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"Cobalt"
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Dual-Engineering Tailored Cosub.3Osub.4 Hollow Microspheres Assembled by Nanosheets for Boosting Oxygen Evolution Reaction
The development of efficient, low-cost electrocatalysts for the oxygen evolution reaction (OER) is crucial for advancing sustainable hydrogen production through water splitting. This study presents a dual-engineering strategy to enhance the OER performance of Co[sub.3]O[sub.4] by synthesizing hollow microspheres assembled from nanosheets (HMNs) with abundant oxygen vacancies and highly active crystal facet exposure. Through a modified one-step hydrothermal process, Co[sub.3]O[sub.4] HMNs with exposed (111) and (100) crystal facets were successfully fabricated, demonstrating superior OER activity compared to Co[sub.3]O[sub.4] nanocubes (NCs) with only (100) facet exposure. The optimized Co[sub.3]O[sub.4]-5% HMNs exhibited a low overpotential of 330 mV at 10 mA cm[sup.−2] and a Tafel slope of 69 mV dec[sup.−1]. The enhanced performance was attributed to the synergistic effects of crystal facet engineering and defect engineering, which optimized the Co-O bond energy, increased the number of active sites, and improved conductivity. The unique hollow structure further facilitated mass transport and prevented nanosheet stacking, exposing more edge sites for catalytic reactions. This work highlights the potential of geometric and electronic structure modulation in designing high-performance OER catalysts for sustainable energy applications.
Journal Article
Cobalt red : how the blood of the Congo powers our lives
\"An unflinching investigation reveals the human rights abuses behind the Congo's cobalt mining operation-and the moral implications that affect us all. Cobalt Red is the searing, first-ever exposé of the immense toll taken on the people and environment of the Democratic Republic of the Congo by cobalt mining, as told through the testimonies of the Congolese people themselves. Activist and researcher Siddharth Kara has traveled deep into cobalt territory to document the testimonies of the people living, working, and dying for cobalt. To uncover the truth about brutal mining practices, Kara investigated militia-controlled mining areas, traced the supply chain of child-mined cobalt from toxic pit to consumer-facing tech giants, and gathered shocking testimonies of people who endure immense suffering and even die mining cobalt. Cobalt is an essential component to every lithium-ion rechargeable battery made today, the batteries that power our smartphones, tablets, laptops, and electric vehicles. More than 70 percent of the world's supply of cobalt is mined in the Congo, often by peasants and children in sub-human conditions. Billions of people in the world cannot conduct their daily lives without participating in a human rights and environmental catastrophe in the Congo. In this stark and crucial book, Kara argues that we must all care about what is happening in the Congo-because we are all implicated\"-- Provided by publisher.
Book
Cobalt oxides : from crystal chemistry to physics
Unparalleled in the breadth and depth of its coverage of all important aspects, this book systematically treats the electronic and magnetic properties of stoichiometric and non-stoichiometric cobaltites in both ordered and disordered phases.
eBook
Effects of folic acid and cobalt sulphate supplementation on growth performance, nutrient digestion, rumen fermentation and blood metabolites in Holstein calves
To investigate the influences of cobalt (Co) and folic acid (FA) on growth performance and rumen fermentation, Holstein male calves (n 40) were randomly assigned to four groups according to their body weights. Cobalt sulphate at 0 or 0·11 mg Co/kg DM and FA at 0 or 7·2 mg/kg DM were used in a 2 × 2 factorial design. Average daily gain was elevated with FA or Co supplementation, but the elevation was greater for supplementing Co in diets without FA than with FA. Supplementing FA or Co increased DM intake and total-tract nutrient digestibility. Rumen pH was unaltered with FA but reduced with Co supplementation. Concentration of rumen total volatile fatty acids was elevated with FA or Co inclusion. Acetate percentage and acetate to propionate ratio were elevated with FA inclusion. Supplementing Co decreased acetate percentage and increased propionate percentage. Activities of xylanase and α-amylase and populations of total bacteria, fungi, protozoa, Ruminococcus albus, Fibrobacter succinogenes and Prevotella ruminicola increased with FA or Co inclusion. Activities of carboxymethyl-cellulase and pectinase increased with FA inclusion and population of methanogens decreased with Co addition. Blood folates increased and homocysteine decreased with FA inclusion. Blood glucose and vitamin B12 increased with Co addition. The data suggested that supplementing 0·11 mg Co/kg DM in diets containing 0·09 mg Co/kg DM increased growth performance and nutrient digestibility but had no improvement on the effects of FA addition in calves.
Journal Article
Heterogenized cobalt oxide catalysts for nitroarene reduction by pyrolysis of molecularly defined complexes
Molecularly well-defined homogeneous catalysts are known for a wide variety of chemical transformations. The effect of small changes in molecular structure can be studied in detail and used to optimize many processes. However, many industrial processes require heterogeneous catalysts because of their stability, ease of separation and recyclability, but these are more difficult to control on a molecular level. Here, we describe the conversion of homogeneous cobalt complexes into heterogeneous cobalt oxide catalysts via immobilization and pyrolysis on activated carbon. The catalysts thus produced are useful for the industrially important reduction of nitroarenes to anilines. The ligand indirectly controls the selectivity and activity of the recyclable catalyst and catalyst optimization can be performed at the level of the solution-phase precursor before conversion into the active heterogeneous catalyst.
Pyrolysis of defined nitrogen-ligated cobalt acetate complexes onto a commercial carbon support transforms the complexes into heterogeneous Co
3
O
4
materials. These reusable non-noble-metal catalysts are highly selective for the industrially important hydrogenation of structurally diverse and functionalized nitroarenes to anilines.
Journal Article
Scalable production of high-performing woven lithium-ion fibre batteries
Fibre lithium-ion batteries are attractive as flexible power solutions because they can be woven into textiles, offering a convenient way to power future wearable electronics
1
–
4
. However, they are difficult to produce in lengths of more than a few centimetres, and longer fibres were thought to have higher internal resistances
3
,
5
that compromised electrochemical performance
6
,
7
. Here we show that the internal resistance of such fibres has a hyperbolic cotangent function relationship with fibre length, where it first decreases before levelling off as length increases. Systematic studies confirm that this unexpected result is true for different fibre batteries. We are able to produce metres of high-performing fibre lithium-ion batteries through an optimized scalable industrial process. Our mass-produced fibre batteries have an energy density of 85.69 watt hour per kilogram (typical values
8
are less than 1 watt hour per kilogram), based on the total weight of a lithium cobalt oxide
/
graphite full battery, including packaging. Its capacity retention reaches 90.5% after 500 charge–discharge cycles and 93% at 1C rate (compared with 0.1C rate capacity), which is comparable to commercial batteries such as pouch cells. Over 80 per cent capacity can be maintained after bending the fibre for 100,000 cycles. We show that fibre lithium-ion batteries woven into safe and washable textiles by industrial rapier loom can wirelessly charge a cell phone or power a health management jacket integrated with fibre sensors and a textile display.
Rechargeable lithium-ion batteries produced in the form of metre-long fibres can be woven into sturdy, washable textiles on an industrial loom and used to power other fabric-based electronic components.
Journal Article
Exogenous application of sulfur-rich thiourea (STU) to alleviate the adverse effects of cobalt stress in wheat
Heavy metal stress affects crop growth and yields as wheat (
Triticum aestivum
L.) growth and development are negatively affected under heavy metal stress. The study examined the effect of cobalt chloride (CoCl
2
) stress on wheat growth and development. To alleviate this problem, a pot experiment was done to analyze the role of sulfur-rich thiourea (STU) in accelerating the defense system of wheat plants against cobalt toxicity. The experimental treatments were, i) Heavy metal stress (a) control and (b) Cobalt stress (300 µM), ii) STU foliar applications; (a) control and (b) 500 µM single dose was applied after seven days of stress, and iii) Wheat varieties (a) FSD-2008 and (b) Zincol-2016. The results revealed that cobalt stress decreased chlorophyll
a
by 10%, chlorophyll
b
by 16%, and carotenoids by 5% while foliar application of STU increased these photosynthetic pigments by 16%, 15%, and 15% respectively under stress conditions as in contrast to control. In addition, cobalt stress enhances hydrogen peroxide production by 11% and malondialdehyde (MDA) by 10%. In comparison, STU applications at 500 µM reduced the production of these reactive oxygen species by 5% and by 20% by up-regulating the activities of antioxidants. Results have revealed that the activities of SOD improved by 29%, POD by 25%, and CAT by 28% under Cobalt stress. Furthermore, the foliar application of STU significantly increased the accumulation of osmoprotectants as TSS was increased by 23% and proline was increased by 24% under cobalt stress. Among wheat varieties, FSD-2008 showed better adaptation under Cobalt stress by showing enhanced photosynthetic pigments and antioxidant activities compared to Zincol-2016. In conclusion, the foliar-applied STU can alleviate the negative impacts of Cobalt stress by improving plant physiological attributes and upregulating the antioxidant defense system in wheat.
Graphical Abstract
Journal Article