Surface covalent sulfur enriching Ni active sites of Ni3S2 nanoparticles for efficient oxygen evolution

Abstract

Simply and rapidly synthesizing non-noble metal electrocatalysts is strategically significant to realize highly efficient oxygen evolution reaction (OER) in a cost-saving and easy-producing route. Herein, a rapid melting synthesis of surface covalent sulfur engineered Ni₃S₂ nanoparticles has been demonstrated by using nickel foam, in which the content of surface covalent sulfur is conveniently adjusted by varying the melting temperature. It is found that the surface covalent sulfur content shows a significant positive correlation with the increase of catalytically active Ni³⁺ during the OER, indicating that the moderate surface covalent sulfur can maximize the Ni³⁺ content of Ni₃S₂ to effectively promote OER activities. Consequently, Ni₃S₂-200 shows the highest ECSA-normalized current density of 0.85 mA cm⁻² at 320 mV and the lowest overpotential of 290 mV at 100 mA cm⁻² among other samples as well as commercial benchmarks. The protocol simplifies the synthesis of highly efficient and stable non-noble electrocatalysts to display enormous potential for water splitting.