Effect of Co/Ni ratio on electrocatalytic oxygen evaluation reaction of hydrothermally derived CoNi2S4 in alkaline medium

Abstract

Bimetallic sulfide materials are considered as suitable candidates for improving the oxygen evaluation reaction (OER) performance. Here, CoNi2S4 materials are developed by an effective hydrothermal approach and employing anhydrous Na2S.xH2O as sulfur precursor. Altering the molar concentrations of Co and Ni precursors affects the morphologies, Co, Ni contents, Co3+ and Ni3+ centers. CoNi2S4–1 with lower concentrations possesses higher Co3+, Ni3+ and Co3+/Co2+ ratios boosting the OER performance. In addition, CoNi2S4–1 demonstrates a potential of 1.60 V vs. RHE to generate a 10 mA cm−2 with a lower Tafel slope, better mass activity and stability in an alkaline solution.

Keywords

• Bimetallic sulfide
• Oxygen evolution reaction
• Hydrothermal method
• High Co3+/Co2+ ratio
• CoNi2S4 electrocatalyst