MgH_(2)with a large hydrogen capacity is regarded as a promising hydrogen storage material.However,it still suffers from high thermal stability and sluggish kinetics.In this paper,highly dispersed nano-Ni has been suc...MgH_(2)with a large hydrogen capacity is regarded as a promising hydrogen storage material.However,it still suffers from high thermal stability and sluggish kinetics.In this paper,highly dispersed nano-Ni has been successfully prepared by using the polyol reduction method with an average size of 2.14 nm,which significantly improves the de/rehydrogenation properties of MgH_(2).The MgH_(2)–10wt%nano-Ni sample starts releasing H_(2)at 497 K,and roughly 6.2wt%H_(2)has been liberated at 583 K.The rehydrogenation kinetics of the sample are also greatly improved,and the adsorption capacity reaches 5.3wt%H_(2)in 1000 s at 482 K and under 3 MPa hydrogen pressure.Moreover,the activation energies of de/rehydrogenation of the MgH_(2)–10wt%nano-Ni sample are reduced to(88±2)and(87±1)kJ·mol−1,respectively.In addition,the thermal stability of the MgH_(2)–10wt%nano-Ni system is reduced by 5.5 kJ per mol H_(2)from that of pristine MgH_(2).This finding indicates that nano-Ni significantly improves both the thermodynamic and kinetic performances of the de/rehydrogenation of MgH_(2),serving as a bi-functional additive of both reagent and catalyst.展开更多
Magnesium hydride(MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign;however, it suffers from high dehydrogena...Magnesium hydride(MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign;however, it suffers from high dehydrogenation temperature and slow sorption kinetics.Exploring proper catalysts with high and sustainable activity is extremely desired for substantially improving the hydrogen storage properties of MgH2. In this work, a composite catalyst with high-loading of ultrafine Ni nanoparticles(NPs) uniformly dispersed on porous hollow carbon nanospheres is developed, which shows superior catalytic activity towards the de-/hydrogenation of MgH2. With an addition of 5wt% of the composite, which contains 90 wt% Ni NPs, the onset and peak dehydrogenation temperatures of MgH2are lowered to 190 and 242 ℃, respectively. 6.2 wt% H2is rapidly released within 30 min at 250 ℃. The amount of H2that the dehydrogenation product can absorb at a low temperature of 150 ℃ in only 250 s is very close to the initial dehydrogenation value. A dehydrogenation capacity of 6.4wt% remains after 50 cycles at a moderate cyclic regime, corresponding to a capacity retention of 94.1%. The Ni NPs are highly active,reacting with MgH2and forming nanosized Mg2Ni/Mg2NiH4. They act as catalysts during hydrogen sorption cycling, and maintain a high dispersibility with the help of the dispersive role of the carbon substrate, leading to sustainably catalytic activity. The present work provides new insight into designing stable and highly active catalysts for promoting the(de)hydrogenation kinetics of MgH2.展开更多
This paper investigated the influences of surface properties of carbon support and nickel precursors(nickel nitrate, nickel chloride and nickel acetate) on Ni nanoparticle sizes and catalytic performances for steam re...This paper investigated the influences of surface properties of carbon support and nickel precursors(nickel nitrate, nickel chloride and nickel acetate) on Ni nanoparticle sizes and catalytic performances for steam reforming of toluene. Treatment with nitric acid helped to increase the amount of functional groups on the surface and hydrophilic nature of carbon support, leading to a homogeneous distribution of Ni nanoparticles. The thermal decomposition products of nickel precursor also played an important role, Ni nanoparticles supported on carbon treated with acid using nickel nitrate as the precursor exhibited the smallest mean diameter of 4.5 nm. With the loading amount increased from 6 wt% to 18 wt%, the mean particle size of Ni nanoparticles varied from4.5 nm to 9.1 nm. The as-prepared catalyst showed a high catalytic activity and a good stability for toluene steam reforming: 98.1% conversion of toluene was obtained with the Ni content of 12 wt% and the S/C ratio of3, and the conversion only decreased to 92.0% after 700 min. Because of the high activity, good stability, and low cost, the as-prepared catalyst opens up new opportunities for tar removing.展开更多
Monodispersed Ni nanoparticles were successfully prepared by chemical reduction with hydrazine hydrate in ethylene glycol. The effect of the amount of polyvinylpyrrolidone (PVP-K30) on the preparation of Ni nanopart...Monodispersed Ni nanoparticles were successfully prepared by chemical reduction with hydrazine hydrate in ethylene glycol. The effect of the amount of polyvinylpyrrolidone (PVP-K30) on the preparation of Ni nanoparticles was investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM) were employed to characterize the nickel powders. The average nickel particle size can be controlled from 103 nm to 46 ran with increasing the mass ratio of PVP to NiCl2·6H2O. The particles are spherical in shape and are not agglomerated. A possible extensive mechanism of nickel nanoparticle formation has been suggested.展开更多
Ni nanoparticles plating was prepared in reverse microemulsion. The deposition was carried out through the Brownian motion of water pools in the reverse microemulsion and the adsorption of water pools on the electrode...Ni nanoparticles plating was prepared in reverse microemulsion. The deposition was carried out through the Brownian motion of water pools in the reverse microemulsion and the adsorption of water pools on the electrode surface. Effects of electrolytic parameters on the size of Ni particles were studied. The performances of hydrogen evolution and hydrogen storage of the Ni nanoparticles plating electrode were also investigated. The results indicate that the size of Ni nanoparticles decreases with the increase of Ni2+ concentration and the decrease of current density. The electrochemical activity of Ni nanoparticles plating electrode is much higher than that of bulk Ni electrode.展开更多
Low cost,highly selective and efficient electrocatalysts for CO_(2)reduction reaction(CO_(2)RR)is crucial for lowering the global carbon footprint and mitigating energy shortages.Here,we first report a highly selectiv...Low cost,highly selective and efficient electrocatalysts for CO_(2)reduction reaction(CO_(2)RR)is crucial for lowering the global carbon footprint and mitigating energy shortages.Here,we first report a highly selective and efficient electrocatalyst for CO_(2)RR to CO using a surface-regulated Ni nanoparticles supported on N-doped CMK-3(N,O-Ni/CMK3).Compared with most Ni metal catalysts previously reported with severe competitive hydrogen evolution during the CO_(2)RR,the N,O-Ni/CMK3 catalyst presents a superior CO faradaic efficiency of about 97%,a high CO partial current density(13.01 mA cm^(-1))and turnover frequency(4.25 s^(–1)).The comprehensive characterization provides evidence that the N,O co-regulated Ni acts as the active center.Taking advantage of the N,O co-regulated chemical environment,N,O-Ni/CMK3 also displays a decent stability at negative potentials.Our work paves a novel approach for developing transition metal catalysts for CO_(2)RR with enhanced activity and selectivity via regulating surface chemical environment.展开更多
A simple solvothermal approach was developed to synthesize uniform spherical monodisperse Ni nanoparticles, which can easily disperse in nonpolar solvents to form homogenous colloidal solution. The as-prepared sample ...A simple solvothermal approach was developed to synthesize uniform spherical monodisperse Ni nanoparticles, which can easily disperse in nonpolar solvents to form homogenous colloidal solution. The as-prepared sample was characterized by XRD, TEM, and FTIR. The results indicate that Ni nanoparticles have the structure of face-centered cube and a narrow distribution with a diameter of (3.5±0.5) nm. The FTIR spectrum reveals that the nanoparticles are coated with oleic acid. In the synthetic process, N2H4·H2O was used as a reducing agent and oleic acid as a surfactant. The probable formation mechanism of the spherical nanoparticles was also discussed.展开更多
The synthesis of primary amines via reductive amination in the presence of NH_(3)and H_(2),as a green and sustainable process,has attracted much attention.In this paper,we prepared series of Ni/SiO_(2)catalysts with d...The synthesis of primary amines via reductive amination in the presence of NH_(3)and H_(2),as a green and sustainable process,has attracted much attention.In this paper,we prepared series of Ni/SiO_(2)catalysts with deposition-precipitation and impregnation methods,and their catalytic performances on the reductive amination of a biomass derived compound of furfural to produce furfurylamine were studied.The catalytic activity and the yield were correlated to the structure and the surface properties of catalysts largely.The Ni/SiO_(2)is of high Lewis acidity and small Ni particle with numerous large Ni flat step surface showed high activity and selectivity,it afforded a reaction rate of 12.8 h^(−1)and a high yield to furfurylamine around 98%.These results are superior to the most non-noble metal catalysts reported so far.Moreover,the reaction route was examined with the unit control reactions of the intermediate.To produce furfurylamine selectively,the most suitable catalyst should have the moderate but not the highest activity in activation of hydrogen and hydrogenation in the reductive amination of furfural.This work provides some useful information for the catalytic reductive amination of aldehydes both in the design of catalyst and the reaction route.展开更多
Electrochemical CO_(2)reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily ac...Electrochemical CO_(2)reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily accessible active sites for CO_(2)electroreduction remains challenging yet indispensable.In this work,a reliable poly(ethyleneimine)(PEI)-assisted strategy is developed to prepare a hollow carbon nanocomposite comprising a single-site Ni-modified carbon shell and confined Ni nanoparticles(NPs)(denoted as Ni@NHCS),where PEI not only functions as a mediator to induce the highly dispersed growth of Ni NPs within hollow carbon spheres,but also as a nitrogen precursor to construct highly active atomically-dispersed Ni-Nx sites.Benefiting from the unique structural properties of Ni@NHCS,the aggregation and exposure of Ni NPs can be effectively prevented,while the accessibility of abundant catalytically active Ni-Nx sites can be ensured.As a result,Ni@NHCS exhibits a high CO partial current density of 26.9 mA cm^(-2)and a Faradaic efficiency of 93.0%at-1.0 V vs.RHE,outperforming those of its PEI-free analog.Apart from the excellent activity and selectivity,the shell confinement effect of the hollow carbon sphere endows this catalyst with long-term stability.The findings here are anticipated to help understand the structure-activity relationship in Ni-based carbon catalyst systems for electrocatalytic CO_(2)reduction.Furthermore,the PEI-assisted synthetic concept is potentially applicable to the preparation of high-performance metal-based nanoconfined materials tailored for diverse energy conversion applications and beyond.展开更多
We report on the preparation of three kinds of Ni nanoparticles supported on carbon (Ni/C) and their application in the catalytic hydrolysis of ammonia borane (AB). Three Ni/C catalysts were prepared from a Ni met...We report on the preparation of three kinds of Ni nanoparticles supported on carbon (Ni/C) and their application in the catalytic hydrolysis of ammonia borane (AB). Three Ni/C catalysts were prepared from a Ni metal-organic framework (Ni-MOF) precursor by reduction with KBI-G calcination at 700 ℃ under Ar, and a combination of calcination and reduction, the products being denoted as Ni/C-1, Ni/C-2, and Ni/C-3, respectively. The structure, morphology, specific surface area, and element valence were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption measurements, and X-ray photoelectron spectra (XPS). The results demonstrate that Ni/C-1 is composed of amorphous Ni particles agglomerated on carbon, Ni/C-2 is characteristic of crystalline Ni nanoparticles (about 10 nm in size) supported on carbon with Ni oxidized on the surface, while the surface of the Ni particles in Ni/C-3 is less oxidized. The specific surface areas of Ni-MOF, Ni/C-1, Ni/C-2, and Ni/C-3 are 1239, 33, 470, and 451 m2·g-1, respectively. The catalytic hydrolysis of AB with Ni/C-3 shows a hydrogen generation rate of 834 mL-min^-1·g-1 at room temperature and an activation energy of 31.6 kJ/mol. Ni/C-3 shows higher catalytic activity than other materials, which can be attributed to its larger surface area of crystalline Ni. This study offers a promising way to replace noble metal by under ambient conditions. Ni nanoparticles for AB hydrolysis展开更多
Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a po...Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a porous Ni-doped carbon matrix were produced by the pyrolysis of zirconium metal–organic–frameworks, in which 2,2′-bipyridine-5,5′-dicarboxylate operating as a ligand can coordinate with Ni^(2+) and Fe^(3+). This strategy allows formation of Fe-modulated Ni nanoparticles with a uniform dimension of about 2 nm which can be ascribed to the spatial blocking effect of ZrO_(2). This unique catalyst displays an efficient oxygen evolution reaction electrocatalytic activity with a low overpotential of 372 mV at 10 mA·cm^(–2) and a small Tafel slope of 84.4 mV·dec^(–1) in alkaline media. More importantly, it shows superior durability and structural stability after 43 h in a chronoamperometry test. Meanwhile, it shows excellent cycling stability during 4000 cyclic voltammetry cycles. This research offers a new insight into the construction of uniform nanoscale transition metals and their alloys as highly efficient and durable electrocatalysts.展开更多
Meso-Ni@HZSM-5 bi-functional catalysts were successfully post-encapsulated with about 3-7 nm Ni nanoparticles within HZSM-5 crystals,which exhibited significantly efficient conversion activity(67.4 g[palmitic acid]g[N...Meso-Ni@HZSM-5 bi-functional catalysts were successfully post-encapsulated with about 3-7 nm Ni nanoparticles within HZSM-5 crystals,which exhibited significantly efficient conversion activity(67.4 g[palmitic acid]g[Ni]^(−1)h^(−1))of palmitic acid and 100%selectivity of hydrocarbons with the outstanding stability during recycling application,compared to the impregnated Ni/HZSM-5 catalyst(14.0 g[palmitic acid]g[Ni]^(−1)h^(−1)).展开更多
This paper reports that metal-oxide-semiconductor (MOS) capacitors with a single layer of Ni nanopartictes were successfully fabricated by using electron-beam evaporation and rapid thermal annealing for application ...This paper reports that metal-oxide-semiconductor (MOS) capacitors with a single layer of Ni nanopartictes were successfully fabricated by using electron-beam evaporation and rapid thermal annealing for application to nonvolatile memory. Experimental scanning electron microscopy images showed that Ni nanoparticles of about 5 nm in diameter were clearly embedded in the SiO2 layer on p-type Si (100). Capacitance-voltage measurements of the MOS capacitor show large flat-band voltage shifts of 1.8 V, which indicate the presence of charge storage in the nickel nanoparticles. In addition, the charge-retention characteristics of MOS capacitors with Ni nanoparticles were investigated by using capacitance-time measurements. The results showed that there was a decay of the capacitance embedded with Ni nanoparticles for an electron charge after 104 s. But only a slight decay of the capacitance originating from hole charging was observed. The present results indicate that this technique is promising for the efficient formation or insertion of metal nanoparticles inside MOS structures.展开更多
Catalytic hydrogenation is a vital industrial means to produce value-added fuels and fine chemicals,however, requiring highly efficient catalysts, especially the nonprecious ones. To date, the majority of high-perform...Catalytic hydrogenation is a vital industrial means to produce value-added fuels and fine chemicals,however, requiring highly efficient catalysts, especially the nonprecious ones. To date, the majority of high-performance industrial hydrogenation catalysts are made of precious metals-based materials, and any given catalyst could only be used to catalyze one or few specific reactions. Herein, we exemplify a crystal phase engineering approach to empower Ni nanoparticles(NPs) with superb intrinsic catalytic activities toward a wide spectrum of hydrogenation reactions. A facile pyrolysis approach is used to directly convert a Ni-imidazole MOF precursor into hexagonal close-packed(hcp)-phased Ni NPs on carbon support. The as-synthesized hcp-phased Ni NPs exhibit unprecedented hydrogenation catalytic activities in pure water towards nitro-, aldehyde-, ketone-, alkene-and N heterocyclic-compounds, outperforming the face-centered cubic(fcc)-Ni counterpart and the reported transition metalsbased catalysts. The density functional theory calculations unveil that the presence of hcp-Ni boosts the intrinsic catalytic hydrogenation activity by coherently enhancing the substrate adsorption strength and lowering the reaction barrier energy of the rate-determining step. We anticipate that the crystal phase engineering design approach unveiled in this work would be adoptable to other types of reactions.展开更多
The Ni nanoparticles coated with Pb(Zr,Ti)O3(PZT) were synthesized by a sol-gel method and in situ reaction. And their structure, oxidation resistance, and electromagnetic properties were investigated. The X-ray d...The Ni nanoparticles coated with Pb(Zr,Ti)O3(PZT) were synthesized by a sol-gel method and in situ reaction. And their structure, oxidation resistance, and electromagnetic properties were investigated. The X-ray diffraction patterns(XRD) exhibited that a small amount of impure phase characterized to Ni(OH)2 was detected from the ammonia-treated Ni nanoparticles and the ammonia-treated Ni nanoparticles coated with PZT. After being pre-treated with aqueous ammonia, the PZT coating layer was more uniform and about 10 nm in thickness. The oxidation resistance of the ammonia-treated Ni nanoparticles coated with PZT, compared with that of the non-treated ones, was improved by about 66 ℃. The PZT shell layer prepared by in-situ reaction can greatly reduce the dielectric constant and improve the natural resonance loss at high frequency, so as to obtain the optimal impedance matching performance of the electromagnetic wave transmission.展开更多
Metallic nanoparticle (NP) shapes have a significant influence on the property of composite embedded with metallic NPs. Swift heavy ion irradiation is an effective way to modify shapes of metallic NPs embedded in an...Metallic nanoparticle (NP) shapes have a significant influence on the property of composite embedded with metallic NPs. Swift heavy ion irradiation is an effective way to modify shapes of metallic NPs embedded in an amorphous matrix. We investigate the shape deformation of Ag NPs with irradiation fluence, and 357 MeV Ni ions are used to irradiate the silica containing Ag NPs, which are prepared by ion implantation and vacuum annealing. The UV-vis results show that the surface plasmon resonance (SPR) peak from Ag NPs shifts from 400 to 377nm. The SPR peak has a significant shift at fluence lower than 1 × 10^14 ions/cm2 and shows less shift at fluence higher than 1 × 10^14 ions/cm2. The TEM results reveal that the shapes of Ag NPs also show significant deformation at fluence lower than 1 × 10^14 ions/cm2 and show less deformation at fluence higher than 1 × 10^14 ions/cm2. The blue shift of the SPR peak is considered to be the consequence of defect production and Ag NP shape deformation, Based on the thermal spike model calculation, the temperature of the silica surrounding Ag particles first increases rapidly, then the region of Ag NPs close to the interface of Ag/silica is gradually heated. Therefore, the driven force of Ag NPs deformation is considered as the volume expansion of the first heated silica layer surrounding Ag NPs.展开更多
Nickel(Ni)nanoparticles can be enriched on the surface of iron-based frictional pairs,which provides the possibility to get rid of the competitive adsorption between the polar species of vegetable oil and the surface-...Nickel(Ni)nanoparticles can be enriched on the surface of iron-based frictional pairs,which provides the possibility to get rid of the competitive adsorption between the polar species of vegetable oil and the surface-active nano-additives thereon.In this paper,nickel acetylacetonate was used as a precursor to in-situ synthesize nickel nanoparticles with an average diameter of about 12 nm in rapeseed oil(RO)as the reducing agent,surface modifier,and solvent as well.The tribological properties of the as-synthesized Ni nanoparticles were evaluated with a four-ball tribometer,and their tribomechanism was investigated based on the characterizations of the tribofilm on rubbed steel surfaces by the scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).It was found that the Ni nanoparticles in-situ prepared in the RO with a mass fraction of 0.3%can reduce the wear scar diameter(WSD)of the steel ball by 36%.This is because,on the one hand,the Ni nanoparticles are adsorbed on the rubbed steel surfaces to repair or fill up the micro-pits and grooves thereon.On the other hand,Ni nanoparticles participate in tribochemical reactions with atmospheric O and steel substrate to form the tribochemical reaction film on the rubbed steel surfaces with the assistance of friction-induced heat and applied normal load.In addition,an amorphous carbon film is formed on the rubbed surface via the carbonization of base oil under the catalysis of Ni nanoparticles.The adsorbed Ni layer,the tribochemical reaction film,and the carbon layer comprise a composite tribofilm composed of amorphous carbon,polar fatty acid,metallic nickel,iron oxides,and nickel oxides on the rubbed steel surfaces,which contributes to significantly improving the antiwear ability and load-carrying capacity of the RO for the steel-steel sliding pair.展开更多
Ni nanocatalysts produced through exsolution have shown strong resistance to particle sintering and carbon coking in a beneficial dry reforming of methane(DRM)reaction utilizing greenhouse gases such as CH_(4)and CO_(...Ni nanocatalysts produced through exsolution have shown strong resistance to particle sintering and carbon coking in a beneficial dry reforming of methane(DRM)reaction utilizing greenhouse gases such as CH_(4)and CO_(2).However,most of the existing oxide supports for exsolution have been limited to perovskite oxide,while studies on fluorite support have been rarely conducted due to the limited solubility despite its excellent redox stability.Here we demonstrate that 3 mol%Ni can be successfully dissolved into the yttria-stabilized zirconia(YSZ)lattice and be further exsolved to the surface in a reducing atmosphere.The YSZ decorated with exsolved Ni nanoparticles shows enhanced catalytic activity for DRM reaction compared to the conventional cermet type of bulk Ni-YSZ.Moreover,the catalytic activity is extremely stable for about 300 h without significant degradation.Overall results suggest that the YSZ-based fluorite structure can be utilized as one of the support oxides for exsolution.展开更多
Carbon nanofibers(CNFs)with high specific surface area show great potential for sodium storage as a hard carbon material.Herein,CNFs anchored with Ni nanoparticles(CNFs/Ni)were prepared through chemical vapor depositi...Carbon nanofibers(CNFs)with high specific surface area show great potential for sodium storage as a hard carbon material.Herein,CNFs anchored with Ni nanoparticles(CNFs/Ni)were prepared through chemical vapor deposition and impregnation reduction methods,in situ growing on the three-dimensional porous copper current collector(3DP-Cu).The coupling effect of high-spin state Ni nanopar-ticles leads to the increase of defect density and the expansion of lattice spacing of CNFs.Meanwhile,the 3DP-Cu ensures a high loading capacity of CNFs and short ion/electron transport channels.As an integral binder-free anode,the 3DP-Cu/CNFs/Ni exhibits excellent electrochemical performance,which demon-strates a high specific capacity with 298.5 mAh g^(-1)at 1000 mA g^(-1)after 1500 cycles,and a high power density with 200 mAh g^(-1)over 1000 cycles at 5000 mA g^(-1).Density functional theory calculation re-sults show that the high-spin state Ni regulates the electronic structure of CNFs,which significantly reduces the adsorption energy for Na^(+)(-2.7 Ev)and thus enables high-rate capability.The regulation of the electronic structure of carbon materials by high-spin state metal provides a new strategy for developing high-power carbonaceous anode materials for sodium-ion batteries.展开更多
Herein,nickel@nitrogen-doped carbon nanotubes(Ni@NCNTs)are prepared by a simple and reliable method with Ni-based complex as single-source precursor.Significantly,the formation of CNTs is not susceptible to the calcin...Herein,nickel@nitrogen-doped carbon nanotubes(Ni@NCNTs)are prepared by a simple and reliable method with Ni-based complex as single-source precursor.Significantly,the formation of CNTs is not susceptible to the calcination temperature and ramping rate and Ni@NCNTs can be attained from 430 to 900℃in an inert atmosphere.Then they are the first time to be applied as the anode material for sodium-ion batteries.The presence of Ni nanoparticles(NPs)facilitates the solid electrolyte interface film over the anode surface and improves the capacity retention of the host material,especially at the high rates.Furthermore,Na+diffusion is reinforced after the introduction of Ni NPs.Ni@NCNTs obtained at 500℃(Ni@NCNTs-500)exhibit the best capacity retention and rate capability.Kinetics analyses demonstrate the faster electron transportation and ion diffusion than others prepared at other temperatures.The surficial capacitance storage favors the fast electrochemistry kinetics.It delivers a high specific capacity(192 mA h g^−1 at 0.5 A g^−1),excellent cycling stability(103 mA h g^−1 after 10,000 cycles at 10 A g^−1),and outstanding high-rate capability up to 20 A g^−1(118 mA h g^−1).The related full cells confirm a high energy density of 140 Wh kg^−1 at 38.16 W kg^−1 and 44.27 W h kg^−1 at 762 W kg^−1.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 52071177)the Natural Science Foundation of Guangxi, China (No. 2020GXNSFAA297074)+1 种基金the Jiangsu Key Laboratory for Advanced Metallic Materials (No. BM2007204)the Guangxi Key Laboratory of Information Materials (No. 211021-K)
文摘MgH_(2)with a large hydrogen capacity is regarded as a promising hydrogen storage material.However,it still suffers from high thermal stability and sluggish kinetics.In this paper,highly dispersed nano-Ni has been successfully prepared by using the polyol reduction method with an average size of 2.14 nm,which significantly improves the de/rehydrogenation properties of MgH_(2).The MgH_(2)–10wt%nano-Ni sample starts releasing H_(2)at 497 K,and roughly 6.2wt%H_(2)has been liberated at 583 K.The rehydrogenation kinetics of the sample are also greatly improved,and the adsorption capacity reaches 5.3wt%H_(2)in 1000 s at 482 K and under 3 MPa hydrogen pressure.Moreover,the activation energies of de/rehydrogenation of the MgH_(2)–10wt%nano-Ni sample are reduced to(88±2)and(87±1)kJ·mol−1,respectively.In addition,the thermal stability of the MgH_(2)–10wt%nano-Ni system is reduced by 5.5 kJ per mol H_(2)from that of pristine MgH_(2).This finding indicates that nano-Ni significantly improves both the thermodynamic and kinetic performances of the de/rehydrogenation of MgH_(2),serving as a bi-functional additive of both reagent and catalyst.
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology of PR China (No. 2018YFB1502103)National Natural Science Foundation of PR China (Nos. 52071287, 51571175, U1601212, 51831009)。
文摘Magnesium hydride(MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign;however, it suffers from high dehydrogenation temperature and slow sorption kinetics.Exploring proper catalysts with high and sustainable activity is extremely desired for substantially improving the hydrogen storage properties of MgH2. In this work, a composite catalyst with high-loading of ultrafine Ni nanoparticles(NPs) uniformly dispersed on porous hollow carbon nanospheres is developed, which shows superior catalytic activity towards the de-/hydrogenation of MgH2. With an addition of 5wt% of the composite, which contains 90 wt% Ni NPs, the onset and peak dehydrogenation temperatures of MgH2are lowered to 190 and 242 ℃, respectively. 6.2 wt% H2is rapidly released within 30 min at 250 ℃. The amount of H2that the dehydrogenation product can absorb at a low temperature of 150 ℃ in only 250 s is very close to the initial dehydrogenation value. A dehydrogenation capacity of 6.4wt% remains after 50 cycles at a moderate cyclic regime, corresponding to a capacity retention of 94.1%. The Ni NPs are highly active,reacting with MgH2and forming nanosized Mg2Ni/Mg2NiH4. They act as catalysts during hydrogen sorption cycling, and maintain a high dispersibility with the help of the dispersive role of the carbon substrate, leading to sustainably catalytic activity. The present work provides new insight into designing stable and highly active catalysts for promoting the(de)hydrogenation kinetics of MgH2.
基金Supported by the National Natural Science Foundation of China(21606008,21436002)the National Basic Research Foundation of China(2013CB733600)the Fundamental Research Funds for the Central Universities(ZY1630,JD1617,buctrc201616,and buctrc201617)
文摘This paper investigated the influences of surface properties of carbon support and nickel precursors(nickel nitrate, nickel chloride and nickel acetate) on Ni nanoparticle sizes and catalytic performances for steam reforming of toluene. Treatment with nitric acid helped to increase the amount of functional groups on the surface and hydrophilic nature of carbon support, leading to a homogeneous distribution of Ni nanoparticles. The thermal decomposition products of nickel precursor also played an important role, Ni nanoparticles supported on carbon treated with acid using nickel nitrate as the precursor exhibited the smallest mean diameter of 4.5 nm. With the loading amount increased from 6 wt% to 18 wt%, the mean particle size of Ni nanoparticles varied from4.5 nm to 9.1 nm. The as-prepared catalyst showed a high catalytic activity and a good stability for toluene steam reforming: 98.1% conversion of toluene was obtained with the Ni content of 12 wt% and the S/C ratio of3, and the conversion only decreased to 92.0% after 700 min. Because of the high activity, good stability, and low cost, the as-prepared catalyst opens up new opportunities for tar removing.
文摘Monodispersed Ni nanoparticles were successfully prepared by chemical reduction with hydrazine hydrate in ethylene glycol. The effect of the amount of polyvinylpyrrolidone (PVP-K30) on the preparation of Ni nanoparticles was investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM) were employed to characterize the nickel powders. The average nickel particle size can be controlled from 103 nm to 46 ran with increasing the mass ratio of PVP to NiCl2·6H2O. The particles are spherical in shape and are not agglomerated. A possible extensive mechanism of nickel nanoparticle formation has been suggested.
基金Projects(20673036,J0830415) supported by the National Natural Science Foundation of ChinaProject(09JJ3025) supported by Hunan Provincial Natural Science Foundation of ChinaProject(09GK3173) supported by the Planned Science and Technology Project of Hunan Province,China
文摘Ni nanoparticles plating was prepared in reverse microemulsion. The deposition was carried out through the Brownian motion of water pools in the reverse microemulsion and the adsorption of water pools on the electrode surface. Effects of electrolytic parameters on the size of Ni particles were studied. The performances of hydrogen evolution and hydrogen storage of the Ni nanoparticles plating electrode were also investigated. The results indicate that the size of Ni nanoparticles decreases with the increase of Ni2+ concentration and the decrease of current density. The electrochemical activity of Ni nanoparticles plating electrode is much higher than that of bulk Ni electrode.
文摘Low cost,highly selective and efficient electrocatalysts for CO_(2)reduction reaction(CO_(2)RR)is crucial for lowering the global carbon footprint and mitigating energy shortages.Here,we first report a highly selective and efficient electrocatalyst for CO_(2)RR to CO using a surface-regulated Ni nanoparticles supported on N-doped CMK-3(N,O-Ni/CMK3).Compared with most Ni metal catalysts previously reported with severe competitive hydrogen evolution during the CO_(2)RR,the N,O-Ni/CMK3 catalyst presents a superior CO faradaic efficiency of about 97%,a high CO partial current density(13.01 mA cm^(-1))and turnover frequency(4.25 s^(–1)).The comprehensive characterization provides evidence that the N,O co-regulated Ni acts as the active center.Taking advantage of the N,O co-regulated chemical environment,N,O-Ni/CMK3 also displays a decent stability at negative potentials.Our work paves a novel approach for developing transition metal catalysts for CO_(2)RR with enhanced activity and selectivity via regulating surface chemical environment.
基金the Research Fund of Shaanxi Key Laboratory(Nos.04JS04 and 05JS50)the Natural Science Foundation of Shaanxi Province, China(No.2005B19)the Significant Special Found of "13115" S & T Innovation Project of Shaanxi Province, China(No.2007ZDKG-61)
文摘A simple solvothermal approach was developed to synthesize uniform spherical monodisperse Ni nanoparticles, which can easily disperse in nonpolar solvents to form homogenous colloidal solution. The as-prepared sample was characterized by XRD, TEM, and FTIR. The results indicate that Ni nanoparticles have the structure of face-centered cube and a narrow distribution with a diameter of (3.5±0.5) nm. The FTIR spectrum reveals that the nanoparticles are coated with oleic acid. In the synthetic process, N2H4·H2O was used as a reducing agent and oleic acid as a surfactant. The probable formation mechanism of the spherical nanoparticles was also discussed.
基金the financial support from the National Natural Science Foundation of China(Nos.22172155 and 22072142)the Youth Innovation Promotion Association CAS(No.2016206).
文摘The synthesis of primary amines via reductive amination in the presence of NH_(3)and H_(2),as a green and sustainable process,has attracted much attention.In this paper,we prepared series of Ni/SiO_(2)catalysts with deposition-precipitation and impregnation methods,and their catalytic performances on the reductive amination of a biomass derived compound of furfural to produce furfurylamine were studied.The catalytic activity and the yield were correlated to the structure and the surface properties of catalysts largely.The Ni/SiO_(2)is of high Lewis acidity and small Ni particle with numerous large Ni flat step surface showed high activity and selectivity,it afforded a reaction rate of 12.8 h^(−1)and a high yield to furfurylamine around 98%.These results are superior to the most non-noble metal catalysts reported so far.Moreover,the reaction route was examined with the unit control reactions of the intermediate.To produce furfurylamine selectively,the most suitable catalyst should have the moderate but not the highest activity in activation of hydrogen and hydrogenation in the reductive amination of furfural.This work provides some useful information for the catalytic reductive amination of aldehydes both in the design of catalyst and the reaction route.
文摘Electrochemical CO_(2)reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy conversion.The development of efficient catalysts with high conductivity and readily accessible active sites for CO_(2)electroreduction remains challenging yet indispensable.In this work,a reliable poly(ethyleneimine)(PEI)-assisted strategy is developed to prepare a hollow carbon nanocomposite comprising a single-site Ni-modified carbon shell and confined Ni nanoparticles(NPs)(denoted as Ni@NHCS),where PEI not only functions as a mediator to induce the highly dispersed growth of Ni NPs within hollow carbon spheres,but also as a nitrogen precursor to construct highly active atomically-dispersed Ni-Nx sites.Benefiting from the unique structural properties of Ni@NHCS,the aggregation and exposure of Ni NPs can be effectively prevented,while the accessibility of abundant catalytically active Ni-Nx sites can be ensured.As a result,Ni@NHCS exhibits a high CO partial current density of 26.9 mA cm^(-2)and a Faradaic efficiency of 93.0%at-1.0 V vs.RHE,outperforming those of its PEI-free analog.Apart from the excellent activity and selectivity,the shell confinement effect of the hollow carbon sphere endows this catalyst with long-term stability.The findings here are anticipated to help understand the structure-activity relationship in Ni-based carbon catalyst systems for electrocatalytic CO_(2)reduction.Furthermore,the PEI-assisted synthetic concept is potentially applicable to the preparation of high-performance metal-based nanoconfined materials tailored for diverse energy conversion applications and beyond.
文摘We report on the preparation of three kinds of Ni nanoparticles supported on carbon (Ni/C) and their application in the catalytic hydrolysis of ammonia borane (AB). Three Ni/C catalysts were prepared from a Ni metal-organic framework (Ni-MOF) precursor by reduction with KBI-G calcination at 700 ℃ under Ar, and a combination of calcination and reduction, the products being denoted as Ni/C-1, Ni/C-2, and Ni/C-3, respectively. The structure, morphology, specific surface area, and element valence were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption measurements, and X-ray photoelectron spectra (XPS). The results demonstrate that Ni/C-1 is composed of amorphous Ni particles agglomerated on carbon, Ni/C-2 is characteristic of crystalline Ni nanoparticles (about 10 nm in size) supported on carbon with Ni oxidized on the surface, while the surface of the Ni particles in Ni/C-3 is less oxidized. The specific surface areas of Ni-MOF, Ni/C-1, Ni/C-2, and Ni/C-3 are 1239, 33, 470, and 451 m2·g-1, respectively. The catalytic hydrolysis of AB with Ni/C-3 shows a hydrogen generation rate of 834 mL-min^-1·g-1 at room temperature and an activation energy of 31.6 kJ/mol. Ni/C-3 shows higher catalytic activity than other materials, which can be attributed to its larger surface area of crystalline Ni. This study offers a promising way to replace noble metal by under ambient conditions. Ni nanoparticles for AB hydrolysis
基金financial support from the National Key Technologies R&D Program of China(Grant No.2017YFA0205103)the National Natural Science Foundation of China(Grant No.21971045)+1 种基金the Natural Science Foundation of Shanghai(Grant No.18ZR1402900)Shanghai Leading Academic Discipline Project(Grant No.B108).
文摘Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a porous Ni-doped carbon matrix were produced by the pyrolysis of zirconium metal–organic–frameworks, in which 2,2′-bipyridine-5,5′-dicarboxylate operating as a ligand can coordinate with Ni^(2+) and Fe^(3+). This strategy allows formation of Fe-modulated Ni nanoparticles with a uniform dimension of about 2 nm which can be ascribed to the spatial blocking effect of ZrO_(2). This unique catalyst displays an efficient oxygen evolution reaction electrocatalytic activity with a low overpotential of 372 mV at 10 mA·cm^(–2) and a small Tafel slope of 84.4 mV·dec^(–1) in alkaline media. More importantly, it shows superior durability and structural stability after 43 h in a chronoamperometry test. Meanwhile, it shows excellent cycling stability during 4000 cyclic voltammetry cycles. This research offers a new insight into the construction of uniform nanoscale transition metals and their alloys as highly efficient and durable electrocatalysts.
基金financial supports from the Natural Science Foundation of China (No.21908225)the National Key Research and Development Program (No.2018YFC1801501)。
文摘Meso-Ni@HZSM-5 bi-functional catalysts were successfully post-encapsulated with about 3-7 nm Ni nanoparticles within HZSM-5 crystals,which exhibited significantly efficient conversion activity(67.4 g[palmitic acid]g[Ni]^(−1)h^(−1))of palmitic acid and 100%selectivity of hydrocarbons with the outstanding stability during recycling application,compared to the impregnated Ni/HZSM-5 catalyst(14.0 g[palmitic acid]g[Ni]^(−1)h^(−1)).
基金Project supported by National Natural Science Foundation of China(Grant Nos.10874070,60976001,and 50872051)Natural Science Foundation of Jiangsu Province of China(Grant No.BK2008253)+2 种基金State Key Program for Basic Research of China(Grant Nos.2007CB935401 and 2010CB934402)Natural Science Foundation of Jiangsu Province for Universities(Grant No.09KJB510014)Nanjing University of Posts and Telecommunications Research Fund(Grant No.NY208057 and JG03309JX37)
文摘This paper reports that metal-oxide-semiconductor (MOS) capacitors with a single layer of Ni nanopartictes were successfully fabricated by using electron-beam evaporation and rapid thermal annealing for application to nonvolatile memory. Experimental scanning electron microscopy images showed that Ni nanoparticles of about 5 nm in diameter were clearly embedded in the SiO2 layer on p-type Si (100). Capacitance-voltage measurements of the MOS capacitor show large flat-band voltage shifts of 1.8 V, which indicate the presence of charge storage in the nickel nanoparticles. In addition, the charge-retention characteristics of MOS capacitors with Ni nanoparticles were investigated by using capacitance-time measurements. The results showed that there was a decay of the capacitance embedded with Ni nanoparticles for an electron charge after 104 s. But only a slight decay of the capacitance originating from hole charging was observed. The present results indicate that this technique is promising for the efficient formation or insertion of metal nanoparticles inside MOS structures.
基金financially supported by the National Natural Science Foundation of China (51902311 and 51871209)。
文摘Catalytic hydrogenation is a vital industrial means to produce value-added fuels and fine chemicals,however, requiring highly efficient catalysts, especially the nonprecious ones. To date, the majority of high-performance industrial hydrogenation catalysts are made of precious metals-based materials, and any given catalyst could only be used to catalyze one or few specific reactions. Herein, we exemplify a crystal phase engineering approach to empower Ni nanoparticles(NPs) with superb intrinsic catalytic activities toward a wide spectrum of hydrogenation reactions. A facile pyrolysis approach is used to directly convert a Ni-imidazole MOF precursor into hexagonal close-packed(hcp)-phased Ni NPs on carbon support. The as-synthesized hcp-phased Ni NPs exhibit unprecedented hydrogenation catalytic activities in pure water towards nitro-, aldehyde-, ketone-, alkene-and N heterocyclic-compounds, outperforming the face-centered cubic(fcc)-Ni counterpart and the reported transition metalsbased catalysts. The density functional theory calculations unveil that the presence of hcp-Ni boosts the intrinsic catalytic hydrogenation activity by coherently enhancing the substrate adsorption strength and lowering the reaction barrier energy of the rate-determining step. We anticipate that the crystal phase engineering design approach unveiled in this work would be adoptable to other types of reactions.
基金Funded by the National Natural Science Foundation of China(No.61201051)
文摘The Ni nanoparticles coated with Pb(Zr,Ti)O3(PZT) were synthesized by a sol-gel method and in situ reaction. And their structure, oxidation resistance, and electromagnetic properties were investigated. The X-ray diffraction patterns(XRD) exhibited that a small amount of impure phase characterized to Ni(OH)2 was detected from the ammonia-treated Ni nanoparticles and the ammonia-treated Ni nanoparticles coated with PZT. After being pre-treated with aqueous ammonia, the PZT coating layer was more uniform and about 10 nm in thickness. The oxidation resistance of the ammonia-treated Ni nanoparticles coated with PZT, compared with that of the non-treated ones, was improved by about 66 ℃. The PZT shell layer prepared by in-situ reaction can greatly reduce the dielectric constant and improve the natural resonance loss at high frequency, so as to obtain the optimal impedance matching performance of the electromagnetic wave transmission.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11475230 and U1532262
文摘Metallic nanoparticle (NP) shapes have a significant influence on the property of composite embedded with metallic NPs. Swift heavy ion irradiation is an effective way to modify shapes of metallic NPs embedded in an amorphous matrix. We investigate the shape deformation of Ag NPs with irradiation fluence, and 357 MeV Ni ions are used to irradiate the silica containing Ag NPs, which are prepared by ion implantation and vacuum annealing. The UV-vis results show that the surface plasmon resonance (SPR) peak from Ag NPs shifts from 400 to 377nm. The SPR peak has a significant shift at fluence lower than 1 × 10^14 ions/cm2 and shows less shift at fluence higher than 1 × 10^14 ions/cm2. The TEM results reveal that the shapes of Ag NPs also show significant deformation at fluence lower than 1 × 10^14 ions/cm2 and show less deformation at fluence higher than 1 × 10^14 ions/cm2. The blue shift of the SPR peak is considered to be the consequence of defect production and Ag NP shape deformation, Based on the thermal spike model calculation, the temperature of the silica surrounding Ag particles first increases rapidly, then the region of Ag NPs close to the interface of Ag/silica is gradually heated. Therefore, the driven force of Ag NPs deformation is considered as the volume expansion of the first heated silica layer surrounding Ag NPs.
基金the financial support provided by the National Natural Science Foundation of China(Grant Nos.51875172 and 52105180)Zhongyuan Science and Technology Innovation Leadership Program(Grant No.214200510024)+1 种基金the Tribology Science Fund of State Key Laboratory of Tribology in Advanced Equipment(Grant No.SKLTKF21B06)Key Research and Development and Promotion Projects in Henan Province(Grant Nos.212102310410,232102230067,and 232102230081).
文摘Nickel(Ni)nanoparticles can be enriched on the surface of iron-based frictional pairs,which provides the possibility to get rid of the competitive adsorption between the polar species of vegetable oil and the surface-active nano-additives thereon.In this paper,nickel acetylacetonate was used as a precursor to in-situ synthesize nickel nanoparticles with an average diameter of about 12 nm in rapeseed oil(RO)as the reducing agent,surface modifier,and solvent as well.The tribological properties of the as-synthesized Ni nanoparticles were evaluated with a four-ball tribometer,and their tribomechanism was investigated based on the characterizations of the tribofilm on rubbed steel surfaces by the scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).It was found that the Ni nanoparticles in-situ prepared in the RO with a mass fraction of 0.3%can reduce the wear scar diameter(WSD)of the steel ball by 36%.This is because,on the one hand,the Ni nanoparticles are adsorbed on the rubbed steel surfaces to repair or fill up the micro-pits and grooves thereon.On the other hand,Ni nanoparticles participate in tribochemical reactions with atmospheric O and steel substrate to form the tribochemical reaction film on the rubbed steel surfaces with the assistance of friction-induced heat and applied normal load.In addition,an amorphous carbon film is formed on the rubbed surface via the carbonization of base oil under the catalysis of Ni nanoparticles.The adsorbed Ni layer,the tribochemical reaction film,and the carbon layer comprise a composite tribofilm composed of amorphous carbon,polar fatty acid,metallic nickel,iron oxides,and nickel oxides on the rubbed steel surfaces,which contributes to significantly improving the antiwear ability and load-carrying capacity of the RO for the steel-steel sliding pair.
基金This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(No.20173020032120)This work also was supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2019R1C1C1005801)Partial support from“CO2 utilization battery for hydrogen production based on fault-tolerance deep learning”(1.200097.01)is also acknowledged.
文摘Ni nanocatalysts produced through exsolution have shown strong resistance to particle sintering and carbon coking in a beneficial dry reforming of methane(DRM)reaction utilizing greenhouse gases such as CH_(4)and CO_(2).However,most of the existing oxide supports for exsolution have been limited to perovskite oxide,while studies on fluorite support have been rarely conducted due to the limited solubility despite its excellent redox stability.Here we demonstrate that 3 mol%Ni can be successfully dissolved into the yttria-stabilized zirconia(YSZ)lattice and be further exsolved to the surface in a reducing atmosphere.The YSZ decorated with exsolved Ni nanoparticles shows enhanced catalytic activity for DRM reaction compared to the conventional cermet type of bulk Ni-YSZ.Moreover,the catalytic activity is extremely stable for about 300 h without significant degradation.Overall results suggest that the YSZ-based fluorite structure can be utilized as one of the support oxides for exsolution.
基金supported by the National Natural Science Foundation of China(Nos.52271011,52102291).
文摘Carbon nanofibers(CNFs)with high specific surface area show great potential for sodium storage as a hard carbon material.Herein,CNFs anchored with Ni nanoparticles(CNFs/Ni)were prepared through chemical vapor deposition and impregnation reduction methods,in situ growing on the three-dimensional porous copper current collector(3DP-Cu).The coupling effect of high-spin state Ni nanopar-ticles leads to the increase of defect density and the expansion of lattice spacing of CNFs.Meanwhile,the 3DP-Cu ensures a high loading capacity of CNFs and short ion/electron transport channels.As an integral binder-free anode,the 3DP-Cu/CNFs/Ni exhibits excellent electrochemical performance,which demon-strates a high specific capacity with 298.5 mAh g^(-1)at 1000 mA g^(-1)after 1500 cycles,and a high power density with 200 mAh g^(-1)over 1000 cycles at 5000 mA g^(-1).Density functional theory calculation re-sults show that the high-spin state Ni regulates the electronic structure of CNFs,which significantly reduces the adsorption energy for Na^(+)(-2.7 Ev)and thus enables high-rate capability.The regulation of the electronic structure of carbon materials by high-spin state metal provides a new strategy for developing high-power carbonaceous anode materials for sodium-ion batteries.
基金financial supports provided by the National Natural Science Foundation of China(21871164)the Taishan Scholar Project Foundation of Shandong Province(ts20190908)+1 种基金the Natural Science Foundation of Shandong Province(ZR2019MB024)Young Scholars Program of Shandong University(2017WLJH15)。
文摘Herein,nickel@nitrogen-doped carbon nanotubes(Ni@NCNTs)are prepared by a simple and reliable method with Ni-based complex as single-source precursor.Significantly,the formation of CNTs is not susceptible to the calcination temperature and ramping rate and Ni@NCNTs can be attained from 430 to 900℃in an inert atmosphere.Then they are the first time to be applied as the anode material for sodium-ion batteries.The presence of Ni nanoparticles(NPs)facilitates the solid electrolyte interface film over the anode surface and improves the capacity retention of the host material,especially at the high rates.Furthermore,Na+diffusion is reinforced after the introduction of Ni NPs.Ni@NCNTs obtained at 500℃(Ni@NCNTs-500)exhibit the best capacity retention and rate capability.Kinetics analyses demonstrate the faster electron transportation and ion diffusion than others prepared at other temperatures.The surficial capacitance storage favors the fast electrochemistry kinetics.It delivers a high specific capacity(192 mA h g^−1 at 0.5 A g^−1),excellent cycling stability(103 mA h g^−1 after 10,000 cycles at 10 A g^−1),and outstanding high-rate capability up to 20 A g^−1(118 mA h g^−1).The related full cells confirm a high energy density of 140 Wh kg^−1 at 38.16 W kg^−1 and 44.27 W h kg^−1 at 762 W kg^−1.