The Role of Gold‐Alumina Template in the Electrochemical Deposition of CeO₂ Nanotubes

Abstract

Electrochemical synthesis employing porous membranes previously metalized with a gold layer as a template is an easy and widespread method to obtain 1D nanostructures. Nevertheless, experimental factors for tuning the morphology and structural details of such nanostructures are still investigated. The influence of the amount of gold on morphology and structure of the 1D systems is studied for the first time. For this purpose, CeO2 nanotubes are synthesized via template‐based electrodeposition inside the pores of gold‐sputtered anodic aluminum oxide (AAO). X‐ray diffraction and electron microscopy techniques, including 3D electron tomography, are applied for the characterization of the template and the nanostructures. On one hand, the results reveal how gold is deposited on top and inside the pores of the AAO as a thin layer or as particles. On the other hand, the 1D systems consist of nanotubes formed by randomly oriented fluorite‐like nanocrystals (2–5 nm), which features a network of inner walls whose compactness directly relates to the thickness of the gold‐sputtered layer. From the combined analysis of voltage–time curves recorded during electrodeposition and the 2D, 3D structural information, a growth mechanism is proposed, which may enlighten paths to tailor the morphology and properties of CeO2 1D nanostructures.

Overview of Engineering Carbon Nanomaterials Such As Carbon Nanotubes (CNTs), Carbon Nanofibers (CNFs), Graphene and Nanodiamonds and Other Carbon Allotropes inside Porous Anodic Alumina (PAA) Templates

“…It is important to point out that the most common metal catalysts for the synthesis of CNTs, such as nickel [ 175 ], iron [ 176 ], and cobalt [ 177 ] have been electrodeposited within PAA. The implementation of the electrodeposition process inside porous templates is not limited to catalyst deposition but is also vastly used for the synthesis of other nanowires [ 171 ] or nanotubes [ 178 ], proposed for a wide range of applications [ 179 ]. Besides, the same experimental setup used for the anodization process can be used for the electrodeposition method.…”