Uncovering the reaction mechanism behind CoO as active phase for CO2 hydrogenation

Transforming carbon dioxide into valuable chemicals and fuels, is a promising tool for environmental and industrial purposes. Here, we present catalysts comprising of cobalt (oxide) nanoparticles stabilized on various support oxides for hydrocarbon production from carbon dioxide. We demonstrate that the activity and selectivity can be tuned by selection of the support oxide and cobalt oxidation state. Modulated excitation (ME) diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveals that cobalt oxide catalysts follows the hydrogen-assisted pathway, whereas metallic cobalt catalysts mainly follows the direct dissociation pathway. Contrary to the commonly considered metallic active phase of cobalt-based catalysts, cobalt oxide on titania support is the most active catalyst in this study and produces 11% C2+ hydrocarbons. The C2+ selectivity increases to 39% (yielding 104 mmol h−1 gcat−1 C2+ hydrocarbons) upon co-feeding CO and CO2 at a ratio of 1:2 at 250 °C and 20 bar, thus outperforming the majority of typical cobalt-based catalysts.

Highly sensitive detection of phosphate using well-ordered crystalline cobalt oxide nanoparticles supported by multi-walled carbon nanotubes

Phosphates are well-known groundwater and surface water contaminants, with even modest increases in their concentration contributing to the eutrophication of lakes and coastal waterways and thus potentially harming the environment....

Fabrication of Conifer Gum Based Metal Nano Particles for Pollution Control Applications

In recent decades, the analysis of nanoparticles is of greater importance for their applications in various fields. This present work also focuses the novel biological green material to synthesize the copper and cobalt oxide nanoparticles. The copper oxide (CuO) and cobalt oxide (Co3O4) nanoparticles (nps)have been synthesized by biological strategy utilizing AH (Araucaria heterophylla) gum extract. The characterization techniques, i.e. UV, GC-MS, FT-IR, XRD, SEM, HR-TEM provide concrete information about the morphology, crystalline nature and structure of the synthesized nanoparticles. The high resolution TEM and SAED images confirm the formation of spherical shaped (Co3O4) and oval shaped (CuO) isolated nanoparticles. The catalytic adequacy of the developed catalyst, copper oxide (CuO) and cobalt oxide (Co3O4) nanoparticles was analyzed for the degradation of dyes: Methylene Blue (MB), Congo Red (CR), Acid Violet (AV).The kinetic investigations for the reduction of synthetic dyes by the nanoparticles were assessed and the reduction contemplates are very much fitted with the pseudo second order kinetic model with less time.The antibacterial and antifungal activity of the prepared nanoparticles have been evaluated against Escherichiacoli, Staphylococcus aureus, Bacillus subtilis, Aspergillusniger and Candida albicans.

Green Synthesis of Iron-Doped Cobalt Oxide Nanoparticles from Palm Kernel Oil via Co-Precipitation and Structural Characterization

In this study, a bio-derived precipitating agent/ligand, palm kernel oil, has been used as an alternative route for the green synthesis of nanoparticles of Fe-doped Co3O4 via the co-precipitation reaction. The palm oil was extracted from dried palm kernel seeds by crushing, squeezing and filtration. The reaction of the palm kernel oil with potassium hydroxide, under reflux, yielded a solution containing a mixture of potassium carboxylate and excess hydroxide ions, irrespective of the length of saponification. The as-obtained solution reacts with an aqueous solution containing iron and cobalt ions to yield the desired metallo-organic precursor, iron cobalt carboxylate. Characterization of the precursors by IR and gas chromatography (GC) attests to the presence of carboxylate fatty acids in good agreement with the proportion contained in the oil, and ICP confirms that the metallic ratios are in the proportion used during the synthesis. Analysis of the products thermally decomposed between 400 °C and 600 °C by XRD, EDX, TEM and ToF-SIMS, established that cobalt iron oxide nanoparticles (Co(1−x)Fex)3O4 were obtained for x ≤ 0.2 and a nanocomposite material (Co(1−x)Fex)3O4/Fe3O4 for x ≥ 0.2, with sizes between 22 and 9 nm. ToF-SIMS and XRD provided direct evidence of the progressive substitution of cobalt by iron in the Co3O4 crystal structure for x ≤ 0.2.