Photoelectrochemical Infiltration of a Conducting Polymer (PEDOT) into Metal-Chalcogenide Decorated TiO2 Nanotube Arrays

•Concept of light induced electrodeposition of conducting polymers has been extended to TiO2/ metal chalcogenide (CdX) scaffolds.•Interfacial energetics affected the concurrent nucleation and growth of the PEDOT oligomers.•Both collective and selective excitation of the SC components was exploited for the photoelectrochemical polymerization of EDOT and bis-EDOT.•Sensitizer QDs act as seeds for the initial growth of PEDOT.•Parallel optimization of the monomer, irradiation wavelength, and the electrochemical method is indeed necessary.

ABSTRACTPhotoelectrochemical synthesis of TiO2/CdX/PEDOT [X: S, Se; PEDOT = poly(3,4-ethylenedioxythiophene)] ternary hybrids was carried out by exploiting the semiconductor (SC) nature of both the oxide and the chalcogenide component. To this end, TiO2 nanotube arrays were initially electrosynthesized on titanium foils by anodization in fluoride-containing aqueous media. CdS and CdSe quantum dots were subsequently deposited on the nanotubes using successive ionic layer adsorption and reaction (SILAR). The conjugated polymer, PEDOT, was then grafted using photoelectrochemical excitation of the SC matrix and potentiodynamic deposition, to ultimately afford the ternary hybrid architecture. The morphology, structural properties, and chemical composition of these assemblies were evaluated by scanning electron microscopy, diffuse reflectance UV-Vis spectrophotometry, and Raman spectroscopy, while their electroactivity was evaluated by cyclic voltammetry. Photoelectrochemical deposition of the conducting polymer was carried out both through selective excitation of the chalcogenide sensitizer and the collective photoexcitation of the two SC components. Two precursor molecules, namely, EDOT or bis-EDOT were compared and contrasted in terms of their relative proclivity to oligomer/polymer formation. The use of UV or visible spectral wavelength components allowed for discrimination between the various polymer formation and SC photoexcitation pathways.

Graphical abstractIn situ photoelectrosynthesis of nanostructured TiO2/CdX/PEDOT ternary hybrid assemblies was achieved exploiting the semiconductor behavior of both inorganic components.Figure optionsDownload full-size imageDownload as PowerPoint slide