Manipulating the Self-Assembling Process to Obtain Control over the Morphologies of Copper Oxide in Hydrothermal Synthesis and Creating Pores in the Oxide Architecture

Abstract

Copper oxide with various morphologies was synthesized by the hydrolysis of Cu(ac)2 with urea under mild hydrothermal conditions. In the synthesis, a series of organic amines with one or two amine groups (monoamine and diamine), including isobutylamine, octylamine (OLA), dodecylamine, octadecylamine (monoamines), ethylenediamine dihydrochloride, and hexamethylenediamine (diamines), was used as the "structure-directing agent". The monoamines led to the formation of one-dimensional (1D) aggregates of the copper oxide precursor particles (Pre-CuO), while the diamines led to the formation of two-dimensional (2D) aggregates. In both cases, the shorter carbon-chain amine molecules showed a stronger structure-directing function than that of the longer carbon-chain amine molecules. Next, in a series of syntheses, OLA was selected for further study, and the experimental parameters were systematically manipulated. When the hydrolysis was adjusted to a very slow rate by coupling the hydrolysis reaction with an esterification reaction, 1D aggregates of Pre-CuO were formed; when the hydrolysis rate was in the middle range, spherical Pre-CuO architectures composed of smaller linear aggregates were formed. However, under the high hydrolysis rates achieved by increasing the precipitation agent (urea) or by conducting the reaction at high temperatures (>/=120 degrees C), only Pre-CuO nanoparticles with a featureless morphology were formed. The formed spherical Pre-CuO architectures can be converted to a porous structure (CuOx) after removing the OLA molecules via calcination. Compared to the 1D and 2D aggregates, this porous architecture is highly thermally stable and did not collapse even after calcination at 500 degrees C. Preliminary results showed that the porous structure can be used both as a catalyst support and as a catalyst for the oxidation of CO at low temperatures.

Dispersible crystalline nanobundles of YPO4 and Ln (Eu, Tb)-doped YPO4: rapid synthesis, optical properties and bio-probe applications

“…The nanobundles are tightly packed together to give them a lenticular shape. A similar architecture has been observed by Zhong et al for copper oxide (Zhong et al 2007). It must be noted that increasing the hold time to 15, 30 and 60 min does not alter the product morphology: the reaction product shows only the presence of YPO 4 nanobundles (Fig.…”

Polyphenylene Dendrimer‐Templated In Situ Construction of Inorganic–Organic Hybrid Rice‐Shaped Architectures

“…Subsequently, the solution color gradually changed from black to green after 2 h (Step 3 in Scheme 1A). After incubation at 65 8C for 2 h, this green solution turned orange-yellow (Step 4 in Scheme 1A), suggesting the oxidation of Cu 2 O nanoparticles to CuO nanoparticles [31]. TEM characterization showed that the RSAs were formed during the heating process (Step 4 in Scheme 1A).…”

Interconnected 1D Co3O4 nanowires on reduced graphene oxide for enzymeless H2O2 detection

“…We propose that DDA plays a structure-directing role in the formation of the interconnected 1D nanowires, and rGO provides sites for anchoring Co 3 O 4 nanowires by electrostatic interaction, as illustrated in Scheme 2 [38]. In the reaction, part of the Co(DDA) n 2+ formed at the beginning of the reaction (or DDA) could anchor on the surface of GO by the electrostatic interaction between Co(DDA) n 2+ (or DDA) and the oxygencontaining groups of GO (-COOH or -OH).…”