A novel method for improving the adhesion strength of the electrodeposited Ni films in MEMS

Adhesion performance of MEMS materials is increasingly important with the widely use of miniaturized devices. This paper proposed a novel method for improving adhesion performance between electrodeposited Ni multi-layers. The new method is to treat the Ni substrate in nickel chloride plating solution by pulse reverse current technique before electrodeposition. The dense oxide film of Ni substrate can be removed effectively by this electrochemical method, meanwhile, the proper roughness of Ni substrate is in favor of epitaxial growth during electrodeposition. Moreover, the Ni film is electrodeposited by the new method with low stress and coarse crystal grain. Consequently, the adhesion performance of Ni films is improved dramatically. The experimental results show that the adhesion performance of Ni film electrodeposited by the new method is about 3 times that of by traditional method.     

Facile fabrication of Zn/Zn5(OH)8Cl2·H2O flower-like nanostructure on the surface of Zn coated with poly (N-methyl pyrrole)

Zn/Zn₅(OH)₈Cl₂·H₂O flower-like nanostructures was electrodeposited on the coated Zn with poly (N-methyl pyrrole) in 0.1 M Zn (NO₃)₂ and 0.1 M KCl solution. The morphology and the structure of the Zn/Zn₅(OH)₈Cl₂·H₂O were characterized by Field Emission Scanning Electron Microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction analysis (XRD). The FT-IR results showed special peaks at 908 and 728 cm⁻¹ related to Zn₅(OH)₈Cl₂·H₂O. The FESEM results indicated that Zn/Zn₅(OH)₈Cl₂·H₂O consists of a flower-like nanostructure and these flower-shaped structures contain many shaped nanopetals with the thickness of 27.8 nm. The XRD result confirmed that the major phase of electrodeposited product in 0.1 M KCl as supporting electrolyte was Zn₅(OH)₈Cl₂·H₂O. The ability of PMPy to create a thin film and the existence of several pores in its matrix act as a mold for the growth of Zn/Zn₅(OH)₈Cl₂·H₂O flower-like nanostructure. The trapping of Cl⁻ and OH⁻ within pores can be considered as the reason for the formation of flowerlike Zn/Zn₅(OH)₈Cl₂·H₂O nanostructures in 0.1 M KCl.     

Electrochemical synthesis of ZnO nanoflowers and nanosheets on porous Si as photoelectric materials

Well-aligned ZnO nanoflowers and nanosheets were synthesized on porous Si (PS) at different applied potentials by electrodeposition approach. The deposits were grown using the optimized program and were characterized by means of cyclic voltammetry (CV), amperometry I-t (I-t), open-circuit potentiometry. X-ray diffraction (XRD) analysis proved a strong preferential orientation (1 0 0) on PS. Scanning electronic microscopy (SEM) observation showed the deposits consist of nanoflowers with uniform grain size of about 100 nm in diameter and nanosheets, which may have potential applications in nanodevices and nanotechnologies. Thus, ZnO grown on PS can be used as photoelectric materials due to its larger photoelectric effect compared to Si wafer according to open-circuit potential (OCP) study. Optical band gap measurements were made on samples using UV-visible spectrophotometer thus giving a band gap of 3.35 eV.     

One‐Step Electrochemically Deposited Nanocomposite Film of CS‐Fc/MWNTs/GOD for Glucose Biosensor Application

A simple and controllable electrodeposition approach was proposed for one‐step construction of glucose biosensors by in situ co‐deposition of ferrocene‐branched chitosan derivatives (CS‐Fc), multiwalled carbon nanotubes (MWNTs), and glucose oxidase (GOD) onto electrode surface. The formation of CS‐Fc could not only effectively prevent the leakage of Fc and retain its electrochemical activity, but also provide a biocompatible microenvironment for retaining the native activity of the immobilized biomolecules. Further entrapment of MWNTs into the CS matrix improved electronic conductivity of the biocomposite significantly. The facile procedure of immobilizing GOD and the promising feature of biocomposite will offer a versatile platform to fabricate biosensors and bioelectronic devices.     

Anomalous scaling in surface roughness evaluation of electrodeposited nanocrystalline Pt thin films

Atomic force microscopy (AFM) is used to measure the surface roughness of crystalline Pt thin films as a function of film thickness and growth rate. Our films were electrodeposited on Au/Cr/glass substrates, under galvanostatic control (constant current density), from a single electrolyte containing Pt⁴⁺ ions. Crystalline structure of the films was confirmed by X-ray diffraction (XRD) technique. The effect of growth rate (deposition current density) and film thickness (deposition time) on the kinetic roughening of the films were studied using AFM and roughness calculation. The data is consistent with a rather complex behaviour known as “anomalous scaling” where both local and large scale roughnesses show power law dependence on the film thickness.     

Synthesis of hollow carbon nitride microspheres by an electrodeposition method

Hollow carbon nitride microspheres have been synthesized using a novel liquid phase electrodeposition technique. The microspheres are composed of numerous nanoparticles with size of about 5-30 nm. The diameters of the spheres range from 800 nm to 1.1 μm, and shell thickness is about 80-250 nm. This is the first attempt to synthesize carbon nitride with specific nanostructure by the electrodeposition method, which is proved to be facile and effective, and can be performed in an atmospheric environment and at a rather low temperature. The hollow carbon nitride may have potential applications as lubrication, catalysis, biomolecule adsorption, drug delivery, electronic materials, etc. in the future.     

Effective electrodeposition of Co-Ni-Cu alloys nanoparticles in the presence of alkyl polyglucoside surfactant

The effect of alkyl polyglucoside (APG) surfactant on the electrodeposition Co-Ni-Cu alloys nanoparticles has been investigated. In a typical electrodeposition experiment, it was found that as prepared Co-Ni-Cu alloys nanoparticles characteristics, such as size homogeneity, density, dispersion on the electrode substrate and the chemicals composition, depended strongly on the concentration of APG used in the reaction as well as the applied deposition potential. For the case of chemicals composition, low APG concentration (below CMC) was found to be effective for the preparation of excellent composition of the nanoalloys. Meanwhile, for the case of size homogeneity, density, and dispersion on the surface, high APG concentration (above CMC) and high deposition potential were preferred. It was also found that, at concentration above the CMC, the APG surfactant showed a metals ions deposition inhibition characteristic that caused increasing in the electrodeposition overpotential of the entire metals ions, namely cobalt, nickel and copper. As the result the copper was found to place a high percentage in the nanoalloys deposits. Owing to its simple procedure in controlling the composition and the nanoalloys growth characteristic, present approach should find a potential application in preparing Co-Ni-Cu magnetic nanoparticles for used in currently existing applications.     

Electrodeposition of novel Sn-Ni-Fe ternary alloys with amorphous structure

Tin-nickel-iron (Sn-Ni-Fe) ternary alloys have been successfully prepared for the first time by electrochemical deposition. ⁵⁷Fe and ¹¹⁹Sn conversion electron Mössbauer and PXRD investigations of these alloys showed that the alloys were dominated by new metastable phases which do no occur in the thermally prepared alloys and are not to be found in the corresponding equilibrium phase diagram. Essentially these ternary alloys proved to be amorphous and ferromagnetic.