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/CeO 2 heterostructure (HS) consisting of NiO and CeO 2 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/CeO 2 HS, rich in oxygen vacancies, demonstrates attractive electrocatalytic properties for both the HER and OER in 1 m KOH, including low onset overpotential ( η 1 ), η 10 and Tafel slope, excellent durability, as well as large active surface area. Therefore, the self‐assembled 2 D NiO/CeO 2 HS is believed to be an efficient bifunctional electrocatalyst toward the HER and OER.