Hollow CoS_x Nanoparticles Grown on FeCo-LDH Microtubes for Enhanced Electrocatalytic Performances for the Oxygen Evolution Reaction

Hollow CoSx nanoparticles grown on FeCo-LDH microtubes (FeCo-LDH@CoSx) were successfully developed as a highly efficient and low-cost electrocatalyst for the oxygen evolution reaction (OER) in an alkaline solution. The as-prepared FeCo-LDH@CoSx microtubes were characterized by X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM)-EDS elemental mapping. Experiments showed that the as-obtained hollow FeCo-LDH@CoSx electrocatalyst required low overpotentials of 229, 270, and 308 mV to deliver current densities of 10, 100, and 400 mA cm–2 in a 1 M KOH distilled water solution, respectively. Also, the as-obtained catalyst exhibited good durability in various alkaline electrolytes, including distilled water, tap water, and natural river water. In a two-electrode water-splitting device with nickel foams separately coated by FeCo-LDH@CoSx and 20% Pt/C as the anode and the cathode, respectively, using distilled water as the electrolyte, voltages of 1.495, 1.600, and 1.785 V were separately required for achieving current densities of 10, 100, and 400 mA cm–2. Simultaneously, the present two-electrode system continuously worked for 50 h at a current density of 50 mA cm–2 in various alkaline electrolytes, including distilled water, tap water, and natural river water, and no obvious voltage fluctuation was detected, implying remarkable stability. Obviously, the present FeCo-LDH@CoSx microstructure provides a catalyst selection for the OER in practical applications.