Controlled synthesis of CeOx-NiCo2O4 nanocomposite with 3D umbrella-shaped hierarchical structure: A sharp-tip enhanced electrocatalyst for efficient oxygen evolution reaction over a broad pH region.

Simultaneously improve the activity and durability of complex metal oxides based OER electrocatalyst is crucial important for the conversion and storage of renewable energy, and is still confronted with significant challenges because of their easy dissolution and surface reconstruction in alkaline or acid electrolyte, as well as poor electrical conductivity. Herein, CeO x -NiCo 2 O 4 -U/NF electrocatalyst with umbrella-shaped hierarchical structure was synthesized through a three-step processes including the surfactant induced in-situ fabrication of umbrella-shaped nickel-cobalt complex hydroxide precursor on nickel foam, calcination treatment, and potentiostatic electro-deposition of CeO x. Owing to the co-existence of multiple redox couples, synergistic effect between active sites, enriched quantity of surface oxygen defects, multiple electron transport channels, sharp-tip effects originated from the umbrella-shaped hierarchical structure, the as-prepared CeO x -NiCo 2 O 4 -U/NF electrocatalyst exhibited advanced OER activity with a small overpotential of 219 mV at 10 mA cm−2 and Tafel slope of 67 mV dec−1 in 1.0 M KOH solution, and 328 mV in 0.05 M H 2 SO 4 solution with a Tafel slope of 96 mV dec−1, much lower than those of reported nickel- or cobalt-based OER catalyst. Moreover, due to the in-situ fabrication strategy and excellent acid-alkali resistance of NiCo 2 O 4 and CeO x components, the as-prepared CeO x -NiCo 2 O 4 -U/NF electrocatalyst exhibited long-term structure and chemical stability over a broad pH region. Furthermore, the synthetic strategy presented here offers a new method for the rational design and synthesis of complex metal oxides based electrocatalyst for energy conversion and storage applications with excellent catalytic performance and long-term stability. [Display omitted] [ABSTRACT FROM AUTHOR]