Cobalt single atom catalysts for efficient electrosynthesis of hydrogen peroxide

We report the synthesis of cobalt (Co) single atoms (SAs) anchored on N-doped graphitic carbon (Co-SAs/NC) by pyrolysis of a mixture of cobalt chloride hexahydrate, ethylene diamine tetraacetic acid (EDTA)...

Statistical Approach of Nutrient Optimization for Microalgae Cultivation

The Plackett-Burman Design (PBD) was applied to study fresh water microalgae cultivation using Chlorella sp. TISTR 8411 to select the influential nutrient factors for biomass and lipid production. The PBD for 13 trials from 11 nutrient factors with 3 levels was studied in the mixotrophic cultivation at 28 0C under 16:8 light and dark photoperiods over 7 days of cultivation time. Two influential factors were chosen as glucose and cobalt chloride hexahydrate to further design via Box-Behnken Design (BBD) in order to optimize the cultivation of this microalgae for biodiesel production. The 17 trials of 3 factors and 3 levels of BBD experimental design technique were applied with varying factors of glucose (20-40 g/L), cobalt chloride hexahydrate (0.01-0.04 mg/L) and light intensity (4,500-7,500 Lux) under 16:8 light and dark photoperiods over 7 days of cultivation time at 28 0C. Result showed that Chlorella sp. TISTR 8411 cultivation yield 0.52 g/L biomass and 0.31 g/L lipid production resulting in approximately 60% of lipid production when cultivated in 20.05 g/L glucose, 0.04 mg/L CoCl26H2O under light intensity of 4,614 Lux with the supplementation of 4.38 g/L NaHCO3 coupled with 1 g/L of both NaNO3 and KH2PO4. Under statically mixotrophic cultivation, result indicated that Chlorella sp. TISTR 8411 had potential to produce high lipid content for biodiesel application and biomass production for nutraceutical application. Further experiment with the longer cultivation period up to 2 weeks would implement not only for monitoring the growth kinetics but also evaluating the suitable type of fatty acid production.

Solid-State NaBH4/Co Composite as Hydrogen Storage Material: Effect of the Pressing Pressure on Hydrogen Generation Rate

A solid-state NaBH4/Co composite has been employed as a hydrogen-generating material, as an alternative to sodium borohydride solutions, in the long storage of hydrogen. Hydrogen generation begins in the presence of cobalt-based catalysts, immediately after water is added to a NaBH4/Co composite, as a result of sodium borohydride hydrolysis. The hydrogen generation rate has been investigated as a function of the pressure used to press hydrogen-generating composites from a mechanical mixture of the hydride and cobalt chloride hexahydrate. The hydrogen generation rate was observed to increase with the increase of this pressure. Pre-reduction of the cobalt chloride, using a sodium borohydride solution, leveled this dependence with a two-fold decrease in the gas generation rate. According to TEM and XPS data, oxidation of the particles of the pre-reduced cobalt catalyst took place during preparation of the composites, and it is this oxidation that appears to be the main reason for its low activity in sodium borohydride hydrolysis.

Solvothermal synthesis and magnetic properties of β-Co2P nanorods

Hexagonal high temperature phase β-Co2P nanorods with a diameter of around 50 nm were synthesized via a mild solvothermal route. The reaction was carried out at 180 °C using cobalt chloride hexahydrate (CoCl2 · 6H2O) as Co source and yellow phosphorous as P source. The composition, structure as well as morphology were characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and transmission electron microscopy (TEM). The magnetic susceptibility curve indicates that the β-Co2P nanorods show canted antiferromagnetic state, different from the paramagnetic state of orthorhombic low temperature phase β-Co2P.

Facile Preparation of Co3O4 Nanoflower through Forced Hydrolysis

One of the interesting structures in nanoCo3O4's preparation that have been reported fairly recent is the flower-like structure often referred as nanoflower. Several interesting applications involving Co3O4 nanoflower have also been reported. This paper present a facile approach to prepare Co3O4 nanoflower using one step forced hydrolysis technique using cobalt chloride hexahydrate as starting material as opposed to the standard two steps hydrothermal technique. The produced nanoscale Co3O4 is in agglomerate of nanorods producing a dandelion-like flower structure. The prepared Co3O4 is in hydrated and amorphous forms with a surface area of 62 m2/g and average pore size of 12 nm.