A Molecule with Dual Functionality 4‐aminophenylmethylphosphonic Acid: A Comparison Between Layers Formed on Indium Tin Oxide by in Situ Generation of an Aryl Diazonium Salt or by Self‐Assembly of the Phosphonic Acid

4-Aminophenylmethylphosphonic acid was grafted on ITO surfaces by 1) electrochemical reductive adsorption of the corresponding aryl diazonium salt and 2) by self-assembly via the phosphonic acid moiety. The aryl diazonium salt derived surfaces are reasonably stable within a wide potential range from -600 mV to 600 mV compared to a very narrow stable range between -40 mV and 40 mV for the self-assembled layers. The different surface stabilities were assessed with a view to forming ITO-organic layer-gold nanoparticle (AuNPs) constructs. As expected the ITO-organic layer-AuNPs construct formed by electrochemical adsorption (ITO-Ph-AuNP) was significantly more stable than the construct formed by self-assembly of phosphonates (ITO-PO3Ph-AuNPs).