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.

Influence of the interfacial charge-transfer resistance at the counter electrode in dye-sensitized solar cells employing cobalt redox shuttles

Abstract: We highlight the effect of the interfacial charge-transfer resistance at the counter electrode in dye-sensitized solar cells based on two cobalt redox shuttles, namely cobalt(III/II) tris(2,2′-bipyridine) and cobalt(III/II) tris(1,10-phenanthroline). Highly porous counter electrodes based on poly(3,4-ethylenedioxythiophene) (PEDOT) prepared by electro-oxidative polymerization are compared to the typically employed platinized FTO glass, with the former showing much lower charge transfer resistances for both cobalt complexes, leading to improved fill factors and to linear response of the short circuit photo-current density to light intensity up to one sun. Based on these findings, an excellent power conversion efficiency of 10.3% was achieved with a recently reported organic sensitizer and PEDOT as counter electrode.

Hollow Iron–Vanadium Composite Spheres: A Highly Efficient Iron‐Based Water Oxidation Electrocatalyst without the Need for Nickel or Cobalt

Abstract: Noble-metal-free bimetal-based electrocatalysts have shown high efficiency for water oxidation. Ni and/or Co in these electrocatalysts are essential to provide a conductive, high-surface area and a chemically stable host. However, the necessity of Ni or Co limits the scope of low-cost electrocatalysts. Herein, we report a hierarchical hollow FeV composite, which is Ni- and Co-free and highly efficient for electrocatalytic water oxidation with low overpotential 390 mV (10 mA cm−2 catalytic current density), low Tafel slope of 36.7 mV dec−1, and a considerable durability. This work provides a novel and efficient catalyst, and greatly expands the scope of low-cost Fe-based electrocatalysts for water splitting without need of Ni or Co.

Production of cobalt binding ligands in a Synechococcus feature at the Costa Rica upwelling dome

Abstract: The Costa Rica upwelling dome (CRD; ;8.678N and 90.68W) was characterized chemically for cobalt and nickel abundances and speciation and biologically using cyanobacterial abundances and phylogeny. Total dissolved cobalt was 93 pmol L 21 at 90 m depth and decreased in surface waters to 45 pmol L 21 at 10 m. Cobalt was 40% labile at 90 m but was completely complexed by strong ligands at 10 m. A surface transect out of the dome showed decreasing total dissolved cobalt from 57 pmol L 21 to 12 pmol L 21 . Detection window studies showed that natural cobalt-ligand complexes have conditional stability constants greater than 10 16.8 and that competition with nickel did not release cobalt bound to organic complexes, consistent with natural cobalt ligands being Co(III) complexes. Synechococcus cell densities at the CRD are among the highest reported in nature, varying between 1.2 3 10 6 and 3.7 3 10 6 cells ml 21 . Phylogenetic analysis using the 16S‐23S rDNA internally transcribed spacer showed the majority of clones were related to Synechococcus strain MIT S9220, while the remaining subset form a novel group within the marine Synechococcus lineage. In a bottle incubation experiment chlorophyll increased with cobalt and iron additions relative to each element alone and the unamended control treatment. Cobalt speciation analysis of incubation experiments revealed large quantities of strong cobalt-ligand complexes in the cobalt addition treatments (401 pmol L 21 ), whereas cobalt added to a 0.2-mm filtered control remained predominantly labile (387 pmol L 21 ), demonstrating that the Synechococcus-dominated community is a source of strong cobalt ligands.