Ni Substitution Research Articles

Adsorption of ɳ2 (O, C)-tilted formaldehyde geometry on transition metal substituted p(2 × 1) SnO2 (1 1 0) surface: A first-principles analysis

Density Functional Theory was used to study the adsorption mechanisms of bidentate η2(O, C)-tilted formaldehyde on SnO2 (110) surfaces modeled with a p(2 × 1) periodicity and substituted with transition metals (Au, Cu, Ni, Pd). Formation energies identified suitable substitution sites between Sn5c and Sn6c for each of the selected dopant atoms. Except for Pd, the other dopants were found to be more stably substituted at the five-fold coordinated Sn site. Adsorption energy analysis showed that Ni and Pd substitutions enhanced adsorption compared to the pristine SnO2 (110) surface by 0.038 eV and 0.077 eV, respectively. Pd substitution in the first two surface layers had the highest negative adsorption energy, showcasing a maximum increment by 0.101 eV, but its co-substitution with Ni did not yield improved adsorption. Bader charge analysis confirmed a two-fold charge transfer from the surface Sn5c site to OHCHO atom and from CHCHO atom to the surface Sn2c site, which is attributed to the diagonal-span bridged configuration of the η2(O, C) bidenate formaldehyde. The charge transfer from the surface to the gas molecule was found to be the highest for the Pd co-substituted SnO2 surface (|1.332|e). The charge transfer is visually supported by charge density plots. Pd substitution was seen to introduce additional states at the Fermi energy. On the other hand, the introduction of the gas molecule predominantly injected additional states for the Ni-substituted surface, thereby improving the adsorption mechanism. Recovery times were calculated using the transition state equation, with values ranging from 7 to 11 s for the effectively substituted surfaces.

Effect of charge-discharge with higher capacitance performance of Ni-substituted CoFe2O4 magnetic nanoparticles for energy storage

In this work, we synthesized NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) magnetic nanoparticles (MNPs) by using ultrasonication-assisted reverse chemical co-precipitation method. The X-ray diffraction (XRD) patterns confirm the single-phase with mixed spinel structure of the NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs with the crystallite size range between 12 nm - 17 nm. The molecular dynamics and oleic acid coated Ni-substituted CoFe2O4 magnetic nanoparticles were confirmed by FTIR measurements. The surface composition of NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs (Ni, Co, Fe and O) and their oxidation states were estimated using X-ray photoelectron spectroscopy. The NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs are spherical in shape and polycrystalline in nature, confirmed by FESEM and HRTEM measurements. The Ni-substituted CoFe2O4 MNPs with higher zeta potential (ζ) from −24 mV to -41 mV with an increase in Ni concentration, signifies the stable colloidal stability due to the electrostatic repulsion between MNPs. The DC magnetization (M-vs-H) measurements reveal the ferrimagnetic behavior of NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs, which suppress the saturation magnetization (MS) from 48.6 emu/g to 5.3 emu/g with the enhanced coercivity (HC) from 335 Oe to 1700 Oe with the substitution of Ni2+ ions is in corroboration with electron paramagnetic resonance (EPR) measurements. The enhanced EPR resonance field (Hres = 2335 Oe - 3261 Oe) with the substitution of Ni2+ ions is attributed to the generation of oxygen vacancies and defects, which are predominant in Ni0.8Co0.2Fe2O4, resulting in significantly enhanced electrochemical performance. Therefore, the three-electrode system was utilized to investigate the electrochemical properties of NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs. The Ni-substituted CoFe2O4 MNPs have demonstrated significantly enhanced capacity retention of 77 % even after 5000 cycles in 1 M H2SO4 electrolyte solution. NixCo1-xFe2O4 (0 ≤ x ≤ 0.8) MNPs exhibit an excellent specific capacity (Cs) of 794.5 F/g at a current density of 1 A/g, signifies the rate of redox reaction at surface electrolyte interface (SEI) is greatly influenced by the surface to volume ratio. Thus, with the enhancement of Ni2+ ions, redox reaction kinetics might become more efficient resulting in the enhanced charge storage capacity.

Magneto-dielectric effect in corundum-type oxide: Co4NbTaO9

We have thoroughly studied the structure, magnetic and magneto-dielectric properties of Co4NbTaO9 along with the isotypic Co4Nb2O9, Co4Nb1.5Ta0.5O9 and Co3NiNb2O9 phases, which are noncollinear antiferromagnet with trigonal structure. The transition temperature decreases with Ta substitution, whereas it increases with Ni substitution. In the absence of external magnetic fields, no dielectric anomaly is noticed below the magnetic transition temperature. However, prominent dielectric peak appears under external magnetic fields and the peak magnitude increases with increasing field strengths, depicting magneto-dielectric and magnetoelectric phenomena. We describe the magnetic field induced dielectric effect due to the spin-flop magnetic transition.

Inverse and conventional dual magnetocaloric effects in Ni substituted Y-type Sr2Zn2-xNixFe12O22 hexaferrites

The effects of Ni substitution on magnetic and magnetocaloric effect (MCE) are investigated in polycrystalline Y-type hexaferrites of Sr2Zn2-xNixFe12O22 (x = 0.0, 0.8, and 2.0). With the increasing of temperature, the M-T curves indicate successive magnetic structure transitions exist in Sr2Zn2-xNixFe12O22 (x = 0.0, 0.8, and 2.0), which play significant roles in MCE behaviors. As the Ni2+ doping ratio increases, the shape of −ΔSM−T curves near room temperature evolves gradually from a table-like to a peak-like form. Particularly, a significant contrast between CMCE and IMCE is observed below 100 K, whose behavior can be inherently exploited for heat sink in magnetic refrigeration applications. Among the samples in this series, Sr2Zn1.2Ni0.8Fe12O22 plays the best CMCE and IMCE performances, with the maximum magnetic entropy change (−ΔSMmax) values of 0.78 J/kg K at 354 K and −0.56 J/kg K at 16 K for ΔH=50kOe , respectively. Our work demonstrates that Sr2Zn2-xNixFe12O22 hexaferrites have great potential to be tailored for magnetic refrigeration with special needs such as different operating temperature zones, Ericsson cycle or heat sink at refrigeration.

Effect of Ni substitution atom on electronic properties and surface oxidation of pyrrhotite

The crystal and surface electronic properties of minerals are fundamentally linked to their flotation behavior. To investigate the effects of Ni substitution for Fe in pyrrhotite on the crystal and surface properties, as well as its oxidation by O2, density functional theory (DFT) was employed to analyze these changes at a microscopic level in both monoclinic and hexagonal pyrrhotite. The findings reveal that Ni substitution increases electron activity in monoclinic pyrrhotite, enhancing its resistance to oxidation by O2, while also strengthening the interaction between Ni-substituted monoclinic pyrrhotite and butyl xanthate. Conversely, in hexagonal pyrrhotite, Ni substitution enhances electron stability but makes it more susceptible to oxidation by O2 and weakens its interaction with butyl xanthate. Understanding the electronic properties and interaction mechanisms of Ni-substituted pyrrhotite with O2 is crucial for elucidating the surface oxidation mechanisms of pyrrhotite. This research offers insights and guidance for optimizing pyrrhotite flotation processes.

Influence of Ni substitution on Structural, Optical, magnetic and transport properties of Mn0.5-xNixZn0.4Cu0.1Fe1.95Al0.05O4

A series of spinel ferrites Mn0.5-xNixZn0.4Cu0.1Fe1.95Al0.05O4 have been prepared by auto-combustion technique. X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) have been used for structural and morphological investigations. The XRD patterns confirm the formation of cubic spinel structure of ferrites. The lattice constants decrease with the increase of Ni contents due to the smaller ionic radii of Ni2+ compared to Mn2+ as well as particle size decreases. Density is increased and porosity is decreased with the increase of Ni contents in the samples due to the higher atomic weight of Ni2+ compared to Mn2+. The FESEM analysis reveal that the average size of the irregularly shaped grains increased with Ni contents. The mixed spinel structure is further confirmed by the FTIR spectra, which show a doublet band at about 600 cm−1. The observed optical band gap and the particle size variations are comparable, and the quantum size effect supports this conclusion. The real part of initial permeability and relative quality factor increase with the increase of Ni contents due to increase of density and grain size as well as decrease of porosity. Also, it is found that magnetic loss decreased with the increase of Ni contents. All the samples exhibit ferrimagnetic behavior and the number of Bohr magneton has been calculated for all compositions. The dielectric constant shows large value in the lower frequencies and decreases with frequency shows dispersion due to Maxwell-Wagner space charge polarization. The investigation of electric modulus has demonstrated the existence of the hopping conduction mechanism. The AC conductivity is very low at lower frequency region and very large at higher frequency region which can be explain according to the polaron hopping model of Austin and Mott. The AC conductivity enhances nearly linearly with frequency, suggesting that the mechanism of conduction is due to small polaron hopping, which can be described according to Jonscher’s power law. Also, the effect of grain and grain boundary resistance on transport properties has been investigated using complex impedance analysis and it has been observed that both exhibit an increase trend as the Ni content increases.

Enhancing thermoelectric properties of spinel ZnFe2O4 by Ni substitution through electron hopping mechanism

The prime goal of this novel work is to investigate the efficacy of spinel zinc ferrite as a thermoelectric material and its performance enhancement for high temperature applications. Zn1-xNixFe2O4 (0 ≤ x ≤ 0.2) were prepared by sol-gel method and their structural, morphological, and thermoelectric behaviours were examined as functions of composition and temperature. Among the studied compositions, Zn0.8Ni0.2Fe2O4 exhibits the highest electrical conductivity (σ) of 49.83 S/m, the largest power factor of 6.66 μW/mK2, and the lowest thermal conductivity (κ) of 0.36 W/mK at 947 K, thus extending to an overall enhancement in the thermoelectric figure of merit (zT). Conduction through electron hopping is proven to be the main driving force for the enhancement in electrical and thus thermoelectric properties. Results reveal that thermoelectric properties of ZnFe2O4 can potentially be enhanced by the doping Ni at Zn site and opens up an exciting opportunity for the utilization of this spinel ferrite as a novel thermoelectric material for applications involving elevated temperatures.

Improving the optical properties of magnesium spinel chromites through Ni and Cu substitutions for optoelectronic applications.

In this study, we investigated the optoelectronic performance of magnesium spinel chromites with nickel (Ni) and copper (Cu) substitutions. Using the sol-gel method, we synthesized two spinel chromites: Mg0.6Ni0.4Cr2O4 (MNCO) and Mg0.6Cu0.4Cr2O4 (MCCO). We extensively characterized these samples to analyze their thermal, structural, elastic, and optical properties. Structural analysis reveals good agreement between the calculated and refined structural parameters, which supports the proposed cation distributions for the samples. By calculating stiffness constants from force constants, we derived elastic moduli such as bulk modulus, longitudinal modulus, and rigidity modulus. MCCO exhibited lower values for these moduli, as well as the Debye temperature, compared to MNCO. Both samples displayed a brittle mechanical nature according to the Pugh ratio, while the Poisson ratio remained constant at 0.25, indicating isotropic elasticity. UV-vis-NIR spectroscopy revealed that MNCO has higher band-gap (E g) and Urbach (E u) energies than MCCO. Further analysis of refractive index, penetration depth, extinction coefficients, nonlinear optical parameters, optical conductivity, and optical dielectric constants highlighted the promising optoelectronic applications of the synthesized materials. Our study found that the band-gap energy values of the as-synthesized samples were smaller than reported values for MgCr2O4 spinel chromites, indicating that Ni and Cu substitutions offer an opportunity to extend the sunlight absorption range of magnesium chromites.

Benefit of Ni addition in Dy-Co diffusion alloys for enhancing the coercivity and corrosion resistance of sintered Nd-Fe-B magnets

Commercial Nd-Fe-B magnets without heavy rare earths (HREs) exhibit low coercivity and poor chemical resistance. Here, the coercivity and anti-corrosion performance of sintered Nd-Fe-B magnets have been successfully improved by grain boundary diffusion of Ni alloyed Dy-Co alloy. Starting from Dy-Co binary alloy, the composition of diffusion source was optimized by modifying Dy/Co ratio and Ni substitution for Co. The coercivity of the magnet was enhanced by Dy60Co10Ni30 diffusion with relatively low Dy content from 1362 to 1853 kA/m, which is even 104 and 91 kA/m higher than those of the Dy80Co20 and Dy70Co15Ni15 diffused magnets, respectively. The formation of higher anisotropic field of (Nd,Dy)2Fe14B and deep diffusion of Dy are the main reasons for the significantly enhanced coercivity. Partial substitution of Co by Ni cannot only promote the infiltration of Dy into the magnet, but also reduce the cost and improve the performance/cost ratio of diffused magnet. Meanwhile, Dy60Co10Ni30 diffusion also improves the corrosion resistance of the magnet by minishing the corrosion electric current density from 9.93 to 3.45 μA·cm−2. The present results indicate that Ni in diffusion source is conducive to simultaneously improving coercivity and chemical stability.

Ni and La substitution of Cobalt nanoferrites preparation: structural, magnetic, and dielectric studies and photocatalytic activity for waste water treatment

Ni and La substitution of Cobalt nanoferrites preparation: structural, magnetic, and dielectric studies and photocatalytic activity for waste water treatment

Systematic Exploration of the Benefits of Ni Substitution in Na–Fe–Mn–O Cathodes (Adv. Sustainable Syst. 8/2024)

Systematic Exploration of the Benefits of Ni Substitution in Na–Fe–Mn–O Cathodes (Adv. Sustainable Syst. 8/2024)

Tailoring oxygen vacancies by synergy of dual metal cations in LaCo0.8M0.2O3 (M = Cu, Ni, Fe, Mn) towards catalytic oxidation of toluene

Enhancing the catalytic performance of transition metal oxide catalysts is prerequisite for the efficient catalytic oxidation of VOCs. Here the B-site partially substituted LaCoO3 (LaCo0.8M0.2O3, M = Cu, Ni, Fe and Mn) catalysts was synthesized for the catalytic oxidation of toluene. Among these catalysts, LaCo0.8Ni0.2O3 catalyst exhibits remarkable catalytic performance for toluene with T50 = 226 °C and T90 = 239 °C at an initial toluene concentration of 1000 ppm, whose T50 (and T90) reduced by 13 °C (and 34 °C) compared with that of LaCoO3. Confirmed by BET, XPS, and EPR characterizations, Ni substitution improves the specific surface area, Co3+/Co2+ ratio, Oads/Olatt ratio, and oxygen vacancies concentration. This improvement indicates the improvement of adsorption and activation of reactant, mobility of oxygen species, thereby contributing to the superior catalytic performance in toluene oxidation. The B-site of LaCoO3 occupied by dual cations caused the lattice distortion and formation of oxygen vacancies due to the ionic radii difference between Co and Ni cations. Moreover, the apparent activation energy of LaCo0.8Ni0.2O3, as the determining factor for the catalytic oxidation rate, was remarkably reduced. Our findings confirmed the synergy effect of Co and Ni cations at B-site on the enhancement of catalytic activity, which provides a promising strategy for oxygen vacancy engineering.

Synergetic effect of Ni substitution and induced porosity: Enhancing the electrocatalytic performance of cobaltite towards OER and MOR in alkaline medium

The quest for sustainable and efficient energy conversion technologies has intensified research into advanced materials for electrochemical reactions, such as the oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). Transition metal oxides have emerged as promising catalysts due to their abundance, low cost, and adjustable electronic properties. Among these, Nickel (Ni)-based compounds are particularly noteworthy for their catalytic activity and stability. This research paper explores the crucial impact of Nickel (Ni) substitution and introducing porosity on the valence states of metal ions and their mass transport in the context of OER and MOR. In this study, we present a step-by-step surfactant (Brij 58) assisted synthesis approach for the preparation of mesoporous Co3O4 and NiCo2O4. The synthesised material has been physiochemically characterised by Fourier transform Infrared Spectroscopy (FTIR), Scanning electron microscopic/Energy-dispersive X-ray spectroscopy (SEM/EDS) and High-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), and inductively coupled plasma mass spectrometry (ICP-MS) analyses. Additionally, the impact of these alterations on electrocatalytic activity, reaction kinetics, and electrochemical stability during OER/MOR has been explored by Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), Tafel, Electrochemical Impedance Spectroscopy (EIS) and chronoamperometric experiments. Mesoporous NiCo2O4 exhibits exceptional electrocatalytic performance with current densities of 46.8 mA/cm2 for OER and 214.5 mA/cm2 for MOR at 550 mV. By shedding light on the intricate interplay between metal substitution, porosity, and valence states, this research aims to provide valuable insights for the evolution of enhanced cobaltite electrocatalysts for sustainable water splitting and MOR.

Exploring Methane Storage Capacities of M2(BDC)2(DABCO) Sorbents: A Multiscale Computational Study

A promising solution for efficient methane (CH4) storage and transport is a metal–organic framework (MOF)-based sorbent. Hence, searching for potential MOFs like M2(BDC)2(DABCO) to enhance the CH4 storage capacity in both gravimetric and volumetric uptakes is essential. Herein, we systematically elucidate the adsorption of CH4 in M2(BDC)2(DABCO) or M(DABCO) (M = Mg, Mn, Fe, Co, Ni, Cu, Zn) MOFs using multiscale simulations that combined grand canonical Monte Carlo simulation with van der Waals density functional (vdW-DF) calculation. We find that, in the M(DABCO) series, Mg(DABCO) has the highest total CH4 adsorption capacities, with mtot= 231.39 mg/g at 298 K, for gravimetric uptake, and Vtot= 231.43 cc(STP)/cc, for volumetric uptake. The effects of temperature, pressure, and metal substitution on enhancing CH4 storage are evaluated, and we predict that the volumetric CH4 storage capacity on M(DABCO) could meet the DOE target at temperatures of ca. 238 K–268 K and pressures of 35–100 bar. The interactions between CH4 and M(DABCO) are dominated by the vdW interactions, as shown by the vdW-DF calculations. The Mg, Mn, Fe, Co, and Ni substitutions in M(DABCO) result in a stronger interaction and thus, a higher CH4 storage capacity, at higher pressures for Mg, Mn, Ni, and Co and at lower pressures for Fe. This work may provide guidance for the rational design of CH4 storage in M2(BDC)2(DABCO) MOFs.

Systematic Exploration of the Benefits of Ni Substitution in Na–Fe–Mn–O Cathodes

AbstractNa‐ion batteries (SIBs) are receiving a great deal of attention as potential sustainable replacements for Li‐ion batteries in electric vehicles and grid storage applications. To date, commercialized SIBs offer inferior energy density with passable extended cycling. By contrast, next‐generation SIBs will likely utilize layered oxide cathodes that offer improved energy density but to date show inferior stability both during cycling and in terms of stability of the cathodes in air during cell assembly. These properties are highly tunable with composition and herein the promising P2 phases are systematically explored in the Na–Fe–Mn–O phase diagram by making 256 different compositions. The optimal material is a P2 material saturated with Ni (a modest 16% of the transition metal layer) and shows a highly competitive energy density of 640 Wh kg−1 while minimizing the amount of sacrificial sodium needed in full cells and also improving the air stability of the material. This study shows the vital role that thorough systematic screening will play in the continued development of these vital materials for sustainable secondary battery production and provides guidance toward sustainable Na‐ion cathodes by minimizing the nickel content required for high performance.

High Capacity and Fast Kinetics Enabled by Metal-Doping in Prussian Blue Analogue Cathodes for Sodium-Ion Batteries.

Prussian blue analogues (PBAs) have gained tremendous attention as promising low-cost electrochemically-tunable electrode materials, which can accommodate large Na+ ions with attractive specific capacity and charge-discharge kinetics. However, poor cycling stability caused by lattice strain and volume change remains to be improved. Herein, metal-doping strategy has been demonstrated in FeNiHCF, Na1.40Fe0.90Ni0.10[Fe(CN)6]0.85 ⋅ 1.3H2O, delivering a capacity as high as 148 mAh g-1 at 10 mA g-1. At an exceptionally high rate of 25.6 A g-1, a reversible capacity of ~55 mAh g-1 still can be obtained with a very small capacity decay rate of 0.02 % per cycle for 1000 cycles, considered one of the best among all metal-doped PBAs. This exhibits the stabilizing effect of Ni doping which enhances structural stability and long-term cyclability. In situ synchrotron X-ray diffraction reveals an extremely small (~1 %) change in unit cell parameters. The Ni substitution is found to increase the electronic conductivity and redox activity, especially at the low-spin (LS) Fe center due to inductive effect. This larger capacity contribution from LS Fe2+C6/Fe3+C6 redox couple is responsible for stable high-rate capability of FeNiHCF. The insight gained in this work may pave the way for the design of other high-performance electrode materials for sustainable sodium-ion batteries.

Theoretical Study of the Multiferroic Properties of Ion-Doped CaBaCo4O7

Using a microscopic model and Green’s function theory, we investigated the magnetization, specific heat, and polarization properties of CaBaCo4O7 (CBCO), scrutinizing their variations with temperature, magnetic field strength, and doping effects. Our analysis revealed a conspicuous kink in the specific heat curve near the critical temperature (TC), indicative of a phase transition. Additionally, the observed increase in polarization, P with escalating magnetic field strength serves as compelling evidence for the multiferroic nature of CBCO. Substituting Co ions with Fe ions resulted in an augmentation of the CBCO magnetization, M, while doping with Zn, Mn, or Ni ions led to a decline. Similarly, doping CBCO with Y or Sr ions at the Ca site exhibited divergent effects on magnetization, M, with an increase in the former and a decrease in the latter case. This modulation of the magnetization, M, can be attributed to the varying strains induced by the doping ions, thereby altering the exchange interaction constants within the system. The polarization, P, increases by Ni, Mn, or Zn substitution on the kagome layer Co sites. It can be concluded that Ni, Mn, or Zn doping enhances the magnetoelectric effect of CBCO. Notably, our findings align qualitatively well with experimental observations, reinforcing the validity of our theoretical framework.

Effect of Ni Substituted MgZrTa2O8 Ceramics on Sintering Characteristics and Microwave Dielectric Properties

Herein, Mg1−xNixZrTa2O8 (x = 0, 0.1, 0.3, 0.5, 0.8, 1) ceramics are synthesized using a solid‐phase reaction method. Ni2+ replacing Mg2+ improves the drawback of high sintering temperature and poor temperature stability. The samples have a relative density above 95% at the optimal sintering temperature. The sintering temperature of Mg1−xNixZrTa2O8 reduces from 1475 to 1400 °C. And single‐phase Mg1−xNixZrTa2O8 ceramics with monoclinic wolframite structures are analyzed. According to the Rietveld refinement results, with the doping of Ni2+, the transformation of unit cell volume leads to the shift of the main peak in the X‐Ray diffraction pattern to a higher angle in 0 ≤ x ≤ 0.3 and a lower angle in 0.5 ≤ x ≤ 1. The εr of Mg1−xNixZrTa2O8 is comparable to MgZrTa2O8. At 1400 °C, the Q × f is increased from 10 598 GHz in the undoped sample to 43 041 GHz in Mg0.9Ni0.1ZrTa2O8 ceramic. The absolute values of τf of ceramic samples decrease with the excessive Ni2+. The desirable dielectric properties (εr = 20.79, Q × f = 43 041 GHz, τf = −33.04 ppm °C−1) are obtained at 1400 °C. Ni substitution is effective for MgZrTa2O8 ceramic to optimize densification temperature and retain the high Q × f value.

First-principles insights into solute partition among various nano-phases in Al−Cu−Li−Mg alloys

First-principles energetics calculations were performed over a group of 25 candidate elements, to investigate their partition energies and behaviors among major nano-phases (δʹ-Al3Li, θʹ-Al2Cu, T1-Al6Cu4Li3 and S-Al2CuMg) in most commercial Al−Cu−Li−Mg alloys. It was revealed that principal alloying element Li cannot directly affect θʹ and S, Cu cannot directly affect δʹ, Mg cannot directly affect θʹ and δʹ but can weakly partition into T1. As for micro-alloying elements, Si is the only element that can partition into all the four nano-phases. Au can partition into δʹ, θʹ and S. Cd can partition into δʹ, T1 and S. Zr can partition into δʹ and T1. Ni substitution can weakly partition into θʹ and S. Ti, V, Zn, Ag and Mo can partition into δʹ only. Cr, Mn, Fe and Co cannot directly affect any of the four nano-phases. Almost all RE-elements can strongly partition into T1, δʹ and S, but would be expelled by θʹ. Only Sc is somehow particular to S, showing no partition preference in S. The newly obtained fundamental results could constitute a simple prototype database in support for the accelerated design of Al−Li based alloys and other related Al alloys.

Tannic acid induced surface functional strategy to synthesize Ni-doped SnO2 nanosheets for enhanced HCHO sensing

Surface functionalization is a promising strategy to modulate the electronic and surface properties of metal oxide semiconductors. Here, we report a tannic acid (TA) induced surface functional strategy to synthesize Ni-doped SnO2 nanosheets. Benefiting from the abundant polyphenolic and catechol groups, the linkage of TA not only exhibit high affinity to various substrate, but also show powerful chelating ability to metal ions. Hence, Ni ions can be highly dispersed on the SnO2 nanosheets via TA, TA linkage also can prevent the aggregation of Ni ions during pyrolysis, and Ni substitution in SnO2 crystals can be obtained. As a proof-of-concept demonstration, the TA-Ni/SnO2 sensor is fabricated to detect HCHO, and exhibit superior sensing performance at low working temperature of 80 °C (Ra/Rg = 184.3), excellent sensing selectivity and long-term stability. Detail experimental and theoretical calculation demonstrate the highly dispersed Ni substitution active sites facilitate the generation of surface O2–(ad) species, and the electronic structure also can be modulated to exhibit high affinity to HCHO, hence, the synergistic effects contribute to the enhanced sensing performance. Our work paves the way for versatile surface functionalization to synthesize advanced materials for application in catalysis and sensing field.