Exposing Single Ni Atoms in Hollow S/N‐Doped Carbon Macroporous Fibers for Highly Efficient Electrochemical Oxygen Evolution

Abstract The development of efficient and cost‐effective electrocatalysts toward the oxygen evolution reaction (OER) is highly desirable for clean energy and fuel conversion. Herein, the facile preparation of Ni single atoms embedded hollow S/N‐doped carbon macroporous fibers (Ni SAs@S/N‐CMF) as efficient catalysts for OER through pyrolysis of designed CdS‐NiS_x/polyacrylonitrile composite fibers is reported. Specifically, CdS provides the sulfur source for the doping of polyacrylonitrile‐derived carbon matrix and simultaneously creates the hollow macroporous structure, while NiS_x is first reduced to nanoparticles and finally evolves into single Ni atoms through the atom migration‐trapping strategy. Benefiting from the abundantly exposed single Ni atoms and hollow macroporous structure, the resultant Ni SAs@S/N‐CMF electrocatalysts deliver outstanding activity and stability for OER. Specifically, it needs an overpotential of 285 mV to achieve the benchmark current density of 10 mA cm⁻² with a small Tafel slope of 50.8 mV dec⁻¹.