Synthesis and self‐assembled mechanism of CuO peony‐flowers by a composite hydroxide‐mediated approach at low temperature

Abstract

A composite‐hydroxide mediated (CHM) method was utilized for the synthesis of CuO peony‐flower nanostructures under temperatures ranging between 25 and 160 °C. The CHM mechanism was confirmed through X‐ray Powder Diffraction (XRD) and a Thermo‐Gravimetric Differential Scanning Calorimeter (TG‐DSC). Cu(NO3)2 was shown to transform into Cu(OH)2 in the mixed alkalis (NaOH/KOH); the reaction was facilitated by the solvent properties of the mixed alkalis. Cu(OH)2 subsequently consumed H2O in the adsorption of the mixed alkalis at 25∼65 °C. At higher reaction temperatures (>65 °C), the Cu(OH)2 was seen to decompose at an accelerated rate. Therefore, crystalline CuO could be obtained not only above 65 °C but also at 25 °C. The crystal morphology and structure of CuO were examined through Filed Emission Scanning Electron Microscopy (FE‐SEM) and Transmission Electron Microscopy (TEM). It was determined that the CuO peony‐flower had a polycrystalline structure composed of single crystalline CuO petals. Using the Selected Area Electron Diffraction (SAED) results, the rings were indexed as (002), (111), (112), (202) and (−113), which was in agreement with the XRD results. With increasing temperature, the CuO flower petals self‐assembled through random aggregation and gathered CuO nanorod parts, which led to incomplete CuO flower petals through orientated aggregation. Prolonged reaction time led to the growth of CuO flower petals in the direction of [001]. An ideal CuO flower structure was observed through TEM observation.

Gold Nanoparticles Supported on Urchin-Like CuO: Synthesis, Characterization, and Their Catalytic Performance for CO Oxidation

“…Among these preparations of CuO supports (including hydrothermal synthesis [24], thermal oxidation [25], ultrasound-assisted method [26], solution-phase method [27], and microwave-assisted method [28]), solution-phase method is a kind of simple and low-energy consumptive preparation one. Moreover, the adjusting of preparation conditions (such as temperature, fabrication time, precursors, solution concentration, and pH) also plays an important role in controlling the CuO morphology [26,29,30].…”