Controlled synthesis of nanoporous tin oxide layers with various pore diameters and their photoelectrochemical properties

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

“…Dendrites are still preserved, and their branches remain separated (see especially Figure 4c). In all cases, the average diameter of nanochannels within the anodic film was estimated to bẽ 60 nm what is in accordance with values previously observed for anodic SnO x formed on the Sn foil (for details see our previous works [24,44]). As can be seen in Figure 2a, no significant changes in XRD patterns of Sn foams were caused by anodization that indicates the amorphous or poorly crystalline nature of the anodic film and is consistent with our previous findings [44].…”

“…Although noticeable dark currents appeared during anodic polarization of the sample, they were stable enough to allow recording of the photocurrent spectrum, which is shown in Figure 5a (red line). It has been proven, that annealing of anodic SnOx layers formed on the plain Sn foil not only can improve the photoresponse of anode [29,40,44] resulting in both higher photocurrents and enhanced electrode stability, but also can affect the Sn 2+ content and, in consequence, bandgap of the semiconductor [40]. For this reason, the photoresponse of annealed Sn/SnOx foams was also tested, and the obtained photocurrent spectrum is also shown in Figure 5a (black line).…”

“…Secondly, the curve recorded during anodization of the Sn foam exhibits a significantly different and unusual shape. For both types of substrates, a current density drop caused by the formation of the compact passive oxide layer is observed immediately after applying the potential and it is followed by the current rise, being an indication of the pore formation (for detailed discussion of current density shapes and particular stages of anodization, please refer to our previous works [24,32,44,45]). After about 100 s of anodization of the Sn foil, a steady-state current is reached, and no significant changes are noticeable until the end of the process.…”

Review of Fabrication Methods, Physical Properties, and Applications of Nanostructured Copper Oxides Formed via Electrochemical Oxidation

“…Currently, the majority of transition metals have been tested as substrates for anodizing. Researchers have obtained nanostructured anodic oxides as the result of the electrochemical oxidation of: W [ 21 , 22 ], Sn [ 23 ], Zr [ 24 , 25 ], Zn [ 26 , 27 ], Nb [ 28 , 29 ], Fe [ 30 ], and FeAl [ 20 , 31 ]. The majority of the nanostructures obtained by transition metals anodization are composed of oxide, where the metallic element is at one fixed oxidation state.…”

“…Therefore, self-organized anodization seems to be a promising method in copper oxides formation, providing high-surface area nanostructures with a band gap tunable by operating conditions (size of the nanostructures) and chemical composition (in situ doping). Per analogiam to the anodization of Al and Ti [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], it can be expected that the morphology of the nanostructures formed by copper anodization can be tailored after the optimization of the operating conditions. Moreover, recent advances in Al and Ti anodization, as well as recent high-tech applications, may provide some inspiration for electrochemical copper oxidation.…”