Chaoying Ni

Chaoying Ni

Professor

Director W. M. Keck, Center for Advanced Microscopy and Microanalysis

Department of Materials Science and Engineering

Email : cni@udel.edu
Phone : (302) 831-6359
ISE 250V

Biosketch

Dr. Ni’s general research interest centers on the characterization of novel structures and composites using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Expertise includes electron crystallography and e-beam associated spectroscopy. Active efforts are on the process-structure-property relationships of advanced composites, mesoporous crystals, functionalized nanostructures and assemblies, thin films, interfaces and coherence growths.

Research Interests

In-situ & low-dose electron microscopy

Due to increasing needs for probing dynamic properties of multifunctional responsive materials or to investigate polymeric/bio-materials of high electron-beam sensitivity, we have acquired and/or customized various types of ancillary equipment in the past few years for in-situ or low-dose electron microscopy. Specifically, electrochemical analysis, cryo-microscopy, and mechanical or mechanoelectrical testing in both TEM and SEM for nano- to micro-scale materials or structures are being explored at present.

Nanostructures for desired functions and/or environmental and energy applications.

Nanostructures and assemblies demonstrate unprecedented potentials for novel phenomena and material or structural properties and applications which were not accessible before. A major component of Dr. Ni’s research centers on the fabrication and/or the characterization of designed novel nanostructures and assemblies. In one effort, we were able to control and characterize the structure of Ag nano-crystals grown via a surfactant method and to discover the structural characteristics as mediated by the surfactant molecules in an aqueous solution. Using transmission electron microscopy, this special nanorod was characterized and was found to be a truncated decahedral structure consisting of five crystal units packing along {111} twining planes with five {111} planes on each end and five circumferential {001} side surfaces parallel to a longitudinal direction so as to allow most active crystal planes exposed.

Pharmaceutical materials and polymorphism

A palladium catalyst supported by Si-Thiol, which was a commercially available mercaptopropyl-modified and TMS-passivated amorphous silica, was synthesized and characterized by SEM、TEM、aberration-corrected STEM-HAADF、XRD、FTIR and XPS. Statistical analysis reveals that the catalytic Pd species in Si-Thiol consist of dominant atom clusters (< 2nm), small amount of single atoms (ca. 0.1nm), and trace amount of nanoparticles (< 5nm). Suzuki coupling reaction shows that the catalyst synergistically plays full functions of what the corresponding homogeneous catalyst can offer. It is believed that the atom clusters dominate the total activity and sever as the key active site for Suzuki coupling. The outcomes of the reaction are greatly affected by choice of solvents, and Pd/Si-Thiol is demonstrated to be reusable over multiple times without noticeable loss of activity.

Process-structure-property of multifunctional composites

Multifunctional composites including polymer matrix composites (PMC), metal matrix composites (MMC) and ceramic matrix composites (CMC) remain to be one of my major research interests. I am especially interested in the interfacial structures, reactive-diffusion phenomena and phase formation that usually need to be resolved by electron microscopy and/or in-situ testing. Currently, there are three on-going projects in this area: CNT or CNT yarn reinforced PMC, steel encapsulated MMC and reaction bonded SiC-Si and B4C-SiC-Si CMC. CNTs are well known for outstanding mechanical and other physical or chemical properties. While significant progresses have been made in cooperating CNTs in polymers to form PMCs, multiple challenges remain to be resolved for practical applications. One effort has been to spin continuous CNT-yarns from pre-fabricated CNT forest. Highly aligned CNT-yarn promises to be an ideal structural component for the aerospace industry due to the light weight, remarkable mechanical properties, and other unique physical and chemical attributes of the CNTs. However, contrary to expectations, the mechanical properties of the CNT yarns fabricated by various methods are not only orders of magnitude below the corresponding properties of individual CNTs, but often compare poorly to those of commercial materials such as carbon fiber and Kevlar. The problem originates from a combination of insufficient interactions either from the van der Waals bonding, or from twist to give efficient load transfer between CNTs in the yarn. Thus as the yarn is strained, individual CNTs break prematurely at a relatively low tensile load.

Chip-scale photonic sensors and associated FIB/SEM fabrication

This project exemplifies the quality work enabled by the nanofabrication capability of a Zeiss Auriga 60 FIB/SEM CrossBeam(TM) acquired and installed in 2012. We developed a method for the fabrication of nano-cavity photonic crystals utilizing the FIB/SEM in conjunction with the local injection and etching of XeF2 to demonstrate the accuracy and integrity of the desired nanostructured cavity arrays on chalcogenide micro-beams. The chalcogenide nano-photonic platform achieved superior sensitivity and specificity by means of nano-cavity enhanced photothermal mid-infrared spectroscopy.

Interfaces and epitaxial growths – structural characteristics

The interfaces in composites or at heterojunctions in magnetic or electronic devices play essential roles for applications ranging from advanced composites for extreme environments to next generation solar or fuel cells, data recording and storage, and sensing. In addition to structural dimension and phase constituents or elemental details, crystal orientation and lattice coherency are the key characteristics to be resolved to elucidate material or device behaviors.

Representative Publications

Ning Ye, Joseph P Feser, Sridhar Sadasivam, Timothy S Fisher, Tianshi Wang, Chaoying Ni, Anderson Janotti, Thennal Transpolt Across Metal Silicide-Silicon Interfaces: An Expenmental

 

Comparison between Epitaxial and Non-epitaxial Interfaces, 2016, arXiv preprint arXiv: 1609.01776

 

Xiazhang Li, Wei Zhu, Yu Yin, Xiaowang Lu, Chao Yao, Chaoying Ni, Lal-xAgxFe03/halloysites nanocomposite with enhanced visible light photocatalytic performance, Journal ofMaterzals Science: Materials in Electronics, 2016, 27(5), 4180-4185.

 

Xiazhang Li, Wei Zhu, Xiangym Yan, Xiaowang Lu, Chao Yao, Chaoying M, Hierarchical Lao. 7Ce0.3Fe03/halloysite nanocomposite for photocatalytic degradation of antibiotics, Applied Physics A, (2016) 122, 723. doi:10.1007/s00339-016-0240-3

 

Huan Yang, Hailan Xu, J Kriss Frank, Guangtong Xu, Weiwei Huan, Chaoying Ni, Yuxiang Yang,

 

Influences of Si02/Na20 Molar Ratio on Aging and Chemical Modification of Water Glass, Open Journal oflnorganic Chemistry, 6(2), 2016, 125-134, DOI: 10.4236/0Jic.2016.62008

 

Xiazhang Li, Zuosong Zhang, Chao Yao, Xiaowang Lu, Xiaobing Zhao, Chaoying M, AttapulgiteCe02/MoS2 temary nanocomposite for photocatalytic oxidative desulfurization, Applied Surface Science, 2016, 364, 589-596, doi:10.1016/j.apsusc.2015.12.196

 

Xiazhang Li, Yu Yin, Chao Yao, Shixiang Zuo, Xiaowang Lu, Shiping Luo, Chaoying Ni, LalxCexMn03/attapulgite nanocomposites as catalysts for NO reduction with M-13 at low temperature, Partzcuology, 2016, 26, 66-72

 

Yufu Zhu; Chengfeng Yu; Chaoying Ni, Low temperature synthesis and photocatalytic perfonnance of mngsten trioxide film, Surface Engineermg, 32(1), 2016, 26-31 http://dx.d0i.org/10.1179/1743294415Y.0000000104

 

Xiaoqian Ma, Jinglin Liu, Chaoying Ni, David C Maltin, D Bruce Chase, John F Rabolt, Estrella Laredo, Dinorah Newman, Romina Pezzoli, Alejandro J Muller, Alfredo Bello, Madeleine P.

 

Gordon, Lawson T. Lloyd, and David S. Boucher Poly (3-hexylthiophene) Films Prepared Using

 

Bmary Solvent Mixtures, Journal ofP01ymer Science I Part B: Polymer Physics, 54, 2016, 525610, DOI: 10.1002/p01b.23987

 

Xiazhang Li, Chaoying Ni, Xiaowang Lu, Shlxiang Zuo,Wenjie Liu, Chao Yao, In situ fabrication of Cel-xLax02-õ/palygorskite nanocomposite for efficient catalytic oxidation of CO: effect of La dopmg, Catalysis Science & Technology, 2016, 6, 545-554, DOI: 10.1039/C5CY00909J.

 

Xiaoqian Ma, Jinglin Liu, Chaoymg Ni, David C. Martin, D. Bruce Chase, John F. Rabolt, The effect of collector gap width on the extent of molecular orientation in polymer nanofibers, Journal ofP01ymer Science I Part B: Polymer Physics, 54, 2016, 617-623, DOI: 10.1002/p01b.23944

 

l l. Liang Gong, D. Bruce Chase, Isao Noda, Jinglin Liu, David C. Martin, Chaoying Ni, and John F.

 

Rabolt, Discove1Y of ß-Fonn Crystal Structure in Electrospun Poly[(R)-3-hydroxybutyrate-co(R)-3-hydroxyhexanoate] (PHBHx) Nanofibers: From Fiber Mats to Single Fibers, Macromolecules, 2015, 4807), 6197-6205, DOI: 10.1021/acs.macrom01.5b00638.

 

Jinglin Liu, Bin Wei, Jennifer D. Sloppy, Liangqi Ouyang, Chaoying Ni, and David C. Martin, Direct Imaging of the Electrochemical Deposition of Poly(3,4-2 ethylenedioxythiophene) by Transmission Electron Microscopy, ACS Macro Lett., 2015, 4, 897-900, DOI: 10.1021/acsmacrolett.5b00479

 

G. Hassnain Jaffari, Abdul K. Rumaiz, C. Ni, Emre Yassitepe, M. Bah, S. Ismat Shah, Observation of metastable phase separation and amorphous phase in Fe 67 Co 33 alloy thin films synthesized by pulsed laser depositions, Current Applied Physics, 15(6), 2015, 717-721.

 

Xiazhang Li, Chao Yao, Xiaowang Lu, Yu Yin, Shixiang Zuo, Chaoying Ni, Ti02/Attapulgite Nanocomposite as Photocatalyst: Impact of Phase Transition, Science ofAdvanced Materials, 7, 2015, 1400-1405.

 

Jianqing Chen, Donghui Yang, Dan Song, Jinghua Jiang, Aibin Ma, Michael Z Hu, Chaoying Ni, Recent progress m enhancing solar-to-hydrogen efficiency, Journal ofPower Sources, 280, 2015 649-666.

 

Xiazhang Li, Chao Yao, Xiaowang Lu, Zonglin Hu, Yu Ym, Chaoymg Ni, Halloysite-Ce02-AgBr nanocomposite for solar light photodegradation of methyl orange, Applied Clay Science, 104, 2015 74-80.

 

Xiazhang Li, Fei Deng, Chaoying Ni, Zhigang Chen, Progress in in-situ transmission electron microscopy, Physical Testing and Chemical Analysis Part A: Physical Testing, 51 (4), 2015, 225228, (in Chinese).