Microstructural evolution and optical properties of TiO2 synthesized by eggshell membrane templating for DSSCs application

This article presents the bio-inspired synthesis of TiO2 using eggshell membranes (ESM) as a biotemplate on which the crystals of TiO2 are nucleated and grown. The microstructure, phase transformations and optical behavior were studied with the objective of understanding the effects of the thermal treatment on the properties of the TiO2 powder for application in dye sensitized solar cells (DSSC). The technique used for the mimetization of the ESM consists of submerging the biotemplate in an alcoholic solution of TiCl4 and thermal treating the samples at 600, 700 and 800 °C. Thermal analysis (DTA and TGA) was used to investigate the thermal decomposition of the membranes. X-ray diffraction (XRD) studies revealed the phase evolution and the average crystal sizes. Scanning and transition electron microscopy (SEM and TEM, respectively) were used to investigate the morphology of the obtained powders. UV–vis diffuse reflectance was used to investigate the optical properties. The porosity was also evaluated using a BET instrument. The results indicated that the best features for DSSC application were presented by the sample that was thermally treated at 600 °C. This is reflected in the good replication of the morphology of the used biotemplate, with a nanocrystalline anatase phase (average crystal size 15.82 nm), high surface area (64.8 m2/g), mesoporous structure (average pore size of 26.31 Å) and large band gap (3.31 eV).

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► TiO2 was obtained by mimetization of eggshell membranes (ESM).
► Three temperatures of thermal treatment were investigated (600, 700 and 800 °C).
► The optical properties were investigated by UV–vis diffuse reflectance.
► The morphology of the ESM was replicated in form of nanocrystalline TiO2.
► It was obtained samples with good porosity, bandgap and crystallinity for DSSCs.