Graphene Oxide to Diamond Transformation by Ultrasound Waves Adi M. Abdul Hussien 1 & Russel R. Ghanim 2 & Iman Ismael AL-Saedi 1 Received: 29 February 2020 /Accepted: 29 July 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract The well-known high pressure high temperature (HPHT) method has been used for preparing diamond since 1986. This research introduces a new method for preparing diamond by using the global Hummer method after changing two main agents, namely, the frequency of ultrasound waves and the exposure time of these waves. The frequency was increased to 40 kHz, while the exposure time was increased to 2 h. It was found that applying the Hummer method on graphene oxide with an ultrasound exposure time of 20 min and 2 h can result in graphene oxide and nanodiamond (ND), respectively. The resulting ND began to grow after it was left for 10 days. The spectral properties of the diamond were characterized by using Ultraviolet-visible (UV-Vis) and Raman. The UV-Vis showed that the absorption peak at 220 nm is within the ultraviolet region, while the bandgap was found to be 5.6. The Raman confirmed the presence of the functional group for the diamond at 1332 cm -1 wavenumber. Moreover, the morphology property of the diamond and stages of diamond formation have been visualized by using scanning electron micro- scope (SEM) and optical microscope. Keywords Hummer method . Graphene oxide . Diamond . Ultrasound waves Introduction Diamond is an allotrope of carbon. It is a unique and beautiful substance. It has an elegant crystal structure. Diamond existed in nature and formed hundreds of kilometres under the earth’s surface, where the pressure and temperature are very high [1, 2]. Now, there are a variety of methods for producing the diamond industrially including physical and chemical. In fact, the synthesis of diamond considers the fantastic topic and attracts commercial attention in the world [3]. Lately, the ad- vancement in the preparation of carbon nanostructure mate- rials especially diamond is ultrasonication techniques. These techniques control over the composition, size, and morpholo- gy of carbon nanomaterials by using a common and versatile laboratory tool [4]. Flynn in 1986 converted the graphite to diamond by using cavitation method that is based on ultra- sound waves and explained it [5]. In this work, we have con- verted the graphene oxide to diamond by using sonication, and we found that the diamond has formed as a result of cavitation method as Flynn interpreted. In comparison with HPHT method, the current method can be considered simpler and less expensive, and it causes less contamination and hence is less dangerous. Finally, it can be performed at room condi- tions which means that it does not require high pressure and high temperature. In this work, there are physical/chemical conditions that should be fulfilled to obtain diamond: 1 Physical conditions: the size of graphite should be of 212 μm diameter, while the exposure time of the graphene oxide solution to the ultrasound waves should be at least 2 h with 40 kHz frequency. 2 Chemical conditions: the same conditions of global Hummer method should be provided. Materials and Experimental Techniques Chemicals Artificial diamond has been synthesized by a novel method from graphene oxide from these reagents, the laboratory Graphite powder, which has been supplied by Sigma- Aldrich Company (Germany). The sulphuric acid (H 2 SO 4 ) * Russel R. Ghanim bme.visit.09@uotechnology.edu.iq 1 Applied Science Department, University of Technology, Baghdad, Iraq 2 Biomedical Engineering Department, University of Technology, Baghdad, Iraq Plasmonics https://doi.org/10.1007/s11468-020-01251-2