# One-Step Synthesis of Bunsenite Cadmium Oxide Nanoparticles
## 1 Introduction  
Transition metal oxide nanoparticles have unique structural, optical, magnetic, and electrical properties that allow them to have small crystallite sizes, large surface areas, and quantum dimensions [1, 2]. These nanoparticles have lately been exploited in biological, physical, chemical, and electrical applications as a result of their properties [3, 4, 5, 6]. Cadmium oxide (CdO) is an n-type semiconductor with a direct bandgap ranging from 2.2 to 2.5 eV and an indirect bandgap ranging from 1.36 to 1.98 eV [7, 8, 9]. It is very electrically conductive, has a high carrier concentration, is highly chemically stable, widely available, highly transparent in the visible electromagnetic spectrum region, and is relatively inexpensive [10, 11]. Consequently, it is compatible with many applications, including solar cells, photodiodes, photoresistors, photosensors, and transparent electrodes [12, 13, 14]. A semiconductor of the P-type, bunsenite (NiO) has a broad bandgap between 3.6 and 4.0 eV [15, 16, 17, 18]. Its electronic, magnetic, chemical, and electrical properties [19, 20, 21] make it appropriate for catalysis, the storage of energy, and conversion in many applications [22, 23, 24, 20].  
The properties of distinct individual oxides have been improved by combining multiple metal oxides to form innovative nanocomposites for usage in a variety of applications [25, 26, 27]. Because of parameters such as chemical composition, crystallite size, and constituent phase volume, the physical properties of the nanocomposites differ from those of bulk materials [28, 29, 30, 31, 32, 33, 34, 35]. Additionally, nanocomposites may have features that complementone another. For example, several band gaps can form from both oxide semiconductors, which may or may not share properties with the constituents of individual metal and metal oxide nanoparticles [36; 37; 38]. As a result, a composite arising from the suitable integration of bunsenite cadmium oxide nanoparticles and other metal oxides could potentially boost photocatalytic activity [25; 39; 40]. However, there are some advantages to using a thermal treatment strategy to synthesize bunsenite cadmium oxide nanocomposites, such as scalability, product stability, low cost, and ease of handling. Because it is capable of absorbing specific solar energy wavelengths, this approach enables exact particle size control and great purity, making it perfect for use in solar cell energy applications.  
Bunsenite and cadmium oxide nanoparticles have been produced using a simple thermal treatment approach. This process does not necessitate the use of hazardous chemicals, does not generate hazardous waste, and does not flush hazardous materials down the drain [27]. In this study, a bunsenite cadmium oxide nanoparticle was synthesized using nickel nitrate, deionized water, cadmium nitrate, and polyvinylpyrrolidone (PVP). Thermogravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) scanning, Fourier transform infrared (FTIR) spectroscopy, and UV-Vis were used to characterize the prepared samples.