Dear colleagues,
In the lab, I tried to synthesize photocatalyst using PEG-1000 as directing or controlling agent in crystal formation. Based on the results, SEM using secondary and backscattering methods showed that the photocatalyst surfaces were covered by the transparent layer as the attached figure. I assumed that they were the PEG-1000 residuals because there were no additional compounds besides PEG. But, when it is analyzed using FTR, the peak absorption of PEG-assisted photocatalyst synthesis is different from their reference (pure PEG-1000). How do we explain this? Is FTIR powerful to analyze the left PEG residuals on the material surfaces? Can you help me by attaching some related references?
Dear Dr. F. Febiyanto,
FTIR spectrometers employing attenuated total reflectance (ATR) sampling interfaces are a proven and powerful tool for the non destructive analysis of polymeric materials.
FTIR (Fourier Transform Infrared Spectroscopy) is also sometimes used when residues appear to exhibit high levels of carbon or other low energy elements, or are too thin to accurately analyze with the SEM/EDS system.
Surely, you could easily find suitable refences for your research work.
Best regards, Pierluigi Traverso
No comments on FTIR, only on SEM. You do not have a "transparent layer". Electrons of 15KeV have very small depts of penetration, much, much less than your scale bar of 1 micron. You do not see surfaces covered with some layer (may be you have one, but you do not see it at least), you have just something (artifact?) on the bottom of one of the particles. For proper observation in secondary electrons you had too high voltage and as a result - very strong edge effect which obscure details. You may want to repeat your observations at lower accelerating voltages (1-5 kV) and higher magnifications.
Dear Febiyanto,
Did you use ATR-FTIR spectroscopy for the sample as SEM? If it was, then you could say that peak around 3300-3400 cm-1 on AP-1000 20% was attributed to the -OH residual PEG which was similar to the spectra of PEG 1000.
It is better to use FE-SEM combined with EDX. After taking the images, you analyze the same sample at the same spot with EDX to get the element content. with this, you can justify whether it is residual PEG or not.
Best regards,
Dear F. Febiyanto ,
You can try thermal analysis such as TGA run the pure PEG 1000 and the photocatalyst synthesized using PEG 1000. Then, compare the decomposition steps for both samples. Should the be similar decomposition steps then it is an indication that the residual maybe the PEG 1000.
Regards,
Themba Dominic Ntuli
The broad band below 1000cm-1 and the sharp band at approx 500 cm-1 are typical of inorganics. A Broad band as low as 900 cm-1 is not one which I have previously seen.
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