Combined local anodization of titanium and scanning photoelectrochemical mapping of TiO2 spot arrays

Abstract

Localized growth of TiO2 and rapid screening of TiO2 photoelectrochemical properties by scanning electrochemical microscopy (SECM) are described. We report the fabrication and operation of an electrochemical tool comprising a microcapillary and an ultramicroelectrode (Cap-UME) that is used for the local formation of TiO2 microspots. This tip allows the generation of arrays of TiO2 of different physicochemical and catalytic characteristics.Moreover, these results prove that local anodization is an efficient method to obtain TiO2 films with micrometre resolution. The use of a combined optical fibre-ultramicroelectrode (OF-UME) in a SECM configuration may operate in two different detection modes. In the first mode, the array is biased and the OF-UME is used as a scanning light source allowing a photocurrent 2 mapping of the surface. In the second mode, the dual OF-UME system serves simultaneously as a light source and an O2 electrochemical sensor which resolved spatially the photoelectrochemically generated O2 species. A direct correlation between the potentials used to produce TiO2, the photocatalytic properties of the TiO2 spots and the amount of oxygen produced was found, demonstrating the strong potential of these tools for the rapid and convenient mapping of TiO2 array properties on a single surface.

In situ characterizations of photoelectrochemical cells for solar fuels and chemicals

“…Additionally, sub-diffraction limit light spots were already presented. 180 This nanoscale resolution introduces new methods to study local anodization 181 or isolate the area of interest to study it without the overall substrate contribution. 182 Moreover, a specific SPECM setup allowed to monitor simultaneously multiple parameters.…”

Local Anodizing of a Newly Prepared Aluminum Micrometric Disk

“…However, due to the insulating nature of an anodic film, conventional local electrochemical techniques, such as SECM (scanning electrochemical microscopy), cannot be applied as they lead to the scattering of the current as the film grows. To avoid this issue [ 7 , 8 , 9 ], local anodizing is usually conducted in an electrolyte droplet. However, both approaches use macroscopic aluminum surfaces onto which a small anodic film is added.…”

3D printed solution flow type microdroplet cell for simultaneous area selective anodizing

“…Traditional lithographic, masking and subtractive manufacturing techniques are well-established for the fabrication of micro-sized structures on desired substrates but involve multiple steps and result in significant material wastage [7] , [8] , [9] . Recently, localized electrochemical fabrication techniques such as scanning electrochemical microscopy (SECM), atomic force microscope (AFM) and scanning tunneling microscopy (STM) have been applied to selectively characterize and fabricate minute structures on specimen surfaces at desired areas [10] , [11] , [12] , [13] . These techniques are preferable over conventional lithographic and masking methods since the specimen needs no initial preparation, small quantity of electrolyte is required, and precisely defined area is wetted.…”