ao8b02543_si_001.pdf (196.83 kB)
Adsorption Dynamics of Redox Active Species onto Polarized Surfaces of Sensitized NiO
journal contribution
posted on 2019-01-18, 19:18 authored by Andrea G. Marrani, Matteo Bonomo, Danilo DiniMesoporous NiO films were deposited
by means of a screen printing
technique onto fluorine-doped tin oxide transparent electrodes and
consequently sensitized with Erythrosin B (EryB) dye. The obtained
colored NiO material was used as a working electrode in a three-electrode
cell to study the evolution of the triple semiconductor/dye/electrolyte
interface upon electrochemical polarization in dark conditions. The
electrolyte was a solution of I3–/I– in acetonitrile, with the redox couple representing
the typical redox shuttle of dye-sensitized solar cells (DSCs). The
adopted electrochemical conditions were devised in order to simulate
the actual electrical environment of the NiO/dye photocathode in a
light-soaked DSC. The use of a benchmark sensitizer EryB and of the
most widely used redox mediator I3–/I– is particularly meaningful for the study of the adsorption
dynamics and the determination of possible degradative phenomena on
the basis of the behavior of numerous analogue systems. Therefore,
for the first time, the evolution of the NiO/EryB/I3–/I– multiple interface was investigated
combining the electrochemical characterization with ex situ spectroscopic
analysis by means of X-ray photoelectron spectroscopy. The resulting
picture shows that EryB in the immobilized state promotes the redox
processes based on the I3–/I– couple. Moreover, the EryB sensitizer inhibits the phenomena of
recombination between the metal oxide semiconductor and the redox
couple.