Showing papers on "Nickel boride published in 2019"

Redox Tuning in Crystalline and Electronic Structure of Bimetal-Organic Frameworks Derived Cobalt/Nickel Boride/Sulfide for Boosted Faradaic Capacitance.

Abstract: The development of efficient electrode materials is a cutting-edge approach for high-performance energy storage devices. Herein, an effective chemical redox approach is reported for tuning the crystalline and electronic structures of bimetallic cobalt/nickel-organic frameworks (Co-Ni MOFs) to boost faradaic redox reaction for high energy density. The as-obtained cobalt/nickel boride/sulfide exhibits a high specific capacitance (1281 F g-1 at 1 A g-1 ), remarkable rate performance (802.9 F g-1 at 20 A g-1 ), and outstanding cycling stability (92.1% retention after 10 000 cycles). An energy storage device fabricated with a cobalt/nickel boride/sulfide electrode exhibits a high energy density of 50.0 Wh kg-1 at a power density of 857.7 W kg-1 , and capacity retention of 87.7% (up to 5000 cycles at 12 A g-1 ). Such an effective redox approach realizes the systematic electronic tuning that activates the fast faradaic reactions of the metal species in cobalt/nickel boride/sulfide which may shed substantial light on inspiring MOFs and their derivatives for energy storage devices.

Interfacial Engineering of Nickel Boride/Metaborate and Its Effect on High Energy Density Asymmetric Supercapacitors.

Abstract: Solid materials with special atomic and electronic structures are deemed desirable platforms for establishing clear relationships between surface/interface structure characteristics and electrochemical activity. In this work, nickel boride (NixB) and nickel boride/graphene (NixB/G) are chosen as positive materials of supercapacitors. The NixB/G displays higher specific capacitance (1822 F g-1) than that of NixB (1334 F g-1) at 1 A g-1, and it still maintains 1179 F g-1 at 20 A g-1, suggesting the high rate performance. The asymmetric supercapacitor device (NixB/G//activated carbon) also delivered a very high energy density of 50.4 Wh kg-1, and the excellent electrochemical performance is ascribed to the synergistic effect of NixB, Ni(BO2)2, and graphene that fully enhances the diffusion of OH- and the electron transport. During the cycles, the prepared ultrafine NixB nanoparticles will be gradually in situ converted into β-Ni(OH)2 which has a smaller particle size than that prepared by other methods. This will enhance the utilization of Ni(OH)2 and decrease the ion diffusion distance. The electron deficient state of B in Ni(BO2)2 amorphous shell will make it easy to accept extra electrons, enhancing the adsorption of OH- at the shell surface. Moreover, Ni(BO2)2 makes strong adhesion between NixB (or β-Ni(OH)2) and graphene and protects the core structure in a stable state, extending the cycle life. The above properties of NixB/G endow the electrode good capacitive performance.

Ultrathin nickel boride nanosheets anchored on functionalized carbon nanotubes as bifunctional electrocatalysts for overall water splitting

Abstract: Transition metal boride (TMB) materials have recently gained vast interest as a new class of catalysts. However, their catalytic performance is still limited due to poor electrical conductivity and limited specific surface area. Here, we demonstrate a generalizable approach to overcome these limitations by anchoring ultrathin nickel boride (NixB) sheets on the surfaces of functionalized small-diameter multi-walled carbon nanotubes (f-MWCNTs). The electrochemically active surface area and charge transfer resistance of the resulting hybrid materials (NixB/f-MWCNT) is 3.4 and 0.24 times that of the NixB nanosheets, respectively. And, NixB/f-MWCNT exhibited superior catalytic activities and stability toward both oxygen evolution and hydrogen evolution reactions. For the overall water splitting, it requires a cell voltage of 1.60 V to reach the current density of 10 mA cm−2, outperforming existing metal boride catalysts as well as commercial IrO2/Pt/C catalysts. Further, X-ray photoelectron spectroscopy revealed the strong chemical coupling between NixB and f-MWCNTs and the in situ formation of highly active NiOOH/NixB and Ni(OH)2/NixB heterojunctions, which contributes to the superior activity. The developed design concept can serve as a general approach to improve other electrocatalysts with low electrical conductivity and specific surface area, such as metal oxides, metal hydroxides, and metal–organic framework-derived materials.

In situ structural evolution of a nickel boride catalyst: synergistic geometric and electronic optimization for the oxygen evolution reaction

Abstract: The oxygen evolution reaction (OER), as a kinetically sluggish half-reaction, plays a crucial role in the overall efficiency of some important electrochemical energy conversion systems. Herein we report the synthesis of nickel boride layers supported on a nickel plate via a direct solid boronization of the nickel substrate with amorphous boron powder. The resulting boronized nickel plate was studied systematically to illustrate its surface structural evolution and activity variation during the OER. The initial electrochemical OER testing process resulted in the in situ generation on the nickel boride of thin nanosheet films that consist of metaborate-containing oxyhydroxides, as the efficient catalytically active phase. Correspondingly, this electrochemically activated, boronized nickel plate exhibits a nearly ten-fold increase in catalytic activity compared to the nickel plate, and shows remarkable catalytic stability for over 1500 hours. The enhanced catalytic performance during electrochemical activation is attributed to synergistic catalytic effects from the thin nanosheet structural features of the oxyhydroxides (i.e., geometric optimization) and modification of the electronic structure of the oxyhydroxides by metaborates (i.e., electronic optimization). Our results provide new insights into boride-based oxygen evolution electrocatalysts, and provide a new strategy for the design of high-performance electrocatalytic materials for the OER.

Facile Synthesis of Amorphous Ternary Metal Borides–Reduced Graphene Oxide Hybrid with Superior Oxygen Evolution Activity

Abstract: Metal borides represent an emerging family of advanced electrocatalyst for oxygen evolution reaction (OER). Herein, we present a fast and simple method of synthesizing iron-doped amorphous nickel boride on reduced graphene oxide (rGO) sheets. The hybrid exhibits outstanding OER performance and stability in prolonged OER operation. In 1.0 M KOH, only 230 mV is required to afford a current density of 15 mA cm-2 with a small Tafel slope of 50 mV dec-1. DFT calculations lead to a suggestion that the in situ formation of MO xH y during electrochemical activation acts as active sites for water oxidation. The superior OER activity of the as-prepared catalyst is attributed to (i) its unique amorphous structure to allow abundant active sites, (ii) synergistic effect of constituents, and (iii) strong coupling of active material and highly conductive rGO. This work not only provides new perspectives to design a highly effective material for OER but also opens a promising avenue to tailor the electrochemical properties of metal borides, which could be extended to other materials for energy storage and conversion technologies.

Sliding wear resistance of nickel boride layers on an Inconel 718 superalloy

Abstract: New results about the wear resistance of nickel boride layers under dry sliding conditions were obtained in this work. For this purpose, an Inconel 718 superalloy was borided under different conditions: 1173 K with 2 h of exposure and 1223 K with 6 h of exposure, using the powder-pack process. Before the wear tests, the nickel boride layer was characterized by the depth-sensing Vickers microindentation technique to determine indentation properties such as hardness, Young's modulus, residual stresses and fracture toughness. The dry sliding wear tests were performed on the borided Inconel 718 superalloy obtained for the two boriding conditions, and on the surface of the reference material (Inconel 718 superalloy), using the ball-on-flat technique, under a constant load of 20 N and considering relative wear distances between 50 and 200 m. In addition, the development of the failure mechanisms over the surface of the wear tracks was analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) techniques. For the overall set of experimental conditions, the results showed that the presence of nickel boride layers on the surface of the Inconel 718 superalloy increased the wear resistance compared with the reference material. However, the presence of a deeper zone of compressive residual stresses at the inner-zone of the nickel boride layer formed at 1223 K with 6 h of exposure, enhanced the wear resistance by approximately two- and three-fold compared with the values estimated for the nickel boride layer obtained at 1173 K with 2 h of exposure.

Computationally Driven Discovery of a Family of Layered LiNiB Polymorphs

Abstract: Two novel lithium nickel boride polymorphs, RT-LiNiB and HT-LiNiB, with layered crystal structures are reported. This family of compounds was theoretically predicted by using the adaptive genetic algorithm (AGA) and subsequently synthesized by a hydride route with LiH as the lithium source. Unique among the known ternary transition-metal borides, the LiNiB structures feature Li layers alternating with nearly planar [NiB] layers composed of Ni hexagonal rings with a B-B pair at the center. A comprehensive study using a combination of single crystal/synchrotron powder X-ray diffraction, solid-state 7 Li and 11 B NMR spectroscopy, scanning transmission electron microscopy, quantum-chemical calculations, and magnetism has shed light on the intrinsic features of these polymorphic compounds. The unique layered structures of LiNiB compounds make them ultimate precursors for exfoliation studies, thus paving a way toward two-dimensional transition-metal borides, MBenes.

Synthesis of Metal Boride Nanoparticles Using Triple Thermal Plasma Jet System.

Abstract: Titanium, nickel, and tungsten boride nanoparticles were synthesized in the triple thermal plasma jet system. The coalesced high-enthalpy thermal plasma jet not only generates extensive high temperature regions but also allows the starting materials to penetrate into the center of high temperature regions effectively. The synthesis process of metal boride was investigated according to the nucleation temperature of three metals and boron. In the case of titanium and nickel borides synthesis, metals nucleation temperatures are lower than boron. The crystallinity of synthesized titanium boride nanoparticles was higher than nickel boride nanoparticles, since not only the nucleation temperature of titanium is higher than nickel but also the Gibbs free energy of all titanium boride was lower than whole nickel boride. However, the nucleation temperature of tungsten is higher than boron where nanoparticle synthesis process differed from former synthesis processes. It had influence on the crystal growth time in the high temperature regions where tungsten boride crystal structure was strongly prepared than nickel boride nanoparticles.

Contact Interaction of Zirconium Diboride with Nickel and Nickel Alloys. II. Contact Interaction in the Zirconium Boride–Nichrome System

Abstract: Zirconium boride–nichrome (Ni–20 Cr) interaction at zirconium boride concentration in the charge varying from 3.6 to 60% and at annealing temperatures of 1100–1850°C has been studied. It is shown that the interaction begins at 1200°C as a solid-phase reaction to form nickel borides. At 1300–1350°C, contact melting that is characteristic of eutectic systems follows the solid-phase interaction. The eutectic liquid appears and wets zirconium boride with a contact angle of 0° at 1500°C. The eutectic melting point is 1320 ± 20°C at a zirconium boride concentration of 11–13% in the alloy. The phase composition of the interaction products depends on the ratio of alloy components and temperature. It is represented by binary and ternary compounds in the Ni–Cr–B–(in part) C system formed from chromium and nickel boride crystal lattices. The main part of zirconium in the alloy is concentrated in the formed intermetallides. Thus, the contact pairs made of zirconium boride –nichrome materials can operate only at temperatures below 1200°C.

Preparation of Ni nanoparticles by liquid-phase reduction to fabricate metal nanoparticle–polyimide composite films

Abstract: Nickel-nanoparticle-containing polyimide composite films were prepared by liquid-phase reduction of Ni2+ ions with potassium borohydride (KBH4). The nanoparticles were amorphous with diameters of approximately 10–20 nm, depending on the KBH4 concentration and reduction temperature. At high KBH4 concentrations, the nanoparticles appeared to contain various nickel boride species. The number of nanoparticles and Ni content both increased upon repeated adsorption/reduction of Ni2+ ions, where the particle growth was inhibited by the rigid polymer chain and the formation of smaller particles was favored.

Preparation method of nickel boride base oxygen evolution catalyst

Abstract: The invention provides a preparation method of a nickel boride base oxygen evolution catalyst. The method comprises the following steps that a nickel net used for an afflux base is soaked in diluted hydrochloric acid to remove an oxidation layer, then ultrasonically washed with ethyl alcohol and redistilled water in sequence, and dried on the vacuum condition for standby application; a cobalt nitrate water solution and a sodium hydroxide solution of sodium borohydride are prepared respectively, and dissolved oxygen in the cobalt nitrate water solution and the sodium hydroxide solution of the sodium borohydride are removed for standby application; the nickel net is sequentially soaked in the cobalt nitrate water solution and the sodium hydroxide solution of the sodium borohydride, one-timesoaking in the cobalt nitrate water solution and the sodium hydroxide solution of the sodium borohydride is taken as one circulation, the circulation is repeated for a plurality of times, and a cobaltboride nanometer layer is generated on the surface of the nickel net and dried to obtain the nickel boride base oxygen evolution catalyst. The preparation method has the following beneficial effectsthat in comparison with a conventional method of synthesizing boride powder firstly and then dripping and spraying the solution to the afflux base, higher electrochemical stability and activity are possessed.

Oxidation-resistant conductive paste composition, conductive coating and preparation method thereof

Abstract: The invention belongs to the technical field of material preparation and in particular relates to an oxidation-resistant conductive paste composition, a conductive coating and a preparation method thereof. The conductive paste composition comprises, in parts by weight, 75 to 95 parts of boron nickel powder, 5 to 15 parts of boron-containing inorganic binder, 1 to 5 parts of organic vehicle, and 10 to 30 parts of solvent, wherein the boron nickel powder is a conductive metal powder having a surface coated with nickel boride; the boron content in the boron nickel powder is 2 to 8%; the boron content in the boron-containing inorganic binder is 2 to 20%. The conductive paste composition can be sintered under an air atmosphere, has excellent oxidation resistance, can be sintered at about 600 degrees, and has a simple application process and a low energy consumption process. The conductive coating prepared from the conductive paste composition has the characteristics of low cost, good electrical conductivity and good adhesion, and can be widely used in RFID antenna production.