Cation Radius Research Articles

Adsorption behaviors and influencing factors of antibiotic norfloxacin on natural kaolinite-humic composite colloids in aquatic environment

Particles are ubiquitous and abundant in natural waters and play a crucial role in the fate and bioavailability of organic pollution. In the present study, natural mineral (kaolinites, KL), organic (humic/fulvic acid, HA/FA) and their composite particles were further separated into particles fractions (PFs, >1 μm) and colloidal fractions (CFs, 1 kDa-1 μm) by cross-flow ultrafiltration (CFUF). This research demonstrated the role of kaolinite-humic composite colloids on the adsorption of fluoroquinolone norfloxacin (NOR). The Freundlich model satisfactory described adsorption curves, showing strong affinity of NOR to CFs, with sorption capacity (KF) between 8975.50 and 16638.13 for NOR. The adsorption capacities of NOR decreased with the particle size increasing from CFs to PFs. In addition, composite CFs showed excellent adsorption capacity, which was mainly attributed to the larger specific surface area of composite CFs and electronegativity and numerous oxygen-containing functional groups on the surfaces of the complexes, and electrostatic attraction, hydrogen bond and cation exchange could dominate the NOR adsorption onto the composite CFs. The best pH value under adsorption condition of composite CFs varied from weakly acidic to neutral with the increase of load amount of humic and fulvic acids on the surface of inorganic particles. The adsorption decreased with higher cation strength, larger cation radius and higher cation valence, which depended on the surface charge of colloids and the molecular shape of NOR. These results provided insight into the interfacial behaviors of NOR on the surfaces of natural colloids and promoted the understanding of the migration and transport of antibiotics in environmental systems.

Structural, optical, electrical, and dielectric relaxation properties of rare earth containing sodium bismuth titanate [formula omitted] perovskite: Effect of ionic radius

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE3+ (RE = La, Sm, Dy, and Ho) on structural and various physical properties of sodium bismuth titanate (Na0.5Bi0.5TiO3, NBT) based perovskite nanomaterials. The X-ray diffraction data indicate the successful formation of the rhombohedral phase (space group R3c) of NBT nano perovskite incorporated with various rare earth ions in Bi-site. The lattice parameters were found to increase linearly with the ionic radius of the dopant cation. The ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared compositions. The grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic radius. Field emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and stoichiometry. The UV–Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap, which unfolds the application of NBT-based perovskite as photoactive material. The ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius, i.e., La-doped NBT compound, exhibits the highest dc and bulk conductivity with the lowest activation energy. The frequency-dependent dielectric data follows Havriliak–Negami (HN) formalism and non-Debye type relaxation phenomena. Results also indicate that La-doped NBT composition exhibits the highest dielectric strength value. Thus, this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural, optical, and electrical properties.

Growth of Sesquioxide Crystals from Tungsten Crucibles by Vertical Gradient Freezing Method

Sesquioxides of lanthanides, yttrium, and scandium are promising hosts for laser and scintillation materials; however, the crystallization of such compounds is complicated by very high melting temperatures, as well as polymorph transitions. This work reports for the first time the growth of Y2O3 and Y2−xScxO3 crystals by the Vertical Gradient Freezing method from tungsten crucibles, proposing an alternative to extremely expensive rhenium and iridium crucibles. Translucent Y2O3 samples are obtained, and their luminescent and scintillation parameters are evaluated. The main issues of Y2O3 crystallization under the proposed conditions are discussed, as well as ways of enhancing the crystal quality. Finally, polymorph transitions are avoided by decreasing the average radius of the rare earth cation by Y3+/Sc3+ substitution, providing transparent Y2−xScxO3 crystals with a cubic structure.

Doped cation radius optimization of Li0.99M0.01Ni0.8Co0.1Mn0.1O2 (M=Ca, Sr, Ba) based on DFT calculation and electrochemical performance of Li-ion battery

Doped cation radius optimization of Li0.99M0.01Ni0.8Co0.1Mn0.1O2 (M=Ca, Sr, Ba) based on DFT calculation and electrochemical performance of Li-ion battery

Synthesis of coral-like structures of Pr–Yb co-doped YIG: Structural, optical, magnetic and antimicrobial properties

Coral-like structures of the Y3–xPrxFe5–yYbyO12, (0.00 ≤ x ≤ 0.04), (0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona‒O‒Iond angle, Iona‒O, Iond‒O and Ionc‒O bond distances and decrease in the average crystallite size. Fourier transform infrared (FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy (EDS) spectra and textural properties show coral-like structures, peaks associated with Pr3+ and Yb3+ atoms and the effect of dopants on surface area, diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer, correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y3–xPrxFe5–yYbyO12 compound. The saturation magnetization (Ms), cubic anisotropy constant (K1) and coercive field (Hc) increase with the Pr3+ cations content, as consequence of their magnetic nature and distribution around of Fe3+ ions due to the coexistence with the Yb3+. Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr3+ and Yb3+ and it is shown that, relatively high dosages of Pr3+ cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.

Do specific ion effects influence the physical chemistry of aqueous graphene-based supercapacitors? Perspectives from multiscale QMMD simulations

Whether or not specific ion effects determine the charge storage properties of aqueous graphene and graphite-based supercapacitors remains a highly debated topic. In this work we present a multiscale quantum mechanics – classical molecular dynamics (QMMD) investigation of aqueous mono- and divalent salt electrolytes in contact with fully polarizable charged graphene sheets. By computing both the electrochemical double layer (EDL) and quantum capacitance we observe a constant electrode specific capacitance with cationic radii and charge. Counterintuitively, we determine that a switch in the cation adsorption mechanism from inner to outer Helmholtz layers leads to negligible changes to the EDL capacitance, this appears to be due to the robust electronic structure of the graphene electrodes. However, the ability of ions (such as K+) with a relatively low hydration free energy to penetrate the inner Helmholtz plane and adsorb directly on the electrode surface is found to slow their diffusion parallel to the interface. Ions in the outer Helmholtz layer are found to have higher diffusivity at the surface due to their position in ion channels between water layers. Our results show that surface effects such as the surface polarization and the partial dehydration and local structuring of ions on the surface underpin the behaviour of cations at the interface and add a vital new perspective on trends in ion mobilities seen under confinement.

On the Effect of Standard Deviation of Cationic Radii on the Transition Temperature in Fluorite-Structured Entropy-Stabilized Oxides (F-ESO)

It is confirmed that Fluorite-structured Entropy-Stabilized Oxides (F-ESO) can be obtained with multicomponent (5) equimolar systems based on cerium, zirconium, and other rare earth elements, selected according to the predictor already proposed by the authors. Indeed, in the present study, three different samples owning a standard deviation (SD in the following) of their cationic radii greater than the threshold value (i.e., SD > 0.095 with cationic radii measured in Å) needed to ensure the formation of the single-phase fluorite structure, were prepared via co-precipitation method. After a calcination step at 1500 °C for 1 h, the entropy-driven transition from multiple phases to single-phase fluorite-like structure has been actually confirmed. Thus, with the aim of defining the temperature at which such entropy-driven transition occurred, and identifying possible relation between such temperature and the actual value of SD, the phase evolution of all the prepared samples as a function of temperature (ranging from 800 °C to 1300 °C) was analyzed by in situ High Temperature X-ray Diffraction. An apparent inverse correlation between the standard deviation and the entropy-driven transition temperature has been identified, i.e., the higher the former, the lower the latter. These results, based on the conducted basic structural analysis, provide further support to the SD-based empirical predictor developed by the authors, suggesting that high values of SD could bring additional contribution to the overall entropy of the system, other than the configurational one. Thus, this SD-driven entropy contribution directly increases with the increasing of the standard deviation of the cationic radii of a given F-ESO.

Stability of the Structural and Transport Characteristics of (ZrO2)0.99−x(Sc2O3)x(R2O3)0.01 (R–Yb, Y, Tb, Gd) Electrolytic Membranes to High-Temperature Exposure

The effect of long-term high-temperature annealing on the phase composition, local crystal structure, and oxygen-ion conductivity of SOFC membranes based on zirconium dioxide solid solutions was studied. Crystals with the composition of (ZrO2)0.99-x(Sc2O3)x(R2O3)0.01 (where x = 0.08-0.1; R-Yb, Y, Tb, Gd) were obtained by the method of directed melt crystallization in a cold crucible. The crystals were annealed in air at a temperature of 1000 °C for 400 h. The phase analysis of the crystals before and after annealing was studied by X-ray diffractometry and Raman spectroscopy. The study of the ionic conductivity of the crystals was carried out by the method of impedance spectroscopy in the temperature range 400-900 °C. It has been shown that when various rare earth cations (Yb, Y, Tb, and Gd) are used, the maximum conductivity is observed for the compositions (ZrO2)0.91(Sc2O3)0.08(Yb2O3)0.01, (ZrO2)0.89(Sc2O3)0.1(Y2O3)0.01, (ZrO2)0.90(Sc2O3)0.09(Tb2O3)0.01, and (ZrO2)0.89(Sc2O3)0.1(Gd2O3)0.01. At the same time, these crystals have a highly symmetrical pseudocubic structure, which is retained even after crystal annealing. At comparable concentrations of Sc2O3, the conductivity of crystals decreases with an increase in the ionic radius of the rare earth cation. The high-temperature degradation of the conductivity is also discussed depending on the type of rare earth oxide and the concentration of scandium oxide.

Probing local site disorder in zirconate pyrochlores

Structure disorder in pyrochlore oxides is critical to various physical properties such as radiation damage resistance and ionic conductivity, but the mechanism of atomic structural transitions of pyrochlores to their disordered phases is not well understood. Here we present the density functional theory calculations probing the local site disorder with respect to the oxygen migration and cation antisite for zirconate pyrochlores. Induced by the migration of 48f oxygen to the nearest vacant 8a site in the disordering process, the local pyrochlore structure tends to partially or fully transform to the weberite structure depending on the cation properties. The degree of such disordering can be characterized by the oxygen migration ratio. In A2Zr2O7 zirconate pyrochlores with an A cation radius less than Gd3+, no more than 25% of the critical oxygen migration ratio drives the systems to the most stable disordered phases. However, the disorder can hardly occur in the A2Zr2O7 with the A cation radius larger than Gd3+. The origin of such disordering is primarily attributed to a strong chemical preference of Zr atoms that adopt a 7-coordinated local environment and similar size of two cations. This study will provide new insight into the disordering mechanism of pyrochlores and may further inspire the design of these materials with tailored material properties.

Design rules for the thermal and elastic properties of rare-earth disilicates

Rare-earth silicates are the current standard material for use as environmental barrier coatings for SiC-based ceramic matrix composites as hot-section components in gas-turbine engines. Expanding the design space to all available rare-earth elements to facilitate optimizing functionality requires an understanding of systematic trends in RE2Si2O7 properties. In this work, we combine first-principles calculations with experimental measurements of Young’s modulus, coefficient of thermal expansion, and thermal conductivity for a range of different RE2Si2O7 compositions and phases. Clear trends are observed in these properties as a function of the radius of the rare-earth cation. In the case of Young’s modulus and thermal expansion, these trends also hold for multi-component systems; while the thermal conductivity of multi-component systems is noticeably lower, indicating the potential of such materials to also act as thermal barriers. These results provide design rules for developing new thermal and environmental barrier coatings with stiffness and thermal expansion engineered to match that of the substrate, while simultaneously having reduced thermal conductivity.

ANi5Bi5.6+δ (A = K, Rb, and Cs): Quasi-One-Dimensional Metals Featuring [Ni5Bi5.6+δ]- Double-Walled Column with Strong Diamagnetism.

A new series of compounds, ANi5Bi5.6+δ (where A = K, Rb, and Cs) are discovered with a quasi-one-dimensional (Q1D) [Ni5Bi5.6+δ]- double-walled column and a coaxial inner one-dimensional Bi atomic chain. The columns are linked to each other by intercolumn Bi-Bi bonds and separated by an A+ cation. Typical metallic behaviors with strong correlation of itinerant electrons and the Sommerfeld coefficient enhanced with the increasing cationic radius were experimentally observed and supported by first-principles calculations. Compared to AMn6Bi5 (where A = K, Rb, and Cs), the enhanced intercolumn distances and the substitution of Ni for Mn give rise to strong diamagnetic susceptibilities in ANi5Bi5.6+δ. First-principles calculations reveal possible uncharged Ni atoms with even number of electrons in ANi5Bi5.6+δ, which may explain the emergence of diamagnetism. ANi5Bi5.6+δ, as Q1D diamagnetic metals with strong electron correlation, provide a unique platform to understand exotic magnetism and explore novel quantum effects.

Trends in high-temperature H2 production on CeO2 Co-doped with trivalent cations in solid oxide electrolysis cells

CeO2-based catalysts incorporated with cooperative dopants show excellent potential for promoting H2 production via the water-splitting reaction (WSR) in solid oxide electrolysis cells (SOECs). Here, we report that CeO2 co-doped with Gd + Sb, Pr + Sb, and Bi + Sb trivalent cations have superior performance for WSR with the reaction rate 2–5 orders of magnitude larger than that of individual trivalent dopants including Ga, Sb, Lu, Gd, Sm, Pr, Bi, and La, owing to improved stability of hydridic H-species and accordingly decreased barrier for their decompositions into H2 by co-doping. The energy of hydridic H-species and the turn-over frequency (TOF) toward H2 production is shown to correlate well with the average ionic radius of trivalent cations, where the TOF increases with decreasing ionic radius and Gd + Sb, Pr + Sb, and Bi + Sb with smaller ionic radius show better WSR activity than other dopants. Our studies suggest incorporating ceria with proper co-dopants with an average radius close to Gd + Sb, Pr + Sb, or Bi + Sb pairs as an effective strategy for enhancing WSR performance on CeO2 in SOECs.

A theoretical adsorption study of the inner‐core and outer‐core hydrated alkali metal cation–circumcoronene complexes

AbstractCation‐π interactions are theoretically investigated for alkali metal cation (M+)‐circumcoronene (CC) complexes (M = Li, Na, K), in gas phase and in aqueous solution with consideration of micro‐ and global solvation models using the DFT/PBEh‐3c‐RI/TZVP method. The solvent effect on the M+–CC energy interaction regarding the cation size and the stability of inner‐ and outer‐sphere [M(H2O)n]+–CC complexes are calculated by means of geometry optimizations and potential energy (PE) curves. The PE curves, calculated as a function of perpendicular distance of M+ to the CC plane, predicted one energy minimum for each of the isolated M+–CC complexes. However, for microhydrated complexes, two minima assigned to two different surface complexations were obtained. Microhydrated Li+ and Na+ favored outer‐sphere complexation while inner‐sphere complexation was found more stable for microhydrated K+. These results illustrate nicely the key role, which the cation radius plays for the polarization of the water molecules and the aromatic system.

Probing the mechanism of salts destroying the cage structure of methane hydrate by molecular dynamics simulation

Much attention has been generated in the exploitation of natural gas hydrate by injecting brine due to its low cost and eco-friendliness. However, it is not clear how inorganic salts destroy the cage structure of methane hydrate. This work focuses on the mechanism of inorganic salts destroying the cage structure of methane hydrate by molecular simulation. And the influence of cation type on methane hydrate decomposition is studied in detail. The results show that inorganic salts can effectively reduce the temperature required for methane hydrate decomposition. And inorganic salts can weaken the interaction between water molecules by reducing the dipole moment of water molecules in methane hydrate, then the cage structure of methane hydrate is destroyed. Methane hydrate both can completely decompose without and with CaCl2 solution at 307 K and 20 MPa, but the decrease rate of the dipole moment autocorrelation function (DACF) of water molecules in the system with CaCl2 solution is 6.10 times than that without CaCl2 solution, and the decomposition rate of methane hydrate increased by 5.8 times because of adding CaCl2 solution. In addition, the increasing charge and radius of cations result in greater methane hydrate decomposition which is caused by the faster destruction speed of cage structure, the faster rate of methane molecules escaping from cage structure and the faster diffusion velocity of cations are demonstrated. This study provides a theoretical basis for the efficient exploitation of methane hydrates by brine injection.

Structural Damage and Recrystallization Response of Garnet Crystals to Intense Electronic Excitation (Adv. Funct. Mater. 8/2023)

Recrystallization Effects In article number 2212853, Peng Liu, Miguel L. Crespillo, Eva Zarkadoula, and co-workers demonstrate the track damage formation and recrystallization effects in garnet crystals under the intense electronic excitation, attributed to the key role of thermal parameters and cation radius ratio. The irradiation-induced nanostructures in garnet crystals enable the significant bandgap regulation and defect-related luminescence enhancement.

Long-range A-site cation disorder in NaA(MO4)2 (M = Mo, W) double scheelite oxides

Synchrotron X-ray and neutron powder diffraction methods have been used to obtain accurate long-range average structures of some double scheelite compounds of the type NaA(BO4)2 (A ​= ​La, Pr, Nd, Sm, Lu, and Bi; B = Mo, W) at room temperature. Phase pure samples were synthesized using standard solid-state methods. Rietveld refinements using combined synchrotron X-ray diffraction (SXRD) and neutron diffraction (NPD) revealed a random distribution of the Na and A-type cations regardless of the presence of 6s2 lone pairs (such as Bi3+) and the difference in oxidation states and ionic radii between the cations. The NaA(BO4)2 (A ​= ​La, Pr, Nd, Sm, Lu, and Bi) series displayed linear trends in lattice parameters and AO8 polyhedra volume with the ionic radius of the A-type cation for the lanthanoids, but a deviation from the trend was observed for A ​= ​Bi3+. The NaBi(BO4)2 structure has a smaller than expected unit cell volume than based on extrapolation from the corresponding NaLn(BO4)2 series, possibly due to short-range ordering of the 6s2 lone pair electrons.

Silesiaite, ideally Ca2Fe3+Sn(Si2O7)(Si2O6OH), a new species in the kristiansenite group: crystal chemistry and structure of holotype silesiaite from Szklarska Poręba, Poland, and Sc-free silesiaite from Häiviäntien, Finland

AbstractTwo silesiaite crystals, one from Szklarska Poręba, Poland (type locality), and the other from Häiviäntien, Finland, were studied with electron-probe microanalysis, Raman spectroscopy and single-crystal X-ray diffraction. The crystals have the following compositions normalised to 13 O2– + 1 (OH)– anions: Ca2.001(2)[(Sn1.105(6)Zr0.009(1))Σ1.114(Fe3+0.523(78)Sc0.185(62)Al0.070(14))Σ0.779(Fe2+0.065(12)Mn2+0.041(5)Mg0.003(3))Σ0.110]Σ2.003(Si3.997(2)O13OH), and Ca2.006(8)[(Sn1.110(18)Ti0.006(3))Σ1.107(Fe3+0.648(50)Al0.063(11))Σ0.710(Fe2+0.140(30)Mn2+0.011(3)Mg0.005(2))Σ0.155(Nb0.020(6)Ta0.011(3))Σ0.040]Σ2.009(Si3.991(14)O13OH), respectively. The structure of the crystals was refined in the triclinic system with unconventional space-group symmetry C1 to R1 = 2.02% and 3.56%, respectively. The unit cells were found to be a = 10.0080(2), b = 8.3622(1), c = 13.2994(2) Å, α = 89.987(1), β = 109.095(2), γ = 89.978(1)° and V = 1051.77(3) Å3 for silesiaite from Szklarska Poręba, and a = 9.9985(3), b = 8.3446(2), c = 13.2760(4) Å, α = 89.986(3), β = 109.122(2), γ = 90.020(2)° and V = 1046.55(5) Å3 for silesiaite from Häiviäntien. In both crystals, the Ca sites are occupied solely by calcium and Si sites by silicon atoms. Optimised occupancies of the four M sites indicated slightly different site fillings. In the Szklarska Poręba silesiaite, the M1 site is predominantly occupied by trivalent Fe + Sc and the M2–M4 sites by Sn. In contrast, in the Häiviäntien silesiaite, the M1–M3 sites are Sn-dominant, while Fe3+ predominantly occupies the M4 site. The differences can be considered a result of an evolution of the M1–M4 site occupancies following a decrease of the <M–O> distance. Among the minerals of the kristiansenite group, Sc-free silesiaite from the Häiviäntien pegmatite has the smallest average radius of M-site cations and a unit-cell volume that increases proportionally to the (Fe2+ ± Sc) content. The hydrogen atoms form moderate hydrogen bonds between disilicate groups (Si2O7 and Si2O6OH) linked in rows along [101], indicating the presence of one hydroxyl in the formula calculated for Z = 4. All three kristiansenite-group species, i.e. silesiaite, kozłowskiite and kristiansenite, are isostructural.

Strong energy transfer and color tunable emission in Eu2+ and Mn2+ co-doped Na2BaSr(PO4)2 phosphor

The new dual-emitting and color tunable single phase of Na2BaSr(PO4)2:0.03Eu2+, xMn2+ (NBSP:0.03Eu2+, xMn2+) phosphor are successful prepared in this work. The phase purity and photoluminescence properties are investigated. Regarding to the coordination, valence and cation radius, the Eu2+ ions occupy the Sr2 and Sr3 site and Mn2+ ions occupy the Sr3 site. According to the photoluminescence (PL) spectra of NBSP:0.03Eu2+, xMn2+ (x = 0–0.09), the strong energy transfer (ET) between Eu2+ and Mn2+ exists in these phosphors. The strong ET efficiency from Eu2+ to Mn2+ is as high as 92%, while the ET mechanism of Eu2+ and Mn2+ is quadrupole-quadrupole interaction. Moreover, the CIE coordinate of Eu2+ and Mn2+ co-doped Na2BaSr(PO4)2 phosphors can realize the color tunable emission from blue to cold white. The temperature dependent photoluminescence intensity of NBSP:0.03Eu2+, 0.05Mn2+ phosphor still keeps 75.8% of that initial intensity when the temperature is 150 °C. In summary, the NBSP:0.03Eu2+, xMn2+ phosphors have a promising application in white light LED.

Structure, Judd-Ofelt analysis and spectra studies of Sm3+-doped MO-ZnO-B2O3–P2O5 (M = Mg, Ca, Sr, Ba) glasses for reddish-orange light application

In the present work, a series of Sm3+-doped MO-ZnO-B2O3–P2O5 (M = Mg, Ca, Sr, Ba) glasses were prepared. The glass structure and luminescence properties were investigated by XRD, DSC, IR, absorption spectroscopy, Judd-Ofelt theory and photoluminescence spectra. The J-O parameters of Sm3+-doped glasses follow the trend of Ω4＞Ω6＞Ω2. Under the excitation of 401 nm Xenon lamp, Sm3+-doped glasses exhibited four emissions from the transitions of 4G5/2→6HJ/2 (J = 5, 7, 9, 11) in the visible spectra. The luminous intensity of Sm3+ increases with the asymmetry in local environments and decreases with the increasing radius of the alkaline-earth cation. Among the as-prepared glass, the Sm3+-doped glass containing magnesium oxide exhibits higher values of stimulated emission cross-section (2.18 × 10−21 cm2), gain bandwidth (1.40 × 10−27 cm3), and optical gain (3.83 × 10−24 cm2). All the Sm3+-doped glasses show intense orange light in the CIE 1931 chromaticity diagram with a high color purity exceeding 99%. In addition, the time-resolved emission spectra reveal the decay process of the Sm3+ ions for the transitions 4G5/2 → 6H7/2 and 4G5/2 → 6H9/2 in the glass containing magnesium oxide. It suggests that Sm3+-doped alkaline-earth zinc borophosphate glasses could be a potential candidate for reddish-orange light-conversion fluorescent materials based on the ultraviolet light-emitting diode.

Palladium doped with boron and phosphorus on activated carbon: a high-performance nanocatalyst for the hydrogenation of alkenes

Fabrication of high-performance palladium on activated carbon (Pd/AC) nanocatalysts for hydrogenation of alkenes to reduce the cost of reaction products has always been of interest to researchers and industries. Herein, the purpose was the step-by-step investigation of the simple precipitation-reduction method to determine the best chemicals usable in producing the high-performance 10%Pd/AC nanocatalyst for the hydrogenation of alkenes. Hence, different types of carbon supports, alkaline agents, and reducing agents were selected for this purpose. Catalytic hydrogenation of cinnamic acid to hydrocinnamic acid was used as a well-known standard test for evaluating the activity of the nanocatalysts. The AC prepared by pine wood, H2PdCl4, KHCO3, and NaBH4/NaH2PO2 were the most suitable materials for producing high-performance Pd/AC using the mentioned method. It was specified that activity is increased with the lower amount of oxygenated acidic functional groups on the AC, greater cation radius of the alkaline agent, weaker alkaline agent, and higher reduction power of the reducing agent. NaH2PO2 and especially NaBH4 increase the activity more than other reducing agents because of their high reduction power and adding phosphorus (P) and boron (B) to Pd, respectively. Three nanocatalysts with the most activity were chosen for more investigations by different analyses. The results of these analyses were according to the procedure obtained for their catalytic activity. The reusability test of chosen nanocatalysts indicated that the stability of Pd/AC is increased by doping the Pd with B and especially P. According to the obtained results, Pd nanocatalyst doped with both P and B is strongly recommended for application in alkenes hydrogenation.