Modulating electronic structure of CoS2 nanorods by Fe doping for efficient electrocatalytic overall water splitting

To rationally fabricate efficient nonprecious-metal electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for developing the sustainable electrolytic water system but still remain a great challenge. The Fe-doped CoS₂ (Fe-CoS₂) nanorods are proposed and synthesized in this work by a heteroatomic doping strategy. Compared with single CoS₂ and FeS₂, the Fe-CoS₂ catalyst requires an overpotential of 217 mV for HER and 280 mV for OER at 10 mA cm⁻², along with a robust durability in alkaline electrolyte. Remarkably, the water electrolytic cell assembled with Fe-CoS₂ delivers a voltage of 1.62 V at 10 mA cm⁻². Experimental characterizations and theoretical calculations cooperatively reveal that the promoted bifunctional catalytic performances of Fe-CoS₂ can be ascribed to the intriguing nanorod-like morphology and the modulation of electronic structure. This work not only highlights the heteroatom doping strategy to regulate the electronic structure, but also offers a straightforward protocol for constructing advanced metal sulfides as bifunctional electrocatalysts for overall water splitting.