Core‐shell engineering is a unique method for activating MOFs for electrocatalytic applications without altering their fundamental characteristics. Encapsulating MOFs in nitrogen‐doped hollow carbon spheres (N‐HCS) improves electrocatalyst performance by modulating the band structure. We synthesized a ZIF‐67@N‐HCS catalyst by embedding nanocrystals into nitrogen‐doped hollow carbon spheres using a diffusion‐driven, space‐confined approach. For the electrocatalytic oxygen evolution reaction (OER), the ZIF‐67@N‐HCS catalyst shows decreased overpotential of 290 mV to reach the current density of 20 mA cm⁻ 2 and better reaction kinetics, as demonstrated by a lower Tafel slope value of 86 mV dec⁻¹. The catalyst has a high electrochemically active surface area (ECSA) of 320 cm 2 and an electric double‐layer capacitance of 12.8 mF cm⁻ 2 . This study proposed a strategy of core‐shell engineering, which has the potential to improve the efficiency of electrocatalysts for water oxidation.