Functionalization of nickel oxide using alkylphosphonic acid self-assembled monolayers

Self-assembled monolayer formation of alkylphosphonic acids on the native nickel oxide surface has been accomplished. These monolayers are the first formed on the native nickel oxide surface that did not require electrochemical reduction of the surface to metallic nickel. Two different deposition methods, immersion and aerosol spraying, were used to form monolayers on the oxide surface. Both methods led to complete monolayer formation, with the aerosol method requiring shorter deposition time, lower temperature and decreased solution concentration compared to the immersion method. These deposition methods now allow nickel oxide substrates to be functionalized easily. Monolayer formation was investigated by diffuse reflectance Fourier transform infrared spectroscopy, non-contact mode atomic force microscopy, contact angle measurements and matrix-assisted laser desorption ionization mass spectrometry. Furthermore, cyclic voltammetry and electrochemical impedance spectroscopy studies show that the monolayer increased surface resistance to oxidation.