Co3O4 Nanoparticles Research Articles

Green synthesis of Co3O4 nanoparticles using spent coffee: Application in catalytic and photocatalytic dye degradation

Clean water is vital for societal progress, however, the pollution caused by dyes presents a significant global challenge. Dye-contaminated industrial effluent overwhelms wastewater treatment facilities, causing harm to water bodies and ecosystems. This study demonstrates the synthesis of Co3O4 nanoparticles using spent coffee extract as a bioreducing agent and its application in dye degradation. The structural and optical properties of nanostructures were confirmed using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), and UV–vis spectroscopy. The Co3O4-activated peroxymonosulfate (PMS) system exhibited exceptional catalytic efficiency by attaining a degradation rate of 89.27 % for Tartrazine dye within a 30-minute timeframe, even in the absence of illumination. When exposed to simulated visible light, the degradation kinetic rate increased by 37.60 %, highlighting the excellent photocatalytic activity of Co3O4 nanoparticles. Furthermore, leveraging natural sunlight led to a notable Tartrazine degradation rate of 97.11 %, signifying a substantial 45.41 % enhancement in reaction efficiency when contrasted with the conventional Co3O4/PMS system. Lastly, the Co3O4 nanoparticles illustrated remarkable degradation of synthetic industrial dye effluents (Tartrazine, Methyl Orange, and Remazol Brilliant Red), reaching up to 92.77 % removal, indicating its potential for use in real-world scenarios.

Ice crystal guided folding of graphene oxides in a confined space: a facile approach to 1D functional graphene structures.

The controlled conformational changes of planar graphene nanosheets are of great importance to the realization of their practical applications. Despite substantial effort in the area, the controlled folding of two-dimensional (2D) graphene sheets into one-dimensional (1D) structures still remains a significant challenge. Here, for the first time, we report an ice crystal guided folding strategy to fabricate 1D folded graphene nanobelts (FGBs), where the formation and growth of ice crystals in a confined space function to guide the folding of 2D graphene oxide (GO) nanosheets into 1D nanobelts (i.e. folded graphene oxide belts, FGOBs), which were subsequently converted to FGBs after annealing. Thin aqueous GO containing films were obtained by blowing air through a GO dispersion in the presence of a surfactant, polyoxypropylenediamine (D400), resulting in a foam containing uniform air bubbles. Subsequent shock cooling of the foam using liquid nitrogen resulted in the facile fabrication of FGOBs. This technique provides a general approach to encapsulate catalytic nanomaterials such as Fe3O4 nanorods, TiO2 and Co3O4 nanoparticles into the folded graphene structure for practical applications such as Li-ion batteries.

Electrical and Mechanical Properties of Epoxy Composites Filled with Carbon and Co3O4 Nanoparticles

Electrical and Mechanical Properties of Epoxy Composites Filled with Carbon and Co3O4 Nanoparticles

Probing spin waves in Co3O4 nanoparticles for magnonics applications.

The magnetic properties of spinel nanoparticles can be controlled by synthesizing particles of a specific shape and size. The synthesized nanorods, nanodots and cubic nanoparticles have different crystal planes selectively exposed on the surface. The surface effects on the static magnetic properties are well documented, while their influence on spin waves dispersion is still being debated. Our ability to manipulate spin waves using surface and defect engineering in magnetic nanoparticles is the key to designing magnonic devices. We synthesized cubic and spherical nanoparticles of a classical antiferromagnetic material Co3O4 to study the shape and size effects on their static and dynamic magnetic proprieties. Using a combination of experimental methods, we probed the magnetic and crystal structures of our samples and directly measured spin wave dispersions using inelastic neutron scattering. We found a weak, but unquestionable, increase in exchange interactions for the cubic nanoparticles as compared to spherical nanoparticle and bulk powder reference samples. Interestingly, the exchange interactions in spherical nanoparticles have bulk-like properties, despite a ferromagnetic contribution from canted surface spins.

Enhanced CO oxidation in porous metal-oxide nanoparticles derived from MOFs

Porous nanoparticles of Co3O4, Fe2O3 and Fe3O4 were successfully developed. Among them, the porous Co3O4 nanoparticles greatly improved the catalytic CO oxidation performance due to their large specific surface area and excellent Co active sites.

Hierarchical structure promoted lithiation/delithiation behavior of a double-carbon microsphere supported nano-Co3O4 anode.

Due to limited mass loading, high-capacity electrode materials such as transition metal oxides (TMOs) are essential for microscale Li-ion batteries (LIBs) integrated in nano-/micro-electromechanical systems (N/MEMS). Unfortunately, their electrochemical performances are largely plagued by severe mechanical degradation and slow electron transport. Therefore, it is crucial to develop strategies that can improve the structural stability and electronic conductivity of TMO electrodes. In this work, double-carbon (carbon nanotubes and ketjen black) microsphere (DCMS) supported Co3O4 electrodes are fabricated simply through a spray drying and solvothermal method, which are designed to have a mesoporous three-dimensional (3D) hierarchical heterostructure containing well-dispersed Co3O4 nanoparticles within the DCMS framework. An in situ transmission electron microscopy (TEM) study reveals that the DCMS framework can not only provide facile strain accommodation, but also good electronic conductivity, leading to a much improved Li-storage performance compared to other Co3O4-based anodes. The hierarchical electrode exhibits maximum charge capacities of 1205.2 and 678.1 mA h g-1 at current densities of 0.1 and 2 A g-1, respectively, as well as a capacity retention of 92.2% at 0.3 A g-1 after 100 cycles. This study provides a low-cost, simple and general method for developing advanced high-capacity electrodes.

Enhanced photocatalytic degradation and antimicrobial activities of biogenic Co3O4 nanoparticles mediated by fenugreek: sustainable strategies

The present study introduces Trigonella foenum-graecum (TFG, fenugreek)-mediated Co3O4 nanoparticles (NPs) as an innovative solution for eliminating industrial azo dyes from contaminated water.

Decrypting the hydrogen evolution in alkaline water with novel magnetoactive cobalt(II) complex-driven cobalt oxide electrocatalysts.

Under the gravity of future socio-economic development, the viability of water electrolysis still hinges on the accessibility of stable earth-abundant electrocatalysts and net energy efficiency. This work emphasizes the design and synthesis of two newly developed cobalt(II) complexes, [Co(HL)2(NCS)2] (Comono) and [Co2(L)3(CH3OH)]ClO4 (Codi), with a (N,O)-donor ligand, HL (2-methoxy-6-(((2-methoxyphenyl)imino)methyl)phenol). The study delves into understanding their structural, morphological, magnetic, and charge transport characteristics. Moreover, the study explores the potential of these complexes in catalyzing hydrogen production through heterogeneous electrocatalysis. The X-ray crystal structure of Comono reveals the octahedral geometry of the Co(II) ion, adopting two HL units and two NCS- units. The Codi complex exhibits a doubly-phenoxo-O-bridged (μ1,1) dinuclear complex, forming a typical octahedral geometry for both the Co(II) centres in coupling with three units of L-. Temperature-dependent magnetic susceptibility measurements showed that all of the Co(II) ion in Comono shows a typical paramagnetic behaviour for high spin octahedral Co(II) ions while the Co(II) centres in Codi are coupled with doubly-phenoxo-bridges bearing weak ferromagnetic characteristics at low temperature. Electron transport properties of the Co(II) complex-mediated Schottky device address the superior carrier mobility (μ) for Codi (9.21 × 10-5) over Comono (2.02 × 10-5 m2 v-1 s-1) with respective transit times of 1.70 × 10-9 and 7.77 × 10-9 s. Additionally, electron impedance spectral analysis supports the lower electrical transport resistance of Codi relative to Comono. The heterogeneous electrocatalytic HER activity of Codi and Comono in 0.1 M KOH shows excellent electrocatalytic efficiency in terms of the various electrochemical parameters. Constant potential electrolysis, multi-cycle CVs, and post-HER analysis reveal the pre-catalytic nature of the complexes, which in turn delivers Co3O4 nanoparticles as the active catalysts for efficient hydrogen evolution.

Engineering of Co3O4 electrode via Ni and Cu-doping for supercapacitor application.

Although cobalt oxides show great promise as supercapacitor electrode materials, their slow kinetics and low conductivity make them unsuitable for widespread application. We developed Ni and Cu-doped Co3O4 nanoparticles (NPs) via a simple chemical co-precipitation method without the aid of a surfactant. The samples were analyzed for their composition, function group, band gap, structure/morphology, thermal property, surface area and electrochemical property using X-ray diffraction (XRD), ICP-OES, Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-visible (UV-Vis), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and/or Differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET), and Impedance Spectroscopy (EIS), Cyclic voltammetry (CV), respectively. Notably, for the prepared sample, the addition of Cu to Co3O4 NPs results in a 11.5-fold increase in specific surface area (573.78m2g-1) and a decrease in charge transfer resistance. As a result, the Ni doped Co3O4 electrode exhibits a high specific capacitance of 749Fg-1, 1.75 times greater than the pristine Co3O4 electrode's 426Fg-1. The electrode's enhanced surface area and electronic conductivity are credited with the significant improvement in electrochemical performance. The produced Ni doped Co3O4 electrode has the potential to be employed in supercapacitor systems, as the obtained findings amply demonstrated.

Well-defined tricobalt tetraoxide's critical morphology effect on the structure-reactivity relationship.

This review focuses on exploring the intricate relationship between the catalyst particle size and shape on a nanoscale level and how it affects the performance of reactions. Drawing from decades of research, valuable insights have been gained. Intentionally shaping catalyst particles makes exposing a more significant percentage of reactive facets possible, enabling the control of overactive sites. In this study, the effectiveness of Co3O4 nanoparticles (NPs) with nanometric size as a catalyst is examined, with a particular emphasis on the coordination patterns between oxygen and cobalt atoms on the surface of these NPs. Investigating the correlation between the structure and reactivity of the exposed NPs reveals that the form of Co3O4 with nanometric size can be modified to tune its catalytic capabilities finely. Morphology-dependent nanocatalysis is often attributed to the advantageous exposure of reactive crystal facets accumulating numerous active sites. However, experimental evidences highlight the importance of considering the reorganization of NPs throughout their actions and the potential synergistic effects between nearby reactive and less-active aspects. Despite the significant role played by the atomic structure of Co3O4 NPs with nanometric size, limited attention has been given to this aspect due to challenges in high-resolution characterizations. To bridge this gap, this review strongly advocates for a comprehensive understanding of the relationship between the structure and reactivity through real-time observation of individual NPs during the operation. Proposed techniques enable the assessment of dimensions, configuration, and interfacial arrangement, along with the monitoring of structural alterations caused by fluctuating temperature and gaseous conditions. Integrating this live data with spectroscopic methods commonly employed in studying inactive catalysts holds the potential for an enhanced understanding of the fundamental active sites and the dynamic behavior exhibited in catalytic settings.

Ampere-level oxygen evolution reaction driven by Co3O4 nanoparticles supported on layered TiO2

The Co3O4 nanoparticles supported on a layered TiO2 surface by Co–O–Ti covalent bond towards the highly active ampere-level oxygen evolution reaction.

ZIF-derived oxygen vacancy-rich Co3O4 for constructing an efficient Z-scheme heterojunction to boost photocatalytic water splitting.

With ZIF-67 as the precursor, oxygen vacancy-rich Co3O4 nanoparticles were derived and anchored on the surface of 2D polyimide (PI) to construct a Z-scheme hybrid heterojunction (20ZP) through a simultaneous solvothermal in situ crystallization and polymerization strategy. XRD, XPS and EPR confirmed that both Co(III) and oxygen vacancies are formed during the low temperature conversion of ZIF-67 to Co3O4 nanoparticles that in turn accelerate the polymerization of PI. Synchronous crystallization makes the interfacial architecture intermetal and compact, inducing a strong interfacial electronic interaction between Co3O4 nanoparticles and PI. UV-vis DRS spectra and transient photocurrent response demonstrate that the incorporation of Co3O4 on polyimide not only extends the light absorption in the visible range, but also enhances the charge transfer rate. EIS, TRPL techniques and DFT calculations have confirmed that the photoinduced interfacial charge transfer pathway of this hybrid heterojunction characterized the Z-scheme in which the photoinduced electrons transfer from the conduction band of Co3O4 to the valence band of PI, significantly inhibiting the recombination of electrons and holes within PI. More importantly, the oxygen vacancies located below the conductor band of Co3O4 can deepen the band bending, improve the charge separation efficiency and accelerate electron transfer between Co3O4 and PI. This Z-scheme hybrid heterojunction structure can not only maintain the high reducing capacity of photoinduced electrons on the conductor band of PI, but also enhance the oxidative capacity of the heterojunction composite material, thus promoting the overall progress of the photocatalytic hydrogen release reaction.

Co3O4 nanoparticle modified N, P co-doped carbon paper as sodium carrier to construct stable anodes for Na-metal batteries.

Sodium (Na) metal batteries such as Na-ion batteries and Na-CO2 batteries are considered to be excellent alternatives to lithium batteries in terms of their potential applications because of their high specific capacity and low cost. However, the sodium anode showed low efficiency and poor cycling in Na-metal battery performance due to the formation of sodium dendrites and serious corrosion. In this work, nitrogen (N), phosphorus (P) co-doped carbon paper (NP-CP) modified with cobalt tetroxide (Co3O4) nanoparticles was prepared as the Na anode carrier (Co3O4@NP-CP), and a sodium-based composite anode (Na-Co@NP-CP) was further prepared by electrodepositing sodium. The experimental results indicate that the N, P and Co3O4 multi-doped carbon paper has good sodiophilicity, which can induce the uniform plating/stripping of Na+ ions and inhibit the growth of Na dendrites. The N, P doped carbon paper provides a high surface area and tremendous three-dimensional (3D) framework to effectively reduce the areal current density, facilitate the transfer of electrons, and enhance battery life. Therefore, Na-Co@NP-CP based symmetric cells exhibit stable cycling of over 1100 hours at current densities of 1 mA cm-2 and fixed capacity of 1 mA h cm-2. When the Na-Co@NP-CP anode couples with CO2, the assembled batteries can deliver a stable cycling of 165 cycles at current densities of 500 mA g-1 and limited capacity of 500 mA h g-1. When Na-Co@NP-CP anode couples with Na3V2(PO4)3 (NVP) cathode, the assembled cells exhibit lower hysteresis and batter cycling performance.

Atomically dispersed silver atoms incorporated in spinel cobalt oxide (Co3O4) for boosting oxygen evolution reaction

Incorporating noble metal single atoms into lattice of spinel cobalt oxide (Co3O4) is an attractive way to fabricate oxygen evolution reaction (OER) electrocatalysts because of the high activity and economic benefit. The commonly used high valence noble metal dopants such as ruthenium, iridium and rhodium tend to supersede Co3+ at octahedral site of Co3O4 and result in great activity, the origins of admirable activity were also wildly investigated. However, bare explorations on doping noble metal single atom into tetrahedral site of Co3O4 to construct OER catalyst have been reported, corresponding catalytic activity and mechanism remain mystery. Here, a promising structure that tetrahedrally substituent Ag single atom embedded in Co3O4 nanoparticles on the surface of carbon nanotube (Ag-Co3O4/CNT) was presented, and its performance in OER was probed. The high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption spectroscopy (XAS) demonstrate the successful embeddedness of atomical Ag atom in Co3O4 lattice, the resultant electronic interaction is conducive to promote charge transfer for OER. Theoretical calculations further disclose that atomical Ag dopant prefers to replace tetrahedral Co2+ rather than octahedral Co3+. The substitution Ag acts as the active site through Ag-Co bridge and facilitates the desorption process, which improves the turnover frequency (TOF) and boosts the intrinsic activity of Ag-Co3O4/CNT. Benefiting from the essentials above, Ag-Co3O4/CNT displays remarkable activity (236 mV@10 mA cm−2) and robust stability for alkaline OER. This finding offers a potential direction for the design of noble metal single atom involved Co3O4 based OER electrocatalysts.

Trace PdO and Co-MOF derivative modified SnO2 nanofibers for rapid triethylamine detection with little humidity disturbance

Triethylamine (TEA) is a significant compound, but it is toxic and flammable. Since the humidity in the environment is constantly changing, it is meaningful to develop a sensor that can detect TEA efficiently and is less disturbed by humidity. Here, Pd nanoparticles with a small particle size (about 4 nm) were prepared by reduction method and dispersed on Co-MOF (ZIF-67). Pd@ZIF-67-derived trace PdO and Co3O4 nanoparticles were evenly decorated on SnO2 nanofibers by electrospinning and calcination. The ratios of PdO to SnO2 in PdO-Co3O4-SnO2 were 0.012 wt% and 0.048 wt%, respectively. The response of the sensor based on 0.012 wt% PdO-Co3O4-SnO2 to 20 ppm TEA was 14 at 240 °C. The response time was 3 s and the lowest concentration actually detected was 1 ppm. The synergistic effects of oxygen vacancy, p-n junction, electron sensitization of PdO and morphology of composite improved sensing performance. In addition, due to the inhibition of hydroxyl poisoning by PdO and the oxidation assisting effect of Co3O4, the composite had excellent humidity resistance.

Structure-Function Relationship of Highly Reactive CuOx Clusters on Co3 O4 for Selective Formaldehyde Sensing at Low Temperatures.

Designing reactive surface clusters at the nanoscale on metal-oxide supports enables selective molecular interactions in low-temperature catalysis and chemical sensing. Yet, finding effective material combinations and identifying the reactive site remains challenging and an obstacle for rational catalyst/sensor design. Here, the low-temperature oxidation of formaldehyde with CuOx clusters on Co3 O4 nanoparticles is demonstrated yielding an excellent sensor for this critical air pollutant. When fabricated by flame-aerosol technology, such CuOx clusters are finely dispersed, while some Cu ions are incorporated into the Co3 O4 lattice enhancing thermal stability. Importantly, infrared spectroscopy of adsorbed CO, near edge X-ray absorption fine structure spectroscopy and temperature-programmed reduction in H2 identified Cu+ and Cu2+ species in these clusters as active sites. Remarkably, the Cu+ surface concentration correlated with the apparent activation energy of formaldehyde oxidation (Spearman's coefficient ρ = 0.89) and sensor response (0.96), rendering it a performance descriptor. At optimal composition, such sensors detected even the lowest formaldehyde levels of 3 parts-per-billion (ppb) at 75°C, superior to state-of-the-art sensors. Also, selectivity to other aldehydes, ketones, alcohols, and inorganic compounds, robustness to humidity and stable performance over 4 weeks are achieved, rendering such sensors promising as gas detectors in health monitoring, air and food quality control.

A Comparative Study of NiCo2O4, NiO, and Co3O4 Electrocatalysts Synthesized by a Facile Spray Pyrolysis For Electrochemical Water Oxidation

AbstractExploiting low‐cost, highly active, and robust oxygen evolution reaction (OER) electrocatalysts based on earth‐abundant elements by a simple synthesis approach holds paramount importance for green hydrogen production through water electrolysis. In this work, the NiO, Co3O4 and NiCo2O4 nanoparticle layers with identical surface morphologies are prepared under same deposition conditions by a simple spray pyrolysis method and their OER activities are comparatively investigated. Among all these three electrocatalysts, NiCo2O4 shows the lowest overpotential of 420 mV to drive benchmark current density of 10 mA cm−2 and the smallest Tafel slope (84.1 mV dec−1), which are comparable to the OER performance of the benchmark commercial RuO2 electrocatalyst. The high OER activity of NiCo2O4 is attributed to the synergy effect and the modulation of electronic properties between Co and Ni atoms, which drastically reduces the overpotential required to drive OER activities. Therefore, it is believed that the NiCo2O4 synthesized by this simple method would be a competitive candidate as an industrial electrocatalyst with high‐efficiency and low cost for large‐scale green hydrogen production via water electrolysis.

Cationic Disorder and Surface Effects on the Magnetic Properties of Co3O4$\left(\text{Co}\right)_{3} \left(\text{O}\right)_{4}$ Nanoparticles Synthesized by Co‐Precipitation with Addition of Sucrose

Herein, the effect of adding sucrose chelating agent on the structural and magnetic properties of single‐phase Co3O4 nanoparticles is examined. The samples are obtained using coprecipitation with varying concentrations of sucrose. The X‐ray diffraction data and the scanning electron microscopy and transmission electron microscopy images indicate that the average particle size, their shape, and size distribution depend on the sucrose concentration. The smallest size obtained is around 6 nm for the sample grown with 0.32 mol L−1 of sucrose. Magnetic measurements as a function of magnetic field and temperature indicate that the samples exhibit superparamagnetic behavior below 10 K, and the peak in susceptibility decreases with increasing sucrose concentration, reaching a minimum value of 4.5 K for the sample grown with 0.32 mol L−1 of sucrose. After subtracting the high‐field linear contribution, likely attributed to superparamagnetism, saturation in the M vs. H curves measured at T = 2 K is observed. The saturation is approximately 1.2 emu g−1 for all samples. Since bulk Co3O4 is expected to be antiferromagnetic at T = 40 K, this value of magnetization may be linked to the degree of cationic disorder in the occupation of and ions between A and B sites.

Solid state conversion of novel coordinated precursors to visible light active photocatalysts with enhanced photocatalytic activity

The new polydentate N'1,N'3‐bis((E)‐3‐oxopentan‐2‐ylidene)malonohidrazide chelating agent (H2L) and its coordinated complexes of Co2+, Cu2+, and Ni2+ were prepared and characterized by elemental analysis, molar conductance, and spectra (Fourier transform infrared [FT‐IR], ultraviolet–visible spectroscopy [UV–vis], and Fast‐Atom Bombardment Mass Spectrometry (FAB‐MS). Also, thermal and magnetic investigations were conducted. X‐ray single crystal of the H2L ligand revealed a triclinic structure with space group P‐1. In this study, we provide a one‐pot preparation approach for transition metal oxide nanoparticles (NPs) such as CuO, Co3O4, and NiO NPs. The methodology entails the thermal decomposition of coordinated metal precursors in a solid‐state environment, obviating the necessity for agitation and rinsing. The remarkable significance of this method lies in its ability to produce highly pure NPs without the requirement of washing, and it allows for systematic and efficient production. Herein, we propose a large‐scale, environmentally benign and renewable, transition metals oxide NPs such as CuO, Co3O4, and NiO using solid‐state thermal degradation of their coordinated precursors. The NPs are subjected to analysis employing a range of techniques, such as X‐ray powder diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), N2 sorpometry (BET), and UV–vis). The photocatalytic activities of the synthesized NPs were assessed using photodegradation of organic contaminants in wastewater.

Cobalt species immobilized on nitrogen‑doped ordered mesoporous carbon for highly efficient catalytic ozonation of atrazine

The strategy of coupling transition metal and N-doped carbon catalysts have garnered great attention in catalytic ozonation. To overcome the inferior mass transfer of O3, we prepared a hetero-structure catalyst (Co3O4@Co-N-CMK3), which was composed of Co3O4 nanoparticles (NPs) and cobalt-nitrogen doped ordered mesoporous carbon. Co3O4@Co-N-CMK3 displayed a uniformly arranged long-range mesoporous channel structure with large surface area (537.24 m2/g). The adsorption efficiency of ATZ (10 μM) was 55% at 15 min in presence of 0.05 g/L catalyst. After aeration of 3.5 mg/L O3 gas (50 mL min-1), the ATZ removal increased to 99.6% with rate constant of 0.354 min-1 in Co3O4@Co-N-CMK3/O3, 35.4-fold that in ozonation. The turnover frequency (TOF) value of Co3O4@Co-N-CMK3 reached 7.08 min-1 g-1, which was 2.2-93.2 folds higher than the reported ozonation catalysts. Co3O4@Co-N-CMK3 displayed the adsorption performance for ATZ and could activate O3 into O2- and OH effectively. The ≡Co2+ and ≡Co-Nx were main active sites. The synergy between Co3O4 and Co-N-CMK3 accelerated interface electron transfer, which was conducive to the redox of ≡Co2+/≡Co3+. The degradation pathway and intermediates toxicity were speculated using HPLC-MS measurement and Toxicity Estimation Software Tool simulation. The stability of Co3O4@Co-N-CMK3 for ATZ removal was certified by five consecutive experiments in catalytic ozonation. Moreover, the Co3O4@Co-N-CMK3/O3 process had good applicability to common anions and humic acid, real water and different pollutants.