Double Molten Salt Engineered Highly Exposed Ni3Fe Honeycomb Nanospheres with Defect-Rich N/S Codoped Hierarchical Bamboo Carbon for Efficient Oxygen Evolution

Fitting nonprecious metal-based catalysts into a heteroatom-doped porous carbon frame for heterogeneous catalytic reactions has received considerable attention. However, the joint improvement of the structural optimization of the metal catalyst and the defect engineering of the carbon matrix are still challenging. Here, defect-rich N/S codoped hierarchical carbon composite catalysts embedded with highly exposed honeycomb Ni3Fe alloys and even a few single atoms (Ni3Fe/N, S-DPC) were constructed via a dual molten salt strategy. The synergistic optimization of the morphology and structure of Ni3Fe alloy and graphitized carbon enabled the hybrid catalyst to have lower mass transfer resistance, more exposed active sites, and higher active interfaces, resulting in superior OER electrocatalytic performance. Resplendently, the prepared Ni3Fe/N, S-DPC needed only a 243 mV overpotential to drive a current density of 10 mA cm–2 with a Tafel slope of 46.7 mV dec–1. In summary, this work not only provided a strategy for in situ anchoring of Ni3Fe honeycomb microspheres on defect-rich heteroatom-doped carbon but also offered insights into the high-efficiency OER activity.