Growth of Different Nanostructures of Cu₂O (Nanothreads, Nanowires, and Nanocubes) by Simple Electrolysis Based Oxidation of Copper

Abstract

Cuprous oxide (Cu 2 O) nanostructures have been synthesized by anodic oxidation of copper through a simple electrolysis process employing plain water (with ionic conductivity ∼6 µS/m) as an electrolyte. No special electrolytes, chemicals, and surfactants are needed. The method is based on anodization pursuant to the simple electrolysis of water at different voltages. Platinum was taken as cathode and copper as anode. The applied voltage was varied from 2 to10 V. The optimum anodization time of about 1 h was employed for each case. Two different types of Cu 2 O nanostructures have been found. One type was delaminated from copper anode and collected from the bottom of the electrochemical cell and the other was located on the copper anode itself. The nanostructures collected from the bottom of the cell are either nanothreads embodying beads of different lengths and diameter ∼10-40 nm or nanowires (length ∼600-1000 nm and diameter ∼10-25 nm). Those present on the copper anode were nanoblocks with a preponderance of nanocubes (nanocube edge ∼400 nm). The copper electrode served as a sacrificial anode for the synthesis of different nanostructures. A tentative mechanism for the formation of Cu 2 O nanostructures has been suggested. The present work represents the first such attempt where Cu 2 O nanostructures were formed under the oxidation induced by as simple a process as electrolysis of plain water. Both anodization potential and time influence the morphology of nanostructures of Cu 2 O. Thus, nanothreads are formed at 6 V during 15-30 min, whereas nanowires result when anodization time is extended to 45-60 min. Also two different types of Cu 2 O nanostructures, one which is present in the solution (nanothreads and nanowires) and the other which is located on the copper anode (nanocubes), are synthesized in the same electrolysis run. The optical band gap as calculated from the UV-visible absorption spectra of the nanothreads and nanowires corresponds to 2.61 and 2.69 eV, respectively, which is larger than the known band gap (2.17 eV) of bulk Cu 2 O.

Wire-like Bundle Arrays of Copper Hydroxide Prepared by the Electrochemical Anodization of Cu Foil

“…The sequential dehydration of Cu(OH) 2 , as observed above in the thermal treatment process of as-prepared Cu(OH)2, must be responsible for the CuO formation. The electrochemical Cu2O formation on Cu foil was previous reported, 13,26 and could be understood by the following reaction:…”

Highly active 3-dimensional cobalt oxide nanostructures on the flexible carbon substrates for enzymeless glucose sensing

“…It is well known that the surface energy of larger particles is lower than that of the smaller ones; therefore, these small nanoparticles were grown into larger ones via an overgrowth or aggregation process. [48][49][50][51] Afterwards, the adjacent large nanoparticles moved, met and then adhered to form a short chain-shaped structure (elongated nanorod structures). By prolonging the reaction time, the newly formed Co nanoparticle nuclei deposit onto the surface of the connected nanoparticles through the capillary phenomenon, leading to the formation of the nanowire morphology.…”

pH Dependent Hydrothermal Synthesis and Photoluminescence of Gd2O3:Eu Nanostructures

“…Single crystalline nanowires of hydroxides and oxides have been extensively studied. (Sharma & Sunkara, 2002;Singh et al, 2007) Their formations are related to the fact that the growth rate along one crystallographic direction is significantly faster than along the other directions. It has been reported that the growth direction of Gd(OH) 3 to nanorods is parallel to the (110) planes of the hexagonal unit cell.…”