Annealing-induced microfaceting of the CoO(100) surface investigated by LEED and STM

Weichel, S.; Møller, Preben J.

doi:10.1016/s0039-6028(97)00820-0

Cited by 50 publications

(30 citation statements)

References 15 publications

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“…In recent years, transition metal cobalt oxide (Co 3 O 4 ) is known as a promising material due to its extensive applications in lithium-ion batteries, gas sensing, data storage, catalysis and electrochromic devices [1][2][3][4][5][6][7][8][9][10][11]. Co 3 O 4 is very attractive for applications involving oxidation reactions because of the presence of mobile oxygen, such as the use of unsupported cobalt oxide as an active catalyst in air pollution control for the abatement of CO [12], NO x [13] and organic pollutants from effluent streams [14].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

et al. 2009

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Without any surfactant, antiferromagnetic Co 3 O 4 nanoparticles were synthesized successfully for the first time by means of an oxidation-reduction method with cobalt sulfate as starting material, which was oxidized to cobalt salt by NaNO 3 after alkalinizing with NaOH. Morphological, structural, spectroscopic and magnetic characterization of the product were done by SEM, TEM, XRD, and VSM, respectively. The average crystallite size (on the base of line profile fitting method), D and σ, is estimated as 30 ± 6 nm. Some anomalous magnetic properties and their enhanced effect have been observed in Co 3 O 4 antiferromagnetic nanocrystallites, including a bias field, coercivity, permanent magnetic moments and an open loop. These phenomena are attributed to the unidirectional anisotropy which is caused by the exchange coupling between AFM and FM layers, the existence of the spin glass like surface spins of Co 3 O 4 nanoparticles due to size effects and surface-area effect.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

et al. 2009

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“…Cobalt was electrodeposited onto HOPG from a plating bath containing 0.01M CoCl 2 + 1 M NH 4 Cl at pH=7. Under these conditions, the main chemical species of Co(II) ion is the [Co(H 2 O) 6 ] 2+ complex with an equilibrium potential of −0.533 vs Ag/AgCl(KCl sat).…”

Section: Methodsmentioning

confidence: 99%

“…The analysis of the morphology and magnetic properties of the electrodeposits was carried outthrough AFM and MFM images, which were obtained with a JEOL JSPM 4210 microscope in the lift mode. Figure 1 depicts a typical cyclic voltammogram obtained from the HOPG/0.01M CoCl 2 + 1 M NH 4 Cl system at the scan rate of 20 mV s -1 . Note at direct scan, the presence of three slopes.…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8] Specifically, the magnetic properties of isolated cobalt particles change considerably as their sizes enter the nanometer range because they exhibit a large magnetic coercivity, which may be employed to fabricate high density magnetic memory devices. [9][10][11][12][13][14][15] Thus, it is not so strange that different methodologies are being developed to produce magnetic cobalt nanoclusters with controlled size and morphology.…”

Section: Introductionmentioning

confidence: 99%

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Electrodeposition of Cobalt Nanoclusters From Ammonical Chloride Solutions Onto Hopg Electrodes. A Kinetical and Morphological Study

Mendoza-Huízar

Ríos-Reyes

Rivera

2017

J. Chil. Chem. Soc.

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A kinetical study about the Co electrodeposition onto Highly Oriented Pyrolytic Graphite electrodes from an aqueous solution containing 0.01 M CoCl 2 + 1 M NH 4 CI (pH = 7) was conducted at overpotential conditions through potentiostatic studies. The entire chronoamperograms were adequately predicted, considering the contribution to the total current of three different processes: a Langmuir-type adsorption process, a three-dimensional nucleation and growth and a proton reduction process. In all cases, the nucleation rate and the number of active nucleation sites are potential dependent. The Atomic Force Microscopy study revealed the presence of homogeneous cobalt clusters of less of 100 nm in height and 50 nm in diameter at different potential values.Keywords: cobalt; nanoclusters; HOPG; kinetics; AFM; MFM. INTRODUCTIONMaterials based on cobalt have attracted a considerable attention due to their magnetic properties, which can be used in the production of sensors, heterogeneous catalysts, intercalation compounds for energy storage, magnetooptic recording media, among others.1-8 Specifically, the magnetic properties of isolated cobalt particles change considerably as their sizes enter the nanometer range because they exhibit a large magnetic coercivity, which may be employed to fabricate high density magnetic memory devices.9-15 Thus, it is not so strange that different methodologies are being developed to produce magnetic cobalt nanoclusters with controlled size and morphology. [16][17][18][19][20][21] Probably, high vacuum methods, 22 and thermal decomposition 23 have been the preferred techniques to prepare monodisperse magnetic cobalt clusters onto different substrates. But, recently, electrodeposition is being recognized as an useful technique to produce cobalt nanoparticles. Also, it is important to highlight that electrodeposition is a simple electrochemical technique, which can be implemented at room temperature under ambient conditions. Moreover, these features make electrodeposition a non-expensive technique easily scalable to the industrial level. However, a good knowledge of the kinetic parameters involved during the electrodeposition process is required to achieve a precise control of the cobalt nanoclusters synthesis. In this sense, sulfate solutions have been the preferred systems to electrodeposit cobalt nanoclusters, [24][25][26][27][28][29][30] Although chloride solutions are widely employed for studying the cobalt electrochemistry, these plating baths have been scarcely used to electrodeposit cobalt nanoclusters. Probably, it is because chloride ions induces stress on the cobalt deposited, 31 and may interact strongly with Co adatoms yielding drastic changes on the deposit morphology.32 Nevertheless, chloride electrolytes allow to get a higher electrical conductivity in the electrolyte, lower overpotential for cobalt deposition, and higher cathodic current efficiency.31. These features of chloride plating baths might diminish the cost related to the synthesis of cobalt nanoclusters by ...

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“…It is believed that transition metal oxides are good candidates as electrode materials, because they have variation in oxide states which is suitable for effective redox charge transfer [70][71][72]. That is why as the most active transition metals, Co3O4 has been used extensively as heterogeneous catalysts, solid-state sensors and in pigment, magnet as well [73][74][75]. In last decade researchers have spent a lot of time on Co3O4 nanostructures due to their high electro-chemical performance; because the features like high surface area, short path length for ion transport and easily tunable surface have made Co3O4 a promising material for electrochemical devices [76][77][78].…”

Section: Figure 22 the Unit Cell Structure Of Co3o4(reproduced Frommentioning

confidence: 99%

Synthesis, Characterization and Applications of Metal Oxide Nanostructures

Hussain¹

2014

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The main objective of nanotechnology is to build self-powered nanosystems that are ultrasmall in size, exhibit super sensitivity, extraordinary multi functionality, and extremely low power consumption. As we all know that 21st century has brought two most important challenges for us. One is energy shortage and the other is global warming. Now to overcome these challenges, it is highly desirable to develop nanotechnology that harvests energy from the environment to fabricate self-power and low-carbon nanodevices. Therefore a self-power nanosystem that harvests its operating energy from the environment is an attractive proposition. This is also feasible for nanodevices owing to their extremely low power consumption. One advantageous approach towards harvesting energy from the environment is the utilization of semiconducting piezoelectric materials, which facilitate the conversion of mechanical energy into electrical energy. Among many piezoelectric materials ZnO has the rare attribute of possessing both piezoelectric and semiconducting properties. But most applications of ZnO utilize either the semiconducting or piezoelectric property, and now it’s time to fully employ the coupled semiconducting-piezoelectric properties to form the basis for electromechanically coupled nanodevices. Since wurtzite zinc oxide (ZnO) is structurally noncentral symmetric and has the highest piezoelectric tensor among tetrahedrally bonded semiconductors, therefore it becomes a promising candidate for energy harvesting applications. ZnO is relatively biosafe and biocompatible as well, so it can be used at large scale without any harm to the living environment. The synthesis of another transition metal oxide known as Co3O4 is also important due to its potential usage in the material science, physics and chemistry fields. Co3O4 has been studied extensively due to low cost, low toxicity, the most naturally abundant, high surface area, good redox, easily tunable surface and structural properties. These significant properties enable Co3O4 fruitful for developing variety of nanodevices. Co3O4 nanostructures have been focused considerably in the past decade due to their high electro-chemical performance, which is essential for developing highly sensitive sensor devices. I started my work with the synthesis of ZnO nanostructures with a focus to improve the amount of harvested energy by utilizing oxygen plasma treatment. Then I grow ZnO nanorods on different flexible substrates, in order to observe the effect of substrate on the amount of harvested energy. After that I worked on understanding the mechanism and causes of variation in the resulting output potential generated from ZnO nanorods. My next target belongs to an innovative approach in which AFM tip decorated with ZnO nanorods was utilized to improve the output energy. Then I investigated Co3O4 nanostructures though the effect of anions and utilized one of the nanostructure to develop a fast and reliable pH sensor. Finally to take the advantage of higher degree of redox chemistry of NiCo0O...

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Annealing-induced microfaceting of the CoO(100) surface investigated by LEED and STM

Cited by 50 publications

References 15 publications

Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

Electrodeposition of Cobalt Nanoclusters From Ammonical Chloride Solutions Onto Hopg Electrodes. A Kinetical and Morphological Study

Synthesis, Characterization and Applications of Metal Oxide Nanostructures

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