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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.


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Journal ArticleDOI
TL;DR: In this paper, the graphite produced by the reduction of carbon dioxide over a transition metal catalyst has been used as a sample material in the AMS counting of 14C for several years.
Abstract: Filamentous graphite produced by the reduction of carbon dioxide over a transition metal catalyst has been used as a sample material in the AMS counting of 14C for several years. While iron has been the most common catalyst used, cobalt and nickel have also been investigated. We have compared the reaction's total isotopic fractionation using these three metals in various powder forms. The graphites produced over these catalysts have been compared with respect to ion beam intensity and measured isotope ratio in our AMS system. The use of the reduction catalysts as graphite binders improved the very poor thermal conductivity of pure filamentous graphite. The relative advantages of the elements for modern contamination of the sample material were also determined.

289 citations

Journal ArticleDOI
TL;DR: The cobalt-based layered MOF electrode exhibits a high specific capacitance and excellent cycling stability, and may be ascribed to the intrinsic nature of Co-LMOF, enough space available for the storage and diffusion of the electrolyte, and the particles of nanoscale size.
Abstract: Metal–organic frameworks (MOFs) have recently received increasing interest due to their potential application in the energy storage and conversion field. Herein, cobalt-based layered MOF ({[Co(Hmt)(tfbdc)(H2O)2]·(H2O)2}n, Co–LMOF; Hmt = hexamethylenetetramine; H2tfbdc = 2,3,5,6-tetrafluoroterephthalic acid) has been evaluated as an electrode material for supercapacitors. The Co–LMOF electrode exhibits a high specific capacitance and excellent cycling stability. Its maximum specific capacitance is 2474 F g–1 at a current density of 1 A g–1, and the specific capacitance retention is about 94.3% after 2000 cycles. The excellent electrochemical property may be ascribed to the intrinsic nature of Co–LMOF, enough space available for the storage and diffusion of the electrolyte, and the particles of nanoscale size.

288 citations

Journal ArticleDOI
TL;DR: In this paper, wide band gap semiconductor-zinc oxide nanoclusters have been prepared in the channels of MCM-41 materials by functionalizing the MCM41 with ethylenediamine groups, absorbing zinc cations, and calcinating at high temperatures.
Abstract: Wide band-gap semiconductor-zinc oxide nanoclusters have been prepared in the channels of MCM-41 materials by functionalizing the MCM-41 with ethylenediamine groups, absorbing zinc cations, and calcinating at high temperatures. The products have been characterized by XRD, TEM, EDS, nitrogen adsorption and desorption, and UV-vis and PL spectroscopies. ZnO clusters were mostly confined and dispersed in the pores of mesoporous hosts. No large ZnO particles on the external surfaces have been detected. A massive blue-shift in UV-vis absorption spectra has been observed and large band increase can be expected. The nature of the PL spectrum has been attributed to the defects related to oxygen vacancies. In addition, the assembly of cobalt, nickel, and copper oxides inside MCM-41 materials has also been tried by this scheme, but at the moment, only the cobalt oxide can be prepared with good results. Unfortunately, noble metals have usually grown into large particles on the outside surface of MCM-41 by this scheme, e.g., a lot of silver particles with sizes much larger than the pore diameter of MCM-41 host have been obtained. However, the explanation is not yet clear.

288 citations

Journal ArticleDOI
TL;DR: Implanting atomic metal in mesoporous carbon demonstrates a feasible strategy to endow nanomaterials with targeted functions for Li-S batteries and broad applications.
Abstract: Lithium-sulfur (Li-S) batteries hold great promise to serve as next-generation energy storage devices. However, the practical performances of Li-S batteries are severely limited by the sulfur cathode regarding its low conductivity, huge volume change, and the polysulfide shuttle effect. The first two issues have been well addressed by introducing mesoporous carbon hosts to the sulfur cathode. Unfortunately, the nonpolar nature of carbon materials renders poor affinity to polar polysulfides, leaving the shuttling issue unaddressed. In this contribution, atomic cobalt is implanted within the skeleton of mesoporous carbon via a supramolecular self-templating strategy, which simultaneously improves the interaction with polysulfides and maintains the mesoporous structure. Moreover, the atomic cobalt dopants serve as active sites to improve the kinetics of the sulfur redox reactions. With the atomic-cobalt-decorated mesoporous carbon host, a high capacity of 1130 mAh gS-1 at 0.5 C and a high stability with a retention of 74.1% after 300 cycles are realized. Implanting atomic metal in mesoporous carbon demonstrates a feasible strategy to endow nanomaterials with targeted functions for Li-S batteries and broad applications.

288 citations

Journal ArticleDOI
TL;DR: Monodisperse cobalt (Co) nanoparticles (NPs) were synthesized and stabilized against oxidation via reductive annealing at 600 °C and are a promising new class of noble-metal-free catalyst for water splitting.
Abstract: Monodisperse cobalt (Co) nanoparticles (NPs) were synthesized and stabilized against oxidation via reductive annealing at 600 °C. The stable Co NPs are active for catalyzing the oxygen evolution reaction (OER) in 0.1 M KOH, producing a current density of 10 mA/cm2 at an overpotential of 0.39 V (1.62 V vs RHE, no iR-correction). Their catalysis is superior to the commercial Ir catalyst in both activity and stability. These Co NPs are also assembled into a monolayer array on the working electrode, allowing the detailed study of their intrinsic OER activity. The Co NPs in the monolayer array show 15 times higher turnover frequency (2.13 s–1) and mass activity (1949 A/g) than the NPs deposited on conventional carbon black (0.14 s–1 and 126 A/g, respectively) at an overpotential of 0.4 V. These stable Co NPs are a promising new class of noble-metal-free catalyst for water splitting.

288 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20232,622
20225,202
20212,220
20202,950
20193,215
20183,007