Synergistic integration based on some transition-metal (TM) derived compounds is a unique and appealing technique, especially toward oxygen evolution reaction (OER) under alkaline circumstances. ...Herein, we present a cobalt-selenide (CoSe2) and cobalt-oxide (Co3O4) based composite (CSCO-2) material through a wet chemical method. As-prepared catalyst has been analyzed for various physicochemical characterizations. CSCO-2 offers efficient OER performance in 1.0 M KOH with an overpotential of 252 mV at current density of 20 mA/cm2, with a low Tafel slope value of 69 mV/dec. Importantly, as-prepared catalyst shows stability of 48 h for longer electrochemical performance as a potential candidate for OER.
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•Robust CoSe2 and Co3O4 based electrocatalyst for OER in the alkaline media.•Electrochemical efficiency with lower overpotential of 252 mV and Tafel slope of 69 mV/dec.•Having an electrochemical surface area of 367.5 cm2.•Stability for 48 h as longer performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cholesterol is a lipid molecule in protein and cell membrane and precursor of bile acids, steroids hormones and vitamin D. Higher level of cholesterol, especially low-density lipoprotein (LDL), ...becomes a cause of cardiovascular disease (CVD). Adsorbent of LDL from human blood plasma plays crucial role for the treatment of hyperlipidemia. Therefore, a suitable adsorbent material for efficient and selective adsorption of low-density lipoprotein is beneficial. In this work, amino acids assisted iron oxide (Fe
3
O
4
) was synthesized by hydrothermal method. The morphology, size, crystallinity, and chemical attachment of Fe
3
O
4
nanoparticles are characterized by SEM, FESEM/EDS, HRTEM, XRD, XPS, FTIR, and Raman spectroscopy. The lysine-assisted Fe
3
O
4
(Fe
3
O
4
-L) nanoparticles have successfully absorbed LDL in plasma, which shows a higher selectivity, as well as attain outstanding adsorption capacity as high as 30.19% within 1 h.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Microbial fuel cell is considered one of the tremendous technologies as this possesses a potential to utilize waste for energy as well as for wastewater treatment-related environmental pollution. In ...present work, wet chemical method was adopted to synthesize Ni/G nanocomposite. Scanning electron microscope (SEM) was employed for studying the morphology, phase, and elemental analysis which were done using X-ray diffraction (XRD) and EDS, respectively. Malvern zeta particle sizer was used to determine the particle size of synthesized powder, and by using electrochemical station application, studies were carried out, i.e., cyclic voltammetry and chronocoulometry, and compared with previous studies. In addition, newly developed anode material was used for microbial fuel cell.
Saccharomyces cerevisiae
sp. was utilized as biocatalyst while 180 μmol l
−1
of methylene blue as a mediator in anode and 350 μmol l
−1
potassium ferricyanide was used as an oxidizing agent in cathode chamber for treatment of spent wash. All experiments were carried out through balancing the volume of 1 l for power generation from spent wash in MFC under an optimized parameter of 10% agarose, pH 8, aeration rate 200 ml/min, and 50% substrate concentration. The maximum current and a power density obtained at an optimized concentration are approximately 54.21 mA/m
2
and 71.12 mW/m
2
, respectively. The maximum voltage of (1130 mv) was obtained per liter of processed spent wash.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this study, we used the concept of overnight hydrolysis of polyvinyl amine to grow cobalt oxide (Co
3
O
4
) nanostructures with enhanced catalytic properties. The controlled synthesis of Co
3
O
4
...nanostructures was carried out with the hydrothermal method using hydrolyzed products. Results showed that the hydrocarbon chain and amide groups produced during the growth process have a great impact on both the morphology and catalytic properties of Co
3
O
4
nanostructures. In fact, the hydrolyzed products supported the growth of nanostructures with a well-defined almost one-dimensional (1-D) morphology of Co
3
O
4
nanowires with a high surface/volume ratio. The as-prepared nanowires were loaded with a high amount of glucose oxidase in order to make them sensitive to glucose and observe a potentiometric response in its presence. The performance of the fabricated biosensor was evaluated in terms of different analytical parameters such as linear range, stability, reproducibility, repeatability, life time, selectivity, and response time. Thus, the obtained Co
3
O
4
-based glucose biosensor exhibited a linear response over the concentration range from 0.0005 to 6 mM, with a limit of detection of 0.0001 mM. The estimated Nernstian slope for the glucose biosensor was 42 mV/dec, with stability that exceeds four weeks. Using electrochemical impedance spectroscopy, the Co
3
O
4
nanowires showed a low charge transfer resistance of 2.2 × 10
3
Ohms. Practically, the biosensor was used successfully to measure the glucose concentration in real blood samples. The results obtained confirm that the proposed glucose biosensor can be used as an alternative tool for monitoring glucose levels. The synthesis procedure described herein has a high potential to produce nanostructured materials on a large scale with well-defined morphology and improved catalytic properties for possible applications in batteries, supercapacitors, and water splitting.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Herein, we describe a cost-effective, efficient, sustainable, and environmentally friendly pyrolytic method for the synthesis of highly active carbon materials from Carica papaya fruit juice for the ...photodegradation of various pollutants, such as methylene blue (MB), in aqueous solutions using ultraviolet (UV) light. Various analytical techniques were used to examine the morphology, crystal quality, functional group chemistry, particle size distribution, and optical properties of the materials. For evaluating the performance of the newly prepared carbon material, various photocatalyst parameters were investigated, including initial dye concentration, catalyst dose, pH of dye solution, cyclic stability, and scavenger studies. The obtained findings attest that the optimal degradation efficiency of carbon material for high MB concentrations (2.3 × 10−5 M) is around 98.08%, whereas at low concentrations of MB (1.5 × 10−5 M) it reaches 99.67%. Degradation kinetics indicate that MB degrades in a first-order manner. Importantly, as the pH of the dye solution was adjusted to ~11, the degradation rate increased significantly. The scavenger study indicated that hydroxyl radicals were the predominant species involved in the degradation of MB. In addition, active surface site exposure and charge transfer were strongly associated with efficient MB degradation. On the basis of its performance, this newly developed carbon material may prove to be an excellent alternative and promising photocatalyst for wastewater treatment. Furthermore, the synthetic approach used to produce carbon material from Carica papaya fruit juice may prove useful for the development of a new generation of photoactive materials for environmentally friendly applications, as well as for the production of hydrogen from solar energy.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this study, we synthesized hybrid systems based on manganese oxide@zinc oxide (Mn3O4@ZnO), using sol gel and hydrothermal methods. The hybrid materials exhibited hierarchical morphologies and ...structures characterized by the hexagonal phase of ZnO and the tetragonal phase of Mn3O4. The hybrid materials were tested for degradation of methylene blue (MB), methyl orange (MO), and malachite green (MG) under ultraviolet (UV) light illumination. The aim of this work was to observe the effect of various amounts of Mn3O4 in enhancing the photocatalytic properties of ZnO-based hybrid structures towards the degradation of MB, MO and MG. The ZnO photocatalyst showed better performance with an increasing amount of Mn3O4, and the degradation efficiency for the hybrid material containing the maximum amount of Mn3O4 was found to be 94.59%, 89.99%, and 97.40% for MB, MO and MG, respectively. The improvement in the performance of hybrid materials can be attributed to the high charge separation rate of electron-hole pairs, the co-catalytic role, the large number of catalytic sites, and the synergy for the production of high quantities of oxidizing radicals. The performance obtained from the various Mn3O4@ZnO hybrid materials suggest that Mn3O4 can be considered an effective co-catalyst for a wide range of photocatalytic materials such as titanium dioxide, tin oxide, and carbon-based materials, in developing practical hybrid photocatalysts for the degradation of dyes and for wastewater treatment.
The present study describes the effect of hydrolysis of polyethyleneimines in water/ethanol mixture on the morphology of the cobalt oxide (Co3O4), used as the main sensor component. The structure of ...the generated Co3O4 nanocrystals is consistent with a well-defined cubic phase crystallography, having only cobalt and oxygen elements. Developing simple, low-cost, sensitive, and selective cholesterol biosensors is essential for accurate monitoring of cholesterol to avoid cardiovascular diseases. These nanocrystals exhibit large surfaces suitable for facile and high loading of cholesterol oxidase enzyme through the physical adsorption method. Then, the fabricated cholesterol oxidase/ Co3O4 nanocrystals composite was implemented for potentiometric detection of cholesterol in 10 mM phosphate buffer of pH 7.3. Importantly, the presented cholesterol biosensor revealed a wide linear range of 0.005 mM to 3.0 mM with a limit of detection (LOD) of 0.001 mM. Additionally, the sensitivity of biosensor was estimated around 60 mVdec−1. The selectivity, stability, reproducibility, and repeatability were also observed as satisfactory. The dynamic response of the proposed method demonstrated a fast response time of less than 1 s. Furthermore, the successive addition method confirmed a remarkably stable response towards various cholesterol concentrations. Thus, the developed cholesterol oxidase/ Co3O4 nanocomposite may be used as an efficient alternative method to monitor low cholesterol concentrations form real samples.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Separation of ultrafine hematite from quartz and kaolinite gangue minerals using selective flocculation technique is markedly affected by the state of inter mineral interaction which is governed by ...type and content of polyvalent metal ions. Because of the presence of polyvalent metal ions hetracoagulation of gangue minerals is widely acknowledged, thus selective flocculation of ultrafine hematite from associated gangue minerals is challenging task when their concentration is above 10 ppm. This study has shown that state of strong interaction of gangue minerals with hematite due to presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions can be weakened by addition of optimal dose of Sodium Hexametaphosphate (SHMP) ligand. The optimization of ligand dose is achieved through analysis of Zeta Potential (ZP) as a function of slurry pH. It is noted that 50 ppm of SHMP is sufficient to restore the ZP of hematite, where selective dispersion of the slurry constituents are possible. Our results further showed that conventional strategy of obtaining minimum difference of ±30 mV in the ZP of hematite and gangue minerals quartz and kaolinite would not work especially in the presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions. Attempts to achieve the minimum threshold difference in the ZP of the minerals will cause over dispersion.
Separation of ultrafine hematite from quartz and kaolinite gangue minerals using selective flocculation technique is markedly affected by the state of inter mineral interaction which is governed by ...type and content of polyvalent metal ions. Because of the presence of polyvalent metal ions hetracoagulation of gangue minerals is widely acknowledged, thus selective flocculation of ultrafine hematite from associated gangue minerals is challenging task when their concentration is above 10 ppm. This study has shown that state of strong interaction of gangue minerals with hematite due to presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions can be weakened by addition of optimal dose of Sodium Hexametaphosphate (SHMP) ligand. The optimization of ligand dose is achieved through analysis of Zeta Potential (ZP) as a function of slurry pH. It is noted that 50 ppm of SHMP is sufficient to restore the ZP of hematite, where selective dispersion of the slurry constituents are possible. Our results further showed that conventional strategy of obtaining minimum difference of +-30 mV in the ZP of hematite and gangue minerals quartz and kaolinite would not work especially in the presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions. Attempts to achieve the minimum threshold difference in the ZP of the minerals will cause over dispersion.
For large-scale energy applications, conceiving low-cost and simple earth-abundant electrocatalysts are more difficult. By using an aqueous chemical technique, MnO2 was added into Co3O4 with varying ...concentrations to prepare MnO2@Co3O4 nanocomposite (CM). In an aqueous solution of 1 M KOH, the electrocatalyst with a greater concentration of MnO2 outperforms in terms of OER. To confirm the composition, crystalline structure, and morphology of the electrocatalyst, analytical methods such as X-ray diffraction (XRD) techniques, Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used. At 20 mA/cm2 current density, the electrocatalyst had a lowest overpotential of 310 mV verses Reversible hydrogen electrode (RHE). The CM-0.4 electrocatalyst has a small Tafel slope value and charge transfer resistance of approximately 72 mV/dec and 74 Ω which confirm its high catalytic activity. The electrocatalyst reveals a double layer capacitance (Rct) of 18 µF/cm2 and an electrochemical active surface area (ECSA) of 450 cm2, demonstrating that addition of MnO2 impurities into Co3O4 enhances the active catalyst sites. These findings contribute to the knowledge of these kind of catalysts, that will assist in the development of novel electrocatalysts which are feasible for prospective energy generation technologies.
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