Synthesis and Characterization of Thin Films Based on Azobenzene Derivative Anchored to CeO₂ Nanoparticle for Photoswitching Applications

Abstract

Azobenzene has attracted substantial attention as a photoswitchable molecule since its applications range from energy and data storage to biomedical applications. This work reports a new type of thin‐film based on azobenzene derivative anchored to cerium oxide nanoparticles CeO2NPs for photoswitching applications. The trans–cis isomerization and reverse isomerization occur by UV‐light exposure and thermal relaxation process, respectively. The photoisomerization and reverse isomerization kinetics for CeO2NPs‐MR thin films are studied, investigated, and analyzed using UV‐Vis absorbance spectra, FTIR spectroscopy, XRD, and scanning electron microscopy (SEM), in addition to differential scanning calorimetry (DSC) measurement to study the energy storage capacity. The results found that anchoring azobenzene to CeO2NPs is successful in multisource storage of solar energy applications.

Photoisomerization kinetics of a novel photoswitchable film based on methyl red doped with sodium hexachloroplatinate hosted in polyethylene oxide

“…The total enthalpy variation ( for PEO‐MR and PEO‐(MR‐Na 2 PtCl 6 ) films is 30.52 and 42.91 J g −1 , respectively. This fact confirms that introducing Na 2 PtCl 6 into azobenzene enhances the energy storage properties of the composite for molecular solar thermal energy storage applications 41 …”

“…These shifts indicate the Z‐E transformation around N=N bands in the 1500–1700 cm −1 range. Moreover, the intensity of the N=N band of Z ‐isomers is highly correlated with that of E‐ isomers, confirming the reinforced photoisomerization process of the PEO‐MR and PEO‐(MR‐Na 2 PtCl 6 ) films 42 …”

E/Z reversible photoisomerization of methyl orange doped polyacrylic acid‐based polyelectrolyte brush films

“…Finally, the NH stretching vibrational band is at 3360 cm −1 30 . The FTIR spectra of E ‐ and Z ‐states of the PAA‐MO PEBs films show identical vibrational bands with a little shift in the NN vibrational band, which indicates the Z–E transformation around NN bands 24 …”

Toward real-world applications: promoting fast and efficient photoswitching in the solid state

“…The photoresponsive molecules are introduced on the surface of the substrate either by chemical anchoring or physisorption. Surfaces with various chemical environments, including glass 57 and silicon wafers, 58 metal 59 and metallic oxide, 60 polymers 61 and two-dimensional materials 62 have been widely used as the substrates to reveal the isomerization property of photoswitches. Meanwhile, the hydrophilicity, optical property 63 and conductivity 64 of the surface could be controlled by light.…”

“…Functional groups on the surface are important for the introduction of photoresponsive molecules. Metal 65 or non-metal oxides, including SiO 2 , 57 Al 2 O 3 and CeO 2 60 have been used as substrates for anchoring and depositing photoswitches, because of the abundant hydroxyl on the surface. For example, Ravoo and coworkers reported introducing a monolayer of arylazopyrazole onto the SiO 2 surface through the reaction of silane.…”