Using Time-Resolved Electrochemical Patterning to Gain Fundamental Insight into Aryl-Radical Surface Modification

Scanning electrochemical microscopy is used to carry out local free-radical grafting at a gold surface through mild oxidation of an aryl hydrazine. The process can be deliberately controlled by creation of a local pH gradient at the tip. Comparison of the experimental results with simulations shows that the radial expansion of the pH profile in which successful grafting can be accomplished increases with increasing generation time of OH- and with decreasing initial concentration of the grafting precursor. Furthermore, the radial expansion is faster than the nucleation of the grafting process.