Study of Structural, Optical, Morphology and Photoelectrochemical Properties of Melanin Sensitized TiO2 Thin Films Prepared by Chemical Bath Deposition Method

Abstract

Herein, we report the synthesis of TiO2 thin films by using the simple, inexpensive, low-temperature chemical bath deposition (CBD) method and annealed at 300, 400, and 500 °C. The obtained TiO2 thin films were sensitized with melanin. Influence of annealing temperature on structural, optical, morphology, and photoelectrochemical cell properties were investigated using a variety of techniques such as low angle XRD, Raman spectroscopy, scanning electron microscopy (SEM), UV-Visible spectroscopy, linear sweep voltammetry (LSV), Mott-Schottky (MS), electrochemical impedance spectroscopy (EIS), etc. We found that sensitization of TiO2 with melanin changes its phase from pure rutile to rutile-anatase mixed-phase and the average crystallite size of melanin sensitized TiO2 films lower than TiO2 films over the entire range of annealing temperature studied. SEM analysis shows the development of microcracks when TiO2 is sensitized with melanin. UV-Visible spectroscopy analysis showed that TiO2 films absorb mainly in the UV region whereas melanin sensitized TiO2 thin films absorb significantly in the visible region. Upon melanin sensitization, TiO2 films show a decrease in current density and flat band potential besides an increase in depletion width when annealing temperature increased from 300 °C to 500 °C. Furthermore, EIS analysis revealed that melanin sensitized TiO2 has high charge transfer resistance. The obtained results showed that sensitization of TiO2 with melanin is not advantageous for photocatalytic water splitting.

Influence of Elastic and Optical Properties on AgFeO2 and AgCrO2 Delafossite to be Applied in High-Frequency Applications

“…Optical properties have attracted attention from researchers because they are very useful in electronic devices. [45][46][47] Figure 2a and Table IV illustrate the refractive index n 2 and the wavelength k 2 of AgFeO 2 and AgCrO 2 delafossite. Based on the following equation, the lattice dielectric constant (e l ) was obtained as follows: 48…”

Stabilized Brookite Nanotube Array Films Grown on Transparent Substrates for Photoelectrochemical Water Splitting

“…Microstrain was minimized upon reaching 400 °C (Figure S4c), ascribed to the decrease in average crystallite size within the same temperature range. Note that increasing the crystallite size could increase the average grain size, minimizing the grain boundaries and decreasing the film microstrain . On the other hand, this reduced microstrain might be related to Sn atoms deficiency in the annealed TN8-500 sample, as confirmed by the XPS analysis below.…”

“…Note that increasing the crystallite size could increase the average grain size, minimizing the grain boundaries and decreasing the film microstrain. 63 On the other hand, this reduced microstrain might be related to Sn atoms deficiency in the annealed TN8-500 sample, 64 as confirmed by the XPS analysis below.…”

Preparation of Bi/BiOBr sensitized titania nanorod arrays via a one-pot solvothermal method and construction of kanamycin photoelectrochemical aptasensors

“…The photoelectrochemical (PEC) process 1,2 has been reported for water splitting to produce hydrogen, 3,4 solar cells, [5][6][7] dye degradation, 8,9 and photodectors. 10 PEC sensing is a new analytical detection technology, and has attracted extensive attention because of its high sensitivity and excellent analytical performance.…”