Effect of different supports on activity of Mn-Ce binary oxides catalysts for toluene combustion

The effects of support materials on catalytic performance were investigated in catalytic removal of toluene.And the Mn–Ce binary oxides as active components were supported on ZrO_(2),SiO_(2),γ-Al_(2)O_(3) and TiO_(2) support materials.Many techniques,including X-ray diffraction(XRD),Brunauer–Emmett–Teller method(BET),X-ray photoelectron spectroscopy(XPS),temperature-programmed reduction(TPR)and NH_(3)-temperature-programmed desorption(NH_(3)-TPD),were used to characterize physicochemical properties.Among the different catalysts,the MnCe/ZrO_(2) catalyst with the lowest specific surface area(39.7 m^(2)/g)shows the best catalytic activity.In terms of toluene conversion,the activity order is as follows:MnCe/ZrO_(2)>MnCe/TiO_(2)≈MnCe/SiO_(2)>MnCe/Al_(2)O_(3).The better performance of MnCe/ZrO_(2) should be attributed to the low-temperature reducibility,and abundant surface species(Mn^(4+)and lattice oxygen).And XPS and TPR results reveal that more surface abundant Mn and Ce elements generate good interaction in MnCe/ZrO_(2).The weak interaction between metal oxide and support also boosts the dispersion and complete reduction of MnCe oxides at low temperature.In addition,the in-situ DRIFTS results clarify that the carbonate species are main intermediates in MnCe/ZrO_(2) sample during surface reaction process.

An active learning workflow for predicting hydrogen atom adsorption energies on binary oxides based on local electronic transfer features

Machine learning combined with density functional theory(DFT)enables rapid exploration of catalyst descriptors space such as adsorption energy,facilitating rapid and effective catalyst screening.However,there is still a lack of models for predicting adsorption energies on oxides,due to the complexity of elemental species and the ambiguous coordination environment.This work proposes an active learning workflow(LeNN)founded on local electronic transfer features(e)and the principle of coordinate rotation invariance.By accurately characterizing the electron transfer to adsorption site atoms and their surrounding geometric structures,LeNN mitigates abrupt feature changes due to different element types and clarifies coordination environments.As a result,it enables the prediction of^(*)H adsorption energy on binary oxide surfaces with a mean absolute error(MAE)below 0.18 eV.Moreover,we incorporate local coverage(θ_(l))and leverage neutral network ensemble to establish an active learning workflow,attaining a prediction MAE below 0.2 eV for 5419 multi-^(*)H adsorption structures.These findings validate the universality and capability of the proposed features in predicting^(*)H adsorption energy on binary oxide surfaces.

Catalytic performance for methane combustion of supported Mn-Ce mixed oxides

A series of supported Mn-Ce mixed oxide catalysts were prepared by the impregnation method and used for the oxidation of methane. The catalysts were characterized by N2 adsorption （BET）, X-ray diffraction （XRD）, laser Raman spectrum （LRS）, and temperature programmed reduction （TPR） techniques. The XRD and LRS results confirmed the high dispersion of active components or formation of solid solution between manganese and cerium oxides in the bulk and on the surface of mixed oxide catalysts. The reducibility was remarkably promoted by the stronger synergistic interaction between the two oxides from H2-TPR measurements. As expected, all the experimental mixed oxide catalysts showed excellent activity for methane combustion at low temperature. Especially, for the catalyst with Mn-Ce ratio 3：7, methane conversion reached 92% at a temperature as low as 470 ℃.

Comparison Study on the Microstructure of Nanocrystalline TiO_2 in Different Ti-Si Binary Oxides

Three different Ti-Si oxide structuares, silica supported titania, silica coated titania and intimately mixed silicatitania, containing 10%-40% SiO2, were made by sol-gel process. The variations of microstructure parameters of nanocrystalline （nc） TiO2-anatase in the three kirds of binary oxides, including in-plane spacing d, cell constants （ao, co）, cell volume V, cell axial ratio co/ao and crystal grain size, were comparatively investigated by high resolution transmission electron microscopy （HRTEM） and X-ray diffraction （XRD）. It is found that the microstructure parameters vary remarkably with increasing SiO2 content and annealing temperature. Different structured Ti-Si binary oxides lead to different variation tendencies of microstructure parameters. The more SiO2 the binary oxide contains, the more lattice defects of nc TiO2-anatase appear; diffusion or migration of Si cations could be an important influential factor in the variations of microstructure. The grain size of nc TiO2 in the three kinds of binary oxides not only depends on SiO2 content and annealing temperature but also on the degree of lattice microstrain and distortion of nc TiO2-anatase. Both grain size and phase transformation of nc TiO2-anatase are effectively inhibited with increasing SiO2 content.

CO_2 methanation over TiO_2–Al_2O_3 binary oxides supported Ru catalysts

TiO_2 modified Al_2O_3 binary oxide was prepared by a wet-impregnation method and used as the support for ruthenium catalyst. The catalytic performance of Ru/TiO_2–Al_2O_3catalyst in CO_2 methanation reaction was investigated. Compared with Ru/Al_2O_3 catalyst, the Ru/TiO_2–Al_2O_3catalytic system exhibited a much higher activity in CO_2 methanation reaction. The reaction rate over Ru/TiO_2–Al_2O_3 was 0.59 mol CO_2·(g Ru)1·h-1, 3.1 times higher than that on Ru/Al_2O_3[0.19 mol CO_2·(gRu)-1·h-1]. The effect of TiO_2 content and TiO_2–Al_2O_3calcination temperature on catalytic performance was addressed. The corresponding structures of each catalyst were characterized by means of H_2-TPR, XRD, and TEM. Results indicated that the averaged particle size of the Ru on TiO_2–Al_2O_3support is 2.8 nm, smaller than that on Al_2O_3 support of 4.3 nm. Therefore, we conclude that the improved activity over Ru/TiO_2–Al_2O_3catalyst is originated from the smaller particle size of ruthenium resulting from a strong interaction between Ru and the rutile-TiO_2 support, which hindered the aggregation of Ru nanoparticles.

THE NEW MODEL FOR CALCULATION OF STANDARD ENTROPIES OF SOLID COMPOUNDS Ⅲ CALCULATION FOR STANDARD ENTROPIES OF SOLID BINARY OXIDES

This paper establishes a new model for calculation of the standard entropies of solid binary oxides as follows: S_(29)=27.07×Φ_1+1.120×Φ_2+n_1×k×Φ, -22.19 e.u (R=0.9960) We have invesigated 103 binary oxides. and found good agreemenl between estimated and experimental entropies.

TiO_2-Supported Binary Metal Oxide Catalysts for Low-temperature Selective Catalytic Reduction of NO_x with NH_3

Binary metal oxide（MnOx-A/TiO2）catalysts were prepared by adding the second metal to manganese oxides supported on titanium dioxide（TiO2）,where,A indicates Fe2O3,WO3,MoO3,and Cr2O3.Their catalytic activity,N2 selectivity,and SO2 poisonous tolerance were investigated.The catalytic performance at low temperatures decreased in the following order：Mn-W/TiO2〉Mn-Fe/TiO2〉Mn-Cr/TiO2〉Mn-Mo/TiO2,whereas the N2 selectivity decreased in the order：Mn-Fe/TiO2〉Mn-W/TiO2〉Mn-Mo/TiO2〉Mn-Cr/TiO2.In the presence of 0.01%SO2 and 6%H2O,the NOx conversions in the presence of Mn-W/TiO2,Mn-Fe/TiO2,or Mn-Mo/TiO2 maintain 98.5%,95.8%and 94.2%, respectively,after 8 h at 120°C at GHSV 12600 h？ 1 .As effective promoters,WO3 and Fe2O3 can increase N2 selectivity and the resistance to SO2 of MnOx/TiO2 significantly.The Fourier transform infrared（FTIR）spectra of NH3 over WO3 show the presence of Lewis acid sites.The results suggest that WO3 is the best promoter of MnOx/TiO2,and Mn-W/TiO2 is one of the most active catalysts for the low temperature selective catalytic reduction of NO with NH3.

Enhancement of the formic acid electrooxidation activity of palladium using graphene/carbon black binary carbon supports

Combinations of graphene(Gr)and carbon black(C)were employed as binary carbon supports to fabricate Pd‐based electrocatalysts via one‐pot co‐reduction with Pd2+.The electrocatalytic performance of the resulting Pd/Gr‐C catalysts during the electrooxidation of formic acid was assessed.A Pd/Gr0.3C0.7(Gr oxide:C=3:7,based on the precursor mass ratio)electrocatalyst exhibited better catalytic performance than both Pd/C and Pd/Gr catalysts.The current density generated by the Pd/Gr0.3C0.7catalyst was as high as102.14mA mgPd?1,a value that is approximately3times that obtained from the Pd/C(34.40mA mgPd?1)and2.6times that of the Pd/Gr material(38.50mA mgPd?1).The anodic peak potential of the Pd/Gr0.3C0.7was120mV more negative than that of the Pd/C and70mV more negative than that of the Pd/Gr.Scanning electron microscopy images indicated that the spherical C particles accumulated on the wrinkled graphene surfaces to form C cluster/Gr hybrids having three‐dimensional nanostructures.X‐ray photoelectron spectroscopy data confirmed the interaction between the Pd metal and the binary Gr‐C support.The Pd/Gr0.3C0.7also exhibited high stability,and so is a promising candidate for the fabrication of anodes for direct formic acid fuel cells.This work demonstrates a simple and cost‐effective method for improving the performance of Pd‐based electrocatalysts,which should have potential industrial applications.

Removal of tungsten from molybdate solution by Fe-Mn binary oxide adsorbent

Considering the different geochemical enrichment behaviors of W and Mo,Fe?Mn binary oxide(FMBO),ferric hydroxide(Fe(OH)3)and manganese dioxide(MnO2)were studied to separate W from molybdate solution,respectively.The experimental results demonstrated that Fe?Mn binary oxide(FMBO)was the most suitable adsorbent for the separation.Under a wide pH(6.9?11.3)region,more than80%W removal efficiency and less than3%Mo loss could be obtained.In addition,the Fe?Mn binary oxide adsorbent can be regenerated by treating with3mol/L NaOH,and the W adsorption efficiency was retained after five adsorption?desorption?regeneration cycles.All these indicate that the Fe?Mn binary oxides have the potential for the separation of W from molybdate solution.

Phase Stability, Kinetic Diagrams and Diffusion Path in High Temperature Oxidation of Binary Solid-Solution Alloys

The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams, which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.

Influence of Binary Oxidant (FeCl₃:APS) Ratio on the Spectroscopic and Microscopic Properties of Poly(2,5-Dimethoxyaniline)

Poly(2,5-dimethoxyaniline) (PDMA) has been synthesized by chemical oxidative polymerization technique using varying ratio (wt/wt) of binary oxidants;ferric chloride (FeCl3) and ammonium persulfate (APS). Fourier transform infrared (FT-IR) and ultraviolet-visible (Uv-vis) spectroscopic investigations provide the evidence of the presence of both benzenoid and quinoid ring units. The thermal analysis and structural characterization data suggests that the oxidant ratio greatly controls the molecular ordering in PDMA. Surface morphology shows the existence of both amorphous and crystalline domains wherein the crystalline domain size depends on the oxidant ratio. The dc conductivity (σdc) of PDMA is also a function of binary oxidant ratio and at FeCl3:APS (50:50), it increases by two orders of magnitude. Films of PDMA synthesized using FeCl3:APS (50:50) binary oxidant exhibits a decrease in the surface current on exposure to ammonia gas.

Construction of hollow binary oxide heterostructures by Ostwald ripening for superior photoelectrochemical removal of reactive brilliant blue KNR dye

Although the Ostwald ripening approach is often utilized to manufacture single hollow metal oxide,constructing hollow binary oxide heterostructures as potent photoelectrochemical(PEC)catalysts is still obscure and challenging.Herein,we reveal a general strategy for fabricating hollow binary oxides heterostructures(Co_(3)O_(4)-δ-MnO_(2)and Co_(3)O_(4)–SnO_(2))utilizing Ostwald ripening.Hollow Co_(3)O_(4)-δ-MnO_(2)nano-network with the structure evolution process was systematically explored through experimental and theoretical tools,identifying the origin of hollow binary oxides due to the interfaces acting as landing sites for their growth.In addition,the structural evolution,from hollow Co_(3)O_(4)-δ-MnO_(2)to Co_(3)O_(4)-α-MnO_(2),can be observed when the time of secondary hydrothermal reaches 96 h due to the topotactic layer-to-tunnel transition process.Notably,optimized Co_(3)O_(4)-δ-MnO_(2)-48 exhibits a superior PEC degradation efficiency of 96.42%and excellent durability(20,000 min)under harsh acid conditions,attributed to the massive hollow structures'vast surface area for high intently active species.Furthermore,density functional theory simulations elucidated the Co_(3)O_(4)-δ-MnO_(2)’electron-deficient surface and high d-band center(Co_(3)O_(4)-δ-MnO_(2),-1.06;Co_(3)O_(4)-α-MnO_(2),-1.49),strengthening the interaction between the catalyst's surface and active species and prolonging the lifetime of active species ofO_(2)and 1 O_(2).This work not only demonstrates superior PEC degradation efficiency of hollow Co_(3)O_(4)-δ-MnO_(2)for practical use but also lays the cornerstone for constructing hollow binary oxides heterostructures through Ostwald ripening.

Understanding the catalysis of chromium trioxide added magnesium hydride for hydrogen storage and Li ion battery applications

This study explores how the chemical interaction between magnesium hydride(MgH_(2))and the additive CrO_(3) influences the hydrogen/lithium storage characteristics of MgH_(2).We have observed that a 5 wt.%CrO_(3) additive reduces the dehydrogenation activation energy of MgH_(2) by 68 kJ/mol and lowers the required dehydrogenation temperature by 80℃.CrO_(3) added MgH_(2) was also tested as an anode in an Li ion battery,and it is possible to deliver over 90%of the total theoretical capacity(2038 mAh/g).Evidence for improved reversibility in the battery reaction is found only after the incorporation of additives with MgH_(2).In depth characterization study by X-ray diffraction(XRD)technique provides convincing evidence that the CrO_(3) additive interacts with MgH_(2) and produces Cr/MgO byproducts.Gibbs free energy analyses confirm the thermodynamic feasibility of conversion from MgH_(2)/CrO_(3) to MgO/Cr,which is well supported by the identification of Cr(0)in the powder by X ray photoelectron spectroscopy(XPS)technique.Through high resolution transmission electron microscopy(HRTEM)and energy dispersive spectroscopy(EDS)we found evidence for the presence of 5 nm size Cr nanocrystals on the surface of MgO rock salt nanoparticles.There is also convincing ground to consider that MgO rock salt accommodates Cr in the lattice.These observations support the argument that creation of active metal–metal dissolved rock salt oxide interface may be vital for improving the reactivity of MgH_(2),both for the improved storage of hydrogen and lithium.

Evidence for reversible oxygen ion movement during electrical pulsing:enabler of emerging ferroelectricity in binary oxides

Ferroelectric HfO_(2)-based materials and devices show promising potential for applications in information technology but face challenges with inadequate electrostatic control,degraded reliability,and serious variation in effective oxide thickness scaling.We demonstrate a novel interface-type switching strategy to realize ferroelectric characteristics in atomic-scale amorphous binary oxide films,which are formed in oxygen-deficient conditions by atomic layer deposition at low temperatures.This approach can avoid the shortcomings of reliability degradation and gate leakage increment in scaling polycrystalline doped HfO_(2)-based films.Using theoretical modeling and experimental characterization,we show the following.(1)Emerging ferroelectricity exists in ultrathin oxide systems as a result of microscopic ion migration during the switching process.(2)These ferroelectric binary oxide films are governed by an interface-limited switching mechanism,which can be attributed to oxygen vacancy migration and surface defects related to electron(de)trapping.(3)Transistors featuring ultrathin amorphous dielectrics,used for non-volatile memory applications with an operating voltage reduced to±1 V,have also been experimentally demonstrated.These findings suggest that this strategy is a promising approach to realizing next-generation complementary metal-oxide semiconductors with scalable ferroelectric materials.

Screening of MgO- and CeO_2-Based Catalysts for Carbon Dioxide Oxidative Coupling of Methane to C_(2+) Hydrocarbons

The catalyst screening tests for carbon dioxide oxidative coupling of methane (CO2-OCM) have been investigated over ternary and binary metal oxide catalysts. The catalysts are prepared by doping MgO- and CeO2-based solids with oxides from alkali (Li2O), alkaline earth (CaO), and transition metal groups (WO3 or MnO). The presence of the peroxide (O2-2) active sites on the Li2O2, revealed by Raman spectroscopy, may be the key factor in the enhanced performance of some of the Li2O/MgO catalysts. The high reducibility of the CeO2 catalyst, an important factor in the CO2-OCM catalyst activity, may be enhanced by the presence of manganese oxide species. The manganese oxide species increases oxygen mobility and oxygen vacancies in the CeO2 catalyst. Raman and Fourier Transform Infra Red (FT-IR) spectroscopies revealed the presence of lattice vibrations of metal-oxygen bondings and active sites in which the peaks corresponding to the bulk crystalline structures of Li2O, CaO, WO3 and MnO are detected. The performance of 5%MnO/15%CaO/CeO2 catalyst is the most potential among the CeO2-based catalysts, although lower than the 2%Li2O/MgO catalyst. The 2%Li2O/MgO catalyst showed the most promising C2+ hydrocarbons selectivity and yield at 98.0% and 5.7%, respectively.

Novel synthesis of SiO_x/C composite as high-capacity lithium-ion battery anode from silica-carbon binary xerogel

Micro/nanostructured SiOx/C composite was firstly synthesized by carbothermal reduction of silica-carbon binary xerogel.The homogeneous dispersion feature of the two components in binary xerogel contributes to effectively carbothermally reduce the O/Si atomic ratio,enhancing the electrochemical activity of the SiOx component.The micron-sized SiOx/C spheres are composed of many near-spherical nanoparticles.The synthesized SiOx/C exhibits a stable and high reversible capacity of 830 m A·h·g^-1 for 100 cycles,and excellent rate-capability.The homogeneous dispersion structure of phases,the micro/nanostructure and the high electrochemical activity of SiOx component combinedly contribute the excellent electrochemical performance.

Optimizing Poly(heptazine imide)Photoanodes Using Binary Molten Salt Synthesis for Water Oxidation Reaction

Polymer-based photoanodes for the water oxidation reaction have recently garnered attention,with carbon nitride standing out due to its numerous advantages.This study focuses on synthesizing crystalline carbon nitride photoanodes,specifically poly(heptazine imide)(PHI),and explores the role of salts in their production.Using a binary molten salt system,optimal photocurrent density of 365μA·cm^(−2)was achieved with a voltage bias of 1.23 V versus the reversible hydrogen electrode under AM 1.5G illumination,this performance is ca.18 times to the pristine PCN photoanode.In this process,NH_(4)SCN facilitates the growth of SnS_(2)seeding layers,while K_(2)CO_(3)enhances film crystallinity.In situ electrochemical analyses show that this salt combination improves photoexcited charge transfer efficiency and minimizes resistance in the SnS_(2)layer.This study clarifies the role of salts in synthesizing the PHI photoanode and provides insights for designing high-crystallinity carbon nitride-based functional films.

Synthesis,characterization and fluorescence of N,N'-BIS (6-metyl-2-pyridinecarboxylamide-N-oxide)-1,2-ethane and corresponding rare earth (Ⅲ) complexes

A new ligand, N,N-BIS (6-metyl-2-pyridinecarboxylamide-N-oxide)-1,2-ethane (L) and six lanthanide(Ⅲ) complexes (RE=La, Sm, Eu, Tb, Gd, Yb) were synthesized and characterized in detail. The results indicated that the composition of the binary complexes was determined as [REL(H2O)(NO3)2]NO3·nH2O (n=0-2), and the Eu3+ complex had bright red fluorescence in solid state. Three complexes of Eu3+, Tb3+, and Gd3+ with 6-methylpicolinic acid N-oxide (L’) were also synthesized. The relative intensity of sensitized luminescence for Eu3+ increased in the following order: L>L’. The phosphorescence spectra of the Gd3+ complexes at 77 K were measured. The energies of excited triplet state for the ligands were 20704 cm-1 (L) and 20408 cm-1 (L’). The facts that the ligands sensitized Eu3+ strongly and the order of the emission intensity for Eu3+ complexes were explained by ΔE(T-5D). This meant that the triplet energy level of the ligand was the main factor to influence RE3+ luminescence.

Synthesis, Characterization and Properties of N,N′-Bis(6-methyl-2-pyridine-N-oxide)-1,3-Propane and Europium and Terbium Complexes

A new ligand, N,N′-Bis(6-methyl-2-pyridine-N-oxide)-1,3-propane (L), and some binary lanthanide complexes (Ln=Eu^(3+), Tb^(3+)) were synthesized and characterized in detail. The composition of the binary complexes was determined as LnL(NO_3)_3. They are 1∶1 electrolytes in DMF. The complexes have strong characteristic line fluorescence emission spectra, and it is also found that TbL(NO_3)_3 complex has stronger luminescence intensity than EuL(NO_3)_3 in solid state and in methanol.

二元磁性S_(2)O_(8)^(2-)/Fe_(3)O_(4)-ZrO_(2)固体超强酸催化合成乙酸乙酯工艺研究

以无水氯化锆、过硫酸铵、硫酸亚铁、硝酸铁为原料,采用共沉淀-浸渍法制备了二元磁性S_(2)O_(8)^(2-)/Fe_(3)O_(4)-ZrO_(2)固体酸催化剂,利用IR、XRD、BET、NH_(3)-TPD对二元磁性固体酸进行表征,并用于乙酸乙酯的合成反应。实验结果表明:催化剂制备条件为Fe_(3)O_(4)的添加量35%,过硫酸铵的浸渍浓度0.5 mol/L;适宜的酯化条件为醇酸摩尔比3∶1,酯化时间2 h,固体超强酸的用量0.5 g。以S_(2)O_(8)^(2-)/Fe_(3)O_(4)-ZrO_(2)为催化剂乙酸乙酯酯化率90.25%,重复4次后,乙酸乙酯的酯化率可达62.5%。