A Comparative Study of the Modification of Gold and Glassy Carbon Surfaces with Mixed Layers of In Situ Generated Aryl Diazonium Compounds

<div>In situ generated aryl diazonium cations were synthesized in the electrochemical cell by reaction of the corresponding</div><div>amines with NaNO in aqueous HCl. This paper reports a study of the formation of mixed layers from in situ generated aryl diazonium cations. Firstly, glassy carbon (GC) and gold electrode surfaces were modified with five</div><div>single in situ generated aryl diazonium salts to obtain their corresponding reductive potential followed by the</div><div>modification of GC and gold surfaces with eight binary mixed layers of in situ generated aryl diazonium salts. The</div><div>difference between GC and gold surfaces in terms of in situ formation of two-component aryl diazonium salt films was</div><div>compared. The behavior of the mixed layers formed from in situ generated aryl diazonium salts relative to diazonium</div><div>salts that were pre-synthesized prior to surface modification was also investigated. Cyclic voltammetry and X-ray</div><div>photoelectron spectroscopy were used to characterize the resulting modified GC and gold surfaces. It is found that for</div><div>some aryl diazonium salts the potential at which reductive adsorption is achieved on gold and GC surfaces is</div><div>significantly different. For the eight sets of binary mixed layers, the species with more anodic potential are more</div><div>difficult to attach to the both GC and gold surfaces. The behavior of the mixed layers formed from in situ generated</div><div>aryl diazonium salts and the pre-synthesized diazonium salts is similar; which emphasizes the advantage of the in situ approach without any apparent difference in behavior to the presynthesized diazonium salts.