Spontaneous Grafting of Iron Surfaces by Reduction of Aryldiazonium Salts in Acidic or Neutral Aqueous Solution. Application to the Protection of Iron against Corrosion

Abstract

The chemical grafting of iron surfaces at open-circuit potential by reduction of different aryldiazonium salts in aqueous acidic solution occurs spontaneously without the need of electrochemical assistance. X-ray photoelectron spectroscopy (XPS) and IR allowed to evidence the grafting of organic moieties without any adsorption of diazonium salts. The aryl groups are strongly bonded to the metal since they can withstand sonication in acetone. XPS measurements also show that spontaneous grafting in water is at least as efficient as electrochemical grafting and also indicate the presence of a multiphenyl layer coverage of the iron surface. The surface film of carboxyphenyl groups on iron was chemically derivatized further by octyltriethoxysilane. The anticorrosive effects of the different films were evaluated in 0.01 M H 2 SO 4 aqueous solution, by polarization and impedance measurements. Grafting of the diazonium salt results in an inhibition efficiency up to 73%, which can be slightly increased up to 85% by derivatization of the film by octyltriethoxysilane. The inhibition efficiency can be significantly improved up to 97% when the grafted metal is left in the corrosion medium in the presence of the diazonium salt.

Raman Characterization of Phenyl-Derivatives: From Primary Amine to Diazonium Salts

“…The rise in popularity of aryl-diazonium salts has further resulted from their efficiency in surface functionalization, where covalently attached coatings on (semi)-conducting materials bear a wide range of functional groups [5][6][7][8][9][10][11][12][13][14]. In addition, the grafting can be accomplished by either chemical (spontaneous grafting), electrochemical, or physical methods [5][6][7][8][9][10][11][12]15].…”

“…In addition, the grafting can be accomplished by either chemical (spontaneous grafting), electrochemical, or physical methods [5][6][7][8][9][10][11][12]15]. Surface functionalization using diazonium salts has thus become one of the most powerful methods for coatings [8,13,14] through linking (bio)molecules [16,17], polymers [18][19][20] or nanoparticles [21].…”

Development of a novel flow sensor for copper trace analysis by electrochemical reduction of 4-methoxybenzene diazonium salt

“…As the mechanism involves the formation of highly reactive aryl radicals, multilayers are usually obtained by reaction of the radicals on already-grafted aryl species [3]. The resulting organic layer brings new properties to the covering substrate, leading to applications in many areas such as corrosion [4], insulating material [5] and catalysis [6]. It has also been widely used in the fabrication of sensors and biosensors [7][8][9].…”

Synthesis of Diazonium Tetrachloroaurate(III) Precursors for Surface Grafting

“…Modification of surfaces by redox grafting of diazonium salts is a progressing area of materials chemistry [1][2][3][4][5][6][7][8][9][10][11][12]. Reduction of aryl diazonium salts has been studied on carbon [3,4,6], semiconductors [6], and nanoparticles surfaces [13][14][15][16][17][18][19].…”

“…Reduction of aryl diazonium salts has been studied on carbon [3,4,6], semiconductors [6], and nanoparticles surfaces [13][14][15][16][17][18][19]. Grafted organic layers demonstrated distinctive performance in the formation of corrosion inhibitor film on iron [10,20], modification of graphene [2,11,12] and diamond [5,21], preparation of diazonium-modified enzyme electrodes [22], immobilization of proteins [5,23], grafting polymers [24], and printing gold via soft lithography [25,26]. In addition to surface modification, aryl diazonium salts have been utilized in palladium-catalyzed cross-coupling reactions.…”