Improving the photoelectrochemical performance of porous anodic SnO _x films by adjusting electrosynthesis conditions

Abstract

A comprehensive characterization of photoelectrochemical (PEC) properties of the nanoporous tin oxide (SnO x ) films of different thicknesses and complex internal morphology is presented. Nanoporous SnO x layers were obtained by one-step anodic oxidation (anodization) of Sn foil in 1 M NaOH. Semiconducting films with a uniform diameter of ca. 50 nm were grown if the potential of 4 V was applied during anodization, and the layers with different thicknesses were synthesized by changing the duration of the process. Switching the potential between 2 and 4 V allows the formation of anodic films with segments of different channel diameters. The optimal anodizing duration for layers with uniform channels was found to be 50 minutes, which corresponds to the thickness of SnO x film of slightly above 6 μm. In the case of layers with segments of different channel diameters, the segment arrangement was found to be crucial for optimal PEC performance. Layers with the segment of narrower channels being in the contact with the current collector were found to exhibit enhanced photoelectrochemical performance compared to their counterparts with an opposite segment arrangement. This was mainly attributed to the favorable band arrangement facilitating the transfer of the photogenerated electrons to the external circuit as well as enhanced adhesion of the anodic SnO x layer to the current collector. Highlights 1. Nanoporous SnO x films were synthesized electrochemically.2. Layers with various morphologies were studied as photoanodes. 3. The optimal thickness of anodic SnO x was found to be 6 μm.4. Enhanced PEC performance was observed for multisegment anodic films. 5. The segment arrangement is crucial for optimal PEC performance.

Electrochemistry at Krakowian research institutions

“…The team specialized in Electrochemistry, previously guided by Professor Marian Jaskuła, and now by Professor Grzegorz Sulka, and has been working at the Faculty of Chemistry. The group has impressive achievements in fields of anodization of Al [152][153][154][155]; electrochemical synthesis of nanostructured oxides of, e.g., Sn [156,157] and Zn [158,159]; and nanoporous titanium dioxide [160][161][162]. The obtained anodic alumina oxide (AAO) templates are widely used for the fabrication of nanostructured electrodes of metals [163], alloys [164,165], and polymers [166,167].…”

Enhanced Photoelectrochemical Activity of Anodically Generated FTO/Nanoporous SnOx Decorated with BiVO4

“…Since 2004, when Shin et al for the first time fabricated anodic tin oxide, this material has been under gradually expanding interest in diverse fields, including PEC technology. − Typically, after the anodizing process, the material exhibits a completely irregular structure with randomly distributed nanochannels. Nonetheless, according to the current literature, , to date, great efforts have been made into relating individual anodizing conditions (including anodizing potential, electrolyte type, and its concentration) with the morphological and physicochemical features of the nanostructured SnO x , proving a close relation between them.…”

“…Since 2004, when Shin et al for the first time fabricated anodic tin oxide, this material has been under gradually expanding interest in diverse fields, including PEC technology. − Typically, after the anodizing process, the material exhibits a completely irregular structure with randomly distributed nanochannels. Nonetheless, according to the current literature, , to date, great efforts have been made into relating individual anodizing conditions (including anodizing potential, electrolyte type, and its concentration) with the morphological and physicochemical features of the nanostructured SnO x , proving a close relation between them. The as-received semiconductive layers are rather amorphous independently of the anodizing conditions; thus, numerous reports have been devoted to tailoring the structure of the material by applying the post-treatment procedures primarily annealing. , It was provided that such a strategy enables controllable introduction of defects or additional oxide phases and partial oxidation to the crystalline SnO 2 phase .…”

“…9−11 Typically, after the anodizing process, the material exhibits a completely irregular structure with randomly distributed nanochannels. Nonetheless, according to the current literature, 11,12 to date, great efforts have been made into relating individual anodizing conditions (including anodizing potential, electrolyte type, and its concentration) with the morphological and physicochemical features of the nanostructured SnO x , proving a close relation between them. The as-received semiconductive layers are rather amorphous independently of the anodizing conditions; thus, numerous reports have been devoted to tailoring the structure of the material by applying the post-treatment procedures primarily annealing.…”