Co9S8-CuS-FeS trimetal sulfides for excellent oxygen evolution reaction electrocatalysis.

Cobalt sulfide materials are wildly investigated in oxygen evolution reaction (OER). In order to further decrease the cost of the catalysts, cobalt-copper-iron trimetal sulfides (CoCuFe-S) are designed and successfully fabricated via a simple hydrothermal method following a thermal treatment. CoCuFe-S has a three-dimensional nanostructure, which is assembled by numerous nanosheets. Three components are uniformly distributed in the composite. CoCuFe-S with different ratios are employed as OER catalysts and compared with pure Co 9 S 8 , CuS and FeS. The optimal CoCuFe-S-8 catalyst exhibits high and robust activity for OER with a small overpotential of 0.30 V at current density of 10 mA cm −2 and a low Tafel slope of 79 mV·dec −1 . The turnover frequency is 0.27 s −1 and the mass activity is 114 A g −1 at overpotential of 0.30 V, even better than the commercial RuO 2 . In addition, CoCuFe-S-8 catalyst showed long-term durability under 1 M KOH solution. The excellent OER performance may result from the synergistic effect among the three sulfides. The introduction of FeS and CuS are beneficial for the formation of Co 9 S 8 , increasing the conductivity of the catalyst and decreased the adsorption of the oxygen atoms on Co atom. [ABSTRACT FROM AUTHOR]