Characterisation of gold electrodes modified with methyltrimethoxysilane and (3-mercaptopropyl) trimethoxysilane sol–gel processed films

The hydrophobic silicate film was prepared by methyltrimethoxysilane sol drop evaporation on bare gold and gold premodified by self assembling of 3-mercaptopropyltrimethoxysilane. Premodification of the Au substrate was performed by immersion into mercaptosilane solution until partially blocked surface was obtained. For comparison, sol–gel processed film based on 3-mercaptopropyltrimethoxysilane was also deposited on Au substrate. Morphological and electrochemical properties of films prepared with thiol precursor are markedly different. They are heterogeneous, consisting large number of protrusions. Sulphur atoms are accumulated solely in protrusions. Moreover, these films block access of the redox probes dissolved in aqueous solutions to Au surface more efficiently. Furthermore, the sulphur containing films exhibit stabilising properties towards deposited microdroplets of redox liquid – t-butyloferrocene continuously oxidised and reduced.