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Adsorption Dynamics of Redox Active Species onto Polarized Surfaces of Sensitized NiO
摘要： Mesoporous 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.
关键词： X-ray photoelectron spectroscopy,Sensitized NiO,Dye-sensitized solar cells,Redox active species,Adsorption dynamics,Polarized surfaces
更新于2025-09-23 15:22:29
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Type II heterojunction in hierarchically porous zinc oxide/graphitic carbon nitride microspheres promoting photocatalytic activity
摘要： Graphitic carbon nitride (g-C3N4) is a visible light active semiconductor. However, low conductivity and high recombination rate of photogenerated electrons and holes limit its application in photocatalysis. In this work, we design and synthesize hierarchically porous zinc oxide/ graphitic carbon nitride (ZnO/g-C3N4) microspheres with type-II heterojunction to effectively degrade rhodamine B (RhB) via increasing the charge-separation efficiency. The ultraviolet-visible (UV-Vis) absorption spectra, Mott-Schottky plots and valence band X-ray photoelectron spectroscope confirm the formation of type-II heterojunction between ZnO nanocrystals and g-C3N4 nanosheets. As a result, the 1.5-ZnO/g-C3N4 composite (the mass ratio of zinc acetate dihydrate to g-C3N4 is 1.5) exhibits the highest photocatalytic activity with good stability and higher photocatalytic degradation rate comparing to pure g-C3N4 and pure ZnO. In addition, our results confirm that ?O2- and h+ are the main active species for ZnO/g-C3N4 in degradation of RhB.
关键词： Active species,Heterojunction,Photocatalytic activity,Hierarchically porous structure,ZnO/g-C3N4
更新于2025-09-10 09:29:36