Photostability of apocarotenoids on surface of TiO2 semiconductor nanoparticles

Autor: Pradeep M. Jayaweera, U.G. Chandrika, D.D.D.H Alwis
Rok vydání: 2021
Předmět:
Zdroj: Journal of Photochemistry and Photobiology A: Chemistry. 407:113061
ISSN: 1010-6030
DOI: 10.1016/j.jphotochem.2020.113061
Popis: Dye-sensitized solar cells (DSCs) assembled by natural dyes as a sensitizer recently made considerable attention. Use of inexpensive materials as the sensitizer in DSCs makes it more attractive devices for conversion of solar energy to electricity. UV–vis, fluorescence and fluorescence-excitation spectroscopic studies were used in this work to understand the photochemical stability of apocarotenoids (apocar) containing terminal carboxylic groups, adsorbed onto TiO2 semiconductor surface. Two apocar, bixin and norbixin bind strongly to the surface of the TiO2 nanoparticles, confirmed by the appearance of a red-shifted single broad peak instead of the S0→S2 electronic transition observed for unbound apocar. The binding of apocar to TiO2 surface has been further confirmed using Fourier Transform Infrared spectroscopy (FTIR) spectroscopy. FTIR studies revealed that both apocar binding through carboxylate group to the TiO2 surface. The photodegradation kinetics of bixin and norbixin adsorbed to TiO2 surface are shown to be higher but similar, compared to the apocar in the absence of TiO2, which also suggested a similar mechanism of decaying for both apocar with the formation of radical cations. Fluorescence quenching data revealed that the binding constant Ka for bixin and norbixin at 293 K are 4.9 × 10−3 mol-1 dm3 and 7.7 × 10−3 mol-1 dm3 respectively and have a similar number of binding sites. DSCs assembled suggest that norbixin sensitized cells show greater efficiencies compared to bixin sensitized solar cells. A mechanism was proposed for the enhancement of the rate of photocatalytic degradation of apocar.
Databáze: OpenAIRE
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