Self-Assembled Two-Dimensional NiO/CeO2 Heterostructure Rich in Oxygen Vacancies as Efficient Bifunctional Electrocatalyst for Alkaline Hydrogen Evolution and Oxygen Evolution

The development of high-efficiency bifunctional electrocatalysts toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline surroundings is essential and challenging for the large-scale generation of clean hydrogen. Herein, a novel self-assembled two-dimensional (2 D) NiO/CeO₂ heterostructure (HS) consisting of NiO and CeO₂ nanocrystals is prepared through a facile two-step approach, and utilized as an enhanced bifunctional electrocatalyst for the HER and OER under alkaline conditions. It is concluded that this 2 D NiO/CeO₂ HS, rich in oxygen vacancies, demonstrates attractive electrocatalytic properties for both the HER and OER in 1 m KOH, including low onset overpotential (η₁), η₁₀ and Tafel slope, excellent durability, as well as large active surface area. Therefore, the self-assembled 2 D NiO/CeO₂ HS is believed to be an efficient bifunctional electrocatalyst toward the HER and OER.