In Situ Evaluation of Kinetics and Interaction Mechanism between Chenodeoxycholic Acid and N719 on Dye-Sensitized Nanofilm Surface
The photoanode of a dye-sensitized solar cell is composed of titanium dioxide and a dye adsorbed on the surface. Dye molecules, such as N719 dye, usually agglomerate due to H bond and other factors, forming a multilayer adsorption structure, leading to light loss and electron injection loss. Adding a co-adsorbent to the dye, such as chenodeoxycholic acid (CDCA) molecule, is an effective method to prevent the aggregation of the dye. However, the mechanism of interaction between CDCA and N719 is still unclear. Therefore, in this paper, the mechanism of interaction of CDCA and N719 was studied in detail using quartz crystal microbalance (QCM) combined with UV–vis absorption spectrum. The adsorption kinetics constant of the co-adsorbent CDCA was obtained, and it was found that the adsorption process of CDCA on the surface of TiO2 was more consistent with the Freundlich isothermal adsorption model. Under the condition of continuous adsorption and desorption, the dynamic constants of CDCA adsorption did not change obviously, but molecular rearrangement might occur. In the process of sequential competitive adsorption, pretreatment with CDCA had a small influence on the adsorption kinetic constants of N719. There is competitive adsorption between CDCA and N719 on the surface of TiO2. In the process of mixed adsorption, the interaction mechanism between CDCA and N719 is a cooperative mechanism in the solution and competitive mechanism on the TiO2 surface. In addition, the results of this experiment also showed that CDCA could accelerate the adsorption time of N719. The experimental results in this paper may be helpful for understanding the mechanism of CDCA.
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