Samarium oxide modified Ni-Co nanosheets based three-dimensional honeycomb film on nickel foam: A highly efficient electrocatalyst for hydrogen evolution reaction

The development of highly efficient and stable noble-metal-free electrocatalysts towards HER is of great significance. Herein, an electrodeposition method for the preparation of samarium oxide modified Ni-Co vertical nanosheets assembled three-dimensional honeycomb film on porous Ni foam (Sm2O3-Ni-Co/NF) is proposed. As-prepared Sm2O3-Ni-Co vertical nanosheets interweave together into a honeycomb morphology and uniformly cover the entire surface of Ni foam. The influence of content of Sm2O3 in electroplating bath on the electrocatalytic performances of Sm2O3-Ni-Co/NF electrode towards HER is studied in 1.0 M KOH electrolyte. Polarization curve indicates that the self-supported Sm2O3-Ni-Co/NF electrode exhibits remarkably enhanced electrocatalytic activity towards HER. To attain a current density of 10 mA cm−2, Sm2O3-Ni-Co/NF electrode needs lower overpotential (276 mV) than Ni-Co/NF electrode (301 mV). In addition, Sm2O3-Ni-Co/NF electrode exhibits a lower Tafel slope, demonstrating more favorable HER kinetics. Sm2O3-Ni-Co/NF electrode has smaller charge transfer resistance than Ni-Co/NF electrode, indicating a faster Faradic process and better HER kinetics. Besides, Sm2O3-Ni-Co/NF electrode features satisfactory long-term durability in alkaline media. The results indicate that Sm2O3-Ni-Co/NF electrode has potential application to water splitting devices for hydrogen generation. Shown left is schematic representation of electrodeposition of Sm2O3-Ni-Co vertical nanosheets assembled honeycomb film on Ni foam. Shown right are polarization curves of as-prepared Ni foam based electrodes in 1.0 M KOH solution at the scan rate of 1 mV s−1. [Display omitted] •Sm2O3-Ni-Co vertical nanosheets based honeycomb film is successfully prepared.•Sm2O3 highly enhances HER electrocatalytic activity of Ni-Co/NF based electrode.•Sm2O3-Ni-Co/NF shows satisfactory stability in alkaline medium.