Ultrathin hollow hemisphere-carbon-anchored Ni3FeN nanoparticles as nanoreactors facilitating the formation of NiCx with long-term durability for the oxygen evolution reaction

Abstract

Developing highly active, durable, and low-cost oxygen evolution reaction (OER) electrocatalysts is crucial for the practical implementation of water splitting. Here, a unique category of OER catalyst is prepared via anchoring Ni₃FeN nanoparticles onto hollow hemisphere-carbon (HC) to create a nanoreactor for the OER, and the nanoreactors are fabricated in situ on commercial nickel foam (denoted as Ni₃FeN-HC/NF) to act as a catalytic electrode. The optimized Ni₃FeN-HC/NF electrode shows an ultralow overpotential of 219 mV at 10 mA cm⁻² with a low Tafel slope of 63 mV dec⁻¹, and it also exhibits excellent durability for up to 72 h without significant deactivation. Such superior performance is caused by the introduction of HC. HC, as an ultrathin layer with a large specific surface area, serves as an electrocatalytic support to downsize and tightly anchor Ni₃FeN nanoparticles, enhancing charge transfer and avoiding the aggregation of Ni₃FeN nanoparticles, thereby achieving high electrocatalytic activity and long-term durability. At the same time, our work also reveals that unstable amorphous carbon from HC allows some Ni₃FeN to convert into NiC_x on the surface of the Ni₃FeN nanoparticles under OER conditions. The formation of this NiC_x layer can alleviate the aggregation of Ni₃FeN nanoparticles, further enhancing the stability. The relatively low-cost electrocatalyst with long-term stability reported in this work is expected to inspire more innovative research to advance the commercial and practical feasibility of alkaline water splitting.