Cathodic Electrochemical Deposition Research Articles

纳米结构ZnO在TiO<sub>2</sub>薄膜上的电化学沉积及其表征

One-dimensional structure of ZnO nanorod arrays on nanocrystalline TiO 2 /ITO conductive glass substrates have been fabricated by cathodic reduction electrochemical deposition methods in the three-electrode system, with zinc nitrate aqueous solution as the electrolyte, and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and photoluminescence (PL) spectra. The effects of film substrates, electrolyte concentration, deposition time, and methenamine (HMT) addition on ZnO deposition and its luminescent property were investigated in detail. The results show that, compared with on the ITO glass substrate, ZnO is much easily achieved by electrochemical deposition on the TiO 2 nanoparticle thin films. ZnO is hexagonally structured wurtzite with the c-axis preferred growth, and further forms nanorod arrays vertically on the substrates. It is favorable to the growth of ZnO to extend the deposition time, to increase the electrolyte concentration, and to add a certain amount of HMT in the system, consequently improving the crystallinity and orientation of ZnO arrays. It is demonstrated that the obtained ZnO arrays with high crystallinity and good orientation display strong band-edge UV (375 nm) and weak surface-state-related green (520 nm) emission peaks.

Hybrid Supercapacitor Based on Coaxially Coated Manganese Oxide on Vertically Aligned Carbon Nanofiber Arrays

Hybrid supercapacitor electrodes with remarkable specific capacitance have been fabricated by coaxially coating manganese oxide thin films on a vertically aligned carbon nanofiber array. Ultrathin manganese oxide layers are uniformly coated around each carbon nanofiber via cathodic electrochemical deposition, likely based on water electrolysis initiated electrochemical oxidation. This results in a unique core-shell nanostructure which uses the three-dimensional brush-like vertical carbon nanofiber array as the highly conductive and robust core to support a large effective surface area and provide reliable electrical connection to a thin redox active manganese oxide shell. The pseudo-capacitance of 313 F/g in addition to the electrical double layer capacitance of 36 F/g is achieved by cyclic voltammetry at a scan rate of 50 mV/s and maintains at this level as the scan rate is increased up to 2000 mV/s. A maximum specific capacitance of 365 F/g has been achieved with chronopotentiometry in 0.10 M Na2SO4 aqueous solution with ∼7.5 nm thick manganese oxide. This hybrid core-shell nanostructure demonstrates high performance in maximum specific energy (32.5 Wh/kg), specific power (6.216 kW/kg), and cycle stability (∼11% drop after 500 cycles), which are derived from cyclic voltammetry and galvanostatic charge−discharge measurements. This new architecture can be potentially developed as multifunctional electrical energy storage devices.

Electrochemical deposition of nano-structured ZnO on the nanocrystalline TiO2 film and its characterization

One-dimensional structure of ZnO nanorod arrays on nanocrystalline TiO2/ITO conductive glass substrates has been fabricated by cathodic reduction electrochemical deposition methods in the three-electrode system, with zinc nitrate aqueous solution as the electrolyte, and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and photoluminescence (PL) spectra. The effects of film substrates, electrolyte concentration, deposition time, and methenamine (HMT) addition on ZnO deposition and its luminescent property were investigated in detail. The results show that, compared with on the ITO glass substrate, ZnO is much easily achieved by electrochemical deposition on the TiO2 nanoparticle thin films. ZnO is hexagonally structured wurtzite with the c-axis preferred growth, and further forms nanorod arrays vertically on the substrates. It is favorable to the growth of ZnO to extend the deposition time, to increase the electrolyte concentration, and to add a certain amount of HMT in the system, consequently improving the crystallinity and orientation of ZnO arrays. It is demonstrated that the obtained ZnO arrays with high crystallinity and good orientation display strong band-edge UV (375 nm) and weak surface-state-related green (520 nm) emission peaks.

Electrochemical Preparation and Characterizations of Hierarchically Polycrystalline NiPb Dendrites

Perfect polycrystalline NiPb dendrites were prepared via cathodic electrochemical deposition on Cu substrates from aqueous solution. Cyclic voltammetry was used to gain insight into the Ni/Pb codeposition mechanism. The results reveal that the dendrite consists of a long central backbone and very orderly secondary and tertiary branches. The size and shape of the dendritic structures can be tunable by changing the synthetic parameters. A formation mechanism is proposed to illustrate the growth process.

Electrochemical deposition and superhydrophobic behavior of ZnO nanorod arrays

Vertically aligned ZnO nanorod arrays with different heights are grown on the ZnO seeded indium tin oxide substrate by cathodic electrochemical deposition from zinc nitrate at two temperatures of 60 °C and 80 °C. As-grown ZnO nanorods exhibit wurzite crystal structure and their heights can be well controlled by different deposition times. The fluorination coating tends to induce a superhydrophobicity of ZnO nanorods, i.e., the maximal value of contact angle: 166.9°. The super water repellency can be attributed to the fact that an air layer is confined in the nanorod arrays, and thus leads to water droplets sitting on the ZnO surfaces, referring as Cassie state. Interestingly, their water contact angles are found to vary with the heights of ZnO nanorods, ranged from 99.8 to 746 nm. The superhydrophobicity of ZnO surfaces can be well predicted by a proposed model that is capable of determining the wetted fraction of ZnO pillars. This satisfactory result would shed one light on how the variation of rod height would induce the superhydrophobic behavior of ZnO nanorod arrays.

Influence of the electrochemical deposition parameters on the microstructure of MoS2 thin films

Thin films molybdenum dichalcogenide, MoS2, were prepared by cathodic electrochemical deposition from aqueous and non-aqueous solutions of tetrathiomolybdate ions, at different temperatures. The films were X-ray amorphous as deposited. They consist of an amorphous matrix in which quantum sized nanocrystallites or clusters were embedded. Upon annealing at high temperatures, the films obtained from aqueous solutions become crystalline and highly texturized having their van der Waals planes oriented parallel to the substrate, whereas, those obtained from ethylene glycol solutions kept on the amorphous matrix, with slightly larger sizes MoS2 nanoparticles embedded, than before annealing. Difference in the mechanism of the electrodeposition in aqueous and ethylene glycol solutions is discussed.

The mechanism of electrodeposition and operation of Ni(OH) 2 layers

It is well-known that uniform layers of Ni(OH) 2 can be formed by cathodic electrochemical deposition. The product phase Ni(OH) 2 is predominately an ionic conductor, not an electronic conductor. This means that the electrochemical reaction must occur underneath the ionic conductor at the substrate/Ni(OH) 2 interface, whereas the formation of the hydroxide layer takes place at the Ni(OH) 2/electrolyte interface. A model of a growth mechanism requiring the transport of several species through the growing product layer to the Ni(OH) 2/electrolyte interface is discussed.

ChemInform Abstract: pH‐Sensitive Ni(OH)2‐Based Microelectrochemical Transistors.

AbstractThe electrochemical properties of pH‐sensitive Ni(OH)2‐based microelectrochemical transistors, prepared by cathodic electrochemical deposition of Ni(OH)2 onto Au or Pt microelectrode arrays, have been investigated.

In Situ Preparation of Undoped p‐Type CdTe by Cathodic Electrochemical Deposition

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