Preparation and electrochemical properties of nanoporous transparent antimony-doped tin oxide (ATO) coatings

Nanoporous antimony-doped tin oxide (ATO) coatings with high surface area, optical transparency and electron transfer properties have been prepared using an interpenetrating inorganic-organic hybrid sol-gel approach. UV-Vis and X-ray photoelectron spectroscopic studies were carried out on the prepared materials in addition to the characterization of their microstructures with scanning electron microscopy, transmission electron microscopy, and nitrogen sorption experiments. Cyclic voltammetry (CV) and impedance spectroscopy were employed to characterize the electrochemical and electron transfer properties of the coatings in both acidic and neutral media with an Fe³⁺/Fe ²⁺ redox couple. The material had a specific surface area of over 90 m² g^-1 with a bimodal pore distribution with two distinctive peaks at ca. 8 and 40 nm. The electrochemical capacitance of the material was about 100 times as high as the value obtained for a commercially available nonporous fluorine-doped tin oxide (FTO) electrode. The estimated electron transfer rate of the former was three times larger than that of the FTO. The optical transparency, high surface area and high electron transfer rate of the nanoporous ATO coatings make the material well suited for diverse photoelectrochemical applications.