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1,067 results on '"Chi, Miaofang"'

156. Site Mixing for Engineering Magnetic Topological Insulators

Author

Liu, Yaohua, primary, Wang, Lin-Lin, additional, Zheng, Qiang, additional, Huang, Zengle, additional, Wang, Xiaoping, additional, Chi, Miaofang, additional, Wu, Yan, additional, Chakoumakos, Bryan C., additional, McGuire, Michael A., additional, Sales, Brian C., additional, Wu, Weida, additional, and Yan, Jiaqiang, additional

Published
2021
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162. Direct visualization of anionic electrons in an electride reveals inhomogeneities

Author

Zheng, Qiang, primary, Feng, Tianli, additional, Hachtel, Jordan A., additional, Ishikawa, Ryo, additional, Cheng, Yongqiang, additional, Daemen, Luke, additional, Xing, Jie, additional, Idrobo, Juan Carlos, additional, Yan, Jiaqiang, additional, Shibata, Naoya, additional, Ikuhara, Yuichi, additional, Sales, Brian C., additional, Pantelides, Sokrates T., additional, and Chi, Miaofang, additional

Published
2021
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173. Colloidal silver diphosphide (AgP2) nanocrystals as low overpotential catalysts for CO2 reduction to tunable syngas

Author

Li, Hui, Wen, Peng, Itanze, Dominique S., Hood, Zachary D., Ma, Xiao, Kim, Michael, Adhikari, Shiba, Lu, Chang, Dun, Chaochao, Chi, Miaofang, Qiu, Yejun, and Geyer, Scott M.

Subjects
Heterogeneous catalysis, Carbon capture and storage, Science, Nanoparticles, lcsh:Q, lcsh:Science, Electrocatalysis, Article
Abstract

Production of syngas with tunable CO/H2 ratio from renewable resources is an ideal way to provide a carbon-neutral feedstock for liquid fuel production. Ag is a benchmark electrocatalysts for CO2-to-CO conversion but high overpotential limits the efficiency. We synthesize AgP2 nanocrystals (NCs) with a greater than 3-fold reduction in overpotential for electrochemical CO2-to-CO reduction compared to Ag and greatly enhanced stability. Density functional theory calculations reveal a significant energy barrier decrease in the formate intermediate formation step. In situ X-ray absorption spectroscopy (XAS) shows that a maximum Faradaic efficiency is achieved at an average silver valence state of +1.08 in AgP2 NCs. A photocathode consisting of a n+p-Si wafer coated with ultrathin Al2O3 and AgP2 NCs achieves an onset potential of 0.2 V vs. RHE for CO production and a partial photocurrent density for CO at −0.11 V vs. RHE (j−0.11, CO) of −3.2 mA cm−2., Conversion of CO2 into value-added chemicals by use of renewable energy is promising to achieve a carbon-neutral energy cycle. Here, the authors show that AgP2 is a stable, selective and efficient syngas catalyst for solar-to-fuel conversion with a 3-fold lower overpotential compared to the benchmark Ag catalyst.

Published
2019

175. Kinetically Controlled Synthesis of Pd–Cu Janus Nanocrystals with Enriched Surface Structures and Enhanced Catalytic Activities toward CO2 Reduction

Author

Lyu, Zhiheng, primary, Zhu, Shangqian, additional, Xu, Lang, additional, Chen, Zitao, additional, Zhang, Yu, additional, Xie, Minghao, additional, Li, Tiehuai, additional, Zhou, Shan, additional, Liu, Jingyue, additional, Chi, Miaofang, additional, Shao, Minhua, additional, Mavrikakis, Manos, additional, and Xia, Younan, additional

Published
2020
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179. Anisotropic Strain Tuning of L10 Ternary Nanoparticles for Oxygen Reduction

Author

Li, Junrui, primary, Sharma, Shubham, additional, Wei, Kecheng, additional, Chen, Zitao, additional, Morris, David, additional, Lin, Honghong, additional, Zeng, Cheng, additional, Chi, Miaofang, additional, Yin, Zhouyang, additional, Muzzio, Michelle, additional, Shen, Mengqi, additional, Zhang, Peng, additional, Peterson, Andrew A., additional, and Sun, Shouheng, additional

Published
2020
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195. Maximizing the Catalytic Performance of Pd@AuxPd1−x Nanocubes in H2O2 Production by Reducing Shell Thickness to Increase Compositional Stability.

Author

Zhang, Yu, Lyu, Zhiheng, Chen, Zitao, Zhu, Shangqian, Shi, Yifeng, Chen, Ruhui, Xie, Minghao, Yao, Yao, Chi, Miaofang, Shao, Minhua, and Xia, Younan

Subjects
CATALYSTS, OXYGEN reduction, SURFACE structure, PRECIOUS metals, SURFACE stability, GOLD alloys, ELECTROCATALYSTS, NANOCRYSTALS
Abstract

We report a simple route based upon seed‐mediated growth to the synthesis of Pd@AuxPd1−x (0.8≤x≤1) core–shell nanocubes. Benefiting from the well‐defined {100} facets and an optimal Au/Pd ratio for the surface, the nanocubes bearing a shell made of Au0.95Pd0.05 work as an efficient electrocatalyst toward H2O2 production, with high selectivity of 93–100 % in the low‐overpotential region of 0.4–0.7 V. When the Au0.95Pd0.05 alloy is confined to a shell of only three atomic layers in thickness, the electrocatalyst is able to maintain its surface structure and elemental composition, endowing continuous and stable production of H2O2 during oxygen reduction at a high rate of 1.62 mol g(Pd+Au)−1 h−1. This work demonstrates a versatile route to the rational development of active and durable electrocatalysts based upon alloy nanocrystals. [ABSTRACT FROM AUTHOR]

Published
2021
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196. Effect of TiO2–SiO2distribution on bimodal microstructure of TiO2-doped α-Al2O3ceramics

Author

Chi, Miaofang, Gu, Hui, Qian, Pengxiang, Wang, Xin, and Wang, Peiling

Abstract

Distribution of TiO2dopants and SiO2impurities in the bimodal microstructure of Al2O3with anisotropic and equiaxed grains is systematically analyzed using analytical electron microscopy (AEM). The TiO2-doped ceramic materials were hot-pressed at 1500 °C in a reducing environment. Different amounts of Ti solutes in the anisotropic or equiaxed grains were observed after removal of the contamination signal stemming from Ti on the surface. SiO2and TiO2exhibit a selective segregation behavior. The boundary between the equiaxed grains is segregated mainly by TiO2but the boundary at the (0001) basal plane of anisotropic grains is covered with a thin amorphous film made up of mostly SiO2. Precipitation of Al2TiO5occurs at high TiO2doping levels.

Published
2022
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197. Atomistic insights into the nucleation and growth of platinum on palladium nanocrystals.

Author

Gao, Wenpei, Elnabawy, Ahmed O., Hood, Zachary D., Shi, Yifeng, Wang, Xue, Roling, Luke T., Pan, Xiaoqing, Mavrikakis, Manos, Xia, Younan, and Chi, Miaofang

Subjects
DISCONTINUOUS precipitation, NANOCRYSTALS, PALLADIUM, TRANSMISSION electron microscopy, PLATINUM, PLATINUM catalysts
Abstract

Despite the large number of reports on colloidal nanocrystals, very little is known about the mechanistic details in terms of nucleation and growth at the atomistic level. Taking bimetallic core-shell nanocrystals as an example, here we integrate in situ liquid-cell transmission electron microscopy with first-principles calculations to shed light on the atomistic details involved in the nucleation and growth of Pt on Pd cubic seeds. We elucidate the roles played by key synthesis parameters, including capping agent and precursor concentration, in controlling the nucleation site, diffusion path, and growth pattern of the Pt atoms. When the faces of a cubic seed are capped by Br−, Pt atoms preferentially nucleate from corners and then diffuse to edges and faces for the creation of a uniform shell. The diffusion does not occur until the Pt deposited at the corner has reached a threshold thickness. At a high concentration of the precursor, self-nucleation takes place and the Pt clusters then randomly attach to the surface of a seed for the formation of a non-uniform shell. These atomistic insights offer a general guideline for the rational synthesis of nanocrystals with diverse compositions, structures, shapes, and related properties. Creating predictable, controllable nanoparticles relies on a mechanistic understanding of their synthesis. Here, through integrated in situ liquid microscopy and first-principles calculations, the authors elucidate the atomistic details involved in the formation of colloidal core-shell nanoparticles. [ABSTRACT FROM AUTHOR]

Published
2021
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198. Neutron diffraction study of magnetism in van der Waals layered MnBi2nTe3n+1.

Author

Ding, Lei, Hu, Chaowei, Feng, Erxi, Jiang, Chenyang, Kibalin, Iurii A, Gukasov, Arsen, Chi, MiaoFang, Ni, Ni, and Cao, Huibo

Subjects
QUANTUM Hall effect, MAGNETISM, MAGNETIC structure, MAGNETIC materials, MAGNETIC crystals, ANOMALOUS Hall effect, NEUTRON diffraction
Abstract

Two-dimensional van der Waals MnBi2nTe3n+1 (n = 1, 2, 3, 4) compounds have been recently found to be intrinsic magnetic topological insulators rendering quantum anomalous Hall effect and diverse topological states. Here, we summarize and compare the crystal and magnetic structures of this family, and discuss the effects of chemical composition on their magnetism. We found that a considerable fraction of Bi occupies at the Mn sites in MnBi2nTe3n+1 (n = 1, 2, 3, 4) while there is no detectable Mn at the non-magnetic atomic sites within the resolution of neutron diffraction experiments. The occupancy of Mn monotonically decreases with the increase of n. The polarized neutron diffraction on the representative MnBi4Te7 reveals that its magnetization density is exclusively accumulated at the Mn site, in good agreement with the results from the unpolarized neutron diffraction. The defects of Bi at the Mn site naturally explain the continuously reduced saturated magnetic moments from n = 1 to n = 4. The experimentally estimated critical exponents of all the compounds generally suggest a three-dimensional character of magnetism. Our work provides material-specified structural parameters that may be useful for band structure calculations to understand the observed topological surface states and for designing quantum magnetic materials through chemical doping. [ABSTRACT FROM AUTHOR]

Published
2021
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199. Back Cover: Significant Roles of Surface Hydrides in Enhancing the Performance of Cu/BaTiO2.8H0.2 Catalyst for CO2 Hydrogenation to Methanol (Angew. Chem. Int. Ed. 1/2024).

Author

He, Yang, Li, Yuanyuan, Lei, Ming, Polo‐Garzon, Felipe, Perez‐Aguilar, Jorge, Bare, Simon R., Formo, Eric, Kim, Hwangsun, Daemen, Luke, Cheng, Yongqiang, Hong, Kunlun, Chi, Miaofang, Jiang, De‐en, and Wu, Zili

Subjects
HYDRIDES, HYDROGENATION, CATALYSTS, METHANOL, COPPER, METHANOL as fuel
Abstract

The article titled "Back Cover: Significant Roles of Surface Hydrides in Enhancing the Performance of Cu/BaTiO2.8H0.2 Catalyst for CO2 Hydrogenation to Methanol" discusses the use of surface hydrides in improving the efficiency of a catalyst for converting CO2 to methanol. The cover picture depicts a BaTiO3 lattice with Cu nanoparticles representing the catalytic process. The researchers, led by Zili Wu, demonstrate that replacing lattice oxygen with hydrides enhances the catalyst's performance. The article provides valuable insights into the reaction mechanism and includes an operando study. [Extracted from the article]

Published
2024
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200. Rücktitelbild: Significant Roles of Surface Hydrides in Enhancing the Performance of Cu/BaTiO2.8H0.2 Catalyst for CO2 Hydrogenation to Methanol (Angew. Chem. 1/2024).

Author

He, Yang, Li, Yuanyuan, Lei, Ming, Polo‐Garzon, Felipe, Perez‐Aguilar, Jorge, Bare, Simon R., Formo, Eric, Kim, Hwangsun, Daemen, Luke, Cheng, Yongqiang, Hong, Kunlun, Chi, Miaofang, Jiang, De‐en, and Wu, Zili

Subjects
COPPER, BARIUM titanate, RESEARCH personnel, CARBON dioxide, HYDRIDES
Abstract

The article titled "Significant Roles of Surface Hydrides in Enhancing the Performance of Cu/BaTiO2.8H0.2 Catalyst for CO2 Hydrogenation to Methanol" explores the use of hydrides in improving the efficiency of catalysts for converting CO2 to methanol. The cover picture depicts a BaTiO3 lattice with Cu nanoparticles representing the catalytic process. The study conducted by Zili Wu et al. demonstrates that replacing lattice oxygen with hydrides enhances the performance of the catalyst. The article is authored by a diverse group of researchers. [Extracted from the article]

Published
2024
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