The Experts below are selected from a list of 1204161 Experts worldwide ranked by ideXlab platform
Israel E Wachs - One of the best experts on this subject based on the ideXlab platform.
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monitoring surface metal oxide catalytic active sites with raman spectroscopy
Chemical Society Reviews, 2010Co-Authors: Israel E Wachs, Charles A RobertsAbstract:The molecular aspect of the Raman vibrational selection rules allows for the molecular structural and reactivity determinations of metal oxide catalytic active sites in all types of oxide catalyst systems (supported metal oxides, zeolites, layered hydroxides, polyoxometalates (POMs), bulk pure metal oxides, bulk mixed oxides and mixed oxide solid solutions). The molecular structural and reactivity determinations of metal oxide catalytic active sites are greatly facilitated by the use of isotopically labeled molecules. The ability of Raman spectroscopy to (1) operate in all phases (liquid, solid, gas and their mixtures), (2) operate over a very wide temperature (−273 to >1000 °C) and pressure (UHV to ≫100 atm) range, and (3) provide molecular level information about metal oxides makes Raman spectroscopy the most informative characterization technique for understanding the molecular structure and surface chemistry of the catalytic active sites present in metal oxide heterogeneous catalysts. The recent use of hyphenated Raman spectroscopy instrumentation (e.g., Raman–IR, Raman–UV-vis, Raman–EPR) and the operando Raman spectroscopy methodology (e.g., Raman–MS and Raman–GC) is allowing for the establishment of direct structure–activity/selectivity relationships that will have a significant impact on catalysis science in this decade. Consequently, this critical review will show the growth in the use of Raman spectroscopy in heterogeneous catalysis research, for metal oxides as well as metals, is poised to continue to exponentially grow in the coming years (173 references).
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recent conceptual advances in the catalysis science of mixed metal oxide catalytic materials
Catalysis Today, 2005Co-Authors: Israel E WachsAbstract:The catalysis science of mixed metal oxides (supported metal oxides, molecular sieves and bulk mixed metal oxides) has undergone dramatic paradigm changes over the past 25 years as new characterization techniques became available (X-ray absorption spectroscopy (EXAFS/XANES/soft XANES), Raman, solid-state NMR, HR-TEM, UV–vis DRS and LEISS) to catalysis researchers. The major advantages offered by these spectroscopic improvements are that (1) they can detect XRD inactive amorphous surface metal oxide phases as well as crystalline nanophases and (2) their ability to collect information under various environmental conditions. Application of these spectroscopic techniques to the investigation of mixed metal oxide catalysts have provided new fundamental insights into the electronic and molecular structures of mixed metal oxide catalytic active sites and how they control the catalytic activity and selectivity characteristics. The most significant discovery has been that amorphous metal oxide phases are always present and are the catalytic active sites for many applications of mixed metal oxide catalysts. This has resulted in a significant paradigm shift as to how mixed metal oxide catalytic materials function for different applications. This article reviews the instrumental advances and the resulting conceptual advances that have evolved over the past 25 years in the catalysis science of mixed metal oxide catalysts. # 2004 Elsevier B.V. All rights reserved.
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recent conceptual advances in the catalysis science of mixed metal oxide catalytic materials
Catalysis Today, 2005Co-Authors: Israel E WachsAbstract:Abstract The catalysis science of mixed metal oxides (supported metal oxides, molecular sieves and bulk mixed metal oxides) has undergone dramatic paradigm changes over the past 25 years as new characterization techniques became available (X-ray absorption spectroscopy (EXAFS/XANES/soft XANES), Raman, solid-state NMR, HR-TEM, UV–vis DRS and LEISS) to catalysis researchers. The major advantages offered by these spectroscopic improvements are that (1) they can detect XRD inactive amorphous surface metal oxide phases as well as crystalline nanophases and (2) their ability to collect information under various environmental conditions. Application of these spectroscopic techniques to the investigation of mixed metal oxide catalysts have provided new fundamental insights into the electronic and molecular structures of mixed metal oxide catalytic active sites and how they control the catalytic activity and selectivity characteristics. The most significant discovery has been that amorphous metal oxide phases are always present and are the catalytic active sites for many applications of mixed metal oxide catalysts. This has resulted in a significant paradigm shift as to how mixed metal oxide catalytic materials function for different applications. This article reviews the instrumental advances and the resulting conceptual advances that have evolved over the past 25 years in the catalysis science of mixed metal oxide catalysts.
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recent conceptual advances in the catalysis science of mixed metal oxide catalytic materials
Catalysis Today, 2005Co-Authors: Israel E WachsAbstract:Abstract The catalysis science of mixed metal oxides (supported metal oxides, molecular sieves and bulk mixed metal oxides) has undergone dramatic paradigm changes over the past 25 years as new characterization techniques became available (X-ray absorption spectroscopy (EXAFS/XANES/soft XANES), Raman, solid-state NMR, HR-TEM, UV–vis DRS and LEISS) to catalysis researchers. The major advantages offered by these spectroscopic improvements are that (1) they can detect XRD inactive amorphous surface metal oxide phases as well as crystalline nanophases and (2) their ability to collect information under various environmental conditions. Application of these spectroscopic techniques to the investigation of mixed metal oxide catalysts have provided new fundamental insights into the electronic and molecular structures of mixed metal oxide catalytic active sites and how they control the catalytic activity and selectivity characteristics. The most significant discovery has been that amorphous metal oxide phases are always present and are the catalytic active sites for many applications of mixed metal oxide catalysts. This has resulted in a significant paradigm shift as to how mixed metal oxide catalytic materials function for different applications. This article reviews the instrumental advances and the resulting conceptual advances that have evolved over the past 25 years in the catalysis science of mixed metal oxide catalysts.
Guangmin Zhou - One of the best experts on this subject based on the ideXlab platform.
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balancing surface adsorption and diffusion of lithium polysulfides on nonconductive oxides for lithium sulfur battery design
Nature Communications, 2016Co-Authors: Jianguo Wang, Haotian Wang, Guangyuan Zheng, Weiyang Li, Guangmin Zhou, Chenxi ZuAbstract:Lithium–sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides. Metal oxides can suppress detrimental polysulfide shuttling in lithium-sulfur batteries, however selection criteria for oxide materials are still lacking. Here, the authors investigate polysulfide adsorption and diffusion on metal oxides and propose selection criteria based on balancing these two effects.
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balancing surface adsorption and diffusion of lithium polysulfides on nonconductive oxides for lithium sulfur battery design
Nature Communications, 2016Co-Authors: Jianguo Wang, Haotian Wang, Guangyuan Zheng, Xinyong Tao, Chong Liu, Hongbin Yao, Zhi Wei Seh, Qiuxia Cai, Guangmin ZhouAbstract:Lithium-sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides.
Xinyong Tao - One of the best experts on this subject based on the ideXlab platform.
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balancing surface adsorption and diffusion of lithium polysulfides on nonconductive oxides for lithium sulfur battery design
Nature Communications, 2016Co-Authors: Jianguo Wang, Haotian Wang, Guangyuan Zheng, Xinyong Tao, Chong Liu, Hongbin Yao, Zhi Wei Seh, Qiuxia Cai, Guangmin ZhouAbstract:Lithium-sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides.
Jianguo Wang - One of the best experts on this subject based on the ideXlab platform.
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balancing surface adsorption and diffusion of lithium polysulfides on nonconductive oxides for lithium sulfur battery design
Nature Communications, 2016Co-Authors: Jianguo Wang, Haotian Wang, Guangyuan Zheng, Weiyang Li, Guangmin Zhou, Chenxi ZuAbstract:Lithium–sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides. Metal oxides can suppress detrimental polysulfide shuttling in lithium-sulfur batteries, however selection criteria for oxide materials are still lacking. Here, the authors investigate polysulfide adsorption and diffusion on metal oxides and propose selection criteria based on balancing these two effects.
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balancing surface adsorption and diffusion of lithium polysulfides on nonconductive oxides for lithium sulfur battery design
Nature Communications, 2016Co-Authors: Jianguo Wang, Haotian Wang, Guangyuan Zheng, Xinyong Tao, Chong Liu, Hongbin Yao, Zhi Wei Seh, Qiuxia Cai, Guangmin ZhouAbstract:Lithium-sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides.
Chenxi Zu - One of the best experts on this subject based on the ideXlab platform.
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balancing surface adsorption and diffusion of lithium polysulfides on nonconductive oxides for lithium sulfur battery design
Nature Communications, 2016Co-Authors: Jianguo Wang, Haotian Wang, Guangyuan Zheng, Weiyang Li, Guangmin Zhou, Chenxi ZuAbstract:Lithium–sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides. Metal oxides can suppress detrimental polysulfide shuttling in lithium-sulfur batteries, however selection criteria for oxide materials are still lacking. Here, the authors investigate polysulfide adsorption and diffusion on metal oxides and propose selection criteria based on balancing these two effects.
