Growth Kinetics, Composition, and Morphology of Co3O4 Thin Films Prepared by Pulsed Liquid-Injection MOCVD

Magnetic recyclable α-Fe2O3–Fe3O4/Co3O4–CoO nanocomposite with a dual Z-scheme charge transfer pathway for quick photo-Fenton degradation of organic pollutants

A novel α-Fe₂O₃–Fe₃O₄/Co₃O₄–CoO nanocomposite was developed, integrating multiple degradation pathways. The Z-scheme configuration and oxygen vacancies contributes to in situ H₂O₂ formation and simultaneous reactivation showing excellent performance.

Facile preparation of a cobalt diamine diketonate adduct as a potential vapor phase precursor for Co3O4films

Co3O4 thin films and nanosystems are implemented in a broad range of functional systems, including gas sensors, (photo)catalysts, and electrochemical devices for energy applications. In this regard, chemical vapor deposition (CVD) is a promising route for the fabrication of high-quality films in which the precursor choice plays a key role in the process development. In this work, a heteroleptic cobalt complex bearing fluorinated diketonate ligands along with a diamine moiety [Co(tfa)2·TMEDA; tfa = 1,1,1-trifluoro-2,4-pentanedionate and TMEDA = N,N,N',N'-tetramethylethylenediamine] is investigated as a potential Co molecular precursor for the CVD of Co3O4 systems. For the first time, the compound is characterized by crystal structure determination and comprehensive analytical studies, focusing also on its thermal properties and fragmentation patterns, important figures of merit for a CVD precursor. The outcomes of this investigation, accompanied by detailed theoretical studies, highlight its very favorable properties for CVD applications. In fact, growth experiments under oxygen atmospheres containing water vapor revealed the suitability of Co(tfa)2·TMEDA for the fabrication of high-quality, phase-pure Co3O4 thin films. The versatility of the proposed strategy in tailoring Co3O4 structural/morphological features highlights its potential to obtain multi-functional films with controllable properties for a variety of eventual technological end-uses.

Highly Active Oxygen Evolution on Carbon Fiber Paper Coated with Atomic-Layer-Deposited Cobalt Oxide

In this work, we evaluated the oxygen evolution performance of cobalt oxide (CoO _x)-coated carbon fiber paper in electrochemical water splitting. For a uniform coating of CoO _x layers along the carbon fiber paper, the atomic layer deposition (ALD) technique was applied. We achieved a uniform and conformal coating of atomic-layer-deposited CoO _x (ALD-CoO _x) on the carbon fiber paper. The overpotential for oxygen evolution measured for the optimized ALD-coated carbon fiber paper was as low as 343 mV at 10 mA cm^-2, which is competitive with the activity of state-of-the-art CoO _x prepared on electrodes with large surface areas. Oxygen evolution is not enhanced after a critical thickness, about 28 nm in our study, is reached. The optimal thickness of the ALD-CoO _x film is dependent on two competing effects: the high oxidation state of cobalt ions in thicker CoO _x helps the oxygen evolution, whereas the introduction of a thick oxide coating decelerates the rate of charge transfer at the surface.

One-step wet-chemical synthesis of ternary ZnO/CuO/Co3O4 nanoparticles for sensitive and selective melamine sensor development

Using one-step wet-chemically synthesized ternary ZnO/CuO/Co₃O₄ nanoparticles (NPs) fabricated GCE sensor probe, a selective and sensitive melamine chemical sensor was developed by electrochemical approach, which exhibited the highest sensitivity, better repeatability, broad linear dynamic range, good linearity, fast response time, and lowest detection limit.

Low-temperature chemical vapor deposition of cobalt oxide thin films from a dicobaltatetrahedrane precursor

Application of a novel liquid cobalt precursor, which forms cobalt oxide films at low temperatures using relatively simple CVD process.

Tuning the morphology and composition of ultrathin cobalt oxide films via atomic layer deposition

Composition and morphology controllable cobalt oxide ultrathin film have been fabricated with ALD method on both planar and porous substrate.

Composition-controlled synthesis of LixCo3−xO4 solid solution nanocrystals on carbon and their impact on electrocatalytic activity toward oxygen reduction reaction

The incorporation of Li promotes the formation of the OC–O–Co^III–O bonds at the interfaces in the Li_xCo_3−xO₄/C hybrids, which is responsible for their enhanced ORR activity.

Facet-dependent activity and stability of Co3O4nanocrystals towards the oxygen evolution reaction

The (111) surface of Co₃O₄nanocrystals is more active towards oxygen evolution reaction in alkaline conditions compared to the (100) surface.

Performance of cobalt titanate towards H2O2 based catalytic oxidation of lignin model compound

Mixed metal cobalt titanium oxide (CoTiO₃) prepared by solution phase method has been evaluated for the liquid phase catalytic oxidation of vanillyl alcohol to vanillin using H₂O₂ as an oxygen source.

Atomic layer deposition of a submonolayer catalyst for the enhanced photoelectrochemical performance of water oxidation with hematite

Hematite photoanodes were coated with an ultrathin cobalt oxide layer by atomic layer deposition (ALD). The optimal coating-1 ALD cycle, which amounts to <1 monolayer of Co(OH)2/Co3O4-resulted in significantly enhanced photoelectrochemical water oxidation performance. A stable, 100-200 mV cathodic shift in the photocurrent onset potential was observed that is correlated to an order of magnitude reduction in the resistance to charge transfer at the Fe2O3/H2O interface. Furthermore, the optical transparency of the ultrathin Co(OH)2/Co3O4 coating establishes it as a particularly advantageous treatment for nanostructured water oxidation photoanodes. The photocurrent of catalyst-coated nanostructured inverse opal scaffold hematite photoanodes reached 0.81 and 2.1 mA/cm(2) at 1.23 and 1.53 V, respectively.

Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

Without any surfactant, antiferromagnetic Co3O4 nanoparticles were synthesized successfully for the first time by means of an oxidation-reduction method with cobalt sulfate as starting material, which was oxidized to cobalt salt by NaNO3 after alkalinizing with NaOH. Morphological, structural, spectroscopic and magnetic characterization of the product were done by SEM, TEM, XRD, and VSM, respectively. The average crystallite size (on the base of line profile fitting method), D and σ, is estimated as 30 ± 6 nm. Some anomalous magnetic properties and their enhanced effect have been observed in Co3O4 antiferromagnetic nanocrystallites, including a bias field, coercivity, permanent magnetic moments and an open loop. These phenomena are attributed to the unidirectional anisotropy which is caused by the exchange coupling between AFM and FM layers, the existence of the spin glass like surface spins of Co3O4 nanoparticles due to size effects and surface-area effect.