Surface Functionalization of Ultrananocrystalline Diamond Films by Electrochemical Reduction of Aryldiazonium Salts

Abstract

The surface functionalization of ultrananocrystalline diamond (UNCD) thin films via the electrochemical reduction of aryl diazonium cations is described. The one-electron-transfer reaction leads to the formation of solution-based aryl radicals, which in turn react with the UNCD surface forming stable covalent C-C bonds. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), ac impedance spectroscopy, and contact angle measurements have been employed to characterize the organic overlayer and estimate the surface coverage. The grafting of 3,5-dichlorophenyl groups renders the UNCD surface hydrophobic, whereas the attachment of 4-aminophenyl groups makes the surface relatively hydrophilic. The surface coverage, estimated from the electrochemical and XPS measurements, is as high as 70% of a compact monolayer. The aminophenyl terminated surface was obtained by electrochemical reduction of the tethered nitrophenyl groups. This two-step approach yields a UNCD surface with functional moieties available for the potential covalent coupling of a wide variety of biomolecules (e.g., DNA and proteins).

Boron-doped diamond electrode: synthesis, characterization, functionalization and analytical applications

“…Biofunctionalization of its surface was a very difficult task until Takahashi et al 84,85 introduced a photochemical chlorination/amination/carboxylation process of the initially H-terminated diamond surface. Based on this concept and the work of Wang et al 86 and Zhang et al, 87 a new photochemical method to modify NCD surfaces has become available. 88 This procedure involves the use of a long chain u-unsaturated amine such as 10-aminodec-1-ene that has been protected with a trifluoroacetamide functional group (Fig.…”

Nanoindentation as a Tool to Clarify the Mechanism Causing Variable Stiffness of a Silane Layer on Diamond

“…An H-terminated surface can be directly functionalized, either photochemically by UV irradiation in halogen gases or alkenes [15][16][17], or chemically by thermal decomposition of benzoyl peroxide, activated by argon gas [18], or by electrochemical diazonium salts reduction in an inert atmosphere [19,20]. In contrast, an O-terminated surface can be chemically modified by silanization or by esterification [4], or, as recently reported, aminated by NH3-plazma treatment [1].…”

Atom transfer radical polymerization (ATRP) initiated by aryl diazonium salts: a new route for surface modification of multiwalled carbon nanotubes by tethered polymer chains

“…The use of aryl diazonium salts is indeed a simple and elegant way of modifying conductive substrates such as metals, semi-conductors and carbon in view of elaborating molecular junctions in electronic circuits, biosensors, and protective layers against corrosion [19]. Particularly, grafting aryl groups was successfully achieved on glassy carbon [20], carbon felts [21], ultrananocrystalline diamond [22] and carbon nanotubes [23,24]. Moreover, they impart controlled interfacial properties to the host substrate such as hydrophilic/hydrophobic character [22], or dispersion in organic solvents [23a].…”

“…Particularly, grafting aryl groups was successfully achieved on glassy carbon [20], carbon felts [21], ultrananocrystalline diamond [22] and carbon nanotubes [23,24]. Moreover, they impart controlled interfacial properties to the host substrate such as hydrophilic/hydrophobic character [22], or dispersion in organic solvents [23a].…”