Molecular Catalysis
·
2022
·
IF 5.089
Zhengjie Li,Chen Ma,Miao Qi,Yunlong Li,Yanchao Qu,Ying Zhang,Lilong Zhou,Jimmy Yun
Nano CeO 2 (CeMOF) maintaining the primary micromorphology and pore structure of MOFs was successfully synthesized by controlled pyrolysis of UiO-66(Ce) in air. CeMOFs showed excellent activity for catalytic combustion of VOCs, including toluene, benzene and xylene. The results showed that the T 10% , T 50% and T 90% of toluene over CeMOF were 185, 198 and 206 ℃ (GHSV = 22500 h −1 , toluene concentration = 1000 ppm), respectively, which are the lowest among ever reported ceria catalysts. According to various characterization results, the high catalytic activity of CeMOF can be ascribed to its neat pore structure and high percentage of Ce with low chemical valence. The latter leads to massive surface oxygen species and oxygen vacancies which provides abundant oxidative sites for VOCs. The low-temperature reducibility and multiple weakly acidic sites also enhanced the catalytic activity. In addition, CeMOF shows good ability to resist H 2 O and thermal stability. The in-situ DRIFTs study of CeMOF shows toluene is degraded by continuous stages through quick conversion of toluene to benzaldehyde and adsorbed benzoate, and forms CO 2 and H 2 O at last.
研究领域:
材料科学
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环境科学
✓ 已验证
DOI
高影响因子
MOLECULES
·
2023
·Vol. 28
·期 16
·6005
·
IF 4.6
Yaohui Xu,Liangjuan Gao,Quanhui Hou,Pingkeng Wu,Yunxuan Zhou,Zhao Ding
CeO2is an important rare earth (RE) oxide and has served as a typical oxygen storage material in practical applications. In the present study, the oxygen storage capacity (OSC) of CeO2was enhanced by doping with other rare earth ions (RE, RE = Yb, Y, Sm and La). A series of Undoped and RE–doped CeO2with different doping levels were synthesized using a solvothermal method following a subsequent calcination process, in which just Ce(NO3)3∙6H2O, RE(NO3)3∙nH2O, ethylene glycol and water were used as raw materials. Surprisingly, the Undoped CeO2was proved to be a porous material with a multilayered special morphology without any additional templates in this work. The lattice parameters of CeO2were refined by the least–squares method with highly pure NaCl as the internal standard for peak position calibrations, and the solubility limits of RE ions into CeO2were determined; the amounts of reducible–reoxidizable Cen+ions were estimated by fitting the Ce 3d core–levels XPS spectra; the non–stoichiometric oxygen vacancy (VO) defects of CeO2were analyzed qualitatively and quantitatively by O 1s XPS fitting and Raman scattering; and the OSC was quantified by the amount of H2consumption per gram of CeO2based on hydrogen temperature programmed reduction (H2–TPR) measurements. The maximum [OSC] of CeO2appeared at 5 mol.% Yb–, 4 mol.% Y–, 4 mol.% Sm– and 7 mol.% La–doping with the values of 0.444, 0.387, 0.352 and 0.380 mmol H2/g by an increase of 93.04, 68.26, 53.04 and 65.22%. Moreover, the dominant factor for promoting the OSC of RE–doped CeO2was analyzed.Keywords:CeO2;porous;rare earth;doping;oxygen storage capacity;solvothermal
研究领域:
材料科学
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化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2022
·Vol. 2022
·期 20
·e202200202
·
IF 2.551
Zicong Tan,Ying Wang,Jie Zhang,Zhang Zhang,Samantha Sze Man Wong,Shiqing Zhang,Hongyan Sun,Ken Kin Lam Yung,Yung-Kang Peng
Graphical CeO 2 nanosphere enclosed by (100) and (111) surfaces has been reported to mimic phosphatase and peroxidase by catalyzing substrate dephosphorylation and oxidation (with H 2 O 2 ). We herein successfully boost the reaction specificity for this material by shape control. The acidic Ce species on octahedron (111) surface was found to selectively catalyze substrate dephosphorylation while its electron rich counterpart on cube (100) surface only promotes substrate oxidation. Among reported nanozymes, CeO 2 seems to be the only transition metal oxide that can mimic phosphatase and peroxidase by catalyzing substrate dephosphorylation and oxidation (with H 2 O 2 ). However, no consensus on the key Ce species was reached in the literature using spherical CeO 2 enclosed by (111) and (100) surfaces, not to mention the further control of its reaction specificity. In this study, octahedral and cubic CeO 2 preferentially terminated by (111) and (100) surfaces were found to exhibit high reaction specificity (and activity) towards each of the above reactions. Spectroscopic evidence suggests that this is closely associated with the Lewis acidity (or electron density) of surface Ce species. The acidic Ce species on (111) surface can catalyze substrate dephosphorylation at room temperature but do not for substrate oxidation with H 2 O 2 . This correlation was further evidenced by the electron-rich Ce species on (100) surface, hindering the first reaction while promoting the latter.
研究领域:
材料科学
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生物化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Xiaoxue Zhao,Jingru Guan,Jinze Li,Xin Li,Huiqin Wang,Pengwei Huo,Yongsheng Yan
The conversion of CO 2 into high value-added carbon-based compounds through photocatalytic reduction technology is considered as one of the more promising strategies to solve the greenhouse effect. And construction of heterojunction photocatalysts can promote the separation of photoelectron-hole pairs, so as to achieve higher activity of photocatalytic CO 2 reduction. Hence, Pt@CeO 2 /3DCN heterojunction are prepared by calcination method and photoreduction technology. The photocatalytic results revealed that Pt@CeO 2 /3DCN show better photocatalytic activity for reducing CO 2 into CO and CH 4 , compared with 3DCN. Especially, Pt@45CeO 2 /3DCN shows the maximum photocatalytic activity of 4.69 and 3.03 μmol·h −1 ·g −1 for CO and CH 4 under UV light irradiation, respectively, and the reduction activity did not decrease significantly after five cycles. The enhanced photoreduction of CO 2 performance can be ascribed to the synergistic effects of the oxygen vacancies in CeO 2 for CO 2 activation and heterojunction for electron separation. Besides, Pt nanoparticles (NPs) on CeO 2 /3DCN can further promote the transfer of electrons, resulting in higher photocatalytic activity.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Yane Zheng,Kongzhai Li,Hua Wang,Dong Tian,Yuhao Wang,Xing Zhu,Yonggang Wei,Min Zheng,Yongming Luo
Chemical-looping reforming of methane (CLRM) offers an effective approach for coproducing syngas and pure hydrogen. In this work, CeO 2 nano particles (2–3 nm) are well dispersed on the wall surface of three-dimensional ordered macroporous (3DOM) LaFeO 3 , obtaining a highly efficient oxygen carrier for the CLRM technology. The physical and chemical properties of the oxygen carriers were characterized by SEM, TEM, H 2 -TPR, XPS, XRD, CH 4 -TPR and CH 4 -TPD techniques. It is found that the presence of CeO 2 on LaFeO 3 results in the formation of Ce 3+ and Fe 2+ due to the CeO 2 -LaFeO 3 interaction. The coexistence of Ce 3+ and Fe 2+ irons induces abundant oxygen vacancies on the mixed oxides, which strongly improves the reducibility, oxygen mobility and reactivity for methane oxidation. The presence of CeO 2 also improves the resistance towards carbon deposition formation, and this allows the CeO 2 /LaFeO 3 materials own high available oxygen storage capacity (available OSC, the maximum amount of oxygen consumed by methane reduction without the formation of carbon deposition). It is also noted that the agglomeration of CeO 2 nano particles would reduce the reactivity of oxygen carriers. Among all the obtained samples, the 10% CeO 2 /LaFeO 3 sample exhibits the highest yields of syngas (9.94 mmol g −1 ) and pure hydrogen (3.38 mmol g −1 ) without the formation of carbon deposition, which are much higher than that over the pure LaFeO 3 sample (5.73 mmol g −1 for syngas yield and 2.00 mmol g −1 for hydrogen yield). In addition, the CeO 2 /LaFeO 3 oxygen carrier also showed high stability during the successive CLRM testing either in the activity (yields of syngas and pure hydrogen) or structure (macroporous frameworks) aspect.
研究领域:
能源科学
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2022
·
IF 9.794
Hengyi Chen,Minghao Hu,Peng Jing,Baocang Liu,Rui Gao,Jun Zhang
Transition metal disulfides (TMD) are considered as promising catalysts for hydrogen evolution reaction (HER) due to their unique structural and electronic properties. However, as a representative, the tungsten disulfide (WS 2 ) shows an insufficient HER performance and is still needed to be further improved. Herein, we report the synthesis of CeO 2 -modified WS 2 nanosheets with abundant heterostructures on carbon cloth (CeO 2 /WS 2 /CC) as an efficient self-supported integral electrode for HER. Experimental results and theoretical calculations imply that the intimate electronic interaction between CeO 2 and WS 2 promotes the production of more oxygen vacancies in CeO 2 to regulate the electronic structure of WS 2 , endowing extra active sites, high electron transfer efficiency, and downshifted d-band center of W, which can lead to thermoneutral hydrogen adsorption Gibbs free energies (ΔG H* ) and thus boosts HER. The optimized CeO 2 /WS 2 /CC electrode displays an improved HER performance with an overpotential of 128 mV at 10 mA cm −2 in 0.5 M H 2 SO 4 aqueous solution, 87 mV smaller than that of the WS 2 /CC electrode. Meanwhile, it also could maintain a 20 h of stable HER activity. Our work provides an effective approach to achieve various hybrid catalysts of rare earth compounds-transition metal compounds with highly active sites for superior electrocatalysis .
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2018
·
IF 4.229
Bin Li,Baohua Zhang,Qingqing Guan,Shanshuai Chen,Ping Ning
An effective Ni/CeO 2 catalyst prepared by the polyol reduction method for degrading phenol into CH 4 , H 2 and CO 2 in supercritical water (SCW) was developed. About 80% carbon gasification efficiency can be achieved at 525 °C and 60 min with 5 wt% phenol, 0.098 kg/m 3 water density and 0.5 g Ni/CeO 2 /g phenol catalyst, forming CH 4 and H 2 as the main gaseous products. Comparison study indicated that the efficiency of present Ni/CeO 2 catalyst was about 20% higher than that of a commercial catalyst, i.e., Ni/SiO 2 Al 2 O 3 from Sigma-Aldrich with 65 wt%Ni, at a reaction conditions of 500 °C and 30 min. The characterization analyses of BET, TPR, XRD , XPS and TEM indicated that there was a NiCe alloy formed in Ni/CeO 2 , which could be important to enhance the activities of the carbon gasification efficiencies and gas yields. A kinetic modelings were conducted and the results showed that the lnA and the activation energy (Ea) of gasification were 7.1 ± 0.5 and 58.1 ± 3.2 kJ/mol for the gaseous product, and were 2.6 ± 0.9 and Ea is 36.6 ± 5.6 kJ/mol for the char formation , respectively. The present Ni-based-metal Ni/CeO 2 catalyst is cheaper and has a potential application for the gasification to convert phenol into gases fuels in SCW process.
研究领域:
化学工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2023
·Vol. 148
·期 21
·12311-12320
·
IF 4.4
Fang Jia,Yi Chengcheng,Pu Ping,Chen Chen,Yang Yi,Wang Jiaxin,Lin Bin
Ag/CeO 2 catalyst is synthesized by hydrothermal method, which has been studied under the effects of different catalyst content, ash and Ag load through activity and characterization tests. Ag loading increases the catalytic activity of CeO 2 , and the peak combustion temperature of soot decreases by 74 °C. The catalytic effect of Ag/CeO 2 is affected by catalyst content, Ag load and ash content. The optimum mass ratio of soot/catalyst is 1/10, and 10 mass% is the saturation value of Ag loading at CeO 2 . Ash inhibits the promoting effect of Ag/CeO 2 in the oxidation process of soot. This study provides a theoretical basis for the industrial application of Ag/CeO 2 catalyst in gasoline engine and also provides a research idea for the low-temperature oxidation of soot.
研究领域:
催化
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2021
·Vol. 139
·期 4
·51529
·
IF 3.125
Zhi-gang Yuan,Mohamadou Al Hassan,Zhi-cheng Wang,Jun-yi Wang,Jun Wang,Mehdi Derradji,Wen-bin Liu
Nanoparticles have been widely used in the improvement of the mechanical and thermal properties of the epoxy matrix. In this study, the room temperature curing agent composed of acrylic acid and 2,4,6-trimethyl-m-phenylenediamine was mixed with different concentrations of CeO 2 nanoparticles into the epoxy resin (E51) to obtain a nanocomposite that can be rapidly molded and cured. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to study the curing behavior of nanocomposites and E51 with the synthesized hardener. Through tensile, flexural, and impact tests, the influence of the nanoparticles content on the mechanical and thermal properties of the prepared composites was discussed. The results showed that the curing process was completed in 4 h. An increase of 78.4% in tensile strength, 81.7% in flexural strength, and 122.0% in elongation were obtained for the cured nanocomposite having 5 wt% CeO 2 loading compared to the neat resin. Thermogravimetric analysis result showed that the thermal stability increased with increasing of CeO 2 nanofillers content. Finally, the scanning electron microscope revealed the fracture surface morphology of the composites.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 47
·20061-20070
·
IF 2.7
Jiabing Chen,Yibo Tang,Xiaojun Lu,Zijing Lu,Xingmao Jiang
The industrial production of methyl propionate synthesized via methoxycarbonyl esterification of ethylene achieved 100% atom economy. In this study, we synthesized ruthenium-loaded praseodymium–cerium oxide (Pr–CeO2) catalysts by precipitation impregnation and evaluated their performance in the methoxycarbonylation reaction of ethylene. The effect of Pr doping on the reaction results was analyzed by characterization and mechanistic studies. Pr doping increased the concentration of localized oxygen vacancies in the catalysts and thus modulated the catalytic effect of Lewis acid–base pairs. The increase of local oxygen vacancies significantly enhanced the activation and dissociation of CH3OH. At the same time, since the dissociation activation of the other two feedstock molecules, ethylene and CO, occurred at the Ru site, Pr doping facilitated the dispersion of Ru to a certain extent, thus increasing the dissociation activation of CO and ethylene, which, in combination with Pr doping, further increased the content of oxygen vacancies in the active site as methanol, resulting in a substantial enhancement of the dissociation activation of the feedstock molecules, which then increased the catalytic reaction rate through synergistic effects. The results provide a new perspective for the future study of methoxycarbonylation.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2022
·
IF 13.7
Danfeng Wu,Sixu Liu,Mingqi Zhong,Jiafei Zhao,Congcong Du,Yanling Yang,Yifei Sun,Jingdong Lin,Shaolong Wan,Shuai Wang,Jianyu Huang,Yali Yao,Zhe Li,Haifeng Xiong
Metal single-atom catalysts (SACs) have attracted extensive interest because of their maximum atom efficiency and potentially good performances. However, the understanding of the catalytic behavior and the stability of SACs in high-temperature catalytic reactions remains a major challenge, especially under reducing conditions. In this work, we investigated the nature and stability of Rh/CeO2 SACs with different Rh loadings (0.2–4 wt % Rh) during syngas conversion (260 °C, 2 MPa). Using CO-DRIFTS, we found that atomically dispersed Rh was dispersed on Rh/CeO2 catalysts with an Rh loading up to 3 wt %. The Rh/CeO2 catalysts were stable in H2 up to 350 °C, while Rh nanoclusters were formed in CO at 200 °C. During syngas conversion at 260 °C, the Rh single atoms (Rhiso) on a 0.5 wt % Rh/CeO2 SAC slowly agglomerated to form Rh nanoclusters (RhNC) and a Rhiso/RhNC ratio of ∼1:2.5 was obtained after ∼10 h time-on-stream run. Furthermore, the Rhiso/RhNC ratio did not change with further reaction, indicating that the reaction reached steady state after a 10 h run. After the catalysts reached steady state (∼10 h), the Rhiso/RhNC ratio on the spent Rh/CeO2 catalysts decreased with the increase in Rh loadings, while the reactivity increased first and then decreased. We observed an optimal value of Rhiso/RhNC ≈ 1:3 on the 1 wt % Rh/CeO2 catalyst, showing the maximum reaction rates of CO (rCO) and ethanol selectivity (SEtOH) of 85.8 μmol/s/gRh and 26.2%, respectively. This indicated that the combination of Rh single atoms and Rh nanoclusters is beneficial to the ethanol selectivity and reaction rate, which was confirmed by DFT simulations. Moreover, the ratios of Rhiso/RhNC on the spent catalysts under the steady state have good relationships with the CO conversion rate and product selectivity in the reaction.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Xu Zhang,Shuting Li,Jiyang Zhang,Jihong Liu,Chaoyang Huang,Jiapeng Zhu,Guixiao Jia,Shengli An
CeO 2 is a promising electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Studies have found that F-doping improves its ionic conductivity, but the underlying mechanisms remain unclear. Therefore, this study employs a DFT+U method to calculate geometrical and electronic structures and oxygen ion migrations of Gd-, Ca- and F-dopings co-doped CeO 2 . The calculated results are verified by our experiment. DFT calculations find that oxygen vacancies (V) are easily formed at next-neighboring sites near the F - ions, different with the case of Gd- and Ca-doped CeO 2 . Gd-, Ca- and F-dopings strengthen Ce-O bonds, inconstant with the result from the reported experimental hypothesis for the F-doping. The F-doping restrains the change of Ce 4+ to Ce 3+ . Migration energy barriers E m of oxygen ions are mainly affected by the migration distances and peripherally done by the oxygen vacancy cavity size and the defect association. Due to the lager oxygen vacancy cavity size and the smaller defect association in CGOF and CGOCF, the F-dopings have the smaller E m . This is contrary to the speculation of the reported experimental study based on the electronegative comparison of F and O. Our experiment finds that Ca and F co-doping significantly increases the conductivity, 3.9 times of the conductivity of Gd-doped CeO 2 . The study clarifies the nature mechanism of the ionic conductivity in doped CeO 2 , offering atomic-level insights to aid the development of high-performance CeO 2 -based electrolytes.
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）