Ni Bond Research Articles

Chemical bond formed between electrodeposits and substrate at room temperature with a novel in situ electrochemical treatment

The interfacial adhesion strength between electrodeposits and substrate is crucial in many applications, such as the thrust chamber of hydrogen-oxygen rocket engines. To achieve excellent adhesion, herein we propose a novel in situ electrochemical treatment that promotes formation of chemical bonds at the electrodeposit/substrate interface. This treatment integrates the electrochemical dissolution, substrate transport between baths and electrodeposition in a continuous homologous-acid system, thereby achieving and maintaining the activated interface. As a result of the Ni electrodeposition on the Cu substrate, Cu-Ni bonds forms between the deposits and the substrate at the nanoscale interface roughness (<200 nm), realizing the ultrahigh adhesive strength of 386 MPa. The detected diffraction peak intensities of Cu–Ni bonds, initial electrodeposition potential, and deposit–substrate adhesive strength show that the smooth interfacial micromorphology and the continuous homologous-acid environment are the keys to the formation of the Cu–Ni bonds. Qualitative models are built to further analyze and understand chemical bond formation during electrodeposition.

In Situ Reconstruction NiO Octahedral Active Sites for Promoting Electrocatalytic Oxygen Evolution of Nickel Phosphate.

Electrochemical activation strategy is very effective to improve the intrinsic catalytic activity of metal phosphate toward the sluggish oxygen evolution reaction (OER) for water electrolysis. However, it is still challenging to operando trace the activated reconstruction and corresponding electrocatalytic dynamic mechanisms. Herein, a constant voltage activation strategy is adopted to in situ activate Ni2 P4 O12 , in which the break of NiONi bond and dissolution of PO4 3- groups could optimize the lattice oxygen, thus reconstructing an irreversible amorphous Ni(OH)2 layer with a thickness of 1.5-3.5nm on the surface of Ni2 P4 O12 . The heterostructure electrocatalyst can afford an excellent OER activity in alkaline media with an overpotential of 216.5 mV at 27.0 mA cm-2 . Operando X-ray absorption fine structure spectroscopy analysis and density functional theory simulations indicate that the heterostructure follows a nonconcerted proton-electron transfer mechanism for OER. This activation strategy demonstrates universality and can be used to the surface reconstruction of other metal phosphates.

Unraveling the Structure and Surface Chemistry of the Phosphosulfide Phase Formed on Ni2P under Hydrodesulfurization Reaction Conditions: A DFT Study

There is experimental evidence that the actual active phase of the Ni2P catalyst under hydrodesulfurization (HDS) reaction conditions is a nickel phosphosulfide phase formed on the catalyst surface. Combining DFT calculations and an atomistic thermodynamic approach, we investigated the possibility of sulfur adsorption as well as the replacement of surface phosphorus by sulfur on the (0001) and (1010) surfaces of the Ni2P catalyst. Our DFT calculations showed that sulfur could replace up to 100% of the surface phosphorus under hydrodesulfurization (HDS) reaction conditions. We identify that possible sulfur adsorption sites on both surface terminations are arrangements of Ni trimers (Ni3 sites). We found that only the phosphosulfide phase formed on the (1010)-AB_Ni2P surface termination has coordinatively unsaturated Ni atoms available for the adsorption of organic sulfur-containing compounds. Our results suggest that the phosphosulfide phase formed on the (1010)-AB_Ni2P termination and not on the (0001)-Ni3P2 termination could be responsible for the high HDS activity of the Ni2P catalyst. Upon the replacement of P by S, the Ni3 sites undergo tensile strain, and their reactivity toward S adsorption is modified by the imposed strain. We found that the Ni–Ni bond distance is an important parameter in describing the HDS activity of the Ni2P catalyst. By analyzing the relationship among the ensemble, ligand, and strain effects, we were able to provide a better understanding of the promoting effect introduced by the formation of the nickel phosphosulfide phase.

Tuning of surface morphology in Li layered oxide cathode materials

High-Ni low-Co layered LiNixCoyMnzO2 (NCM, x + y + z = 1) compounds are widely used as cathode materials for the lithium-ion batteries of electrical vehicles due to their high energy density. Intrinsic chemomechanical instability and fast capacity fading of NCM degrade the battery performance; however, an emerging single-crystal particle strategy can potentially overcome these problems. In this study, we investigate possible ways of tuning the single-crystal NCM morphology by performing ab initio calculations combined with Wulff shape construction and crystal orbital Hamilton population analysis. As a result, surface structural units with different Miller indices were identified, and a linear relationship was established between the surface energy and the density of cleaved bonds. By constructing Wulff shapes, we found that LiCoO2 had the largest grain size among the studied NCM materials. Finally, we calculated the X–O (X = Li, Ni, Co, or Mn) bond strengths and concluded that the NCM surface morphology can be effectively tuned by modulating the transition metal–O bond strength.

Quantitative study on Ru local atomic structure in Ni-Al-Ru ternary alloys

The synchrotron radiation X-ray absorption fine structure (XAFS) technique is used to study the local structure of the key atom Ru in a series of Ni-Al-Ru ternary alloys with different Ru contents and heat treatments. All the investigated alloys consist of two phases, γ and γ', and especially Ru exists as an atom coordinated by 12 Ni atoms in the first shell without Ru clusters or intermetallic compounds. In γ phase Ru resides on the Ni lattice site introducing an outward relaxation of the neighboring atoms, while in the γ' phase Ru replaces the Al lattice site causing an inward relaxation. The interatomic distance of Ru–Ni bond and Debye-Waller factor are mainly affected by the composition and increase with the increasing Ru content. While the effect of heat treatment is obvious when the Ru content is higher than 6 at%. The variation of Ru local atomic structure can greatly influence the microstructural evaluation and deformation mechanism by changing the lattice misfit and the vacancy formation energy to control the creep properties of Ni-Ru-Al ternary alloys.

Fe incorporated ternary layered double hydroxides with remarkably improved electrochemical performance towards asymmetric supercapacitors

A nanocomposite composed of ternary NiCo2Fex layered double hydroxide (LDH) anchored to g-C3N4 was prepared for high-performance supercapacitor. In this novel material, Fe played an important part in enhancing the energy storage performance of the NiCo2Fex-LDH. Density functional theory calculations on this material showed that Fe improved the Fermi level of NiCo2Fex-LDH, moreover, the stability of the N–Ni bonds were formed after combining NiCo2Fex-LDH with g-C3N4. The electrochemical test results for this material showed that the NiCo2Fe1.0-LDH@g-C3N4 electrode yielded an extremely high specific capacitance of 1550 F g−1 at a current density of 1 A g−1, which was far superior to that of the NiCo2-LDH@g-C3N4 electrode. An assembled NiCo2Fe1.0-LDH@g-C3N4//AC asymmetric supercapacitor device delivered an impressive specific capacitance of 129.64 F g−1, in addition, the device yielded the energy density of up to 35 Wh kg−1 at the corresponding power density of 701 W kg−1 with superior cycling performance (92.7% capacitance retention after 5000 cycles). The NiCo2Fe1.0-LDH@g-C3N4//AC asymmetric supercapacitors easily powered a blue LED. The results of this work provide a promising research path for constructing high-performance of NiCo2-LDH-based nanostructured electrodes materials, which can be employed in new energy storage devices.

A Silylene Stabilized by a σ‐Donating Nickel(0) Fragment

AbstractA donor‐stabilized silylene 4 featuring a Ni0‐based donating ligand was synthesized. Complex 4 exhibits a pyramidalized and nucleophilic SiII center and shows a peculiar behavior due to the cooperative reactivity of Si and Ni centers. Calculations indicate that the orientation of Ni‐ligands with respect to the silylene moiety is crucial in determining the role of the Ni‐fragment (Lewis acid or Lewis base) towards silylene. Indeed, a simple 90° rotation of the Si−Ni bond, reverses the role of Ni, and transforms a classical silylene→Ni0 complex into an unprecedented Ni0→silylene complex.

Green synthesis of Ni3S2 nanoparticles from a nontoxic sulfur source for urea electrolysis with high catalytic activity

Urea electrolysis receives great attention due to its capability to tackle with urea−containing wastewater and allow energy–saving hydrogen production simultaneously. Ni3S2 has favorably metallic property due to the short Ni−Ni bonds in its structure and the most abundant nickel content in the stoichiometric formula among nickel sulfides, thus it is considered an effective electrocatalyst for urea oxidation. However, the current Ni3S2−based catalysts usually derived from toxic sulfur sources, posing safety concerns in production. Herein, we reveal Ni3S2 nanoparticles (ca. 10 nm) can be directly deposited onto Ni substrate in a facile hydrothermal reaction from nontoxic L–cysteine sulfur source without any additives. Ni3S2 serves as a highly efficient and reliable electrocatalyst for urea oxidation with high current responses, low Tafel slope, and reduced resistance. Moreover, the apparent activation energy of urea oxidation for the prepared Ni3S2 electrocatalyst is evaluated as 3.2 kJ mol−1, which is much lower than that of Ni(OH)2 (15.7 kJ mol−1). As a result, the obtained Ni3S2 demonstrates remarkable catalytic activity of 280.2 A g–1 outperforming the Ni(OH)2 electrocatalyst (61.1 A g–1). In addition, Ni3S2 exhibits reliable catalytic performance, as examined by chronoamperometric, chronopotentiometric, and multi–current steps analyses.

Dynamical Bond Formation in KNi2Se2

AbstractEmphanisis, or the appearance out of nothing, has been used to describe the phenomena of spontaneous atom off‐centering and dipole formation at elevated temperatures in lead chalcogenides. Here, we provide spectroscopic evidence of spontaneous formation of metal‐metal bonds above T∼50 K in the layered metal KNi2Se2. These bonds form zig‐zag chains that lower the local symmetry from tetragonal to monoclinic. Energy‐resolved pair distribution function measurements exclude a pure phonon origin of our observations, and instead imply the existence of extra, slowly fluctuating, Ni−Ni bonds above T=50 K. Density functional theory calculations support this lower symmetry configuration as an instability of tetragonal KNi2Se2. We thus demonstrate that the phenomena of emphansis is not limited to local electric dipole formation, but can also be driven by the formation of metal‐metal bonds.

Well‐defined Nickel P3C Complexes as Hydrogenation Catalysts of N‐Heteroarenes Under Mild Conditions

AbstractThe reactivity of metal complexes can be primarily controlled by their coordinating ligands. Electronic effects and geometric restrictions imposed by ligands, prototypically modify their reactivity, but are not always straightforward accessible. In the course of the study, we explored new C3‐symmetric organometallic nickel (II) complexes ((P3C)Ni)) with the particularity of having a metalated apical carbon trans to a labile coordination site readily available as a catalytic site. The synthetic methodology allowed to tune the electronic properties by introducing substituents on the phosphines. We studied the nature of the C−Ni bond by X‐ray absorption spectroscopy (XAS) and DFT and applied them to the catalytic hydrogenation of quinolines with a good chemical scope and group tolerance. 1H‐NMR monitoring, isotopic labelling, and computational studies are consistent with a heterolytic activation of the dihydrogen molecule after forming a σ‐H2 adduct trans to the metalated carbon.

MOF‐derived Multi‐Shelled NiP2 Microspheres as High‐Performance Anode Materials for Sodium‐/Potassium‐Ion Batteries

Development of high capacity, high‐rate performance, long cycling life, and low‐cost electrode materials is highly desirable for sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) to pave the way for their rapid commercialization. Herein, NiP2 nanoparticles loaded in multi‐shelled hollow N‐doped carbon microspheres (NiP2@MHNC) are successfully prepared. The built‐in heterogeneous interfaces between NiP2 and N‐doped carbon promote Na+/K+ diffusion; the robust C–N, N–Ni bonds stabilize the structure of electrodes and accelerate the electrons transfer; and the multi‐shelled hollow structure with large specific surface area effectively buffers the volume expansion to ensure cycling stability. Endowed with the aforementioned synergistic effect, the NiP2@MHNC exhibits remarkable enhancement in electrochemical performance with 346.6 mA h g−1 after 300 cycles for SIB and 142 mA h g−1 after 200 cycles for PIBs at 0.1 A g−1. Moreover, the synergistic effect on electrochemical reaction kinetics is systematically analyzed. Further, the mechanism of sodium storage for NiP2@MHNC is also investigated. The research experience and conclusions in this study based on synergistic effect of heterogeneous interfaces, N‐doped carbon, and multi‐shelled hollow structure open up a meaningful route to design other similar advanced composite electrode materials in energy storage and conversion field.

Bimetal Mo–Ni/NC as an effective electrocatalyst with accelerated kinetics for the oxygen evolution reaction

Bimetal Mo–Ni/NC electrocatalysts have been successfully prepared via the carbonization of a N-rich Mo–Ni-metal organic framework (MOF) precursor. The samples were characterized using X-ray diffraction (XRD), laser micro-Raman spectrometry, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectrometry (XPS). Due to the increased number of catalytic active sites, good conductivity and stability of porous carbon, N-doped carbon and Mo–Ni bonds, the Mo-0.003-Ni/NC composite exhibits outstanding catalytic activity towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media. The experimental results show that excellent HER activity with a low overpotential of 141 mV at 10 mA cm−2 and Tafel slope of 75.2 mV dec−1, as well as outstanding OER activity with an low overpotential of 270 mV at 10 mA cm−2 and a small Tafel slope of 64.3 mV dec−1 can be achieved by Mo-0.003-Ni-NC. The enhanced reaction kinetics may be attributed to the reconstruction of hierarchical Mo-0.003-Ni-NC micro-/nanoarchitectures. This work may provide a feasible method to design efficient and stable electrocatalysts for application in the renewable energy field.

Two-in-one template-assisted construction of hollow phosphide nanotubes for electrochemical energy storage

Nickel-based phosphide hollow nanotubes were constructed using a template strategy. The introduction of PANI may lead to the formation of C–Ni bonds or C–Ni–P bonds at the electrode interface, which induces electron transfer and improves the electrochemical capacity.

Peroxymonosulfate activation using a composite of copper and nickel oxide coated on SBA-15 for the removal of sulfonamide antibiotics

The sluggish Ni(II)/Ni(III) redox cycle does not benefit perxymonosulfate (PMS) activation for recalcitrant pollutant degradation. To solve this problem, a heterogeneous catalyst, Cu0.2Ni0.8O/SBA-15 (CNS), was constructed to activate PMS for decomposing two sulfonamide antibiotics, sulfachlorpyridazine (SACP) and sulfapyridine (SAP). SACP and SAP were completely degraded over Cu0.2Ni0.8O/SBA-15/PMS (CNSP) after 90 min. O2.- was the dominant active species involved in the degradation of SACP and SAP. Structural analysis and elemental valence state observations indicated that Cu(Ⅰ) provided electrons through Cu–O–Ni bonds to realize the charge compensation for Ni(Ⅲ) in the CNSP system. Thus, the in situ Cu(I)/Cu(II) promoting the Ni(II)/Ni(III) cycle could accelerate the PMS activation. This work provides new insights into the electron transfer between transition metals and the charge compensation mechanism for PMS activation. The degradation mechanism was proposed based on the XPS results before and after the reaction, a radical quenching test, and an EPR test. Combined with the SACP and SAP degradation intermediates identified by LC-MS, we suggest that the choice of treatment process depends on the occurrence of a steric hindrance effect between the molecular structure of the degradation target and free radicals.

Prediction and Optimization of Electroplated Ni-Based Coating Composition and Thickness Using Central Composite Design and Artificial Neural Network

The choice of electroplating conditions of Ni-based alloys has always been a serious research matter. In this study, an artificial neural network based on central composite design modelling were used to determine the desired percentage of Ni and the optimum thickness of the coating before proceeding with the implementation of the work. Three main factors were found to be very important in this process; namely applied current density (I), pH of the bath and the temperature (T) during electrolysis. The optimum conditions generated by the mathematical model proposed in this work were 42 mA/cm², pH 4.5 and 50°C for the Ni-alloys (Zn, Co, Cr and W). The optimal amount of Ni and alloys thickness were found to be 40% and 23 µm, respectively. The SEM images indicated that the optimum (I) would achieve homogenous and compact morphologies. Moreover, the XPS investigations revealed that the optimum pH would form a strong Ni bond. Finally, the XRD analysis showed that the optimum T would result in a stable Ni-alloy crystallinity for Zn, Co and Cr. In contrast, Ni-W alloys showed that the amorphous phases were more stable.

Molecular dynamics simulations of dopant effects on lattice trapping of cracks in Ni matrix* *Project supported by the National Natural Science Foundation of China (Grant No. 11604237), the Natural Science Foundation of Hebei Province of China (Grant Nos. E2019105073 and E2015105079), the Scientific Research Foundation of Tangshan Normal University of China (Grant Nos. 2016A06 and 2020C03), and the Department of

Molecular dynamic analysis was performed on pure and doped (by Re, Ru, Co or W) Ni at 300 K using the embedded-atom-method (EAM) potentials to understand the crack formation of the doped Ni matrix in the (010)[001] orientation. When Ni was doped with Re, Ru, and W, the matrix demonstrated increased lattice trapping limits and, as a result, improved the mechanical properties. Consequently, this prevented the bond breakage at the crack tips and promoted crack healing. The average atomic and surface energy values increased when Re, Ru, and W were added. Analysis of these energy increase helpedus to understand the influence these elements had on the lattice trapping limits. The fracture strength of the Ni matrixat 300 K increased because of the formation of the stronger Ni–Re, Ni–Ru, and Ni–W bonds. At the same time, doping the Ni matrix with Co did not demonstrate any strengthening effects because of the formation of Co–Ni bonds, which are weaker than the Ni–Ni bonds. Out of all dopants tested in this work, Ni doping with W showed the best results.

Origin of Structural Phase Transitions in Ni-Rich LixNi0.8Co0.1Mn0.1O2 with Lithiation/Delithiation: A First-Principles Study

In this work, nonmonotonic lattice parameter changes and phase transitions in LixNi0.8Co0.1Mn0.1O2 (LixNCM811) during delithiation are studied by combining an extensive set of electrostatic and density functional theory (DFT) calculations. To our knowledge,for the first time we simulated and explained the reason behind the experimentally observed hexagonal to monoclinic (H–M) phase transition at x = 0.50 as well as O3 → O1 phase transition at x = 0.00 in this system. An analysis of atomic and electronic structures of ions at each layer indicated that the H–M phase transition is driven by the Jahn–Teller (J–T) distortion effect. Moreover, it was found that the O3 → O1 phase transition is driven by electrostatic forces. This study also shows that the oxidation of Ni cations as well as their nature of bonds with O are not similar at different Ni/Ni, Ni/Co, and Ni/Mn layers. We also found that the significant decrease in the c lattice parameter for low values of x is due to the disappearance of J–T distortions as well as large covalent O–Ni bonds and oxidation of O and, more importantly, the sliding of O–TM–O layers with respect to each other.

Scrutinizing the stability and exploring the dependence of thermoelectric properties on band structure of 3d-3d metal-based double perovskites Ba2FeNiO6 and Ba2CoNiO6

Through the conventional DFT computation, we have designed new oxide double perovskites Ba2FeNiO6 and Ba2CoNiO6. The structural and thermodynamic stabilities are predicted by optimizing the crystal structure and evaluation of enthalpy of formation, respectively. Then by using the optimized lattice constant, we have explored the different physical properties. The GGA + mBJ electronic band-structure illustrates Ba2FeNiO6 is a half-metal with 100% spin polarization at the Fermi level. While Ba2CoNiO6 shows a ferromagnetic semiconducting nature. The change in the electronic structure when Fe is replaced by Co is explained with the help of the orbital diagram and exchange interaction. The eg-eg hybridization that happens via O-p states is strong because Fe–O–Ni and Co–O–Ni bond angles are strictly 180°. The narrow bandgaps in the semiconducting channels prompted us to analyze the applicability of these materials towards thermoelectric technology. Besides this, we have investigated the dependency of transport properties on electronic band structure. The semiconducting nature in Ba2CoNiO6 results in a significant ZT around 0.8 at room temperature makes it suitable for wasted-energy regeneration

Towards high-performance all-solid-state asymmetric supercapacitors: A hierarchical doughnut-like Ni3S2@PPy core−shell heterostructure on nickel foam electrode and density functional theory calculations

In this work, a hierarchical doughnut-like Ni3S2@polypyrrole (PPy) core−shell heterostructure has been successfully constructed on nickel foam (NF) (denoted as Ni3S2@PPy/NF) through a facile hydrothermal followed by electrodeposition method. The coating of highly conductive and electroactive PPy layer on the backbone of Ni3S2@NF can significantly boost the integrated electrochemical performance. More specifically, the resultant Ni3S2@PPy/NF electrode achieves an extremely high specific capacitance of 3148.0 mF cm−2 at a current density of 2.0 mA cm−2, and a desirable rate capability. Further, an asymmetric all-solid-state supercapacitor is assembled using Ni3S2@PPy/NF as the positive electrode and activated carbon (AC)/NF as the negative electrode. Remarkably, the obtained Ni3S2@PPy/NF//AC/NF device delivers a high energy density of 46.4 Wh kg−1 at a corresponding power density of 166.7 W kg−1, outmaneuvering most sulfide- and PPy-based materials or their hybrids reported recently. Moreover, density functional theory calculations disclose the formation of N–Ni and C–Ni bonds at the PPy/Ni3S2 heterostructure interface and the enhancement of the binding of Ni3S2 towards OH− after PPy coating. Such exceptional supercapacitive properties of Ni3S2@PPy/NF owe to its unique porous interpenetrating structure, the combined contribution of both electroactive PPy and Ni3S2 components, highly-conductive PPy as well as the optimized electropolymerization and dopant of PPy.

Strain-modulated ultrafast magneto-optic dynamics of graphene nanoflakes decorated with transition-metal atoms* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11872309, 12172293, and 11504223), the Natural Science Basic Research Plan in Shaanxi Province, China (Grant No. 2020JM-120), and the Program of China Scholarships Council (Grant No. 201906295029).

We perform first-principles calculations and coherent laser-matter interaction analyses to investigate the laser-induced ultrafast spin flip on graphene nanoflakes (GNFs) with transition metal elements attached on the boundary [TM&GNFs (TM = Fe, Co, Ni)]. It is shown that the spin-flip process on TM&GNFs is highly influenced by the involved element species and the position attached to the nanoflakes. Furthermore, taking Ni&GNF as an example, the first-principles tensile test predicts that the variation of the C–Ni bond length plays an important role in the spin density distribution, especially for the low-lying magnetic states, and can therefore dominate the spin-flip processes. The fastest spin-flip scenario is achieved within 80 fs in a Ni&GNF structure under 10% tensile strain along the C–Ni bond. The local deformation modulation of spin flip provides the precursory guidance for further study of ultrafast magnetization control in GNFs, which could lead to potential applications in future integrated straintronic devices.