Controlling the Formation of Nanocavities in Kirkendall Nanoobjects through Sequential Thermal Ex Situ Oxidation and In Situ Reduction Reactions

Abstract

Controlling the porosity, the shape, and the morphology of Kirkendall hollow nanostructures is the key factor to tune the properties of these tailor-made nanomaterials which allow in turn broadening their applications. It is shown that by applying a continuous oxidation to copper nanowires following a temperature ramp protocol, one can synthesize cuprous oxide nanotubes containing periodic copper nanoparticles. A further oxidation of such nanoobjects allows obtaining cupric oxide nanotubes with a bamboo-like structure. On the other hand, by applying a sequential oxidation and reduction reactions to copper nanowires, one can synthesize hollow nanoobjects with complex shapes and morphologies that cannot be obtained using the Kirkendall effect alone, such as necklace-like cuprous oxide nanotubes, periodic solid copper nanoparticles or hollow cuprous oxide nanospheres interconnected with single crystal cuprous oxide nanorods, and aligned and periodic hollow nanospheres embedded in a cuprous oxide nanotube. The strategy demonstrated in this study opens new avenues for the engineering of hollow nanostructures with potential applications in gas sensing, catalysis, and energy storage.

Partial Chemicalization of Nanoscale Metals: An Intra‐Material Transformative Approach for the Synthesis of Functional Colloidal Metal‐Semiconductor Nanoheterostructures

“…El Mei et al have shown that the oxidation‐induced nanoscale Kirkendall effect can be exploited to create copper‐oxide‐based nanotubes with unique morphologies and elemental distribution by applying a calibrated annealing treatment to preformed Cu nanowire precursors. [ 32 ] Cu@Cu 2 O MSHs, composed of a nanotube section embedding a periodic arrangement of Cu domains within its interior, were obtained by a rapid thermal oxidation process (sample was loaded into a preheated oven), while hollow CuO nanostructures with a bamboo‐like shape profile were obtained when temperature was ramped up slowly (Figure 5d,e). Unlike in Ni, in Cu the rate of injection of vacancies is higher than their diffusion.…”

“…[31] Copyright 2010, American Chemical Society. [32] Copyright 2016, Wiley-VCH. TEM images of Fe@𝛾-Fe 2 O 3 MSHs obtained on oxidation of amorphous Fe nanoparticles with dry 20% oxygen for different periods: g) <1 min at 25°C; h) 1 h at 80°C; i) 12 h at 80°C; j) 5 min at 150°C; k) 1 h at 150°C; l) 1 h at 350°C.…”

“…f) Representation of a Cu 2 O nanotube containing a periodic distribution of Cu domains (top) and of a bamboo-like CuO nanotube (bottom); the black arrows indicate the direction and the magnitude of copper atom diffusion occurring during the thermal oxidation process. Reproduced with permission [32]. Copyright 2016, Wiley-VCH.…”

Optimized Self‐Templating Synthesis Method for Highly Crystalline Hollow Cu2O Nanoboxes

“…To overcome the aforementioned obstacles in the syntheses of the hollow structures, some changes and improvements need to be conducted on the currently available strategies. [15] Herein, we report an optimized self-templating synthesis method [16][17][18] and for the first time prepared hollow Cu 2 O nanoboxes (NBs) with regular shapes, high crystallinity, and, in particular, sizes smaller than 100 nm (Figure 1a). After systematic investigations on the evolution processes and hollowing conditions, we found that our refined control over the heating program and the solution compositions is advantageous to minimize the degradation in crystallinity and morphology from precursors.…”

Organic–inorganic hybrid nanomaterials prepared via polymerization-induced self-assembly: recent developments and future opportunities

“…Nanoscience has made significant progress over the past twenty years, and researchers have been able to control the preparation of nanomaterials with various structures such as nanospheres, nano-mesoporous materials, nanowires, hollow nanotubes, core-shell structural nanomaterials and so on. [1][2][3][4][5][6][7][8][9][10] Since the size of nanomaterials is close to the wavelength of light and the coherence length of electrons, materials at the nanoscale exhibit different properties compared to bulk materials. 11 Hybrid nanomaterials are emerging multifunctional nanomaterials that usually integrate with two or more dissimilar materials, 12,13 and typically they are inorganic components and organic components.…”