Enhancing the efficiency and stability of electrocatalysts for water splitting: NiCo-LDH nanosheet arrays at high current density

The development of low-cost, efficient, and stable bifunctional electrocatalysts is very important for the development of renewable energy. Layered double hydroxides (LDHs) are considered to be promising electrocatalysts due to their flexible ion exchange, abundant structural adjustability, excellent thermal stability, and easy functionalization with other materials. In this work, nickel-cobalt layered double hydroxide (NiCo-LDH) nanosheet arrays are prepared by a simple hydrothermal method. Four samples Ni₁Co₄-LDH, Ni₂Co₃-LDH, Ni₃Co₂-LDH and Ni₄Co₁-LDH are obtained by adjusting the Ni/Co ratio (5 − x : x). Among them, the Ni₂Co₃-LDH samples show excellent HER and OER properties. At a current density of 50 mA cm⁻² in a 1.0 M KOH electrolyte, the overpotentials of the HER and OER are 227 mV and 303 mV, respectively. In addition, as a bifunctional electrocatalyst for water splitting, the sample provides a voltage of 1.83 V and long-term stability at 50 mA cm⁻².