Doping of anodic nanotubular TiO2 electrodes with MnO2 for use as catalysts in water oxidation

Catalyst-Doped Anodic TiO2 Nanotubes: Binder-Free Electrodes for (Photo)Electrochemical Reactions

“…As shown in Figure 3a, nanotubes will not be produced if the electrolyte is not suitable for the typical anodic conditions used to produce nanotubular structures [17,24,31,47]. In addition, an electrolyte is difficult to be used if the precursor is vulnerable to F − ion [34].…”

“…However, additional barrier oxide was formed at the bottom of the tubes due to the absence of Fions in the doping electrolyte; its thickness was a function of the applied potential shock voltage (see Figure 5). Using a similar method, Seong et al succeeded in producing TiO 2 nanotubes with 0.7 at.% MnO 2 from the precursor KMnO 4 in ethylene glycol media; the nanotubes showed enhanced water oxidation performance under alkaline conditions [34].…”

“…Specifically, in single-step anodization, some precursors are self-reduced in the electrolyte by F − ions. For example, when single-step anodization is carried out using MnO 4 − in an F − -based electrolyte − , the Mn is deposited on the counter electrode in metallic form rather than being doped into TiO 2 as MnO 4 − due to the facile reduction of MnO 4 − to Mn 2+ [34]. In the potential shock method, the barrier oxide on the bottom of nanotubes grows significantly thicker with increasing potential shock voltage, blocking current flow.…”

“…Therefore, optimization of the potential shock voltage always involves a trade-off between achieving a high degree of doping and reducing the growth of the barrier oxide. Additionally, although electrolytes with high precursor concentrations result in higher doping concentrations in TiO 2 , in some cases the target potential cannot be maintained due to the limiting current-compliance of the power supply [34]. Thus, low potential shock voltages and low concentrations of doping precursors are preferred in the potential shock method, meaning that relatively low doping concentrations are achieved.…”

Binder-free SnO2–TiO2 composite anode with high durability for lithium-ion batteries

“…The hollowcontaining TiO 2 microcones were prepared by anodization, and subsequently, SnO 2 was decorated into the hollow spaces by an anodic potential shock. [36][37][38][39] The potential shock method is an economical and highly reproducible metal oxide decoration method on anodic TiO 2 structures.…”