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645 results on '"Peng, Qiuming"'

256. Hydrogenated Core-Shell MAX@K2Ti8O17 Pseudocapacitance with Ultrafast Sodium Storage and Long-Term Cycling.

Author

Zou, Guodong, Guo, Jianxin, Liu, Xianyu, Zhang, Qingrui, Huang, Gang, Fernandez, Carlos, and Peng, Qiuming

Subjects
SODIUM ions, STORAGE batteries, ENERGY storage, ELECTRIC capacity, LITHIUM-ion batteries
Abstract

Sodium-ion batteries are considered alternatives to lithium-ion batteries for energy storage devices due to their competitive cost and source abundance. However, the development of electrode materials with long-term stability and high capacity remains a great challenge. Here, this paper describes for the first time the synthesis of a new class of core-shell MAX@K2Ti8O17 by alkaline hydrothermal reaction and hydrogenation of MAX, which grants high sodium ion-intercalation pseudocapacitance. This composite electrode displays extraordinary reversible capacities of 190 mA h g−1 at 200 mA g−1 (0.9 C, theoretical value of ≈219 mA h g−1) and 150 mA h g−1 at 1000 mA g−1 (4.6 C). More importantly, a reversible capacity of 75 mA h g−1 at 10 000 mA g−1 (46 C) is retained without any apparent capacity decay even after more than 10 000 cycles. Experimental tests and first-principle calculations confirm that the increase in Ti3+ on the surface layers of MAX@K2Ti8O17 by hydrogenation increases its conductivity in addition to enhancing the sodium-ion intercalation pseudocapacitive process. Furthermore, the distorted dodecahedrons between Ti and O layers not only provide abundant sites for sodium-ion accommodation but also act as wide tunnels for sodium-ion transport. [ABSTRACT FROM AUTHOR]

Published
2017
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263. Unique strengthening mechanisms of ultrahigh pressure Mg alloys

Author

Ge, Bingcheng, Fu, Hui, Deng, Kunkun, Zhang, Qingrui, and Peng, Qiuming

Abstract

Ultrahigh pressure technique remarkably extends solid solubility limitation of Al alloying element (∼25 at.%) in Mg alloys, resulting in unique solid-solution strengthening and age hardening response. Microhardness, yield strength and ultimate compressive strength are improved simultaneously without degrading plasticity by forming homogeneous and globular-shaped Mg17Al12precipitates of 10–30 nm. In addition, thermal resistance is enhanced by eliminating the dominant growth of (101) plane and anchoring dense stacking faults in phase interface.

Published
2018
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264. Fabrication of tunable hierarchical MXene@AuNPs nanocomposites constructed by self-reduction reactions with enhanced catalytic performances

Author

Li, Kaikai, Jiao, Tifeng, Xing, Ruirui, Zou, Guodong, Zhou, Jingxin, Zhang, Lexin, and Peng, Qiuming

Abstract

MXene, a new type of two-dimensional layered transition metal carbide material differing from graphene, demonstrates intriguing chemical/physical properties and wide applications in recent years. Here, the preparation of the self-assembled MXene-gold nanoparticles (MXene@AuNPs) nanocomposites with tunable sizes is reported. The nanocomposites are obtained viathe self-reduction reactions of MXene material in a HAuCl4solution at room temperature. The sizes of the Au particles can be well-controlled by regulating the self-reduction reaction time. They can greatly influence the catalytic behaviors of the MXene@AuNPs composites. MXene@AuNPs composites with optimized reduction time show high catalytic performances and good cycle stability for model catalytic reactions of nitro-compounds, such as 2-nitrophenol and 4-nitrophenol. This work demonstrates a new approach for the preparation of tunable MXene-based self-assembled composites. MXene是一种不同于石墨烯的新型层状二维过渡金属碳化物材料, 近年来表现出有趣的化学、 物理性能并被广泛应用. 本文报道了结构新颖且尺寸可调的自组装层状MXene@AuNPs纳米复合材料的制备方法. 在室温下MXene@AuNPs纳米复合材料可通过MXene材料在HAuCl4溶液中的自还原反应制备. 控制自还原反应的时间可精确地调节Au粒子的颗粒尺寸. 而金纳米颗粒的粒径对MXene@AuNPs复合材料的催化性能具有很大的影响. 适当自还原时间下得到的MXene@AuNPs复合材料表现出对模型硝基化合物(如4-NP和2-NA)催化反应很高的催化性能和良好的循环稳定性. 本研究工作为基于MXene自组装复合材料的制备与调控提供了新方法.

Published
2018
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265. Fabrication of hierarchical MXene-based AuNPs-containing core–shell nanocomposites for high efficient catalysts

Author

Li, Kaikai, Jiao, Tifeng, Xing, Ruirui, Zou, Guodong, Zhao, Qianran, Zhou, Jingxin, Zhang, Lexin, and Peng, Qiuming

Abstract

MXene is a new type of layered two-dimensional transition metal carbide materials differing from graphene, demonstrating intriguing chemical/physical properties. Here the chemical modification of MXene and next fabrication of core–shell MXene–COOH@(PEI/PAA)ncomposites have been investigated. The obtained MXene-based composites were treated with gold nanoparticles to form MXene–COOH@(PEI/PAA)n@AuNPs nanocomposites, and their catalytic properties for nitro-compounds were studied. The prepared nanocomposites demonstrated good catalytic activity and reproducibility, showing potential applications in composite catalysts and environmental fields.

Published
2018
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280. Non-bonding interaction of dual atom catalysts for enhanced oxygen reduction reaction

Author

Tamtaji, Mohsen, Peng, Qiuming, Liu, Tongchao, Zhao, Xue, Xu, Zhihang, Galligan, Patrick Ryan, Hossain, Md Delowar, Liu, Zhenjing, Wong, Hoilun, Liu, Hongwei, Amine, Khalil, Zhu, Ye, Goddard III, William A., Wu, Wenting, and Luo, Zhengtang

Abstract

We demonstrate the design of graphene-supported dual atom catalysts (DACs) for the four-electron oxygen reduction reaction (ORR), by utilizing the non-bonding interaction of counterpart metals (M) that synergistically tune the electronic properties and catalytic activity of the Fe active site in FeMN6-DAC and FeMN8-DAC systems, where M stands for Fe, Co, Ni, Cu, and Zn. More specifically, for Fe-M distances below 15 Å, the non-bonding interaction is significant, making the system act as the DAC. We predicted that FeNiN6-DAC and FeNiN8-DAC exhibit a low ORR overpotential (ηORR) of 0.28 V and 0.47 V, respectively, which are at the summits of volcano plots. This low ηORRoriginates from the high Bader charge transfer coupled with high spin density at the Fe site in both the FeNiN6-DAC and FeNiN8-DAC systems, which weakens the adsorption of OH* intermediate while enhancing its desorption to H2O. Guided by these density functional theory (DFT) computational results, we synthesized FeCoN8-DAC and FeNiN8-DAC along with N-doped graphene and confirmed their structures with scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and electron spin resonance (ESR). We verify experimentally the catalytic activities and find that FeNiN8-DAC has the low experimental overpotential of 0.39 V with a Tafel slope of 47 mVdec−1. Based on these results, we propose a DFT-guided strategy to tune the charge transfer and spin population of the active site toward designing DACs for electrochemical ORR.

Published
2023
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299. Microstructures, mechanical and cytocompatibility of degradable Mg–Zn based orthopedic biomaterials.

Author

Li, Hui, Peng, Qiuming, Li, Xuejun, Li, Kun, Han, Zengsheng, and Fang, Daqing

Subjects
*MICROSTRUCTURE, *MECHANICAL behavior of materials, *BIOMATERIALS, *MAGNESIUM alloys, *CHEMICAL decomposition, *EXTRUSION process, *BIOCOMPATIBILITY
Abstract

Highlights: [•] Sr is an effective grain refiner to backward extruded Mg–Zn–Sr alloy. [•] The improved strength is associated with fine grain and homogenous precipitates. [•] The corrosion properties are decreased with increased Sr concentration. [•] The stable degradation rate is achieved after backward extrusion. [•] High biocompatibility is observed by extract assay method using L929 cell line. [Copyright &y& Elsevier]

Published
2014
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300. Effect of microalloying with rare-earth on recrystallization behaviour and damping properties of Mg sheets.

Author

Ma, Ning, Peng, Qiuming, Pan, Junling, Li, Hui, and Xiao, Wenlong

Subjects
*MICROALLOYING, *MAGNESIUM, *RARE earth metals, *RECRYSTALLIZATION (Metallurgy), *DAMPING (Mechanics), *MECHANICAL properties of metals
Abstract

Highlights: [•] Rare earth additions accelerate recovery, but retard recrystallization. [•] Internal peak at mediate temperatures corresponds to grain boundary relaxation. [•] Internal peak at elevated temperature is a recrystallization peak. [•] Grain size, basal texture and dislocation density affect damping remarkably. [ABSTRACT FROM AUTHOR]

Published
2014
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