Fabrication of one-dimensional CuO nanocrystals via pulsed wire explosion: structural, optical and electronic characterizations

Abstract

One-dimensional nanocrystal is gaining popularity for its potential advantages in electronic, photonic, optoelectric and nanoelectronic devices. In this regard, metal oxide nanocrystals like CuO, ZnO, CdO and TiO2 are gaining research interest for their unique semiconducting characteristics. Specifically, narrow band-gap CuO nanomaterial is being studied extensively for its field emission, catalytic and photovoltaic properties. Recently shape controlled CuO nanocrystal gaining research interest for nanoscale field effect transistor (FET) device fabrication. This material is also being studied as essential element in several high-Tc superconductors and gas sensor. The surfaces of CuO are highly sensitive that when react with gases or solutions it becomes a catalyst or a gas sensor. The ability to control the shape and morphology strongly influences the overall electrochemical and physical properties of a nanostructure. We report the fabrication of shape controlled one-dimensional copper oxide (CuO) nanocrystals using a novel pulsed wire explosion method in liquid medium. This one-dimensional nanocrystal was made in an attempt to fabricate nanoscale FET device for electronic applications. Needle-like highly crystalline CuO nanocrystals were successfully produced in de-ionized (DI) water at 35°C, 65°C and 95°C. This method uses compressed pulsed power for the explosion hence reduces energy consumption and does not produce process by products. The chemical nature and physical structure of the nanocrystals were controlled by simply modulating the exploding medium temperature. The results showed that nanocrystals produced at 95°C are pure CuO with optical band-gap energy of 2.38eV as determined from the UV absorbance spectrum. X-ray photoelectron spectroscopy (XPS) characterization indicates the formation of high purity CuO nanocrystals and the electronic states of the nanocrystals were identified. This study also will provide a mean by which a most energy efficient and eco-friendly synthesis of one-dimensional CuO nanocrystals can be realized.