Nickel oxide, also known as nio powder, is a greenish-yellow or black solid that is an alkali metal oxide with the chemical formula NiO. It is a precursor to many nickel salts that are used as specialty chemicals and catalysts. It is a component of the nickel-iron battery (also called the Edison Battery), and is a key material for fuel cells. NiO is also a common hole transport material in thin film solar cells. In addition, it was the main raw material used to make the cadmium-dioxide rechargeable batteries found in electronic devices until they were replaced by the environmentally superior lithium-ion battery.

nio powder has been the focus of extensive research and development efforts in recent years because of its potential as an anode material for solid oxide fuel cells. The wide-band gap of this material allows for high power density, making it a suitable candidate for energy storage applications. Additionally, it has good chemical and thermal stability, as well as low toxicity. In this article, we report on the synthesis of nanocrystalline nickel oxide using a sonochemical method with nickel hydroxide as the starting material. The crystalline structure of the as-synthesized powder was confirmed by X-ray diffraction, Fourier transform infrared and photoluminescence spectroscopy analyses. The comparison of the crystallite size of the sonochemically synthesized powder with those of the chemically percipitated nickel oxide reported in the literature corroborates that the sonochemical technique is an effective way to achieve high-quality nanocrystalline nickel oxide.