Pulsed Galvanostatic and Potentiostatic Electrodeposition of Cu and Cu[sub 2]O Nanolayers from Alkaline Cu(II)-Citrate Solutions

Abstract

Nanolayers of Cu and Cu 2 O with a wide range of layer thicknesses have been produced using pulsed galvanostatic and potentiostatic electrodeposition from alkaline Cu͑II͒-citrate solutions. The thicknesses of the individual Cu and Cu 2 O layers can be independently controlled and the composition of the multilayered materials, which also were studied using electrochemical quartz crystal microbalance, X-ray diffraction, and scanning electron microscopy, can be varied from pure Cu to pure Cu 2 O by varying the current density or the deposition potential. It is shown that some of the deposited Cu 2 O is reduced during the subsequent copper deposition step and that the influence of this effect depends on the Cu͑II͒ concentration, the Cu 2 O microstructure, and the deposition mode. Additional Cu 2 O deposition is demonstrated to take place after the copper deposition step due to comproportionation and precipitation of Cu 2 O. This effect facilitates electrodeposition of Cu 2 O on Cu. Deposition of Cu on the Cu 2 O layer formed by comproportionation and precipitation was likewise found to be more straightforward than on electrodeposited Cu 2 O. Well-defined nanolayered Cu/Cu 2 O materials are generally best manufactured using pulsed galvanostatic techniques because a much larger fraction of the Cu 2 O was found to be reduced during the subsequent Cu deposition pulse in pulsed potentiostatic depositions.

Electrochemical fabrication and characterization of Cu/Cu2O multi-layered micro and nanorods in Li-ion batteries

“…The electrodeposition of the multi-layered micro and nanorods was carried out based on the combination of a previously described pulsed galvanostatic approach 22 with reported aperiodic pore diameters of 1 µm, 200 nm and 50 nm, respectively.…”

“…The cuprous oxide deposition step involved repeated pulsing of the current density between -0.1 mA cm -2 and -1 mA cm -2 whereas the copper deposition was carried out using a current density of -10 mA cm -2 in analogy with the approach previously used 22 for the deposition on planar substrates. The cuprous oxide deposition step involved repeated pulsing of the current density between -0.1 mA cm -2 and -1 mA cm -2 whereas the copper deposition was carried out using a current density of -10 mA cm -2 in analogy with the approach previously used 22 for the deposition on planar substrates.…”

“…Electrochemical codeposition of alloys and mixtures of oxides have likewise been described 13,[16][17][18] and superlattice thin films can likewise be deposited using electrochemical atomic layer deposition 19,20 . Deposition of metal and metal oxide multilayer structures can, nevertheless, be realized if the metal layers become passivated by the formation of an oxide layer 21 (preventing a complete oxidation of the metal layer) or when metal layers are formed on top of the metal oxide layers 13,22 . The latter is most likely due to the fact that such depositions are fundamentally difficult since the metal oxide layers should be reduced during the deposition of the metal layers while the metal layers should be oxidized during the deposition of the oxide layers.…”

“…Despite the progress within the field of electrodeposition, relatively little attention has so far been paid to electrodeposition of multilayers composed of stacked metalmetal oxide layers 13,16,17 . While anodic passivation of metals is a well-known phenomenon 21,23 , cathodic passivation of oxide layers has so far received much less attention, although the effect has been described by Eskhult et al 13,22 in connection with the deposition of Cu/Cu 2 O multilayer structures on planar substrates. Deposition of metal and metal oxide multilayer structures can, nevertheless, be realized if the metal layers become passivated by the formation of an oxide layer 21 (preventing a complete oxidation of the metal layer) or when metal layers are formed on top of the metal oxide layers 13,22 .…”

Surface Oxidation of Cuprite

“…CuO + H 2 O → Cu(OH) 2 [5] It is postulated also that this 'multilayer' Cu(OH) 2 would have an O 1s binding energy of ~532.1 eV, in agreement with the main O 1s binding energy observed for malachite, but at variance with values of ~531 eV reported for bulk Cu(OH) 2 (24,25,31). Skinner et al (31) assigned an O 1s binding energy of 532.5 eV to adsorbed water rather than hydroxide.…”