Improvement role of CNTs on catalytic performance in the CeO2/xCNTs-CuO catalysts

Xie, Yongbing; Gao, Meiyi; Zhang, Hao; Zeng, Shanghong; Zhao, Xiaozhou; Zhao, Yonggang; Su, Haiquan; Song, Jiachen; Li, Xiang-Shuai; Jia, Qianhui

doi:10.1016/j.ijhydene.2016.08.104

Cited by 15 publications

(12 citation statements)

References 61 publications

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“…The characteristic satellite of Mn 2p core level spectrum (Figure 4c) obviously became weak, indicating a mixed oxidation state of Mn 2+ /Mn 3+ , 21,22 which is also confirmed by the fact that Mn 3p peak (Figure 4d) shifts to 49.6 eV. CuMnO 2 obtained at 180 °C had a narrower Cu 2p 3/2 peak (Figure 4a) with a further shift to lower binding energy, showing a similar tendency reported in other systems, 24,25 which corresponds to the presence of a dominant Cu + in mixed Cu + /Cu 2+ oxidation state. This conclusion is also confirmed by the fact that the Cu Auger peak (Figure 4b) shifts to 916.7 eV.…”

Section: Various Morphologies Of Cumno 2 Crystalssupporting

confidence: 84%

Crystal Growth of Bimetallic Oxides CuMnO₂ with Tailored Valence States for Optimum Electrochemical Energy Storage

Jing

et al. 2018

Crystal Growth & Design

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Bimetallic oxides ABO x (x = 2, 3, and 4) with multiple lattice sites have shown numerous properties, blossoming into diverse applications, while regulating the valence state at the A or B site usually causes a dramatic change in the crystal structure, giving rise to uncertainties in comprehending the structure–property relationships. Herein, we synthesized bimetallic layered crednerite CuMnO2 with double-coordinate Cu cations at the A site and hexa-coordinate Mn cations at the B site via a cetyltrimethylammonium bromide (CTAB) modified hydrothermal method. By controlling the crystal growth temperature, valence states tailoring was implemented along with the stabilization of the monoclinic layered structure. The regulation process was followed by morphology changes of the CuMnO2 crystal in a sequence: triangular sheets (140 °C), nanowires (160 °C), hexagonal prisms (180 °C), and octahedrons (over 200 °C). Interestingly, the oxidation states of Cu2+ and Mn2+ were found for triangular sheets, which transformed to the mixed valency Cu+/Cu2+ and Mn3+/Mn2+ for nanowires, and then to the dominant Cu+ and Mn3+ oxidation states for hexagonal prisms and octahedrons. Among all morphologies, nanowires showed a higher aspect ratio, preferentially growing along the (002) plane, which when first applied to a supercapacitor, exhibited the highest specific capacitance of 921 F/g at the current density of 1 A/g. The synergistic effect between the special redox equilibrium and controlled one-dimensional crystal architecture is uncovered to optimize the electrochemical energy storage. The methodology reported in this work creates a new path of functional bimetallic oxides ABO x with tailored valence states, controllable crystal growth, and stable crystal structure for optimum energy storage applications.

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Section: Various Morphologies Of Cumno 2 Crystalssupporting

confidence: 84%

Crystal Growth of Bimetallic Oxides CuMnO₂ with Tailored Valence States for Optimum Electrochemical Energy Storage

Jing

et al. 2018

Crystal Growth & Design

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“…To verify the above hypothesis, XPS analysis was performed on the MgH 2 /Cu x O composite before and after CO 2 hydrogenation. For raw MgH 2 /Cu x O, the Cu 2p 3/2 peak in the period of 930–938 eV can be decomposed into two peaks of 932.4 and 933.8 eV, corresponding to Cu 0 species (30.8 atom %) and Cu + species (35.3 atom %), respectively (Figure A) . For the spent MgH 2 /Cu x O, Cu 0 species and Cu + species are also obvious; also, Cu 0 species increases to 52.1 atom %, while Cu + species reduces to 13.5 atom %, confirming the reduction of Cu x O during CO 2 hydrogenation.…”

Section: Results and Discussionmentioning

confidence: 98%

MgH₂/Cu_xO Hydrogen Storage Composite with Defect-Rich Surfaces for Carbon Dioxide Hydrogenation

Chen

Liu

et al. 2019

ACS Appl. Mater. Interfaces

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Thermal conversion of CO 2 to value-added chemicals is challenging due to the extreme inertness of the CO 2 molecule and the low selectivity of products. We reported a defect-rich MgH 2 /Cu x O hydrogen storage composite from mechanochemical ball-milling for the catalytic hydrogenation of CO 2 to lower olefins. The defect-rich MgH 2 / Cu x O hydrogen storage composite achieves a C 2 = −C 4 = selectivity of 54.8% and a CO 2 conversion of 20.7% at 350 °C under a low H 2 /CO 2 ratio of 1:5, which increases the efficiency of H 2 utilization by offering lattice H − species for hydrogenation. Density functional theory calculations show that the defective structure of MgH 2 /Cu x O can promote CO 2 molecule adsorption and activation, while the electronic structure of MgH 2 is beneficial for offering lattice H − for CO 2 molecule hydrogenation. The lattice H − can combine the C site of CO 2 molecule to promote the formation of Mg formate, which can be further hydrogenated to lower olefins under a low H − concentration. This work for CO 2 conversion by a defect-rich MgH 2 / Cu x O hydrogen storage composite can inspire the catalysts design for the hydrogenation of CO 2 to lower olefins.

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“…Among the transition metal oxide catalysts, copper oxide has been considered one of the most promising nonprecious metal catalysts in electrochemistry redox processes because of their large surface area, chemical stability and potential synergetic effects of surface-modified mixed valence metal oxides. − However, this material has not attracted much attention for applications in ORR because of its perceived limited catalytic abilities and relatively low electric conductivity. To further improve catalytic activity and conductivity, the combination of CuO with other functional components to form a hybrid structure arouses substantial interest. − In this regard, ceria (CeO 2 ) has been widely used as an oxygen storage medium and stabilizer in multielement oxide catalytic systems based on its ability to adsorb oxygen to regulate the oxygen density on catalyst surfaces. Recently, Wang et al discovered that the ORR catalytic activity of the Co 3 O 4 –CeO 2 /KB composite depends on the amount of CeO 2 , from which they demonstrated that a certain amount of CeO 2 on the composite could increase the oxygen transfer, enhancing the ORR activity.…”

Section: Introductionmentioning

confidence: 99%

CuO Nanoplatelets with Highly Dispersed Ce-Doping Derived from Intercalated Layered Double Hydroxides for Synergistically Enhanced Oxygen Reduction Reaction in Al–Air Batteries

Hong

Wang

2017

ACS Sustainable Chem. Eng.

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Development of highly efficient, low-cost, and durable electrocatalysts for the oxygen reduction reaction (ORR) is still a major obstacle that is preventing widespread commercialization of Al−air batteries. Herein, a cost-effective CuCe-layered double hydroxide (CuCe-LDH) was synthesized using a facile and scalable method of separate nucleation/growth steps, followed by an anion exchange process. The CuCe-LDH was successfully used as a precursor for the mass production of Ce-doped CuO nanoplatelets (Cu−Ce−O) as a Pt-free efficient electrocatalyst, which exhibited not only comparable electrocatalytic activity and durability in the ORR test but also a higher discharge voltage plateau when used in Al−air batteries compared to the benchmark Pt/C catalysts. A combination of structural characterizations and electrochemical analyses showed that the high ORR activity of the Cu−Ce−O catalyst was attributed to its high content of active species combined with their synergetic interactions. These results may provide an option for cost-effective production of ORR electrocatalysts at a large scale for practical applications of Al−air cathodes.

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Improvement role of CNTs on catalytic performance in the CeO2/xCNTs-CuO catalysts

Cited by 15 publications

References 61 publications

Crystal Growth of Bimetallic Oxides CuMnO₂ with Tailored Valence States for Optimum Electrochemical Energy Storage

Crystal Growth of Bimetallic Oxides CuMnO₂ with Tailored Valence States for Optimum Electrochemical Energy Storage

MgH₂/Cu_xO Hydrogen Storage Composite with Defect-Rich Surfaces for Carbon Dioxide Hydrogenation

CuO Nanoplatelets with Highly Dispersed Ce-Doping Derived from Intercalated Layered Double Hydroxides for Synergistically Enhanced Oxygen Reduction Reaction in Al–Air Batteries

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Improvement role of CNTs on catalytic performance in the CeO2/xCNTs-CuO catalysts

Cited by 15 publications

References 61 publications

Crystal Growth of Bimetallic Oxides CuMnO2 with Tailored Valence States for Optimum Electrochemical Energy Storage

Crystal Growth of Bimetallic Oxides CuMnO2 with Tailored Valence States for Optimum Electrochemical Energy Storage

MgH2/CuxO Hydrogen Storage Composite with Defect-Rich Surfaces for Carbon Dioxide Hydrogenation

CuO Nanoplatelets with Highly Dispersed Ce-Doping Derived from Intercalated Layered Double Hydroxides for Synergistically Enhanced Oxygen Reduction Reaction in Al–Air Batteries

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Crystal Growth of Bimetallic Oxides CuMnO₂ with Tailored Valence States for Optimum Electrochemical Energy Storage

Crystal Growth of Bimetallic Oxides CuMnO₂ with Tailored Valence States for Optimum Electrochemical Energy Storage

MgH₂/Cu_xO Hydrogen Storage Composite with Defect-Rich Surfaces for Carbon Dioxide Hydrogenation