Synthesis of spherical cobalt oxide nanoparticles by a polyol method

Abstract

We report the synthesis of spherical cobalt oxide nanoparticles by a polyol method. To obtain spherical nanoparticles, water, polyvinylpyrrolidone (PVP), and cobalt acetate tetrahydrate were mixed in diethylene glycol and refluxed at 200°C. Spherical particles were not obtained in the absence of water or PVP, or when the mixture was refluxed at 180°C. The spherical nanoparticles were found to be composed of cobalt (II) oxide (CoO) with a small amount of cobalt oxyhydroxide (CoOOH). The synthesized spherical nanoparticles had good dispersibility in water, and Fourier transform infrared spectroscopy and thermogravimetrydifferential thermal analysis measurements indicated that the nanoparticles had a coreshell structure, with a core of CoO and a polymer shell.

Gas sensor properties of nanopore-bearing Co3O4particles containing Pt or Pd particles

“…As indicated, the pre-400°C baked Pt-in-out/csCoO, Pd-in-out /csCoO, and csCoO samples contained primary particles of~10 nm in diameter, which converted into secondary particles measuring~20-150 nm. The sizes of these primary particles are comparable to those of the crystallites, and the particulate shapes are similar to those of our previously reported core-shell cobalt oxide particles [12], core-shell cerium oxide particles [15], and coreshell zinc oxide particles [16]. Table 1 shows the secondary particle sizes calculated from the SEM images, where it is apparent that the secondary particle sizes of Pt-in-out/csCoO and Pd-in-out /csCoO are smaller than that of csCoO.…”

“…Peaks that were attributable to Pt and Pd could not be verified, but this is likely due to the particularly low contents of these noble metals within the mixture. In our previous report, we found CoOOH in the XRD pattern of csCoO; however, in this case, only a single phase of CoO was observed [12] likely due to the removal of CoOOH through washing. Figure 3 shows the SEM images of Pt-in-out /csCoO, Pd-in-out/csCoO, csCoO, Pt-in-out/csCo 3 O 4 , Pd-in-out/csCo 3 O 4 , and csCo 3 O 4 .…”

“…We recently reported the synthesis of a core-shell type cobalt oxide (core-shell type CoO; csCoO), which is comprised of a CoO core and a polymer shell [12]. Using the polyol method, core-shell particles with particle sizes between 50 and 100 nm were prepared, where the polymer shells comprised 19 wt% of the total mass.…”

Comparing Different Approaches to Form Cobalt Oxide Layer on CoPt Nanoparticles

“…There are several methods which result in high-quality cobalt oxide formation on clusters by polyol process, solgel method, thermal composition, etc. [17][18][19] techniques are widely used for the synthesis of these NPs to enhance and control the magnetic properties of the NPs. Among them, polyol process provides more control on particle nucleation, growth, and agglomeration of metal NPs so that the particle size can be easily reduced below 10 nm and forming a shell on core structure is possible with two steps polyol process.…”

A review on bio-synthesized Co3O4 nanoparticles using plant extracts and their diverse applications

“…The aim of the present review is to focus on the current knowledge concerning the capability of plant materials for biogenic synthesis of Co3O4 NPs and presents a database that future researchers may be based on the green synthesis of Co3O4 NPs using plants material sources. Microwave assisted [46] 5 Microemulsion method [47] 6 Spray pyrolysis [48] 7 Vapor deposition method [49] 8 Sono-chemical [50] 9 Co-precipitation [51] 10 Mechanochemical processes [52] 11 Ionic liquid assisted method [53] 12 Reflux method [54] 13 Polyol [55] 14 Pulsed laser deposition [56] 15 Sol gel [57] 16 Template method [58] 17 Solvothermal [59] 18 Irradiation technique [60] 19 Chemical reduction method [61] 20…”