Hierarchical Nanoporous Sn/SnO_x Systems Obtained by Anodic Oxidation of Electrochemically Deposited Sn Nanofoams

• Published in: Nanomaterials
• Main Authors: Magdalena Gurgul, Anton S. Lytvynenko, Magdalena Jarosz, Karolina Gawlak, Grzegorz D. Sulka, Leszek Zaraska
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Subjects: sn foams; electrodeposition; tin oxides; anodization; nanopores
• Online Access: https://www.mdpi.com/2079-4991/10/3/410

A simple two-step electrochemical method for the fabrication of a new type of hierarchical Sn/SnO_x micro/nanostructures is proposed for the very first time. Firstly, porous metallic Sn foams are grown on Sn foil via hydrogen bubble-assisted electrodeposition from an acidulated tin chloride electrolyte. As-obtained metallic foams consist of randomly distributed dendrites grown uniformly on the entire metal surface. The estimated value of pore diameter near the surface is ~35 µm, while voids with a diameter of ~15 µm appear in a deeper part of the deposit. Secondly, a layer of amorphous nanoporous tin oxide (with a pore diameter of ~60 nm) is generated on the metal surface by its anodic oxidation in an alkaline electrolyte (1 M NaOH) at the potential of 4 V for various durations. It is confirmed that if only optimal conditions are applied, the dendritic morphology of the metal foam does not change significantly, and an open-porous structure is still preserved after anodization. Such kinds of hierarchical nanoporous Sn/SnO_x systems are superhydrophilic, contrary to those obtained by thermal oxidation of metal foams which are hydrophobic. Finally, the photoelectrochemical activity of the nanostructured metal/metal oxide electrodes is also presented.