Hi,
in particular with a gas flowmeter instead of GC? or the moles of H2 generate are too low?
Experimental conditions: (20 ml H20, 25 mg photocatalyst, 1 ml methanol) in a 100 ml volume Pyrex glass reactor, Uv Lamps on the top of reactor at about 10 cm of distance,
A volumetric method is highly sensitive to the temperature, but you may try to use the technique similar to that of described in J. Am. Chem. Soc., 2008, 130 (15), pp 5006–5007
Sorry, prof. Geletii, Are you sicure that this article talk about volumetric method? I read it and the authors use a GC to determinate the O2 gas evolution.....
Dear Roberto
I personally feel volumetric method depends on a lot of factors ie temperature, pressure, distance, individual volumes, distances, etc...So, people quantitatively follow the GC measurement.
They used GC only to confirm O2 formation. they accurately measured the change of pressure. I know Marcella Bonchio very well personally. She published the detail description of her apparatus elsewhere.
From SI: "Catalytic water oxidation was contained in 40 mL
glass EPA vials with Omega PX-138-015D5V pressure-voltage transducers mounted into the reaction headspace.
The evolution of O2 was thereby monitored within 0.04 mbar using a home-made interface designed in LabView. '''
The use of volumetric method for the determination of H2 generation is ok but you need to work in similar condition (blank test and in the presence of catalyst). However, if you have GC it is perfectly precise.
The advantage of GC is its high sensitivity for quantification AND giving you the qualitative information about the produced gases. Both, volumetric and pressure method's mentioned here, might work equally well, provided high enough amounts of gases are formed, but both require a determination of the product gases after the experiment (as indicated by Yurii V Geletii).
An alternative is the use of H2 resp. clark electrodes (for H2 resp O2) - but they tend to be difficult in handling. Also luminescence based detection of O2 is an interesting approach...
sir, i am doing research in photocatalyst for H2 generation .please suggest me good photocatalyst with low cost, efficiency, stability.
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