Lithium ion can almost reversibly intercalate into or deintercalate from spinel type lithium manganese oxide LiMn2O4. LiMn2O4 is one of the most promising cathode materials for lithium secondary battery because of natural abundance of manganese and its low toxicity to environment. In this paper, the relationship between crystal structure and charge-discharge properties of LiMn2O4 cathode is summarized. Moreover, a part of substitution of manganese with other transition metal brings the improvement of cycle life. We focused on the local structure of the spinels and considered the effect of the local distortion on the cycle life of the spinel cathodes.
New non-azide gas generant having progressive gas output enables the new driver side inflator. The inflator has the advantages of non-toxic gas generant, small size and light weight, low risk for driver injuries and low cost. The gas generant is composed of a guanidine compound as the fuel, a metal nitrate as oxidizer, the inorganic additive and the binder. All the ingredients of the gas generant have larger LD50 than 1000 mg/kg to decrease the risk of environmental pollution. The inorganic additive rapidly reacts with the residue generated from the oxidizer to simplify the inflator structure (small size and light weight) and to decrease the airborne particulates. The propellant is formed as cylindrical shape by extrusion process. The progressive gas output is available by controlling diameter and length of the propellant particle. The inflator also has the property of progressive gas output. This property enables to lower the injury risk and to improve the restrain performance. These advantages are well accepted in the market to reach the annual production of three million units, and still growing.
Recent development in the research on charge-transfer (CT) complex formation based on molecular recognition of organic π-dianions is described. Detailed analyses of the cyclic voltammetric and spectroelectrochemical behaviors of the hydrogen-bonding systems reveal that p-quinone dianions (PQ2−) form 1 : 2 complexes with MeOH at low concentration of MeOH and 1 : 4 complexes at high concentration by the hydrogen bonding involving strong n-σ type charge-transfer (CT) interaction characterized by the geometrical and spectral properties. The results suggest that the differing functions and properties of biological quinones are imparted by the n-σ CT interaction through hydrogen bonding of the dianions with their protein environment. On the other hand, it has been demonstrated that π-dianions of redox-active organic molecules such as chloranil (CL) and TCNE form π-π type CT complexes with 4nπ biphenylene (BP). The complex formations are due to molecular recognition based on the favorable intermolecular HOMO-LUMO interaction of the dianions with BP, and the geometries of the dianion complexes differ from those of the neutral complexes. This background led to the development of the redox-mediated bistable complex formation systems characterized by the geometrical alteration and the chromatic change. The interconversion of the bistable complex formation in the systems is modulated through redox control of the intermolecular HOMO-LUMO interaction, with trichromic change arising from the neutral complex formation, the anion radical generation, and the dianion complex formation. These results are important for extended discussion on the function of biological quinones as a charge separator and the development of highly designed, redox-mediated recognition systems involving the electrogenerated π-dianions.
In order to obtain the basic information of the structure of 1-propanol aqueous solution, the Kirkwood-Buff (KB) integrals, G11, G22 and G12 (1 : 1-propanol, 2 : water), the concentration fluctuation of 1-propanol, N<(Δx1)2>, the density fluctuation, <(ΔN)2>/N, their correlation term, <ΔNΔx1>, the density fluctuations of respective components <(ΔNi)2>/<Ni>, and their correlation term <ΔNiΔNj>/<Nj> have been estimated over the whole concentration range and at the temperature range of 283.15–353.15 K. The KB integrals have been calculated from the thermodynamic properties such as isothermal compressibilities, kT, excess molar Gibbs energies, GmE, and excess molar volumes, VmE. Successively, these KB integrals have been converted to the fluctuations using Nishikawa procedure. In G11, G22, N<(Δx1)2>, <(ΔN)2>/N and <(ΔNi)2>/<Ni>, the maxima have appeared at x1≈0.2, and increased with the increase of temperature. On the other hands, in G12, <ΔNΔx1> and <ΔNiΔNj>/<Nj>, the minima have appeared at the same mole fraction, and decreased. However, this tendency is reversed in x1>0.3. These results suggest us the followings: The self-associations of 1-propanol and water molecules are more preferential in x1<0.3 and consequently the microscopic demixing of this system more advances as the temperature increases, in contrast, the hetero-associations between 1-propanol and water molecules are more progressed in x1>0.3.
Since their discovery, many varieties of discotic liquid crystals, whose molecules resemble flat, circular disks in shape, have been described. Among these compounds, Chandrasekhar et al. first reported the unstable discotic mesophase of tetrahydroxy-p-benzoquinone tetraoctanoate, i.e. 3,6-dioxo-1,4-cyclohexadiene-1,2,4,5-tetrayl tetraoctanoate. Then, Lillya and Thakur resumed this uncertain mesophase and concluded that 3,6-dioxo-1,4-cyclohexadiene-1,2,4,5-tetrayl tetraheptanoate (2a) and tetraoctanoate (2b) both exhibit a columnar mesophase with a narrow temperature range. Since 2,5-cyclohexadiene-1,4-dione has unique functionalities, we pay much attention to 2,5-cyclohexadiene-1,4-dione derivatives to apply them to discotic liquid crystals. In this study three series of 3,6-dioxo-1,4-cyclohexadiene-1,2,4,5-tetrayl tetrakis(4-alkoxybenzoate) 4, 2,3,5,6-tetraalkoxy-2,5-cyclohexadiene-1,4-dione 5, and 2,3,5,6-tetrakis(alkanoylamino)-2,5-cyclohexadiene-1,4-dione 7 were synthesized and their mesomorphic properties were examined. The benzoates 4 exhibited a simple crystal-isotropic liquid transition compared with the aliphatic esters 2. We concluded that the aromatic ring of benzoate 4 was not suitable for improving coplanarity and rigidity to the 2,5-cyclohexadiene-1,4-dione central core. We also obtained ethers 5 to improve chemical stability of esters 2, and found that 5b showed two endothermic peaks at 32 °C and 55 °C, respectively, by differential scanning calorimetry (DSC). However, only a vague texture was observed in the temperature range. Thus, we have not yet demonstrated that this mesophase was a liquid crystalline phase. Finally, we substituted an ester bond of 2 by an amide one to strengthen the inter-molecular interaction, and discovered that 7a displayed a dendric texture with thermal decomposition after being cooled from the isotropic liquid. We deduced this mesophase hexagonal columnar phase (Colh) on the basis of the reported optical texture.
The states of dissolved water in various ethers such as diethyl ether (DEE), dipropyl ether (DPE), dibutyl ether (DBE) di-s-butyl ether (DSBE), dioctyl ether (DOE), didecyl ether (DDE) and ethylene glycol dibutyl ether [1,2-dibut-oxyethane (DBOE)] were studied by FT-IR spectroscopy. Also, thermal stability was examined for water clusters formed in such ethers. The water cluster consists of [–O– · H2O], and [–O– · Cluster], the small clusters (C1 and C2) and the large clusters (LC1, LC2 and LC3). The water molecules in [–O– · H2O] interact with the oxygen atom of ether group through hydrogen bonding, and are surrounded by [–O– · Cluster]. The C1 and C2 are formed in the free volume among alkyl chains, and LC1, LC2 and LC3 exist around C1 and C2. As the negativity on oxygen atom of ether group becomes greater with increasing alkyl-chain length of the ethers, [–O– · Cluster] becomes larger. The amount and the size of C1 and C2 are decreased with increasing alkyl-chain length of the ethers, while those of the large cluster (LC1, LC2 and LC3) are increased. In the range from 40 °C to 80 °C, the C1 are vaporized and finally C1 disappears. LC2 and the LC3 are gradually divided into smaller clusters with increasing temperature.
Two processes are known in the formation of strontium apatite (Sr–Ap) by homogeneous precipitation method using hydrolysis of urea. The alpha strontium hydrogenphosphate (α-SrHPO4) is obtained as the initial product in all the reaction conditions. Sr–Ap is transformed from α-SrHPO4 via strontium phosphate (Sr3(PO4)2) or beta strontium hydrogenphosphate (β-SrHPO4). The effects of reaction conditions on the formation of various strontium phosphates and on the composition of Sr–Ap are discussed. Sr–Ap was prepared at 98(±1) °C by the homogeneous precipitation method from the mixed solution (Sr2+/P mole ratio = 1.00–5.00) of Sr2+ ion, NaH2PO4 and urea. Each of α-SrHPO4, β-SrHPO4 or Sr3(PO4)2 was aged in various reaction solutions. At pH 6.2, α-SrHPO4 transformed easily into Sr3(PO4)2 by aging in the dilute solution of Sr2+ ions and into β-SrHPO4 by aging in the concentrated solution of Sr2+ ions. But, regardless of Sr2+ ions concentration, α-SrHPO4 transformed into β-SrHPO4 at pH 7.2. As the concentration of Sr2+ ions or Cl− ions was high, Sr3(PO4)2 or β-SrHPO4 transformed into Sr–Ap in a short time. The incorporation of Cl− ions or CO32− ions into the crystal of Sr–Ap obtained by hydrolysis of urea is unavoidable. It is known that the incorporation of CO32− ions could be reduced by heating urea solutions of low concentration for a long time. It is an effective method to prepare the high concentration of Sr2+ ions in the initial solution with Sr2+/P mole ratio = 1.67. On the other hand, the heightening Cl− ions concentration in the initial solution increased the amount of incorporation of Cl− ions into the obtained crystal of Sr–Ap. The single phase of α-SrHPO4, β-SrHPO4, Sr3(PO4)2 or Sr–Ap could be obtained readily by the control of the reaction conditions. And, it was clarified that the incorporation of Cl− ions or CO32− ions into the obtained crystal of Sr–Ap could be controlled.
Complex formation (1 : 1) between Al(III) and gallic acid (H4L) was studied by spectrophotometry at 25 °C and at ionic strength I = 0.1. At pH 4–5 buffered with acetate ions, the complex species can be analyzed by measuring the absorbance of the free ligand, which decreases along with the increase in Al(III) concentration. The method is based on the competition between gallic acid and buffer ligands for Al(III) ions, or between hydrogen ions and Al(III) ions for gallic acid. The concentration of the Al(III)-gallate complex formed at constant pH or at constant acetate (buffer) concentration decreased along with the increase in acetate ion or hydrogen ion concentration, respectively. The results showed that the complex species Al(H2A) was formed but Al(H3A) was not in the pH 4–5. By using the acid dissociation constants of gallic acid and the formation constant of Al(III)-acetate complex the intrinsic formation constant of Al(H2A) was determined to be log KAl(H2A) = 8.61 ± 0.02 which was close to the value of pK2 (K2 = the proton dissociation constant of H3L), the protonation constant of the phenolate group of gallic acid.
We analyzed UV absorption, fluorescence and circular dichroism spectra of the title compounds, as well as their fluorescence lifetimes, in the presence of β-cyclodextrin (β-CDx) or γ-cyclodextrin (γ-CDx). The β-CDx cavity turned out to axially incorporate the naphthalene ring of the model 2-naphthylalanine derivative to exert its effect so as to significantly decrease the fluorescence quenching rate. This finding provides a strong piece of evidence for a “through space” mechanism by which the emission quenching occurs. On the other hand, the naphthalene ring of the 1-naphthylalanine derivative was suggested to be immersed into the γ-CDx cavity in both axial and equatorial modes resulting in a less significant decrease of the fluorescence quenching rate.
When each benzene solution of azoxybenzene, 2,2′-dimethylazoxybenzene, 4,4′-dimethylazoxybenzene, 2,2′-dichloroazoxybenzene and 4,4′-dichloroazoxybenzene was irradiated with UV light in the presence of acetic acid. The corresponding 2-hydroxyazobenzene was obtained in higher yield than in the absence of the acid. Rearrangement products 2-hydroxy-4-methylazobenzene(8) and 2-hydroxy-4′-methylazobenzene(9) were also obtained in higher yield under the UV irradiation of 4-methyl-ONN-azoxybenzene(7α) (α : β = 3.5 : 1.0) in the presence of acetic acid. Under the same reaction conditions, two rearrangement products 8 and 9 were also obtained from 4-methyl-NNO-azoxybenzene(7β) (α : β = 0.0 : 1.0). The β,α-isomerization from 7β to 7α did not take place at all in this reaction. This was different from the photochemical reaction of 7β (α : β = 0.0 : 1.0) in the presence of trichloroacetic acid. The product yields of 8 and 9 seem to be dependent on the concentration of acetic acid.
Weathered coal contains much humic acid and a little fulvic acid. Therefore, in this work, the production of fulvic acid, the most valuable humic substance because of its water-solubility, was examined by ozone and hydrogen peroxide oxidation of humic acid extracted form Xinjiang (China) weathered coal. The resulting products of the oxidation were water soluble fulvic acid and organic acids, mainly formic acid and oxalic acid. The product yield of fulvic acid was 20 [C%] and that of organic acids were 39 [C%] for formic and acid 13 [C%] for oxalic acid. The formed fulvic acid showed a higher content of oxygen and carboxyl groups, than those of the extracted one from the original weathered coal.
Basic characteristics of humic acid (HA) and fulvic acid (FA) extracted from three kinds of weathered coal of different coal-producting districts (China) by the standard method of International Humic Substances Society (IHSS), were compared with those of already known substances from peat moss (Canada), peat (China), andosol (Japan) and forest soil (Japan), and also an artificial humic acid. Their compositions and structures were measured by means of their FT-IR and CP/MAS 13C-NMR spectra. It was recognized that regenerated humic acid is formed extensively by the air oxidative degradation of coal under natural environment. The extracted HA from weathered coal has a higher content of aromatic carbon (aromaticity) and acidic functional group (mainly carboxyl group) than those from Canadian peat and forest soil. The content of carbohydrates C is somewhat lower for the HA and FA from weathered coal than for the peat and soil HA, FA. The content of methoxy carbon in the FA from weathered coal was somewhat lower than for the FA from peat and soil.
Starch acrylate was synthesized with waxy corn starch consisting of amylopectin, and application of starch was examined by cross-linking reaction of starch acrylate. In the preparation of highly substituted starch acrylate, it was better to conduct acryloylation of starch with acrylic anhydride in pyridine. Cross-linking reaction by polymerization of the highly substituted starch acrylate did not give desired polymer due to steric hindrance of the branched structure in waxy corn starch. However, copolymerization of the highly substituted starch acrylate with acrylic acid produced the desired copolymer. Because the cross-linking moiety in the copolymer was suggested to be composed of polyacrylic acid with low molecular weight, the copolymer may be useful as a law material for biodegradable polymer. On the other hand, such useful cross-linked material was not obtained by copolymerization of the low substituted starch acrylate with acrylic acid.
The polymerization of cyclic ethers initiated by the reaction of cyclic ethers with hexafluoropropylene oxide (HFPO) were examined. When tetrahydropyrane (THP) was used as a monomer, the polymer could not be obtained. When oxetane was used as a monomer, both yield and molecular weight of the obtained polymer were higher than those obtained in the polymerization using the other cyclic ethers as monomers. This is probably due to the highest homopolymerization reactivity of oxetane of the comonomers used. The polymer obtained in the polymerization of PO had the different structure from that of the other polymers. The steric bulkiness and occurring of both α- and β-ring cleavage of PO probably lead to specific structure of the resulting polymer.
The reactions of tantalum butoxide with several organic diols gave novel net-worked alternative tantalum-organic moieties hybrid copolymers particles whose forms and sizes varied with the organic units. Electron transfer from aromatic groups to tantalum atom in the net-worked structures was demonstrated by the results of ESR spectra and ab-initio calculations.
We examined the repetitive “KUROME” of raw urushi in a reaction vessel for the purpose of refining the polymerized urushi liquid that has a natural drying property in a low humidity environment. Namely, we evaluated the polymerization apparatus of the urushi liquid as a simple experiment. The raw urushi was polymerized by the repetitive “KUROME” process in a traditional method. We also examined the change in urushiol and the drying property in a low humidity environment (20–25 °C, 45–55%RH). Raw urushi undergoes enzymic oxidization by repetitive “KUROME” and decreases the urushiol monomer. Also, in this reaction, we developed a relation formula because there is a correlation in the area of the reaction vessel base, processing quantity and also processing time. Furthermore, with these changes, it was determined that the hydroxy value and anti-oxidization power decrease and the autoxidation of the side chain more easily occurs.
Klason lignin, α-cellulose and hemicellulose were isolated from Sugi (Cryptomerica japonica D. Don) sapwood. Thermogravimetric analysis (TG) and differential thermal analysis (DTA) of the sapwood and its components were examined. The initial temperature of thermal decomposition was 258 °C for the sapwood, 342 °C for the Klason lignin, 280 °C for the α-cellulose, and 153 °C for the hemicellulose, respectively. The results of analysis of pyroligneous vinegar liquors prepared from the Klason lignin, the α-cellulose and the hemicellulose indicate that methanol, pyrocatechol and guaiacols are derived from the lignin, cyclotene and maltol from the α-cellulose, furans from the α-cellulose and the hemicellulose, and acetic acid from the three components. The sapwood was carbonized at different temperature and holding time under nitrogen gas, to give carbonization products such as wood-vinegar, wood-tar, and charcoal. The amounts of the wood-vinegar and the wood-tar increased with an increase of the carbonization temperature and the holding time. The capillary gas chromatographic analysis of the wood-vinegars suggests that furans and maltol in the wood-vinegar were produced at 250 °C by the thermal decomposition of the cellulose and the hemicellulose, and pyrocatechol and guaiacols in the vicinity of 300 °C by that of the lignin.
We have incorporated Ag+ ions in the interlayer region of Mg/Al layered double hydroxide (Mg/Al-LDH) by means of a two-step procedure; thiosulfate was intercalated between layers of Mg/Al-LDH by coprecipitation thus producing a precursor LDH at first, then Ag+ ions were reacted with the precursor in an aqueous solution. FT-IR spectra of the Ag+-incorporated Mg/Al-LDH (Ag+-LDH) indicated that the interlayer metal cation was coordinated by two sulfur atoms of the interlayer thiosulfate thus forming a linear complex. In the DTA curve of the Ag+-LDH, several endo/exothermal peaks, which were observed in the curve of the precursor LDH, were also observed whereas some of these peaks were shifted from the locations in the latter DTA curve. The profile of the TG curves of the Ag+-LDH corresponded to the chemical formulae of the solids. In the powder X-Ray diffraction (PXRD) patterns of the precursor LDH and the Ag+-LDH, well developed (00l) lines are commonly observed, which indicates the stacking regularity of layers along the c-axis. The intensity of (002) relative to that of (001) increased apparently with the increase of the silver content in the LDH. Increment of the diffraction intensity could result from a new crystal lattice including Ag+ ions with the basal spacing as much as a half of the original one.
The six modified β-cyclodextrin (β-CD) derivatives, which have neighboring phenolic oxygens (GA, PA, NH-PA and 2,3-HBA), one phenolic oxygen (SA) and no phenolic oxygen (BA), were synthesized, and the catalytic activity of their transition metal ion complexes in the asymmetric oxidation of aromatic sulfides having phenyl, naphthyl, and phenanthryl rings was examined in the pH range of 1–7. The hydroxy groups attached at the 3, 4 and 5 positions of the phenyl ring in the polyphenol-appended β-CD derivatives were found effective for the asymmetric oxidation of methyl 1-naphthyl sulfide in the presence of Mo(V) ion at pH of 6 to form the corresponding (R)-sulfoxide preferentially in the optical yields of 20–55%. Conversely use of the β-CD derivatives with the phenolic hydroxy group at position of 2 resulted in the formation of (S)-sulfoxide in 19–35% ee. The optical yields also depend on the bridging group with which the 3,4-dihydroxybenzoyl group (PA) is bound to the primary C-6 position of β-CD, that is, the Mo(V) complex of β-CD-PA (ester bonding, optical yield 55%: the highest ee value obtained by the oxidation of methyl 1-naphthyl sulfide in a series of aromatic sulfides) shows higher stereoselectively than that of β-CD-NH-PA (amide bonding, 41% ee). No chiral induction is observed in the presence of β-CD-BA which has no phenolic hydroxy group. The complexes of β-CD-PA with Mo and W (4d- and 5d-blocks) metal ions accelerate the formation of (R)-sulfoxide with 36–55% ee, while those with 3d-block metal ions favor the (S)-sulfoxide production with 10–45% ee.
Isoprene prepolymer having hydroxy groups at their both ends were synthesized in about 75% yields by the solution polymerization of isoprene initiated by sodium naphthalene to living prepolymers, with subsequent treating with dry oxygen stream. Molecular weights of these prepolymers are 1300–1500 and numbers of hydroxy groups are 2.0–2.15 per one molecule. The polyaddition reaction of isoprene prepolymers having hydroxy groups and diisocyanates was also investigated. Besides of anisole, as the reaction medium, N,N-dimethyformamide and dimethyl sulfoxide can be used. The polymer thus obtained was yellow sponge rubber-like and insoluble in common organic solvents. The glass transition temperature of the polymer which synthesized by the methyl (S)-2,6-diisocyanatohexanoate was 73–78 °C.
We investigated the physicochemical characteristic and component of mucilages of Firmiana, utilizing for making Japanese paper etc. An acidic polysaccharide which coats young leaves and stems of mucilages of Firmiana was extracted with ion-exchange water and purified with methanol. The polysaccharide comprises D-galacturonic acid, D-galactose, L-arabinose and L-rhamnose. In addition, the viscosity decreased when mucilage was left for several days. The acid hydrolysis of mucilages of Firmiana afforded amino acids, L-glutamic acid, L-alanine, in addition to L-isoleucine, L-valine, L-lysine, L-tyrosine and glycine. These results suggested that Firmiana polysaccharide must have an extremely complicated structure, to which its unique physical properties are ascribed.
Catalytic NO2 removal by activated carbon loading Ag, Pt, Cu and CuO has been studied. In this experiment, activated carbon from coconut shells was used after washing with 1 mol dm−3 HCl and water. Activated carbon lording metals was prepared by adsorbing metal complexes (H2PtCl6, CuII-picolinate) or metal ion (Ag+), followed by heating the activated carbon at 700 °C in N2 atmosphere. Copper(II) oxide on activated carbon (CuO/AC) was prepared by heating the Cu/AC at 400 °C in air. Nitrogen dioxide was generated by decomposition of Pb(NO3)2 at 550 °C and circulated in a catalyst column packed with activated carbon (Fig. 1). Nitrogen dioxide was highly removed by Pt/AC, Cu/AC and CuO/AC in air or nitrogen atmosphere but less by Ag/AC (Fig. 3, 4). After the removal of NO2, very small amounts of HNO3, HNO2, NO and NH3 existed in the gas phase and the increase in N-contents on activeted carbon was small (Table 1). From the XRD patterns of activated carbon after removal of NO2, it was suggested that the oxidation state of Pt was not changed but the peak height decreased (Fig. 5). On the other hand, XRD patters of Cu/AC and CuO/AC indicated the presence of Cu, Cu2O and CuO in air and Cu and Cu2O in N2 atmosphere (Fig. 6, 7). These results indicate that activated carbon loading Pt or Cu is a good catalyst for removal of NO2 and NO2 may be reduced to N2 by catalysis of Pt, Cu or Cu2O.
Distribution characteristics of fractionated phosphorus content in the sediment mud of tidal river are researched and relationship between fractionated phosphorus content and current velocity, Fe content, Al content in sediment mud, pH of sediment mud is discussed in this paper. Samples were obtained using Ekman dredge from 9 different points. Fractionated phosphorus consisting of inorganic phosphorus (I-P; CDB-P, NaOH-P and HCl-P) and organic phosphorus (Org-P) were analyzed according to previous reports. I-P was analyzed by the method of Williams, T. Mayer, J. O. Nriagu. Total phosphorus (T-P) was analyzed by the method of sulfuric acid-nitric acid decomposition. Org-P is estimated as T-P-I-P. The pH, iron, aluminum and current velocity at each point were measured. Correlation of the data of current velocity with CDB-P, NaOH-P, HCl-P content in sediment mud shows that phosphorus contents of three species increased when the current velocity at the sampling point was slower than that of the upper sampling point. Therefore, relationship between fluctuations of current velocity and CDB-P, NaOH-P, HCl-P content in sediment mud was inspected by field experiment. CDB-P content increases as aluminum content and pH of sediment mud increase. In tidal river it is suggested that CDB-P content in the sediment mud is controlled by phosphorus which is adsorbed in the process of hydrolysis of aluminum(III). Relationship between aluminum content and CDB-P content has very high correlation. Batch experiment using sediment mud and river water at Isobe bridge proved the suggestion to be reasonable.
This report is the investigation results regarding the effect of Ce oxide (CeO2), Ce–Zr double oxide (Ce0.7Zr0.3O2), Ce–Pr double oxide (Ce0.9Pr0.1O2) and Pr oxide (Pr6O11) on the catalytic performances, structure and electronic state of Pt and Rh loaded on these oxides. Based on the TPR evaluation results, it was found that the oxygen absorption-desorption performance of Pt–Rh/Ce0.9Pr0.1O2 and Pt–Rh/Pr6O11 are superior to Pt–Rh/CeO2 and Pt–Rh/Ce0.7Zr0.3O2. Based on the XPS analysis results, it was found that the oxidation state of surface of Pt on Pt–Rh/Ce0.9Pr0.1O2 and Pt–Rh/Pr6O11 are higher than that on Pt–Rh/CeO2 and Pt–Rh/Ce0.7Zr0.3O2. Based on XAFS analysis results, it was found that Rh on Pt–Rh/Ce0.9Pr0.1O2 and Pt–Rh/Pr6O11 are close to metallic in compari