Cation Ordering Research Articles

Hexagonal Halide Perovskite Cs2LiInCl6: Cation Ordering, Face-Shared Octahedral Trimers and Mn2+ Luminescence.

The In-based double perovskite halides have been widely studied for promising optical-electric applications. The halide hexagonal perovskite Cs2LiInCl6 was isolated using solid-state reactions and investigated using X-ray diffraction and solid-state NMR spectra. The material adopts a 12-layered hexagonal structure (12R) consisting of layered cationic orders driven by the cationic charge difference and has Li+ cations in the terminal site and In3+ in the central site of face-shared octahedron trimers. Such a cationic ordering pattern is stabilized by electrostatic repulsions between the next-nearest neighboring cations in the trimers. The LiCl6 octahedron displays large distortion and is confirmed by 7Li SSNMR in the Cs2LiInCl6. The Cs2LiInCl6 material has a direct bandgap of ~4.98 eV. The Cs2LiInCl6: Mn2+ displays redshift luminescence (centered at ~610-622 nm) from the substituted Mn2+ emission in octahedron with larger PLQY (17.8 %-48 %) compared with that of Cs2NaInCl6: Mn2+. The Mn-doped materials show luminescent concentration quenching and thermal quenching. The composition Cs2Li0.99In0.99Mn0.02Cl6 exhibits the highest PL intensity, a maximum PLQY of 48 %, and high luminescent retention rate of ~86 % below 400 K and is suitable for application for pc-LED. These findings contribute to our understanding of the chloride perovskites and hold potential for widespread optical applications.

Atomic order of rare earth ions in a complex oxide: a path to magnetotaxial anisotropy

Complex oxides offer rich magnetic and electronic behavior intimately tied to the composition and arrangement of cations within the structure. Rare earth iron garnet films exhibit an anisotropy along the growth direction which has long been theorized to originate from the ordering of different cations on the same crystallographic site. Here, we directly demonstrate the three-dimensional ordering of rare earth ions in pulsed laser deposited (EuxTm1-x)3Fe5O12 garnet thin films using both atomically-resolved elemental mapping to visualize cation ordering and X-ray diffraction to detect the resulting order superlattice reflection. We quantify the resulting ordering-induced ‘magnetotaxial’ anisotropy as a function of Eu:Tm ratio using transport measurements, showing an overwhelmingly dominant contribution from magnetotaxial anisotropy that reaches 30 kJ m−3 for garnets with x = 0.5. Control of cation ordering on inequivalent sites provides a strategy to control matter on the atomic level and to engineer the magnetic properties of complex oxides.

(Ca0.5Mn0.5)2MnTeO6 - An Anomalously Stable High-Pressure Double Perovskite.

High pressure high temperature treatments of the composition CaMnMnTeO6 are found to yield only an A2BB'O6-type double perovskite (Ca0.5Mn0.5)2MnTeO6, rather than a AA'BB'O6 double double perovskite with A- and B- site cation order as found in analogs CaMnMnReO6 and CaMnMnWO6 with similar cation sizes. Double perovskite (Ca0.5Mn0.5)2MnTeO6 adopts a monoclinic structure in space group P21/n with a framework of highly tilted MnO6 and TeO6 octahedra enclosing disordered Ca2+ and Mn2+ cations. Magnetic measurements show that (Ca0.5Mn0.5)2MnTeO6 is a highly frustrated spin glass with a freezing transition at 5 K, and no long-range spin order is apparent by neutron diffraction at 1.6 K.

The packing fraction of the oxygen sublattice: its impact on the heat of mixing

The heat of mixing of some petrological relevant substitutions (i.e., Mg-Al, Si-Al, Mg-Ti, Mg-Ca, and Mg-Fe) was investigated systematically in silicates, titanates, tungstates, carbonates, oxides, hydroxides, and sulphates by density functional theory calculations (e.g., melilite, chlorite, biotite, brucite, cordierite, amphibole, talc, pseudobrookite, pyroxene, olivine, wadsleyite, ilmenite, MgWO4, ringwoodite (spinel), perovskite, pyrope-grossular, magnesite-calcite, MgO-CaO, anhydrous and different hydrated MgSO4). A specific substitution is characterised by different microscopic interaction energies in different minerals, e.g., the octahedral Mg-Al exchange on a single crystallographic site in pyroxene has a microscopic interaction energy that is more than twice compared to that in biotite. A comparative investigation of the heat of mixing using microscopic interaction energies on a single crystallographic site has the advantage that they are not influenced by cation ordering. They could be successfully correlated with the stiffnesses of the minerals, which in turn were scaled to the oxygen packing fraction, a parameter that is easily available for poorly investigated minerals. With this information, the interaction energies of a certain substitution can be transferred from minerals where they are well-known to mineral groups where they are less- or unknown. Using the cross-site terms and the microscopic interaction energies, the macroscopic interaction energies of the coupled substitution, e.g., Mg + Si = Al + Al, of biotite and pyroxene were calculated, which are, however, affected by cation ordering and different degrees of local charge balance, for which appropriate models are necessary.

Synthesis, crystal structure of Ca6Sb2O11 from experiments and DFT-electron structure calculation

This article reports a new perovskite compound Ca6Sb2O11. The X-ray powder diffraction technique was used to analyze its crystal structure. The results show that Ca6Sb2O11 has a tetragonal structure with the I4/m space group, and the lattice parameters are a = b = 5.658 (1) Å, c = 7.984 (1) Å, α = β = γ = 90°. It exhibits a typical A4B'2B″2X12-x anoxic multi-perovskite structure with rock-salt ordering of the B-site cations. The compound's chemical composition and valence states were characterized through scanning electron microscopy-energy dispersion spectrum (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The presence of oxygen vacancies was confirmed by electron paramagnetic resonance (EPR) spectroscopy. A chemical and structure transition temperature and the full melting temperature of Ca6Sb2O11 were measured, with values of 1515 ± 3 K and 1720 ± 3 K, respectively. The density functional theory (DFT)-electron structure calculation results show that Ca6Sb2O11 is an indirect wide-band gap (∼4.47 eV) semiconductor material, which agrees well with the experimental value (∼4.38 eV) obtained through diffuse reflection spectroscopy (DRS). Moreover, the top of the valence band and bottom of the conduction band are mainly contributed to by O-2p and Ca-3d states, respectively.

Design of magnetic polar double-double perovskite oxides through cation ordering

Design of magnetic polar double-double perovskite oxides through cation ordering

Investigating structural, phonons, optoelectronics, and thermodynamic properties of lead-free double perovskites of A-site cation ordering in LiXTl2Cl6 (X= Sc and Y) compounds for green energy applications

This study explores the structural, phonons, optoelectronic, and thermodynamic properties of LiXTl2Cl6 (X = Sc and Y) compounds. These double perovskite materials are particularly interesting due to their potential for green energy applications. We employ state-of-the-art computational simulation techniques to investigate the structural properties of these compounds, focusing on the cation ordering in the A-site of the perovskite structure. Through density functional theory (DFT) calculations, we determine the equilibrium crystal structure and lattice parameters, shedding light on the stability of these materials. Furthermore, we analyze the phonon spectra to assess the materials' vibrational properties, including the presence of any phonon modes that may impact thermal stability and thermal transport. Optoelectronic properties, such as band gaps and optical absorption spectra, are also explored to evaluate the suitability of these materials for photovoltaic and light-emitting applications. We investigate their electronic structure and consider the potential for efficient charge carrier generation and transport. The thermodynamic properties, such as heat capacity, entropy, and enthalpy, are calculated to provide insight into the compounds' thermal behavior under various environmental conditions, which is crucial for green energy applications, including thermal energy conversion. This comprehensive investigation into the LiXTl2Cl6 (X = Sc and Y) compounds aims to contribute to developing lead-free double perovskite materials with tailored properties for a range of green energy applications, paving the way for more sustainable and environmentally friendly energy solutions.

Controlled Self-Assembly of Nanoscale Superstructures in Phase-Change Ge-Sb-Te Nanowires.

Controlled growth of semiconductor nanowires with atomic precision offers the potential to tune the material properties for integration into scalable functional devices. Despite significant progress in understanding the nanowire growth mechanism, definitive control over atomic positions of its constituents, structure, and morphology via self-assembly remains challenging. Here, we demonstrate an exquisite control over synthesis of cation-ordered nanoscale superstructures in Ge-Sb-Te nanowires with the ability to deterministically vary the nanowire growth direction, crystal facets, and periodicity of cation ordering by tuning the relative precursor flux during synthesis. Furthermore, the role of anisotropy on material properties in cation-ordered nanowire superstructures is illustrated by fabricating phase-change memory (PCM) devices, which show significantly different growth direction dependent amorphization current density. This level of control in synthesizing chemically ordered nanoscale superstructures holds potential to precisely modulate fundamental material properties such as the electronic and thermal transport, which may have implications for PCM, thermoelectrics, and other nanoelectronic devices.

Influence of Interlayer Cation Ordering on Na Transport in P2-Type Na0.67-xLiy Ni0.33-zMn0.67+zO2 for Sodium-Ion Batteries.

P2-type Na2/3Ni1/3Mn2/3O2 (PNNMO) has been extensively studied because of its desirable electrochemical properties as a positive electrode for sodium-ion batteries. PNNMO exhibits intralayer transition-metal ordering of Ni and Mn and intralayer Na+/vacancy ordering. The Na+/vacancy ordering is often considered a major impediment to fast Na+ transport and can be affected by transition-metal ordering. We show by neutron/X-ray diffraction and density functional theory (DFT) calculations that Li doping (Na2/3Li0.05Ni1/3Mn2/3O2, LFN5) promotes ABC-type interplanar Ni/Mn ordering without disrupting the Na+/vacancy ordering and creates low-energy Li-Mn-coordinated diffusion pathways. A structure model is developed to quantitatively identify both the intralayer cation mixing and interlayer cationic stacking fault densities. Quasielastic neutron scattering reveals that the Na+ diffusivity in LFN5 is enhanced by an order of magnitude over PNNMO, increasing its capacity at a high current. Na2/3Ni1/4Mn3/4O2 (NM13) lacks Na+/vacancy ordering but has diffusivity comparable to that of LFN5. However, NM13 has the smallest capacity at a high current. The high site energy of Mn-Mn-coordinated Na compared to that of Ni-Mn and higher density of Mn-Mn-coordinated Na+ sites in NM13 disrupts the connectivity of low-energy Ni-Mn-coordinated diffusion pathways. These results suggest that the interlayer ordering can be tuned through the control of composition, which has an equal or greater impact on Na+ diffusion than the Na+/vacancy ordering.

Hydrogeochemistry and Quality Assessment using Water Quality Indices of Surface and Groundwater of Konar Reservoir Region, Hazaribag District, Jharkhand, India

ABSTRACT In the present paper, the water quality of the Konar reservoir area in the Hazaribag district of Jharkhand, India, has been investigated and with this view, the different physico-chemical variables, including pH, Dissolved Oxygen, Electrical Conductivity, TDS, Temperature, cations (Ca2+, Mg2+, Na+, K+), anions (CO32−, HCO3−, Cl−, F−, SO42−, NO3−) have been analyzed. According to Schoeller diagram, the order of major cations and anions for groundwater are Ca2+ > Na+ > Mg2+ > K+ and HCO3− > SO42− > Cl− > NO3− and for surface water are Na+ > Ca2+ > Mg2+ > K+ and Cl− > HCO3− > NO3− > SO42− respectively. The calculated water quality index shows that 100% of the samples of surface water are of excellent water quality, while 17% of the samples of groundwater are of excellent and 83% fall under the good category. The Gibbs Plot indicates that the rock-water interaction mechanism is dominant, Giggenbach triangle indicates that the waters have not yet reached equilibrium and are still in an immature state, although the Piper plot demonstrates that most of the surface water samples (78%) are mixed facies of Ca2+-Mg2+-Cl− and 22% are of Na+–Cl− type. All groundwater samples are mixed facies of Ca2+– HCO3− type. According to the Durov plot, 100% of surface water samples exhibit simple dissolution or mixing and majority of the ions in all groundwater samples are calcium and bicarbonate, showing the influence of limestone deposits. Almost all of the water samples from the Konar reservoir area were found to be appropriate for irrigation, according to the Residual Sodium Carbonate, Residual Sodium Bicarbonate, Sodium Percentage, Permeability Index, Kelley’s Ratio, Sodium Adsorption Ratio, United States Salinity Laboratory (USSL) and Wilcox diagrams.

Thermochemical and structural study of sodium, iron, and niobium phosphate NASICON solid solutions

Solid solutions NaxFe0.5+0.5xNb1.5-0.5x(PO4)3 (0 ≤ x ≤ 1; x = 2) of NASICON structure (sp.gr. R3-c) and NbOPO4 were prepared via solid-state reaction and characterized by electron microprobe analysis, powder X-ray and neutron diffraction, and differential thermal analysis. The decrease of the a- and b-unit cell parameter prevails over the increase in c-parameters, resulting in nonlinear decrease of the unit cell volume with Na content. Enthalpies of drop solution in molten sodium molybdate solvent at 700 °C were measured by high temperature oxide melt solution calorimetry and were used to derive the enthalpies of formation. Strongly negative enthalpies of formation from elements and from constituent oxides indicate high thermodynamic stability. The mixing enthalpies of solid solutions show negative deviation from the ideality. Negative mixing enthalpies and negative mixing volumes indicate short-range ordering of cations in the structure.

Features of magnetic structure and properties of ceramics (1 − x)Pb(Fe1/2Nb1/2)o3—xPb(Fe2/3W1/3)o3

We studied solid solutions of the system (1−x)PbFe1/2Nb1/2O3 - xPbFe2/3W1/3O3 using X-ray and Neuron diffraction, and Mössbauer spectroscopy. To obtain ceramics, we used the method of two-stage solid-phase synthesis and sintering according to the conventional ceramic technology. Pure solid solutions of the (1−x)PbFe1/2Nb1/2O3-xPbFe2/3W1/3O3 system were obtained. A deviation of the unit cell parameters from the Vegard rule was revealed, which indicates stratification of the structure into microregions differing in composition. The introduction of PbFe2/3W1/3O3 into the system led to partial ordering (clustering) of cations in the B position. An increase in magnetic moment with growing amount of PbFe2/3W1/3O3 was shown.

P2-type layered oxide cathode with honeycomb-ordered superstructure for sodium-ion batteries

Sodium-ion batteries (SIBs) have been proved as one of the most alternative to Lithium-ion batteries (LIBs) by the virtue of the abundant resources of Na. Among the cathodes, layered oxides stand out owing to their high energy density. The Jahn–Teller distortion, structural phase transition and oxygen release are main drawbacks of Mn/Ni based layered oxides. Hence, Li-Ni-Cu co-substituted Na0.67Li0.1(Mn0.7Ni0.2Cu0.1)0.9O2 (NLMNC) sample was prepared. The NLMNC sample exhibits the honeycomb-ordered superstructure at about 22° which is ascribed to cation ordering. By virtue of the Li-Ni-Cu co-substitute, the Jahn–Teller distortion of Mn is suppressed. Attributed to Li+ migrating from the metal oxide layer to the interlayer and the Li+ can play the part of pillar in the interlayer, NLMNC cathode displays the capacity retention rate of 82.5 % at 200 mA g−1 after 100 cycles. The anionic redox reaction of NLMNC is related to the addition of Li ions and O 2p non-bonding which is different from the anionic redox reaction of electrons removing from O 2p in the eg* (Ni–O) states of Na2/3Ni1/3Mn2/3O2. During charge process, peroxo O− emerges with the oxidation of lattice oxygen. During discharge process, the intensity of peroxo O− gradually decreases. DFT calculations were also carried out to reveal the reaction mechanism of NLMNC. The DFT results showed that the anionic redox reaction occurs near Mn ions, while the Ni ions are stable which is corresponding with our results. It is proven that such Li-Ni-Cu co-substituted NLMNC presents a promising cathode material for SIBs.

Structural Characterization of La0.6Sr0.4CoO3-δ Thin Films Grown on (100)-, (110)-, and (111)-Oriented La0.95Sr0.05Ga0.95Mg0.05O3-δ.

In this study, a detailed structural characterization of epitaxial La0.6Sr0.4CoO3-δ (LSC) films grown in (100), (110), and (111) orientations was conducted. LSC is a model air electrode material in solid oxide fuel and electrolysis cells and understanding the correlation of bulk structure and catalytic activity is essential for the design of future electrode materials. Thin films were grown on single crystals of the perovskite material La0.95Sr0.05Ga0.95Mg0.05O3-δ cut in three different directions. This enabled an examination of structural details at the atomic scale for a realistic material combination in solid oxide cells. The investigation involved the application of atomic force microscopy, X-ray diffraction, and high-resolution transmission electron microscopy to explore the distinct properties of these thin films. Interestingly, ordering phenomena in both cationic as well as anionic sublattices were found, despite the fact that the thin films were never at higher temperatures than 600 °C. Cationic ordering was found in spherical precipitates, whereas the ordering of oxygen vacancies led to the partial transition to brownmillerite in all three orientations. Our results indicate a very high oxygen vacancy concentration in all three thin films. Lattice strains in-plane and out-of-plane was measured, and its implications for the structural modifications are discussed.

Effect of Covalence and Degree of Cation Order on the Luminous Efficacy of Mn4+ Luminescence in the Double Perovskites, Ba2BTaO6 (B = Y, Lu, Sc).

The spectroscopic properties of the Mn4+ ion are investigated in the series of isostructural double perovskite compounds, Ba2BTaO6 (B = Y, Lu, Sc). A comparison of these properties highlights the influence of covalent bonding within the perovskite framework and the degree of order between the B3+-Ta cations on the energy and intensity of the Mn4+2E → 4A2 emission transition (R-line). These two parameters of the emission spectrum are of importance for practical application since they determine the phosphor luminous efficacy. The influence of covalent bonding within the corner shared BO6/2 and TaO6/2 perovskite framework on the energy of the R-line energy is investigated. From the spectroscopic data, we have derived information on the influence of the degree of order between the B3+ and Ta5+ cations on the intensity of the R-line. The lowest energy and the highest intensity of the R-line are found in the double perovskite, Ba2ScTaO6. The purpose of this work is to propose for first time an explanation of these effects in the considered double perovskites. The obtained results are useful guidelines for practical improvement and tuning of key parameters of phosphors to the desired values.

Structure and phase transitions in niobium and tantalum derived nanoscale transition metal perovskites, Ba(Ti,MV)O3, M=Nb,Ta.

The prospect of creating ferroelectric or high permittivity nanomaterials provides motivation for investigating complex transition metal oxides of the form Ba(Ti, MV)O3, where M = Nb or Ta. Solid state processing typically produces mixtures of crystalline phases, rarely beyond minimally doped Nb/Ta. Using a modified sol-gel method, we prepared single phase nanocrystals of Ba(Ti, M)O3. Compositional and elemental analysis puts the empirical formulas close to BaTi0.5Nb0.5O3-δ and BaTi0.5Ta0.5O3-δ. For both materials, a reversible temperature dependent phase transition (non-centrosymmetric to symmetric) is observed in the Raman spectrum in the region 533-583K (260-310°C); for Ba(Ti, Nb)O3, the onset is at 543K (270°C); and for Ba(Ti, Ta)O3, the onset is at 533K (260°C), which are comparable with 390-393K (117-120°C) for bulk BaTiO3. The crystal structure was resolved by examination of the powder x-ray diffraction and atomic pair distribution function (PDF) analysis of synchrotron total scattering data. It was postulated whether the structure adopted at the nanoscale was single or double perovskite. Double perovskites (A2B'B″O6) are characterized by the type and extent of cation ordering, which gives rise to higher symmetry crystal structures. PDF analysis was used to examine all likely candidate structures and to look for evidence of higher symmetry. The feasible phase space that evolves includes the ordered double perovskite structure Ba2(Ti, MV)O6 (M = Nb, Ta) Fm-3m, a disordered cubic structure, as a suitable high temperature analog, Ba(Ti, MV)O3Pm-3m, and an orthorhombic Ba(Ti, MV)O3Amm2, a room temperature structure that presents an unusually high level of lattice displacement, possibly due to octahedral tilting, and indication of a highly polarized crystal.

Effects of Calcination Conditions on the Structural and Electrochemical Behaviors of High‐Nickel, Cobalt‐Free LiNi0.9Mn0.1O2 Cathode

AbstractEliminating cobalt from high‐nickel layered oxide cathodes lowers the cost of lithium‐ion batteries for electric vehicles. However, cobalt‐free cathodes with high Mn4+ and Ni2+ contents are prone to Li/Ni mixing after synthesis, potentially compromising battery energy density, rate capability, and cycling stability. Without cobalt facilitating cation ordering in the layered structure, the degree of Li/Ni mixing in cobalt‐free cathodes depends heavily on the calcination conditions. In this study, a systematic exploration of calcination temperatures and LiOH ratio for LiNi0.9Mn0.1O2 (NM‐90) provides detailed insights into the optimal synthesis conditions for high‐capacity cobalt‐free cathodes with extended cycle life. Surprisingly, high Li/Ni mixing does not necessarily lead to poor cycling stability whereas low Li/Ni mixing does not guarantee a long cycle life. More importantly, although excessive calcination temperature can further decrease Li/Ni mixing, it does not necessarily enhance capacity. Instead, the pernicious effects from the H2 → H3 phase transition are amplified due to a pronounced two‐phase reaction. An extensive suite of chemical and structural characterization methods uncovers a correlation between elevated calcination temperature, phase transformation, cation ordering, and capacity fading behavior: “overcooking” high‐nickel, cobalt‐free cathodes induce structural arrangement toward that of LiNiO2, with exacerbated lattice distortion and surface instability accelerating capacity fade.

First-Principles Studies of the Electronic and Optical Properties of Zinc Titanium Nitride: The Role of Cation Disorder.

Cation disorder is an established feature of heterovalent ternary nitrides, a promising class of semiconductor materials. A recently synthesized wurtzite-family ternary nitride, ZnTiN2, shows potential for durable photoelectrochemical applications with a measured optical absorption onset of 2 eV, which is 1.4 eV lower than previously predicted, a large difference attributed to cation disorder. Here, we use first-principles calculations based on density functional theory to establish the role of cation disorder in the electronic and optical properties of ZnTiN2. We compute antisite defect arrangement formation energies for one hundred 128-atom supercells and analyze their trends and their effect on electronic structures, rationalizing experimental results. We demonstrate that charge imbalance created by antisite defects in Ti and N local environments, respectively, broadens the conduction and valence bands near the band edges, reducing the band gap relative to the cation-ordered limit, a general mechanism relevant to other multivalent ternary nitrides. Charge-imbalanced antisite defect arrangements that lead to N-centered tetrahedral motifs fully coordinated by Zn are the most energetically costly and introduce localized in-gap states; cation arrangements that better preserve local charge balance have smaller formation energies and have less impact on the electronic structure. Our work provides insights into the nature of cation disorder in the newly synthesized semiconductor ZnTiN2, with implications for its performance in energy applications, and provides a baseline for the future study of controlling cation order in ZnTiN2 and other ternary nitrides.

Resistance of eogenetic dolomites to geochemical resetting during diagenetic alteration: A case study of the lower Qiulitage Formation of the Late Cambrian, Tarim Basin

Rare earth elements (REEs), carbon, oxygen and Mg isotopes have been widely used to explain the origin of dolomite, but dolomite may undergo complex diagenetic alteration during long geological processes, and whether the geochemical signals of precursor dolomite can be preserved is still unknown. In order to further explore the formation mechanism of dolomite and the influence of diagenetic alteration processes on geochemical parameters, this paper takes the thick-layer dolomite of the Lower Qiulitage Formation of the Late Cambrian in the Tazhong uplift area as an example and divides the dolomite into two categories through petrologic observation. One category is fabric-retentive dolomite (FRD), including algal clotted dolomite, algal psammitic or psammitic grain dolomite, and aphanocrystalline dolomite; the other category is fabric-destructive dolomite (FDD), including crystalline dolomite (CD) and siliceous dolomite (SD). Cation ordering, unit cell parameters, major/trace elements, REEs as well as C–O–Mg isotopes of the pure matrix powders of different types of dolomites are further analyzed. The results show that the dolomites are near-source/far-source seepage reflux type and sabkha type eogenetic origin, and the magnesium ions mainly come from Late Cambrian seawater; dolomite crystals of different sizes are the result of the precursor dolomite suffering varying degrees of recrystallization during the early diagenesis period, inheriting the original geochemical characteristics; hydrothermal alteration occurs in the late stage of diagenesis, with limited magnesium ions in the hydrothermal fluid. Its impact on the dolomite is mainly reflected in local dolomite distortion and a large amount of aphanocrystalline silica and coarse-grained quartz cement filling, which fails to obviously reset the geochemical information of the matrix dolomite. The above results demonstrate that, under favorable conditions, early genetic marine dolomites may resist geochemical resetting over time intervals of more than 400 million years.

High performance Pt/Nb2W3O14 catalyst for glycerol valorization to 1,3-propanediol

Glycerol hydrogenolysis to 1,3-propanediol (1,3-PDO) is of significance in promoting the biomass valorization. To achieve the efficient conversion, the selective activation of the secondary C–O bonds in the glycerol is vital. In this work, we comparatively investigated the catalytic performances of Pt/Nb2W3O14 catalyst for glycerol hydrogenolysis controlled at the reacting conditions of 140 °C and 40 bar. Compared to Pt/WO3 and Pt/NbOx, the space–time yield (STY) of 1,3-PDO over Pt/Nb2W3O14 catalyst can be improved by a factor of 13, reaching 596.4 mg gcat−1 h−1. The cation ordering of Nb and W on atomic-scale were fully synergized their unique advantages, showing preferential adsorption of the secondary C–O bond under in-situ DRIFTS tracking. The prepared Nb2W3O14 is a tetragonal tungsten bronze (TTB) type complex oxides which can effectively promote the dispersion and reduction of Pt nanoparticles. Such strong interaction between Nb2W3O14 and Pt can coordinate the precise adsorption and activation of the secondary C–O bond, simultaneously triggering subsequent hydrogenation. Pt/Nb2W3O14 affords an ultrahigh activity in glycerol hydrogenolysis to produce 1,3-PDO, tripling the record productivity that was previously reported of these Pt-W based catalysts. This study reported the development of highly synergistic catalyst based on efficient and selective activation of the secondary C–O bond, which can be extended to catalyst design for other biomass valorization.