Study on films of organofunctional silanes on transition metal surfaces - The structure of gamma-aminopropyltrimethoxysilane films on nickel electrodes
In die present paper, we prepared the gamma-aminopropyltrimethoxysilane (gamma-APS) films on nickel electrode surfaces and studied their formation and structure. XPS results of the films of the organofunctional silanes modified nickel electrodes show the presence of nitrogen and silicon binding energy peaks indicating the presence of gamma-APS on the metal surface. The results also indicate that the amine is presented in several different states, including the free amine and the protonated one. The potential-dependent Raman spectra gave plenty of information of gamma-APS/metal interface, the silanol and amino groups adsorbed competitively on the nickel surfaces. While the applied potential was changed negatively from open circuit potential, the peak intensity of the SERS spectra of these adsorptive groups and the adjacent groups changed and the frequencies of the bands red-shifted. It is assumed that the quantity and adsorptive orientation of the adsorptive groups changed with the change in the potential and formed more complicated structure of interface. It was also found that the different states of amine transformed with the change in the potential, this can be confirmed by the results of XPS. Atom force microscopy (AFM) was applied to characterize the silane films. It could be concluded that the films, of the organofunctional silanes are porous on the microscopic scale
