Amorphous Nickel Hydroxide Nanosheets with Ultrahigh Activity and Super-Long-Term Cycle Stability as Advanced Water Oxidation Catalysts

Good conductivity is conventionally considered as a typical reference standard in terms of selecting water electrolysis catalysts. Electrocatalyst research so far has focused on crystal rather than amorphous due to poor conductivity. Here, we demonstrate that the amorphous electrocatalyst made of 3D honeycomb-like amorphous nickel hydroxide (Ni­(OH)₂) nanosheets synthesized by a simple, facile, green, and low-cost electrochemistry technique possesses ultrahigh activity and super-long-term cycle stability in the oxygen evolution reaction (OER). The amorphous Ni­(OH)₂ affords a current density of 10 mA cm^–2 at an overpotential of a mere 0.344 V and a small Tafel slope of 46 mV/dec, while no deactivation is detected in the CV cycles even up to 5000 times. We also establish that the short-range order, i.e., nanophase, of amorphous creates a lot of active sites for OER, which can greatly promote the electrochemical performance of amorphous catalysts. These findings show that the conventional understanding of selecting electrocatalysts with conductivity as a typical reference standard seems out of date for developing new catalysts at the nanometer, which opens a door ever closed to applications of amorphous nanomaterials as advanced catalysts for water oxidation

Capillary Electrophoresis–Nanoelectrospray Ionization–Selected Reaction Monitoring Mass Spectrometry via a True Sheathless Metal-Coated Emitter Interface for Robust and High-Sensitivity Sample Quantification

A new sheathless transient capillary isotachophoresis (CITP)/capillary zone electrophoresis (CZE)–MS interface, based on a commercially available capillary with an integrated metal-coated ESI emitter, was developed in this study aiming at overcoming the reproducibility and ruggedness problems suffered to a certain degree by almost all the available CE–MS interfaces, and pushing the CE–MS technology suitable for routine sample analysis with high sensitivity. The new CITP/CZE–MS interface allows the electric contact between ESI voltage power supply and the CE separation liquid by using a conductive liquid that comes in contact with the metal-coated surface of the ESI emitter, making it a true sheathless CE–MS interface. Stable electrospray was established by avoiding the formation of gas bubbles from electrochemical reaction inside the CE capillary. Crucial operating parameters, such as sample loading volume, flow rate, and separation voltage, were systematically evaluated for their effects on both CITP/CZE separation efficiency and MS detection sensitivity. Around one hundred CITP/CZE–MS analyses can be easily achieved by using the new sheathless CITP/CZE interface without a noticeable loss of metal coating on the ESI emitter surface, or degrading of the ESI emitter performance. The reproducibility in analyte migration time and quantitative performance of the new interface was experimentally evaluated to demonstrate a LOQ below 5 attomole

Adsorption isotherms of La³⁺ and Ce³⁺ on SA-PGA gel particles.

<p>Adsorption isotherms of La³⁺ and Ce³⁺ on SA-PGA gel particles.</p

Adsorption of Rare Earths(Ⅲ) Using an Efficient Sodium Alginate Hydrogel Cross-Linked with Poly-γ-Glutamate

<div><p>With the exploitation of rare earth ore, more and more REEs came into groundwater. This was a waste of resources and could be harmful to the organisms. This study aimed to find an efficient adsorption material to mitigate the above issue. Through doping sodium alginate (SA) with poly-γ-glutamate (PGA), an immobilized gel particle material was produced. The composite exhibited excellent capacity for adsorbing rare earth elements (REEs). The amount of La³⁺ adsorbed on the SA-PGA gel particles reached approximately 163.93 mg/g compared to the 81.97 mg/g adsorbed on SA alone. The factors that potentially affected the adsorption efficiency of the SA-PGA composite, including the initial concentration of REEs, the adsorbent dosage, and the pH of the solution, were investigated. 15 types of REEs in single and mixed aqueous solutions were used to explore the selective adsorption of REEs on gel particles. Scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy analyses of the SA and SA-PGA gel beads suggested that the carboxyl groups in the composite might play a key role in the adsorption process and the morphology of SA-PGA changed from the compact structure of SA to a porous structure after doping PGA. The kinetics and thermodynamics of the adsorption of REEs were well fit with the pseudo-second-order equation and the Langmuir adsorption isotherm model, respectively. It appears that SA-PGA is useful for recycling REEs from wastewater.</p></div

Digital photographs of SA gels (a, b, c, d) and SA-PGA gels (e, f, h, i).

<p>Digital photographs of SA gels (a, b, c, d) and SA-PGA gels (e, f, h, i).</p

Effects of the initial concentration of REEs, adsorbent dosage, and pH of solution on the adsorption by gel particles (Adsorption conditions: temperature 30°C; 150 rpm; and 3h adsorption time).

<p>Effects of the initial concentration of REEs, adsorbent dosage, and pH of solution on the adsorption by gel particles (Adsorption conditions: temperature 30°C; 150 rpm; and 3h adsorption time).</p

Adsorption kinetic curves (a) and pseudo-second-order plots (b) for the adsorption by gel particles.

<p>Adsorption kinetic curves (a) and pseudo-second-order plots (b) for the adsorption by gel particles.</p

Assignment of the main vibrational modes.(C_HCl:0.1mol/L,50mL).

<p>Assignment of the main vibrational modes.(C_HCl:0.1mol/L,50mL).</p

Selective adsorption experiments of REEs: (a) single solution, (b) mixed solution.

<p>Selective adsorption experiments of REEs: (a) single solution, (b) mixed solution.</p

Regeneration of these two gel particles (Adsorption conditions: 30 ml of 0.05 M hydrochloric acid solution, 30 min, 150 rpm, 30°C).

<p>Regeneration of these two gel particles (Adsorption conditions: 30 ml of 0.05 M hydrochloric acid solution, 30 min, 150 rpm, 30°C).</p