Co3O4 Nanoparticles Research Articles

Revealing the solid-solution interface interference behaviors between Cu2+ and As(III) via partial peak area analysis of simulations and experiments

The mutual interference in the sensing detection of heavy metal ions (HMIs) is considerably serious and complex. Besides, the co-existed ions may change the stripping peak intensity, shape and position of the target ion, which partly makes peak current analysis inaccurate. Herein, a promising approach of partial peak area analysis was proposed firstly to research the mutual interference. The interference between two species on their electrodeposition processes was investigated by simulating different kinetics parameters, including surface coverage, electro-adsorption, -desorption rate constant, etc. It was proved that the partial peak area is sensitive and regular to these interference kinetics parameters, which is favorable for distinctly identifying different interferences. Moreover, the applicability of the partial peak area analysis was verified on the experiments of Cu2+, As(III) interference at four sensing interfaces: glassy carbon electrode, gold electrode, Co3O4, and Fe2O3 nanoparticles modified electrodes. The interference behaviors between Cu2+ and As(III) relying on solid-solution interfaces were revealed and confirmed by physicochemical characterizations and kinetics simulations. This work proposes a new descriptor (partial peak area) to recognize the interference mechanism and provides a meaningful guidance for accurate detection of HMIs in actual water environment.

Three-dimensional porous N-doped graphitic carbon framework with embedded CoO for ultrahigh and stable lithium storage

A three-dimensional porous N-doped graphite carbon framework embedded with cobalt oxide (CoO@N-GCs) was prepared using a simple polymer heat treatment method. This material is utilized as an anode material for lithium-ion batteries (LIBs). The experimental results demonstrate that the CoO@N-GC-400 shows outstanding performance. The first capacity is 1628 mAh g−1 (0.05 A g−1) and exhibits excellent cycle characteristics, maintaining a capacity of 352.72 mAh g−1 after 1000 cycles at 1 A g−1. During pyrolysis, the interconnected macroporous structure is mostly preserved, and the formation of the macropores happens perpendicular to the surface. This occurrence is mainly due to the high-temperature carbonization of PVP and the significant pore formation resulting from the breakdown of Co(NO3)3. The pore wall undergoes a solid-to-hollow transformation due to the formation of CoO nanoparticles within the walls. This provides a useful approach for designing the anode structure of high-performance LIBs.

Mesoporous cobalt oxide nanoparticles synthesized by a sonochemical method in the presence of a deep eutectic solvent for oxidative sonophotocatalytic decomposition of caffeine

Herein, for the first time, we have prepared mesoporous Co3O4 nanoparticles (NPs) by the ultrasound-assisted method in the presence of deep eutectic solvent (DES) for sonophotocatalytic degradation of caffeine (CAF). The porosity, crystallinity, and morphology of the as-synthesized NPs were investigated by using Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The as-prepared NPs were applied in sonophotocatalytic, photocatalytic, and sonocatalytic degradation of CAF in low energy and low-frequency ultrasound at neutral pH. The sonophotocatalytic process was the most effective in degrading CAF, reaching about 99.5 % in less than an hour with a pseudo-first-order rate constant of 0.0902 min−1. The photocatalytic and sonocatalytic processes degraded 83.4 % and 22.7 % of CAF, respectively, with lower rate constants of 0.0288 and 0.0049 min−1. Notably, the simultaneous application of UV light and ultrasound irradiation in a sonophotocatalytic decomposition process had a positive synergy effect of about 62.64 %. The commercial tablet was degraded by the optimum sonophotocatalytic process to prove the applicability of the catalyst. The reusability test of the NPs was examined, and after four consecutive uses, the NPs had negligible fading of their sonophotocatalytic performance. Due to the excellent sonophotocatalytic performance of the NPs, it is a suitable candidate for a broad range of environmental and remediation applications.

A sustainable carbon-consuming cycle based on sequential activation of CO2 and CH4 using metal oxides

Naturally abundant metal oxides can be used as reusable CO2-philic absorbents, and the resulting CO2-bound metal carbonates are disposed in nature; although common, this carbon capture and sequestration process is unsustainable. Herein, we revisit the use of metal carbonates as pre-activated CO2 reservoir containing reactive carbonate species that can combine with CH4 to produce CH3COOH. The direct stoichiometric coupling of CH4 with CO2 to form CH3COOH is thermodynamically non-spontaneous. However, theoretical calculations identified metal carbonates that spontaneously react with CH4 to form CH3COOH and the corresponding metal oxides. We designed new metal oxide-assisted carbon-consuming cycle involving sequential CO2/CH4 activation to form CH3COOH with nearly 100% selectivity, which can be generalized to various metal oxides. Particularly, Co3O4 nanoparticles encapsulated by mesoporous silica shell produced the best CH3COOH productivity of 0.7 μmolCH3COOH gCo3O4–1 at 250 °C, which enables the sustainable incremental production of CH3COOH without decrease in productivity over 15 repeated cycles.

Interface engineering of Co3O4 nanoparticle for high-efficiency interfacial solar steam generation

Solar steam generation has been proven to be an innovative and sustainable technology to mitigate the issue of clean water shortage. But, to-date, optimizing a suitable candidate material system to improve the evaporation efficiency is an urgent need, especially the interface engineering tailored heat transfer of materials has not yet made a breakthrough. Herein, we successfully designed a Co3O4 nanoparticle that can promote the optimization of the heat transfer performance using interface engineering. The optimized Co3O4 nanoparticles creates a close contact with the cotton sheet, creating an efficient channel for heat transfer and achieving high photothermal steam generation efficiency. The interfacial solar steam generation has been found to achieve a high evaporation rate of 2.72 kg/m2·h, which is higher than that of traditional bulk phase heating. Our findings not only showcase the efficacy of interface engineering in the design of solar steam generation, but also present a cost-effective and straightforward methodology that can be applied for water purification purposes.

A comparative study of single and bi-doped Co3O4 nanocatalysts for the photodegradation of methyl orange dye

In this work, pure Co3O4, Ni-, CuNi-, and CdNi-doped Co3O4 nanoparticles (NPs) were prepared via chemical co-precipitation method. The obtained Co3O4 exhibits a cubic crystalline structure with an average crystallite size of ∼19.9 nm, according to the XRD profiles. Moreover, the effects of Ni-, CuNi- and CdNi-doped Co3O4 on the crystallite size, band gap, and magnetic properties of the cubic Co3O4 were considered. It was observed that the crystallite sizes and the magnetic properties of Ni(0.1)Co3O4(0.9) and Cu(0.05)Ni(0.05)Co3O4(0.9) samples are smaller, while the optical band gaps are wider than that of pure Co3O4. The Cd(0.05)Ni(0.05)Co3O4(0.9) sample has a higher magnetic properties in comparison to the other samples. The elemental composition of the produced Co3O4, Ni-, CuNi- and CdNi-doped Co3O4 NPs is determined using the EDX technique. A morphological study by TEM showed that the CdNi-doped Co3O4 sample has semi-spherical particles with an average particle diameter of ∼70.4 nm. The photodegradation of methyl orange (MO) dye in aqueous solution under visible light irradiation was used to examine the catalytic activity of pure and doped Co3O4 NPs. The results showed that the degradation of MO dye was improved in the doped samples and takes the following order: Cd(0.05)Ni(0.05)Co3O4(0.9) (∼93%) > Cu(0.05)Ni(0.05)Co3O4(0.9) (∼85%) > Ni(0.1)Co3O4(0.9) (∼79.7%) > pure Co3O4 (∼64.4%) in 120 min of irradiation time. The pseudo-first-order reaction rate constant for Cd(0.05)Ni(0.05)Co3O4(0.9) is equal to 0.021 min−1, which is about 1.6-times increased in compared to pure Co3O4. The improved photocatalytic efficiency of this sample was attributed to an extrinsic defect generated by CdNi doping, small particle sized and high surface area, which delayed the electron/hole recombination and caused appropriate band gap configuration.

Cobalt oxide coupled with graphitic carbon nitride composite heterojunction for efficient Z-scheme photocatalytic environmental pollutants degradation performance

The Co3O4/g-C3N4 Z-scheme composite heterojunction has been effectively built in a facile sonication-assisted hydrothermal manner. The as-synthesized optimal 0.2 M Co3O4/g-C3N4 (GCO2) composite photocatalysts (PCs) revealed admirable degradation efficiency towards methyl orange (MO, 65.1%) and methylene blue (MB, 87.9%) organic pollutant compared with bare g-C3N4 within 210 min under light irradiation. Besides, the features of investigating structural, morphological and optical properties have evidence that the unique decoration effect of Co3O4 nanoparticles (NPs) on the g-C3N4 structure with intimate interface heterojunction of well-matched band structures noticeably facilitates the photo-generated charge transport/separation efficiency, reduces the recombination rates and widens the visible-light fascination which could advantageous to upgrading photocatalytic action with superior redox ability. Especially, the probable Z-scheme photocatalytic mechanism pathway is also elucidated in detail based on the quenching results. Hence, this work delivers a facile and hopeful candidate for contaminated water remediation via visible-light photocatalysis over the efficient g–C3N4–based catalysts.

Preparation and characterization of carbon quantum dots grafted Co3O4 nanocomposite for supercapacitors application

A pure Co3O4 nanoparticles and a carbon quantum dots (CQDs) anchored cobalt oxide (Co3O4/CQD) nanocomposite were synthesized by a simple hydrothermal method for supercapacitor application. The powder XRD measurement confirms the formation cubic phase of Co3O4. More HR-TEM measurements. The beneficial surface and electronic properties of CQDs were used for the refinement of the electrochemical accomplishments of Co3O4. The Co3O4/CQD and Co3O4 manifest half-cell specific capacitances of 193.8 F g−1 and 123.6 F g−1 @ current density of 4 A g−1, respectively. The introduction of CQDs into the Co3O4 matrix increased the charge-transfer process, which is primarily responsible for the improved electrochemical capabilities of the nanocomposite. The hybrid asymmetric supercapacitor delivers an energy density of 2.49 W h kg−1 @ a power density of 426 W kg−2 with a capacitance retention of 81.8%.

Removal of azo dye RY17 from wastewater using g-C3N4@CoO nanocomposite photocatalyst: Synthesis, optical and electrochemical characterization and performance evaluation

The purpose of the current study was to develop a photocatalytic method for the efficient removal of the azo dye RY17 from wastewater using g-C3N4 @CoO, a nanocomposite of cobalt oxide and glycine. The g-C3N4 @CoO nanocomposites were made using the heating method and the sintering process. XRD, SEM, and XPS structural studies of the g-C3N4 @CoO nanocomposite revealed that CoO nanoparticles had been successfully fixed to the g-C3N4 structure. According to optical characterizations, the optical band gaps of g-C3N4, CoO nanoparticles, and g-C3N4 @CoO nanocomposite were 2.88, 2.83, and 2.78 eV, respectively. Adding CoO nanoparticles to g-C3N4 nanosheets boosted their roughness and defect sites, according to electrochemical measurements, which resulted in the production of a sizable number of electro-active sites. The total dye elimination efficiencies of g-C3N4, CoO nanoparticles, and g-C3N4 @CoO nanocomposite were determined after 80, 70, and 55 min of solar light exposure. Additionally, g-C3N4 @CoO nanocomposite accelerated the photocatalytic decolorization of RY17 more quickly than g-C3N4, CoO nanoparticles did. After the photocatalytic performance of the substance was examined for RY17 decolorization from deionized water and textile effluent, it was found that g-C3N4 @CoO nanocomposite could be employed successfully for photocatalytically degrading RY17 from real textile wastewater.

Waste eggshell to valuable Co3O4/eggshell material as an efficient catalyst for catalytic decomposition of N2O under simulated real tail gases

Co3O4 shows excellent catalytic activity for N2O decomposition, in which it is urgently needed to develop novel efficient catalysts/supports with cheap and environmentally-friendly properties. Herein, Co3O4 nanoparticles decorated eggshell catalysts (Co3O4/eggshell-GR, Co3O4/eggshell-IM, and Co3O4/eggshell-DP) were prepared using simple grinding, impregnation, and deposition-precipitation methods, where waste eggshells were used as an effective support and reaction-promoter. The results indicated that the preparation methods significantly influenced the catalytic activity of Co3O4/eggshell catalysts; the highest activity was obtained over the Co3O4/eggshell-DP. The activity of Co3O4/eggshell-DP was comparable to that of pure Co3O4. More importantly, its specific activity was about 7.3 times that of Co3O4 at 400 °C. The examined Co3O4/eggshell-DP also displayed outstanding stability and anti-poisoning property in NO, O2, and/or H2O-containing atmospheres. It was also verified that the excellent activity of Co3O4/eggshell-DP correlated with the unique structure of the eggshell and the close incorporation between CaCO3 and Co3O4. The Co3O4/eggshell-DP catalyst owned abundant Co3O4 nanoparticles, more Co3+ species, and excellent redox performance, promoting the conversion of N2O at a lower temperature. The presence of abundant surface basic sites and a larger amount of oxygen vacancies also facilitated the catalytic efficiency of Co3O4/eggshell-DP.

Water-Soluble Nanocomposites Containing Co3O4 Nanoparticles Incorporated in Poly-1-vinyl-1,2,4-triazole.

New water-soluble nanocomposites with cobalt oxide nanoparticles (Co3O4NPs) in a poly(1-vinyl-1,2,4-triazole) (PVT) matrix have been synthesized. The PVT used as a stabilizing polymer matrix was obtained by radical polymerization of 1-vinyl-1,2,4-triazole (VT). The polymer nanocomposites with Co3O4 nanoparticles were characterized by ultraviolet-visible, Fourier-transform infrared spectroscopy, atomic absorption spectroscopy, transmission electron microscopy, dynamic light scattering, gel permeation chromatography, and simultaneous thermogravimetric analysis. The resulting polymer nanocomposites consist of spherical isolated cobalt nanoparticles with a diameter of 1 to 13 nm. The average hydrodynamic diameters of macromolecular coils are 15-112 nm. The cobalt content in nanocomposites ranges from 1.5 to 11.0 wt.%. The thermal stability of nanocomposites is up to 320 °C.

Structural and Morphological Studies of Two-Step Synthesized LiCoO2 and Microwave Synthesized LiFePO4 Particles

ABSTRACT Crystalline dispersible LiCoO2 nanoparticles were synthesized by a rapid two-step method. In the first step, Co3O4 nanoparticles were obtained by facile microwave assisted hydrothermal method. In the second step, the as-sy nthesiz ed Co 3O4 nanoparticles were transformed into LiCoO2 nanoparticles through solid-state reaction method. Olivine LiFePO4 with spindle like microstructure was prepared by rapid microwave assisted hydrothermal method within short time at 140°C. The synthesized samples were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM ) and energy dispersive X-ray spectroscopy (EDX). The XRD reflection peaks revealed that the synthesized LiCoO2 belongs to R-3m space group with hexagonal crystal structure. No impurity phase of Co3O4 was detected in LiCoO2 after calcination at 750°C for 1 h. Powder XRD results also authenticated the formation of LiFePO4 phase with orthorhombic crystal structure. FTIR analysis revealed the structural co-ordination of the prepared L iF ePO4 particles. SEM analysis showed the formation of monodispersed LiCoO2 nanoparticles with spherical particle morphology. For LiFePO4, SEM analysis revealed the formation of porous spindle like microstructure, composed of densely packed secondary nanoflakes. Further, EDX spectra of the samples confirmed the presence of corresponding elements in the synthesized samples.

Quantum dot-derived carbon nanopocket-confined Co3O4 within mesoporous carbon nanofiber for Cu-free anode of flexible Li-ion batteries

Cu-free flexible anodes, which are promising alternatives to the conventional anode type, have received global attention owing to their advantages, such as flexible deformability and elimination of interfacial trouble between active materials and current collector. However, these Cu-free anodes suffer from low specific capacitance and poor mechanical properties. To overcome these issues, we introduced carbon quantum dots (CQDs) as inner structure modification agents and Co3O4 nanoparticles within a mesoporous carbon nanofibers (CNF). Herein, we report a novel strategy for developing highly flexible Cu-free anode using the mesoporous CNF structure together with quantum dot-induced carbon nanopocket effect. During the carbonization process, the surface functional groups of the CQDs decomposed, which led to the formation of a carbon nanopocket. This carbon nanopocket effectively suppressed the particle growth of cobalt oxide. Moreover, mesoporous surface morphology was successfully developed using a post-oxidation process. The resultant Co3O4/CQD-PCNF flexible anode showed superior anode performances, including the high specific capacity of 783.43 and 227.59 mAh/g at a current density of 100 and 2,000 mA/g, respectively, with an excellent high-rate capability of 79.6% after 1,000 cycles of intense flexible test. Therefore, the Co3O4/CQD-PCNF Cu-free anode can provide a new direction to electrode modification strategies for achieving free-standing anode for highly flexible Li-ion batteries.

Rapid and sensitive colorimetric detection of ascorbic acid using carboxymethyl cellulose functionalized Co3O4 nanoparticles as peroxidase mimic

Rapid and sensitive colorimetric detection of ascorbic acid using carboxymethyl cellulose functionalized Co3O4 nanoparticles as peroxidase mimic

Efficient Synthesis and Electrochemical Investigation of Co3O4:PdO/Pd Nanocomposite for High‐Performance Supercapacitor Electrode Material

Advancements in the metal oxides‐based electrode material for the fabrication of supercapacitors have been an important focus of research in recent times. The electrochemical properties of electrode materials play a vital role in the excellent performance of the supercapacitor. In this regard, the doping of Co3O4 nanoparticles (NPs) with PdO/Pd using the ecofriendly extracted foliar reducing and stabilizing agent from Euphorbia cognata is analyzed. The as‐synthesized Co3O4:PdO/Pd nanocomposite exhibits a multifaceted phase composition, characterized by a particle size of 22 nm and a bandgap energy of 2.28 eV. Remarkably, an obvious reduction in bandgap energy is observed, indicative of the heightened electrochemical performance of the Co3O4:PdO/Pd nanocomposite. Galvanostatic charge–discharge techniques elucidate impressive electrochemical properties, including a 202 F g−1 specific capacitance and an exceptionally small resistance value of 1.04 Ω. These findings not only infer efficient charge particle diffusion, but also signify an enhanced charge storage capacity. Thus, the outcomes of this study state the potential of functionalized foliar Co3O4:PdO/Pd nanocomposites as a promising choice for advanced electrode materials in supercapacitor applications. Importantly, this study highlights the significance of utilizing cost‐effective and sustainable materials in the development of pioneering energy storage materials, contributing the advancement of materials field.

Hierarchically structured electrode materials derived from metal-organic framework/vertical graphene composite for high-performance flexible asymmetric supercapacitors

Low conductivity of metal-organic frameworks limits their applications in electrochemical energy storage and conversion. To overcome this shortcoming, we synthesized the zeolitic imidazolate framework-67 on the vertical graphene (VG) surface with abundant defects grown on carbon cloth (ZIF-67-VG-CC). Based on “one-for-two” strategy, the Co3O4 nanoparticles (Co3O4-VG-CC) and nanoporous carbon (NC-VG-CC) can be derived from ZIF-67-VG-CC via selective pyrolysis in the controlled atmospheres. In the hierarchically structured Co3O4-VG-CC and NC-VG-CC, the Co3O4 nanoparticles with a size of 20 nm and N-doped porous carbons were uniformly dispersed on the VG surface, as confirmed by electron microscopies. Both the Co3O4-VG-CC and NC-VG-CC yield high specific capacitance and excellent rate capability. After assembling these two electrodes to make an asymmetric supercapacitor, the Co3O4-VG-CC//NC-VG-CC delivered a maximum energy density of 43.75 Wh/kg at a power density of 5.2 kW/kg as well as excellent cycling stability with 91.5 % specific capacitance retained after 20,000 charge-discharge cycles. All these results should be ascribed to that the VG sheets possess their high electrical conductivity and 3D network structure, and provide the hierarchical supports for the uniform distribution of the ZIF-67-dervied Co3O4 nanoparticles and NC materials, which are beneficial to the fast electron and ion transfer in the electrodes.

Rapid Crystal Structural, Optical and Morphological Studies of Transition Metal Oxide Nanoparticles and their Photocatalytic Activity

In the present work, we report a green synthesis of cobalt oxide (Co3O4), bismuth oxide (Bi2O3) and cobalt-doped bismuth oxide (Co-doped BiO) nanoparticles using Bambusa seed extract. The green synthesized nanoparticles are characterized using various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy and field emission scanning electron microscopy (FESEM). The phase purity of the synthesized nanoparticles is confirmed with the aid of XRD analysis, and the crystallite sizes are found to be 10.42 nm, 18.85 nm and 61.23 nm for Co3O4, Bi2O3 and Co-doped BiO nanoparticles, respectively. Bond length calculations and functional group analysis are done by FTIR technique. The UV–visible analysis depicts higher optical absorption and band gaps varying from 1.81, 2.65 and 1.87 eV for Co3O4, Bi2O3 and Co-doped BiO nanoparticles, respectively. Changes in the surface morphology are observed from FESEM analysis. In addition, the samples' catalytic efficiency in the breakdown of methylene blue (MB) dye was studied and the effects of various process parameters on the extent of dye removals such as photocatalyst amount, irradiation period, the concentration of dye and pH of the solution were also studied. The pseudo-first-order MB photocatalytic decomposition kinetic model has a high correlation coefficient value (R2 > 0.95). The findings support the use of a Co-doped BiO in the field of photocatalytic applications under natural sunlight.

The effect of Cu doping on structural, optical properties and photocatalytic activity of Co3O4 nanoparticles synthesized by sonochemical method

This research article describes pure and different concentrations (2%, 4%, 6%, 10%) of Cu-doped Co3O4 nanoparticles synthesized by sonochemical method and subsequent calcination at high temperature. The synthesized nanoparticles were further characterized using X-ray diffraction, UV–vis spectroscopy, FT-IR spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The analysis results showed that nanoparticle size, band gap and photocatalytic activity of CuxCo3-xO4 compounds can be tuned by changing the Cu doping content. The XRD study reveals no impurity peaks associated with copper or copper oxide phases in the diffractograms of doped samples. The highest degradation of methylene blue dye under visible light was observed in the presence of 2% Cu-doped Co3O4 nanoparticles annealed at 500 °C and found to be 87.51% after 330 min. In addition, the effect of thermal annealing temperature on structural and optical properties of undoped and different concentrations of Cu-doped Co3O4 nanoparticles was investigated in detail.

Continuous polypyrrole nanotubes encapsulated Co3O4 nanoparticles with oxygen vacancies and electron transport channels boosting peroxymonosulfate activation

Continuous polypyrrole nanotubes encapsulated Co3O4 nanoparticles with oxygen vacancies and electron transport channels boosting peroxymonosulfate activation

Enhanced PMS activation by MOF-derived Co3O4/sepiolite composite for norfloxacin degradation: Performance, mechanism and degradation pathway

In this study, cobalt metal-organic framework (Co-MOF) derived Co3O4/sepiolite hybrid catalyst was prepared by a facile wet chemical method followed by the calcination crystallization process. In Co3O4/sepiolite composite, Co3O4 nanoparticles with smaller grain size were well dispersed on sepiolite surface. The larger reaction rate constant was obtained in Co3O4/sepiolite/PMS system for norfloxacin (NFX) degradation (0.2588 min−1), which was almost 3.44 times that in Co3O4/PMS. The greatly enhanced NFX degradation performance was mainly ascribed to the combination of Co-MOF precursor and sepiolite support resulting in higher adsorption capacity, more exposed reaction active sites and overspreading surface hydroxyl groups. The electron paramagnetic resonance (EPR) and quenching experimental results indicated that the radical and non-radical pathway were responsible for the NFX degradation, and the SO4•- and 1O2 were the major contributors. Moreover, the continuous redox cycle of Co(III)/Co(II) and the surface -OH on catalyst played the important roles in the continuous production of the reaction active species thereby achieving the efficient degradation for NFX. In addition, the enhanced catalytic mechanisms and NFX degradation pathways were proposed. Overall, our study provides new insights for designing and developing efficient and environmentally friendly catalysts for practical wastewater treatment via activating PMS.