After the adsorption of the drug (LFV) from the wastewater, my LDH(Ni, Co, Al)/ CS composite exhibits a new peak in conjunction with the Al reference peak (73) at 68 eV. Is there a correlation between the occurrence of the second peak and the interaction between the ligand and the metal? (LMCT), (MLCT)
The extra peak observed at 68 eV in the Al 2p XPS spectrum of the LDH(Ni, Co, Al)/CS composite after drug adsorption is likely due to ligand-to-metal charge transfer (LMCT) or metal-to-ligand charge transfer (MLCT) processes, indicating interaction between the drug and the metal in the composite.
I would be hesitant about assigning such a shake-down process.
Are the other peaks also exhibiting duplications with a similar shift? It would be possible that there are differentially charged domains, i.e. these domains would be behaving differently because the contact to the bulk/ground is not sufficient.
Alternatively, Ni also has emissions in this range and you mentioned Ni in your question, so can you exclude that as the origin?