Solvothermally Doping NiS₂ Nanoparticles on Carbon with Ferric Ions for Efficient Oxygen Evolution Catalysis

Abstract

Exploring efficient non-precious metal based electrocatalysts for the oxygen evolution reaction (OER) is a prerequisite to implement the widespread application of a water electrolyzer and metal-air batteries. Herein, Fe-doped NiS2 nanoparticles on a carbon matrix (Fe-NiS2/C) are facilely prepared via a two-step solvothermal process, where Ni-containing metal organic frameworks (Ni-MOFs) are vulcanized in situ and carbonized by a solvothermal method to form abundant NiS2 nanoparticles homogeneously distributed on a carbon matrix (NiS2/C), followed by doping with ferric ions via a similar solvothermal treatment. The resulting Fe-NiS2/C nanoparticle composites show a rougher surface than the NiS2/C parent, likely due to the formation of more structural defects after ferric ion doping, which maximizes the exposure of active sites. Moreover, ferric ion doping can also regulate the surface electronic state to reduce the activation energy barrier for OER on NiS2/C sample. With these merits, the best sample Fe-NiS2/C-30 only requires a potential of +1.486 V (vs. RHE) to reach an OER current density of 10 mA cm−2 and can retain 96.85% of its initial current after continuous working for about 10 h in 1.0 M KOH aqueous solution, along with a small Tafel slope of 45.66 mV/dec, outperforming a commercial RuO2 catalyst. The results in this work enrich the method to tailor the catalytic activity of transition metal sulfides for electrochemical energy technologies.

Keywords

• oxygen evolution reaction
• electrocatalyst
• nickel disulfide
• doping
• activity