One-pot hydrothermal synthesis of supported CoS electrocatalysts: The effect of support nature on oxygen reduction reaction activity in alkaline medium

The development of efficient and durable earth-abundant electrocatalysts for the oxygen reduction reaction (ORR) is an ongoing challenge. In this work, we directly anchored CoS nanocatalysts (20 wt%) on different supports, namely, carbon nanotubes (CNTs) and reduced graphene oxide by a single-pot hydrothermal route. The developed synthesis processes enabled us to alter the composite nature of CoS by changing the sulfur precursor used. The corresponding electrocatalytic performance of these composite catalysts toward the ORR was studied in alkaline medium. The increase in the effective electrode surface area that accompanies the CoS nanocomposite substantially boosts its ORR catalytic performance. The CoS-CNT-Cy hybrid material shows an onset potential of 0.85 V, which is 60-200 mV less negative than that of other catalysts tested. The catalytic current density achieved with the hybrid material at 0.2 mg cm−2 is comparable with that of commercial Pt/C (20%). The synergistic effect of CNTs and CoS enhances the overall performance of the hybrid catalyst. Extension of this nanocomposite strategy to other earth-abundant materials could similarly enable inexpensive electrocatalysts that lack the high intrinsic activity of the noble metals.