Facile Synthesis of Bio-templated Tubular Co3O4 Microstructure and its Electrochemical Performance in Aqueous Electrolytes

Template-assisted facile synthesis of tubular Co3O4 microstructures and its electrochemical performance was studied to understand its use as a potential electrode material for supercapacitors. Tubular porous Co3O4 microstructures were synthesized using cotton fibers as bio-template. The as-obtained templated Co3O4 structure inherits the morphology and microstructure of cotton fiber. The electrochemical performance of the electrode made up of tubular Co3O4 structure was evaluated in 3M KOH, NaOH, and LiOH aqueous electrolytes. The large-surface-area of tubular Co3O4 microstructure has a noticeable pseudocapacitive performance with a capacitance of 401 F/g at 1 A/g and 828 F/g at 2 mV/s, a Coulombic efficiency averaging ~100%, and excellent cycling stability with capacitance retention of about 80% after 5,000 cycles. Overall, the tubular Co3O4 microstructure displayed superior electrochemical performance in 3M KOH electrolyte with peak power density reaching 5,500 W/kg and energy density exceeding 22 Wh/kg. The superior performance of the tubular Co3O4 microstructure electrode is attributed to its high surface area and adequate pore volume distribution, which allows effective redox reaction and diffusion of hydrated ions. The facile synthesis method can be adapted for preparing various metal oxide microstructures for possible applications in catalysis, electrochemical, sensors, and fuel cell applications

Facile synthesis of bio-template tubular MCo2O4 (M = Cr, Mn, Ni) microstructure and its electrochemical performance in aqueous electrolyte

In this project, wepresent a comparative study of the electrochemical performance for tubular mco2o4 (M = Cr, Mn, Ni) microstructures prepared using cotton fiber as a bio-template. Crystal structure, surface properties, morphology, and electrochemical properties of mco2o4 are characterized using X-ray diffraction (XRD), gas adsorption, scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), cyclic voltammetry (CV), and galvanostatic charge-discharge cycling (GCD). The electrochemical performance of the electrode made up of tubular mco2o4 structures was evaluated in aqueous 3M KOH electrolytes. The as-obtained templated mco2o4 microstructures inherit the tubular morphology. The large-surface-area of tubular microstructures leads to a noticeable pseudocapacitive property with the excellent electrochemical performance of NiCo2O4 with specific capacitance value exceeding 407.2 F/g at 2 mV/s scan rate. In addition, a Coulombic efficiency ~100%, and excellent cycling stability with 100% capacitance retention for mco2o4 was noted even after 5000 cycles. These tubular mco2o4 microstructure display peak power density is exceeding 7000 W/Kg. The superior performance of the tubular mco2o4 microstructure electrode is attributed to their high surface area, adequate pore volume distribution, and active carbon matrix, which allows effective redox reaction and diffusion of hydrated ions

Once Daily Pregabalin Eye Drops for Management of Glaucoma

Elevated intraocular pressure (IOP) is the most significant risk factor contributing to visual field loss in glaucoma. Unfortunately, the deficiencies associated with current therapies have resulted in reduced efficacy, several daily dosings, and poor patient compliance. Previously, we identified the calcium voltage-gated channel auxiliary subunit alpha2delta 1 gene (Cacna2d1) as a modulator of IOP and demonstrated that pregabalin, a drug with high affinity and selectivity for CACNA2D1, lowered IOP in a dose-dependent manner. Unfortunately, IOP returned to baseline at 6 h after dosing. In the current study, we develop a once daily topical pregabalin-loaded multiple water-in-oil-in-water microemulsion formulation to improve drug efficacy. We characterize our formulations using multiple in vitro and in vivo evaluations. Our lead formulation provides continuous release of pregabalin for up to 24 h. Because of its miniscule droplet size (\u3c20 nm), our microemulsion has a transparent appearance and should not blur vision. It is also stable at one month of storage at temperatures ranging from 5 to 40 °C. Our formulation is nontoxic, as illustrated by a cell toxicity study and slit-lamp biomicroscopic exams. CACNA2D1 is highly expressed in both the ciliary body and the trabecular meshwork, where it functions to modulate IOP. A single drop of our lead pregabalin formulation reduces IOP by greater than 40%, which does not return to baseline until \u3e30 h post-application. Although there were no significant differences in the amplitude of IOP reduction between the formulations we tested, a significant difference was clearly observed in their duration of action. Our multilayered microemulsion is a promising carrier that sustains the release and prolongs the duration of action of pregabalin, a proposed glaucoma therapeutic

Effect of terbium ion substitution in inverse spinel nickel ferrite: Structural and magnetic study

Doping rare-earth ions into spinel ferrites can alter their electrical and magnetic properties. The present study delineates the structure–property relationship of the effect of rare-earth terbium doping in NiFe2 O4 ferrite. X-ray diffraction analysis (XRD) showed unit cell lattice expansion with increased Tb3+ content. The Fourier transform infrared spectroscopy (FTIR) results indicate preferential occupancy of Tb3+ at the octahedral B site. The magnetic parameters derived from room temperature hysteresis loops where both the saturation magnetization, Ms, and coercivity, Hc, value decreased with the Tb3+ substitution and reached a minimum value of Ms ~30.6 emu/g at x = 0.1 and Hc ~102 Oe at x = 0.075. The temperature-dependent magnetocrystalline anisotropy derived from the magnetic isotherm was observed to be the highest for x = 0.1 at 5 K with the value K1 ~1.09 × 106 J/m3 . The Tb3+ doping also resulted in the Curie temperature reduction from 938 K at x = 0.0 to 899 K at x = 0.1

Nanosheets of CuCo₂O₄ As a High-Performance Electrocatalyst in Urea Oxidation

The urea oxidation reaction (UOR) is a possible solution to solve the world’s energy crisis. Fuel cells have been used in the UOR to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. Urea is abundantly present in agricultural waste and in industrial and human wastewater. Besides generating hydrogen, this reaction provides a pathway to eliminate urea, which is a hazard in the environment and to people’s health. In this study, nanosheets of CuCo2O4 grown on nickel foam were synthesized as an electrocatalyst for urea oxidation to generate hydrogen as a green fuel. The synthesized electrocatalyst was characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electroactivity of CuCo2O4 towards the oxidation of urea in alkaline solution was evaluated using electrochemical measurements. Nanosheets of CuCo2O4 grown on nickel foam required the potential of 1.36 V in 1 M KOH with 0.33 M urea to deliver a current density of 10 mA/cm2. The CuCo2O4 electrode was electrochemically stable for over 15 h of continuous measurements. The high catalytic activities for the hydrogen evolution reaction make the CuCo2O4 electrode a bifunctional catalyst and a promising electroactive material for hydrogen production. The two-electrode electrolyzer demanded a potential of 1.45 V, which was 260 mV less than that for the urea-free counterpart. Our study suggests that the CuCo2O4 electrode can be a promising material as an efficient UOR catalyst for fuel cells to generate hydrogen at a low cost

Electrochemical performance of aluminum doped ni1−x alx co2 o4 hierarchical nanostructure: Experimental and theoretical study

For electrochemical supercapacitors, nickel cobaltite (NiCo2 O4 ) has emerged as a new energy storage material. The electrocapacitive performance of metal oxides is significantly influenced by their morphology and electrical characteristics. The synthesis route can modulate the morphological structure, while their energy band gaps and defects can vary the electrical properties. In addition to modifying the energy band gap, doping can improve crystal stability and refine grain size, providing much-needed surface area for high specific capacitance. This study evaluates the electrochemical performance of aluminum-doped Ni1−x Alx Co2 O4 (0 ≤ x ≤ 0.8) compounds. The Ni1−x Alx Co2 O4 samples were synthesized through a hydrothermal method by varying the Al to Ni molar ratio. The physical, morphological, and electrochemical properties of Ni1−x Alx Co2 O4 are observed to vary with Al3+ content. A morphological change from urchin-like spheres to nanoplate-like structures with a concomitant increase in the surface area, reaching up to 189 m2 /g for x = 0.8, was observed with increasing Al3+ content in Ni1−x Alx Co2 O4 . The electrochemical performance of Ni1−x Alx Co2 O4 as an electrode was assessed in a 3M KOH solution. The high specific capacitance of 512 F/g at a 2 mV/s scan rate, 268 F/g at a current density of 0.5 A/g, and energy density of 12.4 Wh/kg was observed for the x = 0.0 sample, which was reduced upon further Al3+ substitution. The as-synthesized Ni1−x Alx Co2 O4 electrode exhibited a maximum energy density of 12.4 W h kg−1 with an outstanding high-power density of approximately 6316.6 W h kg−1 for x = 0.0 and an energy density of 8.7 W h kg−1 with an outstanding high-power density of approximately 6670.9 W h kg−1 for x = 0.6. The capacitance retention of 97% and 108.52% and the Coulombic efficiency of 100% and 99.24% were observed for x = 0.0 and x = 0.8, respectively. First-principles density functional theory (DFT) calculations show that the band-gap energy of Ni1−x Alx Co2 O4 remained largely invariant with the Al3+ substitution for low Al3+ content. Although the capacitance performance is reduced upon Al3+ doping, overall, the Al3+ doped Ni1−x Alx Co2 O4 displayed good energy, powder density, and retention performance. Thus, Al3+ could be a cost-effective alternative in replacing Ni with the performance trade off

Electrochemical performance of iron-doped cobalt oxide hierarchical nanostructure

In this study, hydrothermally produced Fe-doped Co3O4 nanostructured particles are investigated as electrocatalysts for the water-splitting process and electrode materials for supercapac-itor devices. The results of the experiments demonstrated that the surface area, specific capacitance, and electrochemical performance of Co3O4 are all influenced by Fe3+ content. The FexCo3-xO4 with x = 1 sample exhibits a higher BET surface (87.45 m2/g) than that of the pristine Co3O4 (59.4 m2/g). Electrochemical measurements of the electrode carried out in 3 M KOH reveal a high specific capacitance of 153 F/g at a current density of 1 A/g for x = 0.6 and 684 F/g at a 2 mV/s scan rate for x = 1.0 samples. In terms of electrocatalytic performance, the electrode (x = 1.0) displayed a low overpotential of 266 mV (at a current density of 10 mA/cm2) along with 52 mV/dec Tafel slopes in the oxygen evolution reaction. Additionally, the overpotential of 132 mV (at a current density of 10 mA/cm2) and 109 mV with 52 mV/dec Tafel slope were obtained for x = 0.6 sample towards hydrogen evolution reaction (HER). According to electrochemical impedance spectroscopy (EIS) measurements and the density functional theory (DFT) study, the addition of Fe3+ increased the conductivity at the electrode–electrolyte interface, which substantially impacted the high activity of the iron-doped cobalt oxide. The electrochemical results revealed that the mesoporous Fe-doped Co3O4 nanostructure could be used as potential electrode material in the high-performance electrochemical capacitor and water-splitting catalysts

Once Daily Pregabalin Eye Drops for Management of Glaucoma

Elevated intraocular pressure (IOP) is the most significant risk factor contributing to visual field loss in glaucoma. Unfortunately, the deficiencies associated with current therapies have resulted in reduced efficacy, several daily dosings, and poor patient compliance. Previously, we identified the calcium voltage-gated channel auxiliary subunit alpha2delta 1 gene (Cacna2d1) as a modulator of IOP and demonstrated that pregabalin, a drug with high affinity and selectivity for CACNA2D1, lowered IOP in a dose-dependent manner. Unfortunately, IOP returned to baseline at 6 h after dosing. In the current study, we develop a once daily topical pregabalin-loaded multiple water-in-oil-in-water microemulsion formulation to improve drug efficacy. We characterize our formulations using multiple in vitro and in vivo evaluations. Our lead formulation provides continuous release of pregabalin for up to 24 h. Because of its miniscule droplet size (\u3c20 nm), our microemulsion has a transparent appearance and should not blur vision. It is also stable at one month of storage at temperatures ranging from 5 to 40 °C. Our formulation is nontoxic, as illustrated by a cell toxicity study and slit-lamp biomicroscopic exams. CACNA2D1 is highly expressed in both the ciliary body and the trabecular meshwork, where it functions to modulate IOP. A single drop of our lead pregabalin formulation reduces IOP by greater than 40%, which does not return to baseline until \u3e30 h post-application. Although there were no significant differences in the amplitude of IOP reduction between the formulations we tested, a significant difference was clearly observed in their duration of action. Our multilayered microemulsion is a promising carrier that sustains the release and prolongs the duration of action of pregabalin, a proposed glaucoma therapeutic