Effect of Synthesis Conditions on CuO-NiO Nanocomposites Synthesized via Saponin-Green/Microwave Assisted-Hydrothermal Method

Abstract

This work presents the synthesis of CuO-NiO nanocomposites under different synthesis conditions. Nanocomposites were synthesized by merging a green synthesis process with a microwave-assisted hydrothermal method. The synthesis conditions were as follows: concentration of the metal precursors (0.05, 0.1, and 0.2 M), pH (9, 10, and 11), synthesis temperature (150 °C, 200 °C, and 250 °C), microwave treatment time (15, 30, and 45 min), and extract concentration (20 and 40 mL of 1 g saponin/10 mL water, and 30 mL of 2 g saponin/10 mL water). The phases and crystallite sizes of the calcined nanocomposites were characterized using XRD and band gap via UV-Vis spectroscopy, and their morphologies were investigated using SEM and TEM. The XRD results confirmed the formation of a face-centered cubic phase for nickel oxide, while copper oxide has a monoclinic phase. The calculated crystallite size was in the range of 29–39 nm. The direct band gaps of the samples prepared in this work were in the range of 2.39–3.17 eV.

The Effect of Composition on the Properties and Application of CuO-NiO Nanocomposites Synthesized Using a Saponin-Green/Microwave-Assisted Hydrothermal Method

“…The synthetic process is illustrated in Scheme 1. The hydroxide precipitate prepared in this step was transferred into a Teflon vessel and then heated in a microwave at 200 • C for 30 min [53]. The synthetic conditions were selected based on a previous study [53].…”

“…The hydroxide precipitate prepared in this step was transferred into a Teflon vessel and then heated in a microwave at 200 • C for 30 min [53]. The synthetic conditions were selected based on a previous study [53]. The sample was subsequently removed from the microwave and the liquor poured into a beaker.…”

Photocatalytic Degradation of Organic Pollutants—Nile Blue, Methylene Blue, and Bentazon Herbicide—Using NiO-ZnO Nanocomposite

“…Several techniques have been adopted, such as the mixing of two or more semiconductors [ 4 ], single doping [ 17 ], dual doping [ 18 ], and co-doping [ 19 ], to improve their charge transport properties and prevent electron-hole recombination. Metal oxides can be synthesized by different approaches, such as precipitation [ 20 ] or co-precipitation in case of two or more metal precursors [ 21 , 22 ], precipitation in the presence of chelating agents [ 23 , 24 ] or even more complex methods [ 25 , 26 ]. Among these approaches, the co-precipitation method ensures an easy, fast, and industrially scalable synthesis.…”