Nickel (III) oxide is the inorganic compound with the formula Ni2O3.
It is not well characterized,[1] and is sometimes referred to as black nickel oxide.
Traces of Ni2O3 on nickel surfaces have been mentioned.
[2][3] Nickel (III) oxide has been studied theoretically since the early 1930s,[4] supporting its unstable nature at standard temperatures.
A nanostructured pure phase of the material was synthesized and stabilized for the first time in 2015 from the reaction of nickel(II) nitrate with sodium hypochlorite and characterized using powder X-ray diffraction and electron microscopy.