Three-dimensional NiCo2O4 nanosheets and nanoflowers electrodeposited with palladium nanoparticles on nickel foam for the hydrogen evolution reaction

By combining NiCo2O4 with good hydrogen evolution reaction (HER) properties and palladium (Pd) nanoparticles with excellent conductivity, a highly efficient and stable catalyst is prepared for HER. The NiCo2O4 nanosheets and NiCo2O4 nanoflowers are produced on the nickel foam (NF) with a large specific surface area by a one-step hydrothermal method and the NiCo2O4 nanoflowers are uniformly distributed in the NiCo2O4 nanosheets to form a three-dimensional (3D) electrode. Compared to conventional NiCo2O4, the 3D NiCo2O4 electrode provides more active sites (Ni and Co) for oxygen adsorption thus reducing the energy required to break H–O bonds to promote HER. When NiCo2O4/NF is combined with Pd nanoparticles (Pd/NiCo2O4/NF), the HER performance is improved greatly because of the synergistic effects rendered by the 3D structure of NiCo2O4 and Pd nanoparticles. The overpotential of Pd/NiCo2O4/NF is 69 mV at a current density is 10 mA/cm2 and it is stable for 10 h in alkaline environments. The materials design and properties provide useful information for future development of commercial hydrogen production.