Dear Malini Manjith

To study electronic properties of photocatalysts, you can simply use an UV-vis DRS instrument and take the spectra in solid state. In addition, you can disperse your photocatalysts in solvents like ethanol and take their UV-vis spectra or photoluminescence spectra. For example, please refer to the enclosed papers.

best wishes

Aziz

If you are using your photocatalyst(s) in a solution, then yes, measuring the spectra under the same conditions would be desirable.

I suggest you not only measure the UV-vis absorption spectrum, but also think on emission and excitation spectrum (so you learn about the other deactivation pathways), try different concentrations (so you can avoind aggregation or or other unwanted behaviour), different solvents (polar, apolar, hydrogen bonding, pH and ionic strength effects) etc. In fact there are countless small things that could affect the photophysical and photochemical behaviour of the system...

Dear Malini Manjith

To study electronic properties of photocatalysts, you can simply use an UV-vis DRS instrument and take the spectra in solid state. In addition, you can disperse your photocatalysts in solvents like ethanol and take their UV-vis spectra or photoluminescence spectra. For example, please refer to the enclosed papers.

best wishes

Aziz

Thank you all I hope I would make it got clarity from you all. Thank you

Hi,

Check whether your UV-Vis Spectrometer has a integrating sphere to do solid analysis. If yes, in integrating sphere mode, run the baseline correction with dried KBr or BaSO4 (must be heated 2-4 hour 60-80 oC). after baseline correction, mix a small a amount your photocatlyst with KBr or BaSO4 and the run analsysis. The data can be recorded in absorbance or Kubelka–Munk (K-M) function or % Reflectance.

Band gap calculation:

The band gap energy of a semiconductor can be calculated by the formula, αhν = A (hν- Eg)n/2

Where, α, hν, Eg and A are absorption coefficient, light frequency, band gap, and a constant respectively, and

The a plot of (αhν)2/n vs. hν was created and a tangential line was plotted near the band edge, with the x-intercept of the tangential line corresponding to the optical band gap.

The coefficient (n) associated with an electronic transition n= 1 for direct transitions and n= 4 for indirect transition. A plot of ln(α hν) vs ln(hν – Eg) was created using an approximate value of Eg (i.e. for TiO2 3.2), and then the value of n was estimated from the slope of the straight line near the band edge.

Kubelka–Munk (K-M) data (α): This data is absorption coefficient (α). Use this data for α in above equation, or the α can be obtained from % Reflectance data using following equation:

α = (1-R)2/2R, where R is reflectance.

Kind regards

Santosh

Thank you sir I wanted to calculate the band gap energy for my catalysts that you have clearly explained could you please suggest where the instrument with integrating sphere would be available. We dont have access here. Generally we give samples for analysis in stic cochin.

Yes, it is possible to to have UV-Vis spectrum directly using your powdered catalysts. Kindly refer to the below link for the same.

Article Synthesis and characterization of solar photoactive TiO2 nan...

Malini Manjith

There are two steps first is about characterization and second is about activity of the prepared materials.

1. First step is characterization of the prepared photocatlysts by using UV-visible spectrophotometer. This will help you to get information about electronic properties of the samples. From this data you can also calculate band gap position of the materials. you can used solid samples for this purpose.

2. Secondly when you will test samples for degradation of the dyes, you can collect liquid samples at certain intervals during degradation reaction. Centrifuge to remove materials particles and measure UV-Visible scan to check the degradation efficiency.

You can consult following papers.

http://pubs.rsc.org/-/content/articlehtml/2017/cy/c7cy00420f

Article Synthesis of Environmentally Encouraged, Highly Robust pollu...

Hello

Use the DRS Test for Solid Powder