title: The effect of triphenylphosphane on corrosion inhibition of benzotriazole at Ag electrode monitored by SERS in nonaqueous solution.
abstract: The corrosion inhibition behavior of benzotriazole (BTAH) on Ag electrodes and the influence of triphenylphosphane (pph(3)) were investigated by electrochemical method, in situ surface-enhanced Raman spectroscopy (SERS) and direct electrochemical synthesis of surface complexes in nonaqueous solution. The results indicated that the BTA(-) ion was coordinated to the Ag surface to form a highly cross-linked surface polymer complex of [Ag(BTA)](n), which suppressed the dissolution and oxidation of Ag effectively. The introduction of a neutral ligand of pph(3) blocked the surface coordination processes of BTAH with the Ag electrode. It resulted in a decrease of inhibition efficiency to Ag surface. The ligand of pph(3) played a negative role on the corrosion inhibition of BTAH to the Ag electrode. The SERS results were well consistent with the cyclic voltammetry and polarization curves measurements. For modeling, two different surface complexes were prepared in acetonitrile with and without pph(3) by direct electrochemical synthesis. A polymer-like complex of [Ag(BTA)](n) attached to the Ag surface was obtained in the absence of pph(3), which suppressed the dissolution and oxidation of Ag effectively. A new binuclear compound, Ag(2)(BTA)(2)(pph(3))(4), was produced in acetonitrile with pph(3) and the final coordination process occurred in solution leading to difficulties in forming a compact surface film, thus decreasing the corrosion inhibition efficiency of BTAH. The role of pph(3) and the mechanism were proposed.
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
authors.forename: Ya-Xian
authors.initials: YX
authors.lastname: Yuan
authors.forename: Feng-Zhu
authors.initials: FZ
authors.lastname: Yang
authors.forename: Clark-Heptinstall
authors.initials: CH
authors.lastname: Morag
authors.forename: Dong
authors.initials: D
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Ren-Ao
authors.initials: RA
authors.lastname: Gu
authors.forename: Jian-Lin
authors.initials: JL
authors.lastname: Yao
mesh_terms: D003343:Corrosion; D004566:Electrodes; D010084:Oxidation-Reduction; D010720:Phosphines / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods; D013499:Surface Properties; D014230:Triazoles / Q000737:chemistry*
chemical_list: D010720:Phosphines; D014230:Triazoles; D012834:Silver; C012771:benzotriazole; C044646:phosphine