Porous Co3O4 Nanorods Research Articles

A novel ternary nanocomposite based electrochemical sensor coupled with regularized neural network for nanomolar detection of sunset yellow FCF

Synthetic dyes are extensively used worldwide although they instigate adverse environmental and health issues at higher concentrations. A reliable and ultrasensitive electrochemical sensor for nanomolar determination of common food colorant sunset yellow FCF is reported in this paper. The electrochemical sensor was integrated with a regularized neural network to enable intelligent sensing of this azo dye. The sensor was fabricated using a ternary nanocomposite based on silver doped spinel Co3O4 nanorods embedded functionalized multi-walled carbon nanotubes (fCNTs). Co-precipitation method was employed for synthesis of porous Co3O4 nanorods and CNTs were functionalized using acid-treatment approach. Electrochemical investigations based on cyclic voltammetry and differential pulse voltammetry techniques revealed stupendous electrocatalytic performance towards sunset yellow detection. A nanomolar detection limit of 0.8 nM and high sensitivity of 8.79 μA μM−1 cm−2 was exhibited by the developed sensor and real sample analysis experiment was conducted in commercial beverages to validate its practical feasibility.

Controllable synthesis of porous Co3O4 nanorods and their ethanol-sensing performance

A simple strategy for synthesizing porous Co3O4 nanostructures through a hydrothermal process with subsequent thermal decomposition of the obtained Co(CO3)0·35Cl0·20(OH)1.10 precursors was introduced. To understand the growth mechanism of the Co(CO3)0·35Cl0·20(OH)1.10 precursors and realize morphology control of the resultant Co3O4 nanomaterials, a series of controlled experiments were carried out by varying CO(NH2)2 dosages, hydrothermal temperatures and time. The Co3O4 nanorods obtained under optimized synthesis conditions demonstrated porous structural features, which were constructed by well-connected nanograins, leaving many pores composed of the space between nanograins. The ethanol-sensing behaviors of these Co3O4 nanostructures were evaluated, showing the highest response (19.581) and a short response and recovery time (1 s/10 s) to 100 ppm ethanol. Moreover, the Co3O4 sensor demonstrated excellent anti-interference ability toward several interfering gases such as methanol, benzene hexane, and dichloromethane. The stability of the Co3O4 sensor was further confirmed by 14 days of continuous testing. Compared with previously reported works, this Co3O4 sensor still demonstrated outstanding gas sensing properties due to its unique advantages such as 1D porous nanostructures, high BET surface area, abundant oxygen vacancies, and active cobalt sites.

A sensitive and economical electrochemical platform for detection of food additive tert-butylhydroquinone based on porous Co3O4 nanorods embellished chemically oxidized carbon black

Artificial food preservatives are widely utilized across the globe to prolong shelf life of food. In this paper, a highly sensitive and cost-effective electrochemical sensor for the nanomolar detection of synthetic antioxidant tert-butyl hydroquinone (TBHQ) commonly used as a food preservative is reported. A hybrid nanocomposite was sonochemically prepared by embedding surface functionalized carbon black (FCB) on spinel Co3O4 nanorods. We used oxalic acid mediated co-precipitation approach in the synthesis of highly porous Co3O4 nanorods and CB was chemically oxidized using acid-treatment. Significant characterization techniques including XRD, SEM, mapping, Raman spectroscopy, FTIR, and EIS were utilized for analyzing morphological and structural properties of materials. The prepared hybrid nanocomposite modified electrode exhibited excellent electrochemical performance. A high sensitivity of 7.94 μA μM−1 cm−2, ultra-low detection limit of 1 nM, and quantification limit of 5 nM was achieved in TBHQ detection based on the modified electrode. Furthermore, the practicality of the developed electrochemical sensor in TBHQ detection is confirmed by conducting real sample analysis experiment in beef tallow, peanut oil, and lake water resulting in adequate recovery values.

Characterization and Pseudo-Capacitance Performance of Porous Co3O4 Nanorods Synthesized by Thermal Decomposition

Characterization and Pseudo-Capacitance Performance of Porous Co3O4 Nanorods Synthesized by Thermal Decomposition

Engineering coordination polymer-derived one-dimensional porous S-doped Co3O4 nanorods with rich oxygen vacancies as high-performance electrode materials for hybrid supercapacitors.

Structure and defect manipulation are regarded as efficacious strategies to boost the electrochemical activity of electrode materials. Herein, the construction of one-dimensional (1D) porous S-doped Co3O4 nanorods with rich oxygen vacancies is demonstrated through a facile metal-organic framework-engaged strategy. Starting from a Co-NTA (NTA = nitrilotriacetic acid) precursor, the S-doped Co3O4 nanorods were obtained after calcination and sulfurization. As a faradaic electrode material, the S-doped Co3O4 nanorods exhibited enhanced specific capacitance (319.3 C g-1 at 0.5 A g-1) in comparison with the Co3O4 intermediate product (98.3 C g-1) and the Co-NTA precursor (40.2 C g-1). Besides, it showed an ultra-high rate capability of 83.3% with a 20-fold increase in current density (10 A g-1). The hybrid supercapacitor comprising the S-doped Co3O4 (cathode) and the activated carbon (anode) showed a high energy density of 38.1 W h kg-1 at a power density of 800 W kg-1, and 31.1 W h kg-1 was maintained at 8000 W kg-1. It also has excellent electrochemical stability, and 87.57% of its initial capacitance was maintained after 5000 cycles, demonstrating great prospects in electrochemical energy storage applications. The excellent energy storage property of the S-doped Co3O4 is due to its unique 1D S-doped Co3O4 porous nanorod structure, i.e., large surface area, easy diffusion of ions, good conductivity, and rich redox reactions. This work may pave the way for the fabrication of desirable electrode materials through vacancy defects and nano-/microstructure engineering.

Facial preparation of N-doped carbon foam supporting Co3O4 nanorod arrays as free-standing lithium-ion batteries’ anode

Here, free-standing lithium-ion batteries (LIBs) anodes were fabricated through using flexible N-doped carbon foam (NCF) derived from melamine foam as substrate and current collector based on triethylamine (TEA)-assisted burning of Co(CO3)0·5OH/NCF in air. The burning not only achieved the simple transformation from Co(CO3)0·5OH to porous Co3O4 nanorods which were arrayed on NCFs evenly, but also maintained the flexibility and integrity of NCF. The as-obtained NCF/Co3O4 composites had a robust three-dimensional framework and porous structure, which improved the electron/ion transfer, enhanced contact area with electrolyte and prevented the volume inflation in discharging/charging process. In the combusting process, TEA was transformed into N and carbon atom coating on NCF and Co3O4 nanorods, and eventually formed cross-linked NCF frame helpful to stabilize Co3O4 nanorods. When the NCF/Co3O4 composites were applied directly as free-standing LIBs’ anode, it had a higher loading mass of ∼2.5 mg cm−2 compared to traditional anode. In addition, the low charge transfer impedance and easy separation caused by the addition of traditional inactive materials were eliminated. Therefore, the flexible porous NCF/Co3O4 anode without any conductive additives and binders showed the discharge capacity of 576 mAh g−1 at 1 A g−1 after 300 cycles and excellent rate capability.

Preparation and Lithium Storage Performances of Porous Co<sub>3</sub>O<sub>4</sub> Nanorods

We report on the porous Co3O4 nanorods synthesized by hydrothermal reaction and applied as an anode material for reversible lithium storage. The Co3O4 with porous nanorods structure increases the contact surface, shortens the diffusion path of ion/electron, and improves its structure stability and collaborative electronic transmission. Due to the nanoparticle subunits, the electrodes exhibit high electrochemical performance. Impressively, a high reversible discharge specific capacity of 1105 mAh g-1 is obtained at 200 mA g-1 after 50 cycles. This indicates the excellent potential of porous Co3O4 nanorods as an anode material for lithium ion batteries. Thus, the porous Co3O4 nanorods might open an insight for transition-metal oxides as energy storage materials.

Porous Co3O4 nanorods anchored on graphene nanosheets as an effective electrocatalysts for aprotic Li-O2 batteries

The large over-potential during the battery operation is a great obstacle for the application of Li-O2 batteries. The porous structure and electrical conductivity of the electrocatalysts are significant for the electrocatalytic performance of Li-O2 batteries. In this work, a porous Co3O4/GN nanocomposite (Co3O4 nanorods anchored on graphene nanosheets) is prepared via a facile hydrothermal method assisted with heat treatment. The unique structure of Co3O4/GN endows efficient electrocatalystic activity for Li-O2 batteries. In comparison to the Co3O4, the Co3O4/GN demonstrates a better cycle performance showing more than 40 cycles with a 1500 mAh g−1 capacity limit strategy at a current density of 300 mA g−1, and a reduced over-potential of 110 mV at high current density (1200 mA g−1). The Co3O4/GN also displays a high initial specific capacity (7600 mAh g−1) and a good reversibility in full cycle with a coulombic efficiency of 99.8% in the first cycle. The impressed cyclability, specific capacity, rate performance, and low over-potentials indicate that the as-prepared Co3O4/GN nanocomposite is a promising catalyst candidate for reversible Li-O2 batteries.

Two-pot synthesis of one-dimensional hierarchically porous Co3O4 nanorods as anode for lithium-ion battery

Poor cyclic stability and low rate capability are two severe stumbling blocks for Co3O4-based anodes due to the insufficient structural stability of the electrode, difficult access of electrolyte to the electrode interior as well as dense structure. In this respect, one-dimensional hierarchically porous Co3O4 nanorods (HP-Co3O4 NR), which are constructed by interconnected nanoparticles, are successfully synthesized via a facile hydrothermal method following calcination. In the architecture, (i) nanoparticle-decoration is favorable to shorten the ions and charge diffusion distance, which improve the rate performance; (ii) the hierarchically porous structure can sufficiently buffer the volume change during the extended cycling, which is conducive to stable electrode structure and good cyclic stability; (iii) 1D porous nanorods ensure more exposed active sites and the contact area of the electrolyte/electrode for lithium storage, which endows the high reversible capacity. As a result, the HP-Co3O4 NR material exhibits high capacity (628 mAh g−1 at 1 A g−1 after 350 cycles), exceptional rate capability (247 mAh g−1 at 6 A g−1) and long cycle life (0.068% capacity decay per cycle after 600 cycles at 5 A g−1), simultaneously. Our results indicate that the one-dimensional hierarchically porous nanoparticle-decorated nanorods structure is beneficial for improving the cycling and rate performance.

Potential of porous Co3O4 nanorods as cathode catalyst for oxygen reduction reaction in microbial fuel cells

This study aims to investigate the potential of porous Co3O4 nanorods as the cathode catalyst for oxygen reduction reaction (ORR) in aqueous air cathode microbial fuel cells (MFCs). The porous Co3O4 nanorods were synthesized by a facile and cost-effective hydrothermal method. Three different concentrations (0.5mg/cm2, 1mg/cm2, and 2mg/cm2) of Co3O4 nanorods coated on graphite electrodes were used to test its performance in MFCs. The results showed that the addition of porous Co3O4 nanorods enhanced the electrocatalytic activity and ORR kinetics significantly and the overall resistance of the system was greatly reduced. Moreover, the MFC with a higher concentration of the catalyst achieved a maximum power density of 503±16mW/m2, which was approximately five times higher than the bare graphite electrode. The improved catalytic activity of the cathodes could be due to the porous properties of Co3O4 nanorods that provided the higher number of active sites for oxygen.

Porous Co3O4 nanorods as anode for lithium-ion battery with excellent electrochemical performance

In this manuscript, porous Co3O4 nanorods are prepared through a two-step approach which is composed of hydrothermal process and heating treatment as high performance anode for lithium-ion battery. Benefiting from the porous structure and 1-dimensional features, the product becomes robust and exhibits high reversible capability, good cycling performance, and excellent rate performance.

Porous Co3O4 nanorods as superior electrode material for supercapacitors and rechargeable Li-ion batteries

Porous aggregated nanorods of Co3O4 with a surface area of ~100 m2 g−1 synthesized without using any templates or surfactants give very high specific capacitance of ~780 F g−1 when used as electrode in a faradaic supercapacitor, with a cycle life of more than 1,000 cycles. Further, in Li-ion batteries when used as an anode, the Co3O4 nanorods achieved a capacity of 1155 mA h g−1 in the first cycle and upon further cycling it is stabilized at 820 mA h g−1 for more than 25 cycles. Detailed characterization indicated the stability of the material and the improved performance is attributed to the shorter Li-insertion/desertion pathways offered by the highly porous nanostructures. The environmentally benign and easily scalable method of synthesis of the porous Co3O4 nanorods coupled with the superior electrode characteristics in supercapacitors and Li-ion batteries provide efficient energy storage capabilities with promising applications.

Porous Co3O4 Nanorods–Reduced Graphene Oxide with Intrinsic Peroxidase-Like Activity and Catalysis in the Degradation of Methylene Blue

A facile two step process was developed for the synthesis of porous Co3O4 nanorods-reduced graphene oxide (PCNG) hybrid materials based on the hydrothermal treatment cobalt acetate tetrahydrate and graphene oxide in a glycerol-water mixed solvent, followed by annealing the intermediate of reduced graphene oxide-supported Co(CO3)0.5(OH)·0.11H2O nanorods in a N2 atmosphere. The morphology and microstructure of the composites were examined by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. It is shown that the obtained PCNG have intrinsic peroxidase-like activity. The PCNG are utilized for the catalytic degradation of methylene blue. The good catalytic performance of the composites could be attributed to the synergy between the functions of porous Co3O4 nanorods and reduced graphene oxide.

Porous Co3O4 nanowires and nanorods: Highly active catalysts for the combustion of toluene

Porous Co3O4 nanowires and nanorods (Co3O4-HT, Co3O4-HT-PEG, Co3O4-HT-CTAB, and Co3O4-ME-CTAB, respectively) have been fabricated via the hydrothermal or microemulsion route in the absence and presence of polyethylene glycol (PEG) or cetyltrimethylammonium bromide (CTAB), respectively. Physicochemical properties of the materials were characterized by means of numerous techniques, and their catalytic activities for toluene combustion were evaluated. It is shown that Co3O4-HT-PEG and Co3O4-HT-CTAB displayed a porous nanowire-like morphology, whereas Co3O4-ME-CTAB exhibited a porous nanorod-like shape. The porous Co3O4 samples (surface area=47–52m2/g) possessed much higher surface oxygen adspecies concentrations and much better low-temperature reducibility than the nonporous counterpart. The Co3O4-HT-CTAB sample showed the highest catalytic performance (T50%=195 and T90%=215°C at a space velocity of 20,000mL/(gh)). It is concluded that the excellent catalytic performance of Co3O4-HT-CTAB was associated with its higher surface area and surface oxygen species concentration, and better low-temperature reducibility.

From cobalt nitrate carbonate hydroxide hydrate nanowires to porousCo3O4 nanorods for high performance lithium-ion battery electrodes

We have developed a simple approach for the large-scale synthesis of cobalt nitrate carbonate hydroxidehydrate (Co(CO3)0.35(NO3)0.2(OH)1.1·1.74H2O) nanowires via the hydrothermal process using sodium hydroxide and formaldehyde as mineralizers at120 °C. Theporous Co3O4 nanorods 10–30 nm in diameter and hundreds of nanometres in length have beenfabricated from the above-mentioned multicomponent nanowires by calcination at400 °C. The morphology and structure of cobalt nitrate carbonate hydroxide hydrate nanowires andCo3O4 nanorods have been characterized by transmission electron microscopy (TEM), fieldemission scanning electron microscopy (FESEM), high resolution transmission electronmicroscopy (HRTEM) and x-ray powder diffraction (XRD). Moreover, the porousCo3O4 nanorods have been applied in the negative electrode materials for lithium ion batteries,which exhibit high electrochemical performance.