Controllable Fabrication of Amorphous CoNi Pyrophosphates for Tuning Electrochemical Performance in Supercapacitors

Incorporation of two transition metals offers an effective method to enhance the electrochemical performance in supercapacitors for transition metal compound based electrodes. However, such a configuration is seldom concerned in pyrophosphates. Here, amorphous phase CoNi pyrophosphates are fabricated as electrodes in supercapacitors. Through controllably adjusting the ratios of Co and Ni as well as the calcination temperature, the electrochemical performance can be tuned. An optimized amorphous NiCo pyrophosphate exhibits much higher specific capacitance than monometallic Ni and Co pyrophosphates and shows excellent cycling ability. When employing NiCo pyrophosphates as positive electrode and activated carbon as a negative electrode, the fabricated asymmetric supercapacitor cell exhibits favorable capacitance and cycling ability. This study provides facile methods to improve the transition metal pyrophosphate electrodes for efficient electrodes in electrochemical energy storage devices

A Superlattice of Alternately Stacked Ni–Fe Hydroxide Nanosheets and Graphene for Efficient Splitting of Water

Cost-effective electrocatalysts based on nonprecious metals for efficient water splitting are crucial for various technological applications represented by fuel cell. Here, 3<i>d</i> transition metal layered double hydroxides (LDHs) with varied contents of Ni and Fe were successfully synthesized through a homogeneous precipitation. The exfoliated Ni–Fe LDH nanosheets were heteroassembled with graphene oxide (GO) as well as reduced graphene oxide (rGO) into superlattice-like hybrids, in which two kinds of oppositely charged nanosheets are stacked face-to-face in alternating sequence. Heterostructured composites of Ni_2/3Fe_1/3 LDH nanosheets and GO (Ni_2/3Fe_1/3-GO) exhibited an excellent oxygen evolution reaction (OER) efficiency with a small overpotential of about 0.23 V and Tafel slope of 42 mV/decade. The activity was further improved <i>via</i> the combination of Ni_2/3Fe_1/3 LDH nanosheets with more conductive rGO (Ni_2/3Fe_1/3-rGO) to achieve an overpotential as low as 0.21 V and Tafel plot of 40 mV/decade. The catalytic activity was enhanced with an increased Fe content in the bimetallic Ni–Fe system. Moreover, the composite catalysts were found to be effective for hydrogen evolution reaction. An electrolyzer cell powered by a single AA battery of 1.5 V was demonstrated by using the bifunctional catalysts

A Superlattice of Alternately Stacked Ni–Fe Hydroxide Nanosheets and Graphene for Efficient Splitting of Water

Cost-effective electrocatalysts based on nonprecious metals for efficient water splitting are crucial for various technological applications represented by fuel cell. Here, 3<i>d</i> transition metal layered double hydroxides (LDHs) with varied contents of Ni and Fe were successfully synthesized through a homogeneous precipitation. The exfoliated Ni–Fe LDH nanosheets were heteroassembled with graphene oxide (GO) as well as reduced graphene oxide (rGO) into superlattice-like hybrids, in which two kinds of oppositely charged nanosheets are stacked face-to-face in alternating sequence. Heterostructured composites of Ni_2/3Fe_1/3 LDH nanosheets and GO (Ni_2/3Fe_1/3-GO) exhibited an excellent oxygen evolution reaction (OER) efficiency with a small overpotential of about 0.23 V and Tafel slope of 42 mV/decade. The activity was further improved <i>via</i> the combination of Ni_2/3Fe_1/3 LDH nanosheets with more conductive rGO (Ni_2/3Fe_1/3-rGO) to achieve an overpotential as low as 0.21 V and Tafel plot of 40 mV/decade. The catalytic activity was enhanced with an increased Fe content in the bimetallic Ni–Fe system. Moreover, the composite catalysts were found to be effective for hydrogen evolution reaction. An electrolyzer cell powered by a single AA battery of 1.5 V was demonstrated by using the bifunctional catalysts

Advanced Supercapacitors Based on α‑Ni(OH)₂ Nanoplates/Graphene Composite Electrodes with High Energy and Power Density

In order to solve the lack of energy sources, researchers devote themselves to the study of green renewable and economical supercapacitors. We demonstrate herein that the α-Ni­(OH)₂ nanoplates/graphene composites are fabricated as active electrodes in supercapacitors with excellent cycling stability, high energy density, and power density. The advantages of graphene can complement the shortcomings of α-Ni­(OH)₂ nanoplates to compose a novel composite. The α-Ni­(OH)₂ nanoplates/graphene composite presents a high specific capacitance of 1954 F g^–1 at 5 A g^–1. The reason for the improving performance is attributed to graphene, which provides an improved conductivity and increased specific surface area by interweaving with α-Ni­(OH)₂ nanoplates. It is particularly worth mentioning that the assembled asymmetric supercapacitor cells yield a high specific capacitance of 309 F g^–1 at 5 A g^–1 and light a 2 V LED sustainable for about 7 min, which may bring great prospects for further fundamental research and potential applications in energy storage devices

Controllable Fabrication of Rare-Earth-Doped Gd₂O₂SO₄@SiO₂ Double-Shell Hollow Spheres for Efficient Upconversion Luminescence and Magnetic Resonance Imaging

Uniform hollow spheres of Yb and Er codoped Gd₂O₂SO₄ (noted as Gd₂O₂SO₄:Yb,Er) have been developed as novel bifunctional contrast agents for efficient upconversion optical and magnetic resonance imaging (MRI) for the first time. Gd-containing organic precursory spheres were first obtained by a facile hydrothermal process. Owing to the innate hydrophilic nature of the precursory spheres, surface modification with a layer of stable and biocompatible silica could be readily achieved through the Stöber sol–gel method and subsequent calcination. The morphology and thickness of the silica shell can be tailored by adjusting the reaction time. Compared with Gd₂O₂SO₄:Yb,Er hollow spheres without silica coating, well-dispersed Gd₂O₂SO₄:Yb,Er@SiO₂ double-shell hollow spheres could generate intense upconversion fluorescence, and showed a significant contrast enhancement of T1-weighted MRI both <i>in vitro</i> and <i>in vivo</i>. These gadolinium oxysulfate-based hollow spheres are thus regarded as a new type of potential bimodal optical-MRI contrast agents

Large-Scale Preparation, Chemical Exfoliation, and Structural Modification of Layered Zinc Hydroxide Nanocones: Transformation into Zinc Oxide Nanocones for Enhanced Photocatalytic Properties

A convenient and effective water-bath method is developed for the preparation of layered zinc hydroxide nanocones (NCs) intercalated with dodecyl sulfate (C₁₂H₂₅OSO₃^–, DS^–) anions in large quantities. Furthermore, the morphology, size, and crystal structure of products could also be readily tuned by adjusting the experimental parameters. In particular, unilamellar zinc hydroxide nanosheets with a thickness of approximately 0.9 nm could be achieved by exfoliating the layered zinc hydroxide NCs in the formamide–water mixed solution. It is worth mentioning that layered zinc hydroxide NCs could be topologically converted to basic zinc sulfates (Zn₄SO₄(OH)₆·5H₂O, Osaka mine) and zinc oxide (ZnO) NCs through a calcination process at different temperatures. Benefitting from a special structure, narrow bandgap, and higher surface area, the photodegradation behavior of ZnO NCs for methylene blue (MB) solution is better than that of ZnO nanorods

Rare Cobalt-Based Phosphate Nanoribbons with Unique 5‑Coordination for Electrocatalytic Water Oxidation

Coordinatively asymmetric or unsaturated metal centers may serve as accessible active sites and allow strong interaction with incoming guests in catalysis, sensing, and separation applications. Herein, a peculiar Co-based phosphate NaCo₄(PO₄)₃, in which all Co atoms were in very rare 5-coordinations, was first synthesized in nanoribbon morphology. With the combined merits of the unique Co coordination, intrinsic half-metallicity, and nanostructured morphology, NaCo₄(PO₄)₃ nanoribbons were characterized with high efficiency for water oxidation in a neutral electrolyte, remarkably outperforming congeneric phosphates such as Na₂CoP₂O₇ with 4-coordinated Co configurations and even comparable to the benchmark RuO₂ nanoparticles. The high catalytic performance validates a great potential in exploiting inorganic nanostructures with coordinatively asymmetric or unsaturated metal centers for energy storage and conversion applications

Electron micrographs of <i>K. pneumoniae</i> strains.

<p>A, B, and C show K7, and D shows K7R¹. B and C are higher magnification views of A. C and D are at the same magnification. The images show that K7 adsorbed to the thick jelly and formed large bacterial aggregates.</p

Experimental Protocol.

<p>Group Ia = non-arrested with chest compressions (to a depth of 5cm); Group Ib = non-arrested with chest compressions (to a depth of 3cm); Group IIa = arrested with chest compressions (to a depth of 5cm) only; Group IIb = arrested with chest compressions (to a depth of 3cm) only; Group IIIa = compressions to a depth of 5cm continued after ROSC; Group IIIb = compressions to a depth of 3cm continued after ROSC; Group IIIc = chest compressions stopped after ROSC; ROSC = return of spontaneous circulation; VF = ventricular fibrillation; CC = chest compressions; DF = defibrillation; SC = stop compressions.</p

Delayed treatment with phage cocktail.

<p>Mice were inoculated intraperitoneally with K7 at the dose of 2.5×10⁸ cfu. Cocktail phages at the dose of 3.0×10⁴ pfu or a buffer were administered into the peritoneal cavities of mice at the indicated time intervals after challenging with K7. Phage cocktail was given at 1 h (black squares), 2 h (black diamond), or 3 h (black triangles) after the K7 challenge. Infected mice treated with buffer (white squares) under the same conditions were used as control. Each symbol represents the average of three experiments.</p