Chemically modified ribbon edge stimulated H2 dissociation: A first-principles computational study

First-principles computational studies indicate that (B, N, or O)-doped graphene ribbon edges can substantially reduce the energy barrier for H2 dissociative adsorption. The low barrier is competitive with many widely used metal or metal oxide catalysts. This suggests that suitably functionalized graphene architectures are promising metal-free alternatives for low-cost catalytic processes.

Electrochemical fabrication of metallic nanostructured electrodes for electroanalytical applications

The use of electrodeposited metal-based nanostructures for electroanalytical applications has recently received widespread attention. There are several approaches to creating nanostructured materials through electrochemical routes that include facile electrodeposition at either untreated or modified electrodes, or through the use of physical or chemical templating methods. This allows the shape, size and composition of the nanomaterial to be readily tuned for the application of interest. The use of such materials is particularly suited to electroanalytical applications. In this mini-review an overview of recently developed nanostructured materials developed through electrochemical routes is presented as well as their electroanalytical applications in areas of biological and environmental importance.

Plasmas meet plasmonics

The term ‘plasmon’ was first coined in 1956 to describe collective electronic oscillations in solids which were very similar to electronic oscillations/surface waves in a plasma discharge (effectively the same formulae can be used to describe the frequencies of these physical phenomena). Surface waves originating in a plasma were initially considered to be just a tool for basic research, until they were successfully used for the generation of large-area plasmas for nanoscale materials synthesis and processing. To demonstrate the synergies between ‘plasmons’ and ‘plasmas’, these large-area plasmas can be used to make plasmonic nanostructures which functionally enhance a range of emerging devices. The incorporation of plasma-fabricated metal-based nanostructures into plasmonic devices is the missing link needed to bridge not only surface waves from traditional plasma physics and surface plasmons from optics, but also, more topically, macroscopic gaseous and nanoscale metal plasmas. This article first presents a brief review of surface waves and surface plasmons, then describe how these areas of research may be linked through Plasma Nanoscience showing, by closely looking at the essential physics as well as current and future applications, how everything old, is new, once again.

Four decades of research in solid state chemistry

Solid state chemistry was in its infancy when the author got interested in the subject. In this article, the author outlines the manner in which the subject has grown over the last four decades, citing representative examples from his own contributions to the different facets of the subject. The various aspects covered include synthesis, structure, defects, phase transitions, transition metal oxides, catalysts, superconductors, metal clusters and fullerenes. In an effort to demonstrate the breadth and vitality of the subject, the author shares his own experiences and aspirations and gives expression to the agony and ecstacy in carrying out experimental research in such a frontier area in India.

Early osseointegration of a strontium containing glass ceramic in a rabbit model

The most important property of a bone cement or a bone substitute in load bearing orthopaedic implants is good integration with host bone with reduced bone resorption and increased bone regeneration at the implant interface. Long term implantation of metal-based joint replacements often results in corrosion and particle release, initiating chronic inflammation leading onto osteoporosis of host bone. An alternative solution is the coating of metal implants with hydroxyapatite (HA) or bioglass or the use of bulk bioglass or HA-based composites. In the above perspective, the present study reports the in vivo biocompatibility and bone healing of the strontium (Sr)-stabilized bulk glass ceramics with the nominal composition of 4.5SiO(2)-3Al(2)O(3)-1.5P(2)O(5)-3SrO-2SrF(2) during short term implantation of up to 12 weeks in rabbit animal model. The progression of healing and bone regeneration was qualitatively and quantitatively assessed using fluorescence microscopy, histological analysis and micro-computed tomography. The overall assessment of the present study establishes that the investigated glass ceramic is biocompatible in vivo with regards to local effects after short term implantation in rabbit animal model. Excellent healing was observed, which is comparable to that seen in response to a commercially available implant of HA-based bioglass alone. (C) 2013 Elsevier Ltd. All rights reserved.

Differentially Selective Chemosensor with Fluorescence Off-On Responses on Cu2+ and Zn2+ Ions in Aqueous Media and Applications in Pyrophosphate Sensing, Live Cell Imaging, and Cytotoxicity

A new benzoyl hydrazone based chemosensor R is synthesized by Schiff base condensation of 2,6-diformyl-4-methylphenol and phenyl carbohydrazide and acts as a highly selective fluorescence sensor for Cu2+ and Zn2+ ions in aqueous media. The reaction of R with CuCl2 or ZnCl2 forms the corresponding dimeric dicopper(II) Cu-2(R)(CH3O)-(NO3)](2)(CH3O)(2) (R-Cu2+) and dizinc(1) Zn-2(R)(2)](NO3)(2) (R-Zn2+) complexes, which are characterized, as R, by conventional techniques including single-crystal X-ray analysis. Electronic absorption and fluorescence titration studies of R with different metal cations in a CH3CN/0.02 M HEPES buffer medium (pH = 7.3) show a highly selective binding affinity only toward Cu(2+)and Zn2+ ions even in the presence of other commonly coexisting ions such as Ne+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cd2+, and Hg2+. Quantification of the fluorescence titration analysis shows that the chemosensor R can indicate the presence of Cu2+ and Zn2+ even at very low concentrations of 17.3 and 16.5 ppb, respectively. R-Zn2+ acts as a selective metal-based fluorescent sensor for inorganic pyrophosphate ion (PPi) even in the presence of other common anions such as F-, Cl-, Br-, I-, CH3COO-, CO32-, HCO3-, N-3(-), SO42-, PPi, AMP, ADP, and ATP in an aqueous medium. The propensity of R as a bioimaging fluorescent probe to detect Cu2+ and Zn2+ ions in human cervical HeLa cancer cell lines and their cytotoxicity against human cervical (HeLa), breast cancer (MCF7), and noncancer breast epithelial (MCF10a) cells have also been investigated. R-Cu2+ shows better cytotoxicity and sensitivity toward cancer cells over noncancer cells than R and R-Zn2+ under identical conditions, with the appearance of apoptotic bodies.

Ag2S sensitized mesoporous Bi2WO6 architectures with enhanced visible light photocatalytic activity and recycling properties

To harvest solar energy more efficiently, novel Ag2S/Bi2WO6 heterojunctions were synthesized by a hydrothermal route. This novel photocatalyst was synthesized by impregnating Ag2S into a Bi2WO6 semiconductor by a hydrothermal route without any surfactants or templates. The as prepared structures were characterized by multiple techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), UV-vis diffuse reflection spectroscopy (DRS) and photoluminescence (PL). The characterization results suggest mesoporous hierarchical spherical structures with a high surface area and improved photo response in the visible spectrum. Compared to bare Bi2WO6, Ag2S/Bi2WO6 exhibited much higher photocatalytic activity towards the degradation of dye Rhodamine B (RhB). Although silver based catalysts are easily eroded by photogenerated holes, the Ag2S/Bi2WO6 photocatalyst was found to be highly stable in the cyclic experiments. Based on the results of BET, Pl and DRS analysis, two possible reasons have been proposed for the enhanced visible light activity and stability of this novel photocatalyst: (1) broadening of the photoabsorption range and (2) efficient separation of photoinduced charge carriers which does not allow the photoexcited electrons to accumulate on the conduction band of Ag2S and hence prevents the photocorrosion.

Carbon-carbon bond forming reactions from bis(carbene)-platinum(II) complexes and olefin polymerization and oligomerization using group 4 post-metallocene complexes

A long-standing challenge in transition metal catalysis is selective C–C bond coupling of simple feedstocks, such as carbon monoxide, ethylene or propylene, to yield value-added products. This work describes efforts toward selective C–C bond formation using early- and late-transition metals, which may have important implications for the production of fuels and plastics, as well as many other commodity chemicals.

The industrial Fischer-Tropsch (F-T) process converts synthesis gas (syngas, a mixture of CO + H₂) into a complex mixture of hydrocarbons and oxygenates. Well-defined homogeneous catalysts for F-T may provide greater product selectivity for fuel-range liquid hydrocarbons compared to traditional heterogeneous catalysts. The first part of this work involved the preparation of late-transition metal complexes for use in syngas conversion. We investigated C–C bond forming reactions via carbene coupling using bis(carbene)platinum(II) compounds, which are models for putative metal–carbene intermediates in F-T chemistry. It was found that C–C bond formation could be induced by either (1) chemical reduction of or (2) exogenous phosphine coordination to the platinum(II) starting complexes. These two mild methods afforded different products, constitutional isomers, suggesting that at least two different mechanisms are possible for C–C bond formation from carbene intermediates. These results are encouraging for the development of a multicomponent homogeneous catalysis system for the generation of higher hydrocarbons.

A second avenue of research focused on the design and synthesis of post-metallocene catalysts for olefin polymerization. The polymerization chemistry of a new class of group 4 complexes supported by asymmetric anilide(pyridine)phenolate (NNO) pincer ligands was explored. Unlike typical early transition metal polymerization catalysts, NNO-ligated catalysts produce nearly regiorandom polypropylene, with as many as 30-40 mol % of insertions being 2,1-inserted (versus 1,2-inserted), compared to <1 mol % in most metallocene systems. A survey of model Ti polymerization catalysts suggests that catalyst modification pathways that could affect regioselectivity, such as C–H activation of the anilide ring, cleavage of the amine R-group, or monomer insertion into metal–ligand bonds are unlikely. A parallel investigation of a Ti–amido(pyridine)phenolate polymerization catalyst, which features a five- rather than a six-membered Ti–N chelate ring, but maintained a dianionic NNO motif, revealed that simply maintaining this motif was not enough to produce regioirregular polypropylene; in fact, these experiments seem to indicate that only an intact anilide(pyridine)phenolate ligated-complex will lead to regioirregular polypropylene. As yet, the underlying causes for the unique regioselectivity of anilide(pyridine)phenolate polymerization catalysts remains unknown. Further exploration of NNO-ligated polymerization catalysts could lead to the controlled synthesis of new types of polymer architectures.

Finally, we investigated the reactivity of a known Ti–phenoxy(imine) (Ti-FI) catalyst that has been shown to be very active for ethylene homotrimerization in an effort to upgrade simple feedstocks to liquid hydrocarbon fuels through co-oligomerization of heavy and light olefins. We demonstrated that the Ti-FI catalyst can homo-oligomerize 1-hexene to C₁₂ and C₁₈ alkenes through olefin dimerization and trimerization, respectively. Future work will include kinetic studies to determine monomer selectivity by investigating the relative rates of insertion of light olefins (e.g., ethylene) vs. higher α-olefins, as well as a more detailed mechanistic study of olefin trimerization. Our ultimate goal is to exploit this catalyst in a multi-catalyst system for conversion of simple alkenes into hydrocarbon fuels.

Criação de mesoporos em zeólitas ZSM-5, mordenita e ferrierita e análise de seu efeito na reação de hidroisomerização do n-heptano

As zeólitas têm recebido grande atenção acadêmica e industrial devido às suas características ácidas e estruturais. A estrutura da zeólita pode ser utilizada para conduzir uma reação catalítica na direção do produto desejado, evitando assim reações paralelas. Porém, essa mesma estrutura cria restrições difusivas com relação ao acesso aos sítios ativos no interior dos microporos. Neste trabalho foram estudados dois métodos de criação de mesoporos (térmico e básico) com o intuito de modificar a acessibilidade aos sítios catalíticos das zeólitas. A reação de hidroisomerização do n-heptano foi selecionada para avaliar as zeólitas após a criação de mesoporosidade. O tratamento térmico (via calcinação em temperaturas elevadas) foi utilizado para as zeólitas do tipo ZSM-5, Mordenita e Ferrierita, tendo sido observado um aumento pouco significativo na mesoporosidade. Este tratamento promoveu, porém, uma significativa desaluminização das amostras, acompanhada da formação de quantidades importantes de espécies de Al extra-rede (ALER), o que se refletiu num bloqueio parcial dos mesoporos gerados e dos microporos preexistentes, e na redução na densidade de sítios ácidos das amostras. A ampliação da escala do tratamento térmico (aumento da quantidade tratada de 2 g para 30 g) não se mostrou reprodutível, gerando menos mesoporos do que o observado no preparo em pequena escala. O tratamento básico (via dessilicação por meio de NaOH), ao contrário do anterior, promoveu a formação de mesoporos gerando menos quantidade de ALER e se mostrou mais reprodutível quando da ampliação da escala. O desempenho dos catalisadores Pt/Al2O3+zeólita na reação de hidroisomerização do n-heptano foi influenciado pela densidade de sítios ácidos fortes e pela estrutura porosa da zeólita. Com relação ao efeito dos tratamentos térmico e básico sobre o desempenho dos catalisadores à base de ZSM-5, os resultados mostraram que o comportamento do catalisador submetido ao tratamento básico (Pt/Al2O3+BZSM-5/85-2) foi similar ao do tratado termicamente (Pt/Al2O3+TZSM-5/1000-2) com relação à distribuição de produtos na reação de hidroisomerização do n-heptano, particularmente com relação aos produtos leves e aos isômeros monorramificados. No entanto, a presença mais significativa de mesoporos na zeólita após tratamento básico (BZSM-5/85-2), se refletiu num leve favorecimento à formação dos isômeros birramificados

Avaliação de catalisadores à base de estanho visando à produção de biodiesel

Atualmente, existe um crescente interesse por fontes de energia renováveis e o desenvolvimento de novas tecnologias para a produção de biocombustíveis. O biodiesel é uma fonte alternativa de combustível bastante atrativa em relação ao diesel em decorrência de seus benefícios ambientais. A obtenção de biodiesel é geralmente realizada através de reações de transesterificação de óleos vegetais com álcool de cadeia curta. Entretanto, também se pode produzi-lo através da esterificação de ácidos graxos livres utilizando-se matérias-primas de baixa qualidade como rejeitos industriais, domésticos ou gorduras animais. O estudo de catalisadores que melhorem os resultados destas reações tem importante papel no desenvolvimento da produção de biodiesel. Normalmente, utilizam-se catalisadores básicos como o NaOH, nas reações de transesterificação. No entanto, o uso destes catalisadores causa impactos ambientais, além de promover a reação de saponificação quando a matéria-prima apresenta teores significativos de acidez, reduzindo o rendimento e dificultando a separação de fases. Este trabalho apresenta o estudo de catalisadores ácidos, à base de estanho, com ênfase especial no sulfato de estanho II, voltados para utilização na reação de esterificação de cargas contendo elevados teores em ácidos graxos. Avaliou-se a influência das variáveis: temperatura, concentração do catalisador, tipo de sistema reacional, quantidade de etanol, tipo de álcool, acidez, natureza dos ácidos graxos e temperatura de calcinação. Uma comparação entre os catalisadores, a questão da reutilização do catalisador e das mudanças proporcionadas pelo tratamento térmico ao qual foram submetidos também foram analisadas. Dentre os catalisadores estudados, os de sulfato de estanho mostraram maior atividade catalítica frente à reação estudada, os mais promissores sendo os calcinados até a temperatura de 500C. O principal motivo para os altos rendimentos encontrados foi associado ao comportamento pseudo-homogêneo do SnSO4, que se solubiliza, acidificando o meio reacional durante as reações de esterificação

Degradation evaluation of microelectromechanical thermal actuators

Metal based thermal microactuators normally have lower operation temperatures than those of Si-based ones; hence they have great potential for applications. However, metal-based thermal actuators easily suffer from degradation such as plastic deformation. In this study, planar thermal actuators were made by a single mask process using electroplated nickel as the active material, and their thermal degradation has been studied. Electrical tests show that the Ni-based thermal actuators deliver a maximum displacement of ∼20μm at an average temperature of ∼420°C, much lower than that of Si-based microactuators. However, the displacement strongly depends on the frequency and peak voltage of the pulse applied. Back bending was clearly observed at a maximum temperature as low as 240°C. Both forward and backward displacements increase with increasing the temperature up to ∼450°C, and then decreases with power. Scanning electron microscopy observation clearly showed that Ni structure deforms and reflows at power above 50mW. The compressive stress is believed to be responsible for Ni piling-up (creep), while the tensile stress upon removing the pulse current is responsible for necking at the hottest section of the device. Energy dispersive X-ray diffraction analysis revealed severe oxidation of the Ni-structure induced by Joule-heating of the current.

Bio-syngas production from biomass catalytic gasification

A promising application for biomass is liquid fuel synthesis, such as methanol or dimethyl ether (DME). Previous studies have studied syngas production from biomass-derived char, oil and gas. This study intends to explore the technology of syngas production from direct biomass gasification, which may be more economically viable. The ratio of H-2/CO is an important factor that affects the performance of this process. In this study, the characteristics of biomass gasification gas, such as H-2/CO and tar yield, as well as its potential for liquid fuel synthesis is explored. A fluidized bed gasifier and a downstream fixed bed are employed as the reactors. Two kinds of catalysts: dolomite and nickel based catalyst are applied, and they are used in the fluidized bed and fixed bed, respectively. The gasifying agent used is an air-steam mixture. The main variables studied are temperature and weight hourly space velocity in the fixed bed reactor. Over the ranges of operating conditions examined, the maximum H-2 content reaches 52.47 vol%, while the ratio of H-2/CO varies between 1.87 and 4.45. The results indicate that an appropriate temperature (750 degrees C for the current study) and more catalyst are favorable for getting a higher H-2/CO ratio. Using a simple first order kinetic model for the overall tar removal reaction, the apparent activation energies and pre-exponential factors are obtained for nickel based catalysts. The results indicate that biomass gasification gas has great potential for liquid fuel synthesis after further processing.

银基催化剂催化氧化反应的研究

银催化剂是工业上较为重要的催化剂，它不仅大量地使用在乙烯环氧化，甲醇脱氢反应中，还在异丙醇氧化脱氢制丙酮，乙醇脱氢制乙醛，乙二醇氧化制乙二醛，烷基胺氧化制睛类化合物等工业过程中广为应用。由于银催化剂具有如此重要的工业应用价值，所以银催化剂一百多年来一直是催化领域的研究重点。银催化剂的特异催化行为得益于银元素较为特殊的电子结构以及氧物种在银催化上的独特催化行为。银催化剂表面既存在导致非选择氧化反应的氧物种（a氧），也存在导致选择氧化反应的氧物种（Y氧），这两种氧物种在催化剂上的状态与反应气氛及催化剂结构密切相关。一氧化碳氧化反应在环境保护、能源利用（燃料电池）、安全防护（火场、煤矿）有较为重要的用途；甲酸甲醋是近年新兴的较为重要的碳一化学中间体，它可以广泛应用于有机合成反应中，也可以作为安全的合成气载体；醇类选择氧化制备相应的醛酮化合物也是有机合成工业的重要反应之一；甲苯气相氧化制备苯甲醛是研究烃类选择氧化较为重要的模型反应，在工业上存在潜在的应用价值。本论文以上述的四个反应为探针反应研究了银基催化剂的催化行为，得到以下的结果：1．以烷基胺为模板剂制备了过渡金属离子掺杂的介孔分子筛，通过模板剂－离子交换技术制备了含银基复合氧化物的介孔分子筛催化剂。该系列催化剂对一氧化碳氧化反应有较好的活性。同时研究了金属盐的种类及掺杂量对介孔分子筛结构的影响，发现金属离子的掺杂会破坏介孔分子筛的结构的有序性，随着掺杂量的增大，介孔分子筛的结构的有序性变差；金属盐的阴离子对介孔分子筛的结构的有序性亦有影响。2．较为系统研究了银基催化剂上由甲醇制备甲酸甲酷的催化行为，发现银基催化剂是一个选择性较高的催化体系。分立测试了不同的氧物种对甲醇反应的影响，提出了a氧与Y氧协同作用的机理，为解决甲醇脱氢反应机理争端提供了有价值的信息。3．系统研究了低级醇在金属银催化剂的脱氢反应，分立测试了不同的氧物种对甲醇、乙醇反应的影响，发现低于550K时不同的氧物种对乙醇的反应性能有显著的差异，认为低温（＜550K）条件下，醇类在金属银催化剂上发生的是氧化脱氢历程。通过借鉴均相醇类氧化脱氢反应研究所取得的成果，试图从本质上解释银是醇类气相氧化脱氢最好的催化剂的原因，即在过渡金属中，金属银上的氧物种的碱性是最强的，氧的再生能力也是很强的。4．在甲苯的选择氧化研究中发现在高温（600℃）、纯氧、甲醇参与的条件下，Pt一Ag催化剂对苯甲醛的收率最好（-6％），提出了分子氧参与生成含氧自由基中间产物、醇类淬灭自由基态中间产物的反应历程，与传统甲苯氧化所经历的Mars-Krevelen机理有差别，为烃类的选择氧化提供了新的信息。

Ce-基催化剂上CH_4低温催化燃烧的研究

Ce-基催化剂在汽车尾气净化，工业废气处理，烃类重整，烃类选择加氢等方面均有广泛的应用。近几十年来关于如何制备高活性、高稳定性的非贵金属复合氧化物催化剂一直是催化研究的重要课题之一。Ce-基催化剂主要都是通过其它金属氧化物M掺杂到CeO_2中形成Ce_(1-x)M_xO（M为掺杂物）固溶体。本文选用CeO_2作为主要研究对象，用柠檬酸法有目的的引入化学特性、离子半径不同的另一组分，用x值表示各元素间的化学计量比，优化催化剂的组成、结构，来调节所合成固溶体氧化物的物理化学性质。分别以碱土金属Ca、稀土金属La以及过渡金属Ni和Mn为掺杂物制备出含其它不同离子的Ce-基催化剂；将具有较高活性的Ni_(0.7)Ce_(0.3)O负载在ZrO_2上，以CH_4燃烧为模型反应，考察催化剂活性和氧化还原性的关系。1．Ce-Ca-La-O体系单独Ca或La分别加入到CeO_2中后催化剂的活性比单独的CeO_2的活性要高出很多，完全转化温度要下降近100℃，而且它们的H_2-TPR实验也证实了其氧化还原能力有很大的提高。将Ca和La同时引入到CeO_2的复合氧化物Ce-La-Ca-O材料，其活性比无La的Ce-Ca-O的活性没有明显的提高，而且反而要比Ce-La-O的活性低，且其HZ一TPR实验也显示出和复合氧化物Ce-Ca-O的轮廓一样。2．Ce-Ni-Mn-O体系对NiO、MnO_x、CeO_2三种金属氧化物，在优化两种金属氧化物最佳配比（组成）后，在复合氧化物中掺杂第三种金属氧化物以考察第三种金属对其甲烷燃烧活性的影响。（l）CeO_2-MnO_x体系中，在Ce_(0.8)Mn_(0.2)O掺杂NiO后，发现当Ni的摩尔量为-10％时，活性提高幅度的很大，完全燃烧的温度下降了近50℃，可在550℃将CH_4完全氧化到CO_2。（2）CeO_2-NiO体系中，Ce_(0.3)Ni_(0.7)O可在530℃将CH_4完全氧化到CO_2。向其中掺杂Mn后，复合氧化物的活性反而下降，要在550oC才能将CH4完全氧化到C02。这可能是阴离子缺陷减少所致。（3）NIO一Mnox体系中，Nio，IMn090掺杂Ce后，催化活性有大幅度提高，特别是Nio．ICeyMno90（0．3三y生0．8）中催化剂的活性更高，可在530oC体系中，其中y＝0．5时更突出。3．Ni-Ce-O／ZrOZ体系（1）Ni1-x一Cex一O体系中，独立的CeOZ相促进了NIO的还原和表面积增加。（2）少量的CeOZ的掺杂明显改善了NIO对cH4完全氧化反应的活性。继续增加Ce的量催化活性弱有增加，然后下降。在Ce的掺杂量为30％时，即Nio7Ceo3O，催化活性最佳，此时甲烷完全转化的温度为530oC。（3）催化剂Ni07Ceo3O具有很好的稳定性，900oC下焙烧，还能在540oC将CH4完全氧化到COZ。（4）催化剂Pd／Ni07Ceo30的催化活性与Pd／A12O3的活性相当。（5）催化剂Ni07Ce03O负载在不同的载体上，发现ZrOZ作载体效果最佳，其次为5102，这可能是ZrOZ、5102对NIO、CeOZ相对惰性有关；而MgO、A1203虽表面积较大，但作为载体效果却不好，可能其易与NIO、CeOZ发生反应有关。（6）Nio7Ceo3O负载在ZrOZ上，提高了表面积同时促进了Nio7Ceo3O还原性，以负载量为50％时活性最好。结构分析发现有两个新相生成，Ni4Zro和CeZO3。（7）通过对比发现Nio7Ceo3O（50％）／ZrOZ体系高活性除了ZrOZ作为载体提高表面积外，Zr02和Ce在这里还起到助催化剂的作用。4．还探讨了Pr掺杂到CeO2，以及YSZ作为载体负载过渡金属氧化物在甲烷催化燃烧反应种的作用。