High-performance single atom bifunctional oxygen catalysts derived from ZIF-67 superstructures

Highlights: • In-situ fabrication of efficient bifunctional catalysts integrated atomic units with 3D MOFs superstructures. • The as-prepared UNT Co SAs/N-C catalysts manifest superior functionality for both ORR/OER. • Outstanding catalytic activities stem from precise local coordination of CoN₄ and well-aligned carbon matrix. • Atomic catalysts derived from MOFs superstructures enrich superior SACs synthesis for ORR/OER. -- Abstract: Single-atom catalysts (SACs) always exhibit distinctive catalytic activities for oxygen reduction/evolution reactions (ORR/OER), making SACs relevant in a number of crucial applications including fuel cells, metal-air batteries, as well as in industrial applications. Recently, fabricating SACs with rich multidimensional nanoarchitectures has become fascinating but challenging. Here, for the first time, we explore a facile and practicable "sacrificed-template" method to prepare cobalt single-atom electrocatalysts with Urchin-like Nano-Tube hierarchical structures (UNT Co SAs/N-C) derived from well-aligned metal-organic-frameworks (MOFs) superstructure (UNT ZIF-67). The as-prepared UNT Co SAs/N-C catalysts exhibit superior performance both in ORR/OER. XAFS and density functional theory (DFT) calculations reveal that outstanding catalytic activities stem from high-quality single-atom dispersion, precise local coordination of CoN₄, and well-aligned carbon matrix based on MOFs superstructures. Our work provides new perspective in enriching SACs synthesis methodologies.