Hierarchically Ordered Macro–Mesoporous Electrocatalyst with Hydrophilic Surface for Efficient Oxygen Reduction Reaction

Abstract

Abstract Metal–organic frameworks (MOFs) offer versatile templates/precursors to prepare supported metal catalysts. However, the afforded catalysts usually exhibit microporous structures and unsuitable wettability, which will restrict the accessibility of active sites in liquid‐phase reactions. Herein, an etching–functionalization strategy is developed for the construction of a tannic‐acid‐functionalized MOF with a unique hollow‐wall and 3D‐ordered macroporous (H‐3DOM) structure. The functional MOF can be further employed as an ideal precursor for the synthesis of cobalt supported on oxygen/nitrogen‐co‐doped carbon composites with H‐3DOM structures, and hydrophilic surface. The H‐3DOM structure can improve the external surface area to maximize the exposure of active sites. Moreover, the oxygen‐containing functional groups can enhance the surface wettability to guarantee the external active sites to be more electrochemically accessible in aqueous electrolyte. Benefitting from these outstanding characteristics, H‐3DOM‐Co/ONC exhibits high electrocatalytic activity in the oxygen reduction reaction, superior to its counterparts without the hierarchically ordered structure and surface functionalization.