查找使用阿拉丁产品的科研文献

Support interaction of Pt/CeO2 and Pt/SiC catalysts prepared by nano platinum colloid deposition for CO oxidation

Kang Xi,Yong Wang,Kang Jiang,Jing Xie,Ying Zhou,Hanfeng Lu

The interaction between Pt and its various supports can regulate the intrinsic electronic structure of Pt particles and their catalytic performance. Herein, Pt/CeO 2 and Pt/SiC catalysts were successfully prepared via a facile Pt colloidal particle deposition method, and their catalytic performance in CO oxidation was investigated. XRD , TEM, XPS and H 2 -TPR were used to identify the states of Pt particles on the support surface, as well as their effect on the performance of the catalysts. Formation of the Pt–O–Ce interaction is one of the factors controlling catalyst activity. Under the oxidative treatment at low temperature, the Pt–O–Ce interaction plays an important role in improving the catalytic activity. After calcining at high temperature, enhanced Pt–O–Ce interaction results in the absence of metallic Pt 0 on the support surface, as evidenced by the appearance of Pt 2+ species. It is consistent with the XPS data of Pt/CeO 2 , and is the main reason behind the deactivation of the catalyst. By contrast, either no interaction is formed between Pt and SiC or Pt nanoparticles remain in the metallic Pt 0 state on the SiC surface even after aging at 800 °C in an oxidizing atmosphere. Thus, the Pt/SiC shows better thermal stability than Pt/CeO 2 . The interaction between Pt and the active support may be concluded to be essential for CO oxidation at low temperature, but strong interactions may induce serious deactivation of catalytic activity.

A basic comprehensive study on synergetic effects among the metal oxides in CeO2-WO3/TiO2 NH3-SCR catalyst

Xuesong Liu,Peng Jiang,Yong Chen,Yaoguang Wang,Qiaoling Ding,Zhiming Sui,Hongfeng Chen,Zhongyun Shen,Xiaodong Wu

Two Ce-W-Ti mixed oxide catalysts were prepared by wet impregnation (CeW/Ti-I) and mechanical mixing (Ce/W/Ti-M) methods. CeW/Ti-I catalyst exhibits over 80% NO x conversion and nearly 100% N 2 selectivity at 200–550 °C. The superior catalytic performance is associated with the high dispersion of active CeO 2 and acidic WO 3 on TiO 2 and the synergistic effects among different components. The X-ray Diffraction, Raman spectroscopy, Nitrogen physisorption, X-ray photoelectron spectroscopy, H 2 temperature-programmed reduction, temperature-programmed desorption of ammonia and infrared spectroscopy were performed. It is found that the formation of solid solutions, as well as the high specific surface area, would increase the amounts of Ce 3+ , oxygen vacancies and acid sites in the catalyst. These broaden the operating temperature window of NH 3 -SCR reaction and enhance the N 2 selectivity by facilitating “fast SCR” reaction at low temperatures and inhibiting the unselective oxidation of NH 3 at high temperatures.

Label-Free Electrochemiluminescent Immunosensor for Detection of Carcinoembryonic Antigen Based on Nanocomposites of GO/MWCNTs-COOH/Au@CeO2

Xuehui Pang,Jianxiu Li,Yongbei Zhao,Dan Wu,Yong Zhang,Bin Du,Hongmin Ma,Qin Wei

A high-sensitivity electrochemiluminescence (ECL) sensor was conducted to detect carcinoembryonic antigen (CEA). Nanocomposites of graphene oxide/carboxylated multiwall carbon nanotubes/gold/cerium oxide nanoparticles (GO/MWCNTs-COOH/Au@CeO2) were used as antibody carriers and sensing platforms to modify on glassy carbon electrodes (GCE). CeO2 nanoparticles were first exploited as an ECL luminescent material and the possible ECL mechanism was proposed in this work. GO/MWCNTs-COOH was used as a loading matrix for CeO2 nanoparticles because of the superior conductivity and large specific surface area. Au nanoparticles were further deposited on this matrix to attach anti-CEA and enhance the sensitivity of immunosensor. The proposed sensing platform showed excellent cathodic ECL performance and sensitive response to CEA. The effects of experimental conditions on the ECL performance were investigated. The proposed immunosensor showed the broad linear range (0.05–100 ng/mL) and the low detection limit (LOD, 0.02 ng/mL, signal-to-noise ratio = 3) according to the selected experimental conditions. The excellent analysis performance for determination of CEA in the human serum samples simplied this immunosensor displayed high sensitivity and excellent repeatability. More importantly, this conducted immunosensor broadens the use scope of CeO2 nanoparticles.

High-Performance Thin-Film Transistors and Inverters Based on ALD-Derived Ultrathin Al2O3-Passivated CeO2 Bilayer Gate Dielectrics

Leini Wang,Gang He,Wenhao Wang,Xiaofen Xu,Bo He,Xiaoyu Wu,Yongchun Zhang

Enhancement of Methanol Oxidation Performance Over Pd/CeO2 Derived from MOF and Mechanism Investigation via In Situ Studies

Yue Yihang,Li Yong,Wang Tingting,Wang Shifeng,Han Lin,Du Chun

A Pd/CeO 2 -M with high methanol oxidation performance was prepared from metal–organic framework (MOF). The reaction results indicate that the Pd/CeO 2 -M could achieve 100% methanol oxidation at 200 °C over the traditional Pd/CeO 2 -C at 350 °C. The high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Raman show that the Pd was uniformly distributed over the CeO 2 that was rich in oxygen vacancies. The methanol temperature program surface reaction (MeOH-TPSR) demonstrates that the Pd/CeO 2 -M could effectively decompose methanol at a lower temperature with the assistance of oxygen vacancies compared with Pd/CeO 2 -C. Methanol oxidation was conducted with in-situ Raman, CO diffuse reflectance infrared Fourier transformed spectroscopy (CO-DRIFTS) and in-situ DRIFTS to elucidate the reaction mechanism and establish the structure–activity relationship. The oxygen vacancies have participated in the assistance of methanol oxidation, which was revealed via in-situ Raman. The CO-DRIFTS indicates that the chemisorbed CO was more in linear form, which demonstrates that the Pd particles were over CeO 2 -M with a smaller size. The in-situ DRIFTS experiments show the methanol could be further effectively oxidized to bidentate formate over Pd/CeO 2 -M with the assistance of oxygen vacancies. The Pd/CeO 2 -M catalysis and its enhancement mechanism studies provided a potential strategy in the VOC removal catalysis development. Graphical Abstract

CeO2-Promoted PtSn/SiO2 as a High-Performance Catalyst for the Oxidative Dehydrogenation of Propane with Carbon Dioxide

Li Wang,Guo-Qing Yang,Xing Ren,Zhong-Wen Liu

The oxidative dehydrogenation of propane with CO2(CO2-ODP) has been extensively investigated as a promising green technology for the efficient production of propylene, but the lack of a high-performance catalyst is still one of the main challenges for its industrial application. In this work, an efficient catalyst for CO2-ODP was developed by adding CeO2to PtSn/SiO2as a promoter via the simple impregnation method. Reaction results indicate that the addition of CeO2significantly improved the catalytic activity and propylene selectivity of the PtSn/SiO2catalyst, and the highest space-time yield of 1.75 g(C3H6)·g(catalyst)−1·h−1was achieved over PtSn/SiO2with a Ce loading of 6 wt%. The correlation of the reaction results with the characterization data reveals that the introduction of CeO2into PtSn/SiO2not only improved the Pt dispersion but also regulated the interaction between Pt and Sn species. Thus, the essential reason for the promotional effect of CeO2on CO2-ODP performance was rationally ascribed to the enhanced adsorption of propane and CO2originating from the rich oxygen defects of CeO2. These important understandings are applicable in further screening of promoters for the development of a high-performance Pt-based catalyst for CO2-ODP.Keywords:oxidative dehydrogenation;propane;carbon dioxide;supported PtSn catalyst;ceria

Tea polyphenols mediated biogenic synthesis of chitosan-coated cerium oxide (CS/CeO2) nanocomposites and their potent antimicrobial capabilities

Appu Manikandan,Wu Huixiang,Chen Hao,Huang Jianying

In the present study, we hypothesized that novel nanocomposites of chitosan-coated cerium oxide (CS/CeO 2 NCs) derived from aqueous extracts of tea polyphenols would be stabilized and reduced by using green chemistry. The UV–visible spectrum of the synthesized material revealed an SPR peak at 279 nm, and the morphological characteristics of nanoparticles (NPs) as a uniformly distributed spherical shape with a size range of 20 nm were confirmed by field emission scanning electron microscopy (FESEM). The Fourier transform infrared spectroscopy (FTIR) spectrum illustrated the amino groups of chitosan-coated with CeO 2 NPs on the surface. While, the hydrodynamic size (376 nm) and surface charge (+ 25.0 mV) of particles were assessed by dynamic light scattering (DLS), and the existence of oxidation state elements Ce 3d, O 1 s, and C 1 s was identified by employing X-ray photoelectron spectroscopy (XPS). A cubic fluorite polycrystalline structure with a crystallite size of (5.24 nm) NPs was determined using an X-ray Diffractometer (XRD). The developed CS/CeO 2 NCs demonstrated excellent antibacterial and antifungal efficacy against foodborne pathogens such as Escherichia coli , Staphylococcus aureus , and Botrytis cinerea with zone of inhibition of 13.5 ± 0.2 and 11.7 ± 0.2 mm, respectively. The results elucidated the potential of biosynthesized CS/CeO 2 NCs could be utilized as potent antimicrobial agents in the food and agriculture industries.

Fe-decorated on Sm-doped CeO2 as cathodes for high-temperature CO2 electrolysis in solid oxide electrolysis cells

Yingjie Zhou,Feifan Wei,Haihua Wu

Electrocatalytic CO 2 reduction in solid oxide electrolysis cells (SOECs) can simultaneously convert CO 2 to valuable chemicals or fuels by integrating with renewable energy so as to alleviate the greenhouse effects and energy crisis. Cerium oxide (CeO 2 ) with high redox stability and catalytic activity toward CO 2 reduction is considered a promising SOEC cathode. However, CeO 2 is rarely directly employed as cathodes due to its unsatisfactory electrical properties. Suitable modification of CeO 2 becomes essential to improve its electrocatalytic activity . Herein, Fe-decorated on Sm-doped CeO 2 via a simple mechanical milling process was employed as cathodes for high-temperature CO 2 electrolysis in SOEC. The addition of Fe species on Sm-doped CeO 2 can greatly enhance the CO 2 electrolysis efficiency, mainly attributing to the increased catalytic active sites, electronic pairs, and oxygen vacancy concentrations, which facilitated the CO 2 adsorption and dissociation as well as the electron-ion transportation. The 1.0 wt.% Fe-decoreated on Sm-doped CeO 2 showed the highest current density of 0.57 A cm −2 at 1.9 V under 800 °C. Moreover, the co-existence of doped and surface coated Fe species on Sm-doped CeO 2 with moderate oxygen vacancies and adequate electronic transportation paths facilitate the high-temperature CO 2 electrolysis.

Synthesis of novel Fe0-Fe3O4/CeO2/C composite cathode for efficient heterogeneous electro-Fenton degradation of ceftriaxone sodium

Jie Chen,Jiafeng Wan,Chi Li,Yuhan Wei,Haolin Shi

Fe 0 -Fe 3 O 4 nanoparticles and cerium dioxide hollow spheres as efficient heterogeneous electro-Fenton reagents were rationally designed to be embedded in porous carbon derived from skimmed cotton for the electrocatalytic degradation of ceftriaxone sodium. Skimmed cotton porous carbon material has a hollow tubular structure, and cerium dioxide is dispersed on the surface of the carbon material in a hollow sphere structure of uniform size. Fe 0 -Fe 3 O 4 nanoparticles were wrapped in irregular particle shapes on the surface of cerium dioxide hollow spheres, and the remaining part was laid flat on the surface of porous carbon material. The as-synthesized Fe 0 -Fe 3 O 4 /CeO 2 /C showed excellent degradation efficiency of 95.59 % for ceftriaxone sodium within 120 mins and obtained a COD removal rate of 95.21 % at 240 mins. The zero-valent iron as a reducing agent effectively accelerated the Fe 3+ /Fe 2+ cycle, allowing the composites to exhibit higher catalytic activity and further reducing the possibility of secondary contamination. Moreover, the existence of cerium dioxide further promoted the redox cycle of Ce 4+ /Ce 3+ and accelerated the electron transfer in the interface of the catalyst. The synergistic effect of iron and cerium greatly facilitated the production of hydroxyl radicals and increased the yield of hydroxyl radicals in the reaction system.

Oxygen vacancy enhancing the Co3O4-CeO2 nanosheets as the cathode to activate peroxymonosulfate for degradation of ceftiofur sodium

Guangtao Wang,Yue Hou,Sha Yu,Yuan Dang,Xiaoqin Sun

Herein, the bimetallic oxides Co 3 O 4 -CeO 2 with abundant oxygen vacancy (V O ) were successfully prepared and applied to activate peroxymonosulfate (PMS) for degradation of ceftiofur sodium (CEF). By optimizing the molar ratio of Co and Ce, nanosheet structures were obtained, which had large surface area and rich oxygen vacancies. The degradation efficiency of CEF can reach 94.3 % and the corresponding TOC removal is as high as 50.3 % after 40 min under the optimum conditions with 10 mA −1 cm −2 current density, pH 3, 5 mM PMS and 25 ℃. 1 O 2 is the main reactive species and its formation is related with V O in the process of degradation CEF. In details, the abundant V O on the catalyst surface can not only accelerate electron transfer to promote the conversion of PMS → ·SO 5 -·  →  1 O 2 but also act as electron transport channels to facilitate Co 3+ /Co 2+ redox cycle. This study is of far-reaching significance for oxygen vacancy-activated PMS to promote the efficient degradation of refractory organic pollutants.

Construction of spindle structured CeO2 modified with rod-like attapulgite as a high-performance photocatalyst for CO2 reduction

Jia Zheng,Zhi Zhu,Ge Gao,Zhi Liu,Qiu Wang,Yongsheng Yan

In this study, a spindle structured CeO2 photocatalyst modified with rod-like attapulgite (CeO2/ATP) was successfully prepared by simple high temperature calcination. ATP was deposited in the precursor solution of CeO2 and then heating up the mixture afforded the CeO2/ATP photocatalyst. The photocatalyst showed remarkable reduction efficiency for CO2. CO (309.44 μmol g−1 h−1) and CH4 (184.33 μmol g−1 h−1) are the major products for CO2 reduction obtained by using the optimum proportion of the CeO2/ATP photocatalyst; the yield of CO and CH4 was about 3 and 3.6 times higher than that of CeO2, respectively. The improvement in the CO2 reduction efficiency originated from the higher conductivity of ATP, which promoted electron transport and enhanced the separation efficiency of the electron holes. At the same time, the introduction of ATP inhibited the accumulation of CeO2 and also increased the active sites for CO2 reduction. Moreover, a possible photocatalytic mechanism for the CO2 reduction reaction was proposed based on the experimental results. In addition, this study provides new insights for the simple preparation of other photocatalysts with high performance for CO2 reduction.

Low–thermal–conductivity and high–toughness CeO2–Gd2O3 co–stabilized zirconia ceramic for potential thermal barrier coating applications

Kuo Jiang,Songbai Liu,Xin Wang

Yttria partially stabilized zirconia (∼4.0 mol% Y 2 O 3 –ZrO 2 , 4YSZ) has been widely employed as thermal barrier coatings (TBCs) to protect the high–temperature components of gas–turbine engines. The phase stability problem existing in the conventional 4YSZ has limited it to application below 1200 °C. Here we report an excellent zirconia system co–doped with 16 mol% CeO 2 and 4 mol% Gd 2 O 3 (16Ce–4Gd) presenting nontransformable feature up to 1500 °C, in which no detrimental monoclinic (m) ZrO 2 phase formed on partitioning. It also exhibits a high fracture toughness of ∼46 J m −2 and shows high sintering resistance. Besides, the thermal conductivity and thermal expansion coefficient of 16Ce–4Gd are more competent for TBCs applications as compared to the 4YSZ. The combination of properties suggests that the 16Ce–4Gd system could be of potential use as a thermal barrier coating at 1500 °C.