Ni-O Bonds Research Articles

Dynamic equilibrium of external Fe3+ to effectively construct catalytic surface of perovskite LaNi1−xFexO3 for water oxidation

The introduction of Fe into rare earth nickelate perovskite oxides such as LaNiO3 can effectively improve its intrinsic activity for oxygen evolution reaction (OER). Whereas, it is still difficult to achieve exact incorporation of Fe ion and maintain the efficient and stable catalytic surface. Bimetallic NiFe-based active sites have been constructed on the surface of LaNiO3 using a straightforward electrochemical technique that involves introducing external and trace Fe3+ ions into the electrolyte. The optimized LaNiO3 with more Ni-O bonds facilitates the adsorption of Fe3+ ions, which promotes the formation of LaNi1−xFexO3 through electrochemical activation. The synthesized LaNi1−xFexO3 exhibited a synergistic impact and electron rearrangement, resulting in a boost in intrinsic activity. The OER measurements show that the overpotential of LaNi1−xFexO3 reduces to 340 mV (η10) and the Cdl value increases by 21 times (0.10 mF cm−2 to 2.18 mF cm−2) in the existence of external Fe3+. Notably, the dynamic equilibrium between the external Fe3+ and Fe3+ in LaNi1−xFexO3 may stabilize the bimetallic NiFe-based active sites and keep the activity during the long-term OER process. The strategy of utilizing dynamic equilibrium of external ion to obtain the robust catalytic surface offers a novel approach to achieving excellent performance for OER.

Tribological properties of Ni-BP/Ni coatings produced by electroless co-deposition

In the field of tribology, black phosphorus (BP) with a layered structure has displayed outstanding performance. To alleviate the high friction and corrosive wear of the friction pairs of marine equipment, four types of coatings including Ni-PP, Ni-BP/Ni30, Ni-BP/Ni60, and Ni-BP/Ni90, which were labelled with different deposition time, were prepared on Q235 steel via electroless co-deposition technique. A ball-on-disk reciprocating tribometer was used to evaluate their tribological properties in 3.5 wt% NaCl, poly-α-olefin 6 (PAO6), and deionized water, respectively. The results show that the Ni-BP/Ni coatings sliding in 3.5 wt% NaCl exhibited better friction reduction and wear resistance than that in deionized water. The Ni-BP/Ni30 coating sliding in 3.5 wt% NaCl showed excellent tribological properties and compared with the Ni-P coating, its average friction coefficient was reduced by 40 % at a load of 4 N and the wear scar cross-sectional area was reduced by 77 % at a load of 10 N. The enhanced tribological properties were attributed to the lamellar slip of BP nanosheets and the formation of a tribofilm composed of NiO, Ni(OH)2, and SiO bonds and an adsorbed film with BP nanosheets. The Ni-BP/Ni coatings present a promising application in seawater corrosive environment.

The Correlation Between Crystal Phase and Acidity in Nickel Doped Zinc Fluoride Solid

Nickel-doped zinc fluoride (Zn 1‑x Ni x F 2 ) with x= 0; 0.025; 0.050; 0.075; 0.100 and 0.150 were synthesized from zinc acetate as precursors. Solid materials were prepared by the fluorolytic sol gel method. The resulting solid materials were characterized by XRD and FTIR. The XRD characterization of the samples showed that there were characteristic peaks of zinc fluoride, zinc oxide and zinc hydrogen fluoride. The IR characterization spectrum showed the presence of Zn-F, Zn-O and -OH bonds in the samples. Pyridine adsorbed FTIR technique explains that the material has Lewis and Brønsted acidity. The acidity site in the solid were influenced by the Zn-O and Ni-O bonds in the catalyst.

SiO2@NiO core/ shell nanoparticles as high-performance anode materials: Synthesis and characterizations of structural, optical and magnetic properties

In this paper, synthesis and structural and optical properties of the SiO2 @ NiO core-shell nanostructures were studied. The SiO2 and NiO nanoparticles and SiO2@NiO core/shell nanoparticles were prepared by co-precipitation and chemical reduction method using the two different agents of functionalized silica and non-functionalized silica. The XRD analysis showed that SiO2 nanoparticles have an amorphous structure and NiO nanoparticles have a cubic structure. The XRD analysis of SiO2@NiO core/shell nanoparticles showed the presence of nickel oxide phase and silica amorphous phase as well as a background of silica nanoparticles. The morphology of SiO2@NiO core/shell nanoparticles by Scanning Electron Microscopy (SEM), shows form of spherical core with a coating of NiO and it was confirmed by transmission electron microscopy (TEM) analysis. Also, the diameter of these nanoparticles was about 125 ± 5 nm as a halo (shell) of NiO nanoparticles on spherical silica nanoparticles The UV-Vis spectroscopic studies showed that the energy gap of the SiO2@NiO core/shell nanoparticles varied in the range of 3.80 – 4.20 eV. The results of the magnetization experiment (VSM) of the samples showed the soft ferromagnetic structure for the nickel oxide nanoparticles and the paramagnetic structure for the SiO2@NiO core shell nanoparticles. Finally, the Fourier transform infrared (FTIR) spectrum confirmed the formation of SiO2-H, NiO-H and Ni-O bonds in core-shell nanostructures. It can be expected that these nanostructures are suitable as high-performance anode materials in various types of fuel batteries, including lithium batteries.

Structural and Magnetic Properties of Ni-doped Yttrium Iron Garnet (Y3Fe5-XNixO12) Nanopowders Synthesized by Self-Combustion Method

This research aimed to investigate the structural and magnetic properties of Yttrium Iron Garnet by Ni-doped using self-combustion method. Ni-doped directly changed the structure into Y3Fe5-XNixO12 (x=0.00, 0.02, 0.04, 0.06, 0.08). Self-combustion method was obtained by stirring raw materials at room temperature (27°–28°C) and heated at 150°C until combustion occurred. The samples were sintered at 900°C with 120 minutes holding time. The phase identification revealed the cubic structure of garnet phase with the crystallite size from 62.73–62.87 nm. The molecular bonding from molecular bonding displayed Ni-O and Fe-O bonds, while the magnetic properties shown the highest saturation magnetization of 27.04 emu/g in the sample with additional Ni x=0.02, the highest magnetic remenance of 16.09 in the sample Ni x=0.02, and the highest coercivity of 0.029 in the sample with Ni x=0.08. This research, by adding nickel element, shows that the coercivity of Y3Fe5-XNixO12 decreased when the particle size is increased. The increase in Ni concentration as doping material cause the double exchange interaction and affected the lattice parameter, molecular bond, and magnetic properties.

Nickel isotope fractionation during precipitation of Ni secondary minerals and synchrotron-based analysis of the precipitates

The determination of fractionation factors associated with important biogeochemical processes controlling Ni availability in the environment is necessary to confidently use Ni isotope signatures as tracers in environmental studies. In this paper we present experimental results on Ni isotope fractionation during the precipitation of Ni secondary minerals (Ni hydroxide, Ni hydroxycarbonate and Ni sulfide minerals) that can control Ni fate and mobility in settings where high dissolved Ni(II) concentrations may pose a serious threat to the environment. Results show a preferential partition of lighter isotopes into the solid phase with associated fractionation factors ε of −0.40‰ ± 0.04‰, −0.50‰ ± 0.02‰, and −0.73‰ ± 0.08‰ relative to the hydroxide, carbonate and sulfide systems, respectively. Early kinetically induced isotope fractionation, followed by possible re-equilibration with the reacting solutions was suggested for the three investigated systems. Distortions of Ni-O bonds in the octahedra constituting the structures of Ni hydroxide and hydroxycarbonate minerals could have also contributed to the isotopic fractionation measured in these systems. In contrast, for Ni sulfide system, the magnitude of Ni isotope fractionation seemed to be determined by water and sulfide ligands exchange in solution prior to mineral nucleation. Although there is insufficient evidence to determine whether complete equilibrium occurred in the three studied systems, the fractionation factors reported in this study can provide useful indicators of Ni isotope fractionation associated with fast precipitation of secondary minerals involved in the sequestration of Ni from contaminated environments. These findings also contribute to the characterization of Ni isotope systematics which is still in the early stages of development.

Synthesis, X-ray structure, Hirshfeld analysis and DFT studies of Ni(II) complexes with pyridine-type ligands and monoanionic (SCN¯, N3¯ and NO3¯) ligands

The molecular and supramolecular structures of two self-assembled Ni(II) complexes with pyridine-type ligands (34Lut: 3,4-lutidine and 4Pic: 4-picoline) comprising different anions (SCN¯, N3¯and NO3¯) were presented. The dinuclear [Ni(34Lut)3(SCN)2]2(1) complexcomprises a hexa-coordinated Ni(II) with NiN5S coordination environment from three 34Lut, one isothiocyanate, in addition to two SCN¯ connecting the two Ni(II) centres via µ(1,3) coordination mode. Structure of complex 2 has the two complex units [Ni(4Pic)4(N3)2][Ni(4Pic)4(NO3)2], in which the two Ni(II) centers have also hexa-coordinated environments with NiN6 and NiN4O2 coordination spheres. In both units, there are four 4Pic ligand units coordinating the Ni(II) via the pyridine nitrogen atom and two anions in anti-positions to one another. In the first unit, the two azides have terminal coordination mode. In the second unit, there are two monodentate nitrate ions coordinating the Ni(II) ion via one oxygen atom. Molecular packing analysis using Hirshfeld calculations revealed the importance of the S…H (20.4%) and CH…π (25.2%) interactions in 1. For complex 2, the N…H (16.2%) and O…H (20.7%) contacts are the most important in [Ni(4Pic)4(N3)2] and [Ni(4Pic)4(NO3)2] complex units, respectively. The H…H contact percentages are 50.5, 54.6 and 51.3%, respectively which are the most common in all complex units. Using DFT calculations, the charge of the Ni(II) ion decreased to 0.7792, 0.8136 and 0.9377 e in the thiocyanato, azido and nitrato complexes, respectively. Using AIM calculations, the Ni-N, Ni-S and Ni-O bonds showed the characteristics of mainly closed shell interactions.

Highly-dispersed iron element decorated nickel foam synthesized by an acid-free and one-pot method for enzyme-free glucose sensor

The highly-dispersed iron element decorated Ni foam was prepared by simple immersion in a ferric nitrate solution at room temperature without using acid etching, and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), EDAX spectrum (EDAX mapping) and Raman spectroscopy. The EDAX spectrum illustrated that iron element was highly-dispersed over the entire surface of nickel foam, and the Raman spectroscopy revealed that both Ni-O and Fe-O bonds were formed on the surface of the as-prepared electrode. Moreover, the iron element decorated Ni foam electrode can be used as non-enzymatic glucose sensor and it exhibits not only an ultra-wide linear concentration range of 1–18 mmol/L with an outstanding sensitivity of 1.0388 mA·mmol/(L·cm2), but also an excellent ability of stability and selectivity. Therefore, this work presents a simple yet effective approach to successfully modify Ni foam as non-enzymatic glucose sensor.

Iron-facilitated surface reconstruction to in-situ generate nickel–iron oxyhydroxide on self-supported FeNi alloy fiber paper for efficient oxygen evolution reaction

High-performance and low-cost electrocatalysts for oxygen evolution reaction (OER) are urgently desired to improve the overall efficiency of electrochemical water splitting. Here, a porous and self-supported FeNi-alloy fiber paper is successfully fabricated to achieve excellent OER performance with an ultralow overpotential, as well as remarkable stability. It is demonstrated that Fe substitution into metallic nickel can enable the inactive metallic nickel to endow highly electrocatalytic activity. Therefore, Fe substitution plays a key role for the outstanding performance. Specifically, the leaching of partial Fe atoms on surface of alloy facilitates surface reconstruction to generate active FeNi-oxyhydroxides under OER conditions. Meanwhile, Fe atoms can induce the lengthening of Ni-O bonds within oxyhydroxides for promoting the decomposition of *OOH intermediate species into O2. This work provides new insights into the underlying mechanisms of Fe substitution into metal nickel for improving OER activity, which can accelerate the exploitation of low-cost, efficient and durable electrocatalysts.

Structural, optical and dielectric properties of Zn-doped NiO thin films synthesized via sol-gel route

In this study, pure and Zn-doped nickel oxide thin films have been prepared on glass slides using the sol-gel spin coating process. The effects of Zn doping level concentration (0, 1, 3, and 5%) on structural, morphological, optical, and dielectric properties were studied. The X-ray diffraction patterns revealed that all synthesized films are polycrystalline and correspond to the cubic crystal structure with predominant orientation along the (200) plane. Besides, it was found that with the increase of Zn doping concentration, a variation in the values of several structural parameters such as the crystallite size, the lattice constant, and the strain was observed. The surface morphology examined by scanning electron microscope (SEM) reveals that the deposited film becomes dense, smooth, and agglomeration is increased as the Zn doping level increases. FT-IR analyses confirm the existence of Ni-O bonds. From UV-vis measurements, it is found that all samples exhibit highly optical transmission, more than 80% in the visible region, while the optical band gap values vary from 3.76 to 3.93eV as a function of Zn doping content. Further, the refractive index, extinction coefficient, and dielectric constants were also determined.

Nickel Oxide Thin Films Grooved by Laser Processing

Nickelous oxide thin films were successfully deposited onto glass substrates via a fully computerized system of Spray pyrolysis technique. The substrate was maintained at 350°C. Dichloronickel tetrahydrate was used as the raw chemical material. XRD investigation revealed a cubic phase of NiO crystal structure. XRD diffraction patterns were found peaks at 2θ = 37.280°, 43.297°, 62.916 and 79.542°, respectively The FTIR certified vibration mode of Ni-O bonds. Debye-Scherrer’s formula found out the grains at 21 nm. Absorption spectrum recorded in the wavelength range of 350-850 nm. Morphology of NiO films was uniformly coated with good surface distribution. The fabricated film was grooved by a blue laser source of 500mW power. Laser grooving process produced a groove width of about 34 μm.

Theoretical studies of the g factors and local structures of the Ni3+ centers in Na2Zn(SO4)2·4H2O and K2Zn(SO4)2·6H2O crystals

The local structures and the g factors gi (i = x, y, z) for Ni3+ centers in Na2 Zn(SO4 )2 ·4H2 O (DPPH) and K2 Zn(SO4 )2 ·6H2 O (PHZS) crystals are theoretically studied by using the perturbation formulas of the g factors for a 3d7 ion with low spin (S = 1/2) in orthorhombically compressed octahedra. In these formulas, the contributions to g factors from both the spin-orbit coupling interactions of the central ion and ligands are taken into account, and the required crystal-field parameters are estimated from the superposition model and the local geometry of the systems. Based on the calculations, the Ni-O bonds are found to suffer the axial compression δz (or Δz) of about 0.111 Å (or 0.036 Å) along the z-axis for Ni3+ centers in DPPH (or PHZS) crystals. Meanwhile, the Ni-O bonds may experience additional planar bond length variation δx (≈0.015 Å) along x- and y-axes for the orthorhombic Ni3+ center in DPPH. The theoretical g factors agree well with the experimental data. The obtained local structural parameters for both Ni3+ centers are discussed.

Rapid laser fabrication of Nickel oxide nanoparticles for UV detector

In the present work, silicon-based Nickel oxide heterojunction photodetectors was manufactured via two-step. First, the NiO was directly synthesised by laser ablation (Model Nd:YAG with a wavelength of 1064 nm) in the liquid approach of a pure Ni target: typically with various number of pulses at constant laser energy. Second, the prepared NiO colloidal was then deposited on a silicon wafer surface by a dip-coating method. The impacts of laser pulses on the NiO particles properties were in briefly presented. The synthesis of NiO NPs with a good-nanocrystalline structure in deionized water was proved. The dominated shape of the NiO NPs was quasi-spherical and their concentration was observed to be affected by the laser conditions. FTIR spectral results proved the formation of NiO bonds at 526 cm−1and 507 cm−1. The optical energy bandwidth decreases from 3.75 to 3.6 eV as the laser pulses increase. The introduction of the prepared NiO nanoparticles into silicon showed a well-performance for UV detection. The nanostructured NiO/Si heterojunction photodetector exhibited clear rectifying I-V behaviour in the dark condition and showed prominent photovoltaic properties under illumination. The contrast ratio of the fabricated detector increases with an increasing number of laser pulses. It demonstrated a maximum value of the responsivity and detectivity 0.7 A/W, 63 × 1012 cm. Hz1/2. W−1, respectively under 330 nm UV light illumination.

Defect induced ferromagnetism in NiO nanocrystals: Insight from experimental and DFT+U study

We investigate the defects induced magnetic properties of NiO nanocrystals prepared by mechanical alloying ball milling process. The average crystallite size reduces to ∼12nm after 40 hours of milling but the face centered cubic structure is stable both in pure and milled NiO powders. The unmilled pure NiO is anti-ferromagnetic in nature, whereas the as-milled nanoparticles are ferromagnetic at room temperature with saturation magnetization reaching a maximum of 0.85 emu/g. X-ray photoelectrons spectroscopy (XPS) shows two distinct peaks at 854.2 and 856.1 eV specifically related to the typical Ni-O bonds from Ni2+ and Ni3+ respectively. This is clearly supports the presence of non-stoichiometry in the milled samples due to decrease in Ni2+-O2−-Ni2+ spin correlation length caused by defects. These defects and crystallinity are characterized by Raman spectra which shows that the two-magnon band disappears, one-phonon (1P) longitudinal optical (LO) band broadens, two-phonon (2P) LO band exhibits red-shift and disappears eventually with decreasing of particle size. Magnetic hysteresis (M-H) loops reveals the ferro-magnetic nature of NiO nanocrystals. Considering these defects, we have also investigated the electronic and magnetic properties systematically within the framework of density functional theory. Our results suggest that the vacancies created by only oxygen as well as both nickel and oxygen are largely responsible for ferro-magnetism in nanoscale NiO powders.

Structural and optical investigations of biosynthesized bunsenite NiO nanoparticles (NPs) via an aqueous extract of Rosmarinus officinalis (rosemary) leaves

Green synthesis of nanoparticles represents an important part of nanotechnology that offers outstanding eco-friendly and financial benefits when compared to conventional methods that use toxic substances and involve complex processes. In this paper, we report a completely green process in which aqueous extract of rosemary leaves containing bioactive molecular compounds (flavonoids, monoterpenoids, phenolic acids, and diterpenoids) acted as both chelating and stabilizing agents to facilitate the synthesis of NiO NPs. Apart from the nickel metal precursor, the synthesis was free of solvents and surfactants in this method to adhere to green chemistry principles and the impartation of environmental benignity. To achieve the aim of the study, structural and optical property analyses of Bunsenite annealed at 500 °C were carried-out using complementary techniques namely high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and UV–Vis-NIR absorption spectroscopy. HRTEM micrographs revealed the self-assembled, highly agglomerated quasi-spherical shaped NPs with a cubic structure and the average size was found to peak at 8.09 ± 0.20 nm. SAED and XRD exhibited the polycrystallinity and the purity of NiO NPs and the average size was found in the range of 11.598–15.527 nm. Besides, EDS depicted the presence of Ni and O in the sample while ATR-FTIR illustrated the Ni-O chemical bonds. From UV–Vis-NIR, the optical band gap amounted to 3.39 eV confirmed the formation of NiO NPs. Thereby, an easy and effective green approach for the synthesis of Bunsenite with efficient properties is reported.

Molten-Salt-Mediated Synthesis of an Atomic Nickel Co-catalyst on TiO2 for Improved Photocatalytic H2 Evolution.

Atomic co-catalysts offer high potential to improve the photocatalytic performance, of which the preparation with earth-abundant elements is challenging. Here, a new molten salt method (MSM) is designed to prepare atomic Ni co-catalyst on widely studied TiO2 nanoparticles. The liquid environment and space confinement effect of the molten salt leads to atomic dispersion of Ni ions on TiO2 , while the strong polarizing force provided by the molten salt promotes formation of strong Ni-O bonds. Interestingly, Ni atoms are found to facilitate the formation of oxygen vacancies (OV) on TiO2 during the MSM process, which benefits the charge transfer and hydrogen evolution reaction. The synergy of atomic Ni co-catalyst and OV results in 4-time increase in H2 evolution rate compared to that of the Ni co-catalyst on TiO2 prepared by an impregnation method. This work provides a new strategy of controlling atomic co-catalyst together with defects for efficient photocatalytic water splitting.

Meso-Diketopyripentaphyrin and Diketopyrihexaphyrin as Macrocyclic Tripyrrinone Ligands for NiII Ions.

We report expanded porphyrins with pyridine rings and two neighboring carbonyl groups, which allow NiII ions to coordinate to the tripyrrinone-type NNNO coordination structure with Ni-O bonds. The selectivity of tripyrrinone is superior to other pyrrolic or pyridinic cavities of expanded porphyrins. Introduction of α-carbonyl pyridine next to the tripyrrolic conjugated structure is a powerful strategy for regioselective metalation of flexible expanded porphyrinoids.

Elaboration and structural characterization of phosphate glasses with composition 37.5Na2O-25[(1-x)MgO-xNiO]-37.5P2O5 (0≤x≤1)

Phosphate glasses, with molar compositions 37.5Na2O-25[(1-x)MgO-xNiO]-37.5P2O5 (0 ≤ x ≤ 1), have been prepared using the conventional melt quenching technique. The free nickel glass is colorless while the glasses containing nickel are yellow. The effect of Ni2+ ions on structural and physico-chemical properties of these glasses has been investigated by XRD, DTA, EPR, Raman, FTIR spectroscopies and by density and chemical durability measurements. Substitution of Ni2+ for Mg2+ strengthens the glass network, as shown by the decrease of the molar volume, the increase of the glass transition temperature, and the improvement of the chemical durability. This behavior is a consequence of the replacement of Mg-O bonds by more covalent Ni-O bonds. The glass structure consists of tri-phosphate (P3O10) 5- and di-phosphate (P2O7) 4- groups, and Mg/NiO6 octahedra, with Mg-O-P and Ni-O-P linkages.

Propagation of uncertainty in experiment: structures of Ni (II) coordination complexes.

Accurate experimental XAFS (X-ray absorption fine-structure) data including uncertainties are required during analysis for valid comparison of results and conclusions of hypothesis testing on structural determinations. Here an approach is developed to investigate data without standard interpolation of experimental data and with minimal loss of information content in the raw data. Nickel coordination complexes bis(i-n-propylsalicylaldiminato)nickel(II) (i-pr) and bis(N-n-propylsalicylaldiminato)nickel(II) (n-pr) are investigated. The additional physical insight afforded by the correct propagation of experimental uncertainty is used to determine newly refined structures for the innermost co-ordination shell. Two sets of data are investigated for each complex; one optimized for high point accuracy and one optimized for high point density. Clearly both are important and in this investigation the quality of the physical insight from each is directly provided by measured and propagated uncertainties to fairly represent the relevant accuracies. The results provide evidence for an approximate tetrahedral geometry for the i-pr Ni complex that is more symmetric than previously concluded, with our high point accuracy data yielding ligand lengths of 2.017 ± 0.006 Å and 2.022 ∓ 0.006 Å for Ni-N and Ni-O bonds, respectively, and an even more skewed square-planar (i.e. rhombohedral) arrangement for the n-pr complex with corresponding bond lengths of 2.133 ± 0.004 Å and 1.960 ∓ 0.003 Å. The ability to distinguish using hypothesis testing between the subtle differences in XAFS spectra arising from the approximate local tetrahedral and square-planar geometries of the complexes is also highlighted. The effect of standard interpolation on experimental XAFS spectra prior to fitting with theoretical model structures is investigated. While often performed as a necessary step for Fourier transformation into position space, this will nonetheless skew the fit away from actual data taken, and fails to preserve the information content within the data uncertainty. The artificial effects that interpolation imposes on χr2 are demonstrated. Finally, a method for interpolation is introduced which locally preserves the χr2 and thus information content, when a regular grid is required, e.g for further analysis in r-space.

Improved stability of Ni-rich cathode by the substitutive cations with stronger bonds

In this work, we select four types of substitute cations, Ti4+, Al3+, Mg2+ and Zn2+, to compare their influence on LiNi0.8Co0.1Mn0.1O2. After modification, the average lengths of NiO bonds are elongated with the turn of the Ti, Al, Mg, pristine and Zn-substituted, namely the bond energies are diminished with this sequence, according to their roughly inverse square relation. This tendency is also obeyed by oxygen defects, which induces the NiLi exchanging and surface decomposition, and then exert the effect on electrochemical behavior of Ni-rich cathodes. Among the investigated samples, the Ti-modified sample, which possesses the highest NiO bond energy, presents the best cyclic stability and rate capability, retaining 93.8% in the 200th cycle and 155.1 mAh g−1 under 5C, which is ∼12% higher than the pristine sample. Our approaches illustrate the importance of NiO network and provide a novel thought to further improve these promising cathodes.