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The homemade, porous carbon material, thermolysis prepared from Novolac phenol-formaldehyde resin, in situ modified with Co3O4 nanoparticles and mixed with single-wall carbon nanotubes, was used in selective sensing of prominent antioxidant α-lipoic acid (LA). XRD, SEM and EIS measurements were used for characterization of material composition, structure, morphology and improved conductivity. The quantification of LA at TPCo3O4&SWCNTCPE was done by a square-wave voltammetric technique in BR buffer solution at pH 6. The linear working range was recorded from 2 to 100 μM of LA and the proposed electrode material was successfully applied in the determination of LA in dietary supplements.

This work presents a desirable bifunctional catalyst - Co3O4 nanoparticles anchored on nitrogen-doped partially exfoliated multiwall carbon nanotubes (Co3O4/N-p-MCNTs) - for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for the rechargeable and flexible solid-state Zn-air battery. The Co3O4/N-p-MCNTs demonstrates good catalytic performance with the ORR half-wave potential of 0.760 V (vs RHE). Additionally, the Co3O4/N-p-MCNTs exhibits superior limiting current density with higher stability than Pt/C in alkaline solutions. The catalyst obtains a low operating potential (Ej10) of 1.62 V (vs RHE) to achieve a 10 mA cm-2 current density for OER. The potential difference (ΔE) between Ej10 of OER and ORR half-wave potential is 0.86 V, which is smaller than that of many highly active bifunctional catalysts reported recently. Moreover, a Zn-air battery utilizing Co3O4/N-p-MCNTs as the catalyst in cathode could successfully generate a specific capacity of 768 mAh g-1 at 10 mA cm-2, and there is no voltage loss after a continuous discharge of 135 h. The fabricated solid-state rechargeable Zn-air battery displays a high power density and superior long-term cycling stability. Furthermore, first-principles density functional theory simulations were conducted to explore the interfacial properties of the hybrid catalyst, hinting that the N-p-MCNTs could significantly enhance the electrical conductivity of Co3O4 nanoparticles. The free energy diagrams generated from our simulations suggest that the N-p-MCNTs influence the superior ORR performance, while cobalt oxide affects the favored performance of OER. The obtained results confirm that the Co3O4/N-p-MCNTs catalyst would have a broad impact and could be used for renewable energy conversion devices. © 2019 American Chemical Society.

Co nanoparticles of well-defined size were synthesized by temperature-controlled injection of Co2(CO)8 into dichlorobenzene. After intercalation into mesoporous MCF-17 and temperature-programmed oxidation, Co3O4/MCF-17 model catalysts were obtained with cobalt oxide particle sizes varying between 3.5 and 12.2 nm. We demonstrate here the occurrence of a distinct particle size effect for the CO oxidation. Maximum reaction rates of about 0.77 nm-2 s-1 at 150 °C were observed for Co3O4 particles with a size in the range of 5 to 8 nm. The reaction rates decreased for either smaller or larger sizes. X-ray photoelectron spectroscopy allowed establishing a clear correlation between the Co3+ trivalent oxidation state and the CO oxidation rate., SCOPUS: ar.j, info:eu-repo/semantics/published

Supported Co3O4 nanoparticles on SBA-15 aluminosilicates (Al-SBA-15) with different cobalt loadings (0.5, 1, 5, 10 wt %) were synthesized by ball-milling. The synthesized materials were characterized by different techniques including, N2 adsorption measurements, XRD, TEM, EDX, ICP-MS, DRIFTs of pyridine among others. The catalysts were studied in the microwave assisted benzyl alcohol oxidation as well as in the akylation of toluene with benzyl chloride. Co3O4 catalysts exhibited moderate conversions in the selective oxidation of benzyl alcohol, with a high selectivity towards benzaldehyde. Lewis acidity increases upon the incorporation of cobalt nanoparticles onto the surface of the support which was found to significantly influence the materials in the alkylation of toluene with benzyl chloride. The high active sites accessibility of ball-milling prepared materials leads to high conversions to alkylated derivatives in short periods of time (>99 mol %, 30 min). A direct correlation acidity/activity could not be obtained in the systems, for which nanoparticle sizes and distribution could influence the observed activities. © 2018