Rapid Dye Adsorption via Surface Modification of TiO₂ Photoanodes for Dye-Sensitized Solar Cells

Abstract

A facile method for increasing the reaction rate of dye adsorption, which is the most time-consuming step in the production of dye-sensitized solar cells (DSSCs), was developed. Treatment of a TiO2 photoanode with aqueous nitric acid solution (pH 1) remarkably reduced the reaction time required to anchor a carboxylate anion of the dye onto the TiO2 nanoparticle surface. After optimization of the reaction conditions, the dye adsorption process became 18 times faster than that of the conventional adsorption method. We studied the influence of the nitric acid treatment on the properties of TiO2 nanostructures, binding modes of the dye, and adsorption kinetics, and found that the reaction rate improved via the synergistic effects of the following: (1) electrostatic attraction between the positively charged TiO2 surface and ruthenium anion increases the collision frequency between the adsorbent and the anchoring group of the dye; (2) the weak anchoring affinity of NO3(-) in nitric acid with metal oxides enables the rapid coordination of an anionic dye with the metal oxide; and (3) sufficient acidity of the nitric acid solution effectively increases the positive charge density on the TiO2 surface without degrading or transforming the TiO2 nanostructure. These results demonstrate the developed method is effective for reducing the overall fabrication time without sacrificing the performance and long-term stability of DSSCs.

Facile synthesis of mesoporous ZnCo2O4 coated with polypyrrole as an anode material for lithium-ion batteries

“…7b) can be found. However, similar phenomena have been observed for metal oxide anodes, such as the ZnMn 2 O 4 reported by Kim et al [47]. This result may be attributed to the irreversible insertion of Li þ into interfacial storage [49].…”

Polyethyleneimine as a novel desorbent for anionic organic dyes on layered double hydroxide surface

“…It is reasonably expected that the diffusion resistance was considerably increased in the interior adsorption process, thus resulting in a decrease in diffusion rate [38]. Adsorption kinetics data were also measured under different temperatures (25, 35 and 45°C) in order to calculate the activation energy (E a ) according to the Arrhenius equation (ln k 2 = ln A À E a /RT) [39], where k 2 (g/mg min) is the pseudo-second-order rate constant at temperature T (K), A is the Arrhenius factor, E a (J/mol) is the activation energy, and R is the gas constant (8.314 J/(mol K)). The Arrhenius plot and activation energy for adsorption of methyl orange on CO 3 -LDHs were shown in Fig.…”

Fabrication of hierarchical porous anodized titania nano-network with enhanced active surface area: Ruthenium-based dye adsorption studies for dye-sensitized solar cell (DSSC) application

“…This is due to the higher active surface areas of hierarchical nanostructures against TNA and NP samples, as depicted in Table 3, and clearly implies that the electrolyte conductivity-modulated two-step anodization process was able to generate hierarchical structures that showed a nearly two-fold increase in the active surface area, in comparison to conventional TNAs. Generally, the dye adsorption reaction is represented as [52,53] follows:…”