Cobalt

About: Cobalt is a research topic. Over the lifetime, 69899 publications have been published within this topic receiving 1242058 citations. The topic is also known as: Co & Element 27.

Gate-controlled ionization and screening of cobalt adatoms on a graphene surface

Abstract: By varying the voltage on an isolated gate electrode beneath a graphene sheet, the ionization state of cobalt atoms on its surface can be controlled. This enables the electronic structure of individual ionized atoms, and the resulting cloud of screening electrons that form around them, to be obtained with a scanning tunnelling microscope.

High-yield preparation of uniform cobalt hydroxide and oxide nanoplatelets and their characterization.

Abstract: Cobalt hydroxide nanoplatelets with a uniform hexagonal shape were prepared in high yield (∼95%) by a facile hydrothermal route in the presence of poly(vinylpyrrolidone). This method provides a simple, low-cost, and large-scale route to produce β-cobalt hydroxide nanoplatelets with an average diameter of 280 nm and a thickness of ca. 26 nm which show a predominant well-crystalline hexagonal brucite-like phase. Their thermal decomposition produced anisotropic nanoplatelets of cobalt oxides (CoO and Co3O4) under designed temperatures. The products were characterized by transmission electronic microscopy, selected-area electron diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetric, and thermogravimetric analysis. The magnetic properties of the products were investigated by a superconducting quantum interference device magnetometer. Co3O4 nanoplatelets exhibit a superparamagnetic behavior, and they might be a promising material to study the magnetic tunneling effect as aniso...

Method and composition for continuous electroless copper deposition using a hypophosphite reducing agent in the presence of cobalt or nickel ions

Abstract: Electroless copper deposition solutions, and method of continuously electrolessly depositing copper onto a workpiece using these solutions, are disclosed. The solutions contain, in addition to water as the usual solvent, a soluble source of copper ions, a complexing agent or mixture of agents to maintain the copper in solution, a non-formaldehyde copper reducing agent, such as hypophosphite, effective to reduce the copper ions to metallic copper as a deposit or plating on a prepared surface of a workpiece brought into contact with the solution, and a soluble source of non-copper metallic ions, such as nickel or cobalt ions, which act as an autocatalysis promoter to enable continuous plating using the solutions. The solutions are maintained in an alkaline condition and preferably in a pH range of 11-14 through the addition of pH adjusters. The properties of plating baths using the solutions, such as bath stability as well as plating process parameters such as plating rate, and the quality of deposit may be advantageously controlled through the appropriate selection of the non-copper metallic ion added and the complexing agent used. Optional additives, such as polymers, wetting agents, and various soluble unsaturated organic compounds, may also be utilized to influence these variables.

COT1, a gene involved in cobalt accumulation in Saccharomyces cerevisiae.

Abstract: The COT1 gene of Saccharomyces cerevisiae has been isolated as a dosage-dependent suppressor of cobalt toxicity. Overexpression of the COT1 gene confers increased tolerance to cobalt and rhodium ions but not other divalent cations. Strains containing null alleles of COT1 are viable yet more sensitive to cobalt than are wild-type strains. Transcription of COT1 responds minimally to the extracellular cobalt concentration. Addition of cobalt ions to growth media results in a twofold increase in COT1 mRNA abundance. The gene encodes a 48-kDa protein which is found in mitochondrial membrane fractions of cells. The protein contains six possible membrane-spanning domains and several potential metal-binding amino acid residues. The COT1 protein shares 60% identity with the ZRC1 gene product, which confers resistance to zinc and cadmium ions. Cobalt transport studies indicate that the COT1 product is involved in the uptake of cobalt ions yet is not solely responsible for it. The increased tolerance of strains containing multiple copies of the COT1 gene is probably due to increased compartmentalization or sequestration of the ion within mitochondria.

A modular strategy for decorating isolated cobalt atoms into multichannel carbon matrix for electrocatalytic oxygen reduction

Abstract: Single-atom catalysts (SACs) with their unique electronic and geometric structures usually exhibit extraordinary catalytic performance for many important chemical reactions. Herein, a modular strategy is used to decorate isolated cobalt sites into a multichannel carbon matrix (Co@MCM) with Co content of about 1.4 wt% for efficient electrochemical reduction of oxygen. As confirmed by X-ray absorption fine structure investigation, the pre-designed CoN4 configuration and geometric structure are well maintained in the newly developed Co@MCM. The decorated CoN4 units together with the multichannel carbon substrate with high conductivity and porosity endow the catalyst with excellent activity for the oxygen reduction reaction (ORR). Our findings not only present some fundamental insights for the accurate modulation of nanostructured catalysts at the atomic scale, but also reveal the structural origin of the enhanced catalytic activity.