The periodical electrochemical oscillations ͑especially differential capacitance and conductance oscillations͒ of nickel electrode can be obviously modified by Triton X-100 in HNO 3 /H 2 O system. Triton X-100 concentration affects the behaviors and parameters of the oscillations. A modifying mechanism of the oscillations is proposed in which the adsorption and desorption of Triton X-100 on the electrode play a key role in the oscillations.Surfactant can form self-assembly aggregation in a bulk solution, such as micelle, microemulsion, vesicle, and lyotropic liquid crystal, because it possesses hydrophilic and hydrophobic groups. 1-7 It can also adsorb on material surface or liquid/solid interface as a single molecule, admicelle, semimicelle, monolayer, and multilayer. [8][9][10][11][12] These change the microenvironments of the interface to bring catalyzed activity 13-15 and the inhibition efficiency of corrosion. [13][14][15][16][17][18][19][20] Electrochemical oscillation is important in electrochemical reaction, electrodeposition, electrocatalyzation, electrosynthesization, and simulating biosensors. 21-27 Generally, the oscillation contains an activation dissolution, prepassivation, and passivation. 27-36 Some surfactants can place a premium on the interface oscillation of liquid film. [37][38][39][40][41][42] The surfactant molecule or aggregation, which is adsorbed on the interface, changes not only the film component on the interface but also the activation and passivation of the oscillation. 20,43,44 The adsorption and desorption of surfactant on the liquid/solid interface almost relate with surfactant structure and properties. Sodium dodecyl sulfate ͑anionic surfactant͒ can regulate the current oscillation of nickel ͑Ni͒ electrode in HNO 3 /Cl − /H 2 O system. 37 In this paper, the modification and effects of Triton X-100 ͑nonionic surfactant͒ on the periodic current and capacitance oscillations of the electrode are investigated in the HNO 3 /H 2 O system by the potential, time scanning, and ac impedance methods. The oscillations of the differential capacitance and conductance are first observed and determined. Nonionic surfactant, with the inhibiting effect of corrosion for some metals, 13,20 can be used as a modifying reagent for the oscillations. Triton X-100 can modify and regulate the electrochemical oscillations of Ni in the HNO 3 /H 2 O system without Cl − . The obtained results can give some important information for new oscillation, protecting corrosion, and nonlinear dynamics.
Materials and MethodsMaterials.-Triton X-100 was bought from Sigma ͑99%͒, and HNO 3 and nickel ͑99.99%͒ were purchased from Shanghai Chemical Reagent Co. ͑analytical reagent͒. Doubly distilled and deionized water was used for the preparation of the solutions.Linear scanning voltammogram and current oscillation measurement.-A three-electrode arrangement was used in a conventional three-compartment cell. Nickel rodlike ͑d = 3 mm͒ was used as the working electrode, a platinum foil ͑3 ϫ 4 mm 2 ͒ as the auxiliary electrode, a...
