hi I am using the impregnation method to dope 2 metal how can I keno the was attached on the surface or by making bond ?
my support is Activated carbon and the active metal was Na and Ni
You can heat the composite in a vaccum. Define the temperature from component properties.
Good luck.
XPS will show if the binding energy of the metal was changed (if there is a shift towards carbide, it might have bonded to the carbon).
A very quick, but not absolute technique, can be to obtain a FT-IR spectra before and after the impregnation. Another is washing the doped carbón with different solvents, in order to do a physio or chemi desorption
thanks for nice replay
Is it possible from TPR if the peak at low temp. its mean on the surface or if the peak at high temp. meat bonding
is that true ??
I agree with M-r Vallejos-Burgos. XPS is a best informative method for this question
You can run a TPR of metal particle, your support and your sample to compare the reduction events.
Zerovalent metal particles will be attached on the carbon supports through electrostatic force of attraction. However, it is explained that the carbon support can exert electronic perturbations on the supported metal. This results in a shift in the density of metal d states (DOS) near the fermi level (refer Nørskov works). This can be characterized with shift in B.E in the XPS spectra. However, with my experience it is very difficult to observe this shift.
Suppose, if your metal is not a zerovalent it can be attached via chemical bonding.In this case, carbon support should have functional groups., so that the metal precursor can be attached on the support via ion exchange. This can characterized by XPS and FTIR.
TPR would give the information regarding the reduction behaviour of your metal I.e. Ni. usually loosely bonded NiO particles reduced at lower temperature whereas strongly bonded NiO particles reduced at higher temperature it is all about the dispersion of Ni. But this bonding does not mean that the Ni should definitely have a chemical bond with your support activated carbon. The size of the NiO particles also show some difference in the reduction behaviour. if Ni really form a different compound with the Activated carbon it should definitely give a different reduction behaviour than the dispersed Ni on activated carbon. All these can be depended on your calcination temperature of material.
in addition, XPS of O 1s peak will give you the information of its bonding with metal and support.
Good Luck......
- Badges
- Science topic