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80 results on '"Jiang, Keren"'

57. Deep understanding of LiCoO2electrode degradation for optimized recycling strategies

Author

Zhang, Difei, Sun, Tianxiao, Jiang, Keren, Zhou, Jigang, Wang, Jian, and Jiang, Huaidong

Abstract

Empowered by a synergistic combination approach of Scanning Transmission X-ray Microscopy (STXM) imaging and X-ray Absorption Near Edge Structure (XANES) spectroscopy, a quantitative analysis on the composition and spatial distribution of the cathode in a failed 18650 LiCoO2(LCO) battery was conducted. Distinct compositional differences between the central and peripheral cathode regions in the failed LCO battery were discerned by utilizing bulk XANES in Total Electron Yield (TEY) and Fluorescence Yield (FY) modes. The central region shows more severe degradation in terms of LCO reduction and excess cathode-electrolyte interface (CEI) buildup. Meanwhile, the STXM technique precisely imaged a specific region of interest in the center of the cathode, covering C, O, and F K-edges, and Co L2,3-edge, to deeply investigate the degradation. Quantitative chemical mapping with spatially resolved XANES spectroscopy, facilitate an in-depth understating of the interfacial reactions on battery electrodes and battery failure fundamentals.

Published
2024
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59. HapticSerpent

Author

Al-Sada, Mohammed, primary, Jiang, Keren, additional, Ranade, Shubhankar, additional, Piao, Xinlei, additional, Höglund, Thomas, additional, and Nakajima, Tatsuo, additional

Published
2018
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69. Scaled-up Direct-Current Generation in MoS2Multilayer-Based Moving Heterojunctions

Author

Liu, Jun, Liu, Feifei, Bao, Rima, Jiang, Keren, Khan, Faheem, Li, Zhi, Peng, Huihui, Chen, James, Alodhayb, Abdullah, and Thundat, Thomas

Abstract

Techniques for scaling-up the direct-current (dc) triboelectricity generation in MoS2multilayer-based Schottky nanocontacts are vital for exploiting the nanoscale phenomenon for real-world applications of energy harvesting and sensing. Here, we show that scaling-up the dc output can be realized by using various MoS2multilayer-based heterojunctions including metal/semiconductor (MS), metal/insulator (tens of nanometers)/semiconductor (MIS), and semiconductor/insulator (a few nanometers)/semiconductor (SIS) moving structures. It is shown that the tribo-excited energetic charge carriers can overcome the interfacial potential barrier by different mechanisms, such as thermionic emission, defect conduction, and quantum tunneling in the case of MS, MIS, and SIS moving structures. By tailoring the interface structure, it is possible to trigger electrical conduction resulting in optimized power output. We also show that the band bending in the surface-charged region of MoS2determines the direction of the dc power output. Our experimental results show that engineering the interface structure opens up new avenues for developing next-generation semiconductor-based mechanical energy conversion with high performance.

Published
2019
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76. Investigation of pH-Induced Protein Conformation Changesby Nanomechanical Deflection.

Author

Thakur, Garima, Jiang, Keren, Lee, Dongkyu, Prashanthi, Kovur, Kim, Seonghwan, and Thundat, Thomas

Subjects
*PH effect, *PROTEIN conformation, *NANOELECTROMECHANICAL systems, *DEFLECTION (Mechanics), *BIOSENSORS, *AMINES, *BIOMARKERS
Abstract

Broad-spectrum biosensing technologiesexamine sensor signals usingbiomarkers, such as proteins, DNA, antibodies, specific cells, andmacromolecules, based on direct- or indirect-conformational changes.Here, we have investigated the pH-dependent conformational isomerizationof human serum albumin (HSA) using microcantilevers as a sensing platform.Native and denatured proteins were immobilized on cantilever surfacesto understand the effect of pH on conformational changes of the proteinwith respect to the coupling ligand. Our results show that protonationand deprotonation of amino acid residues on proteins play a significantrole in generating charge-induced cantilever deflection. Surface plasmonresonance (SPR) was employed as a complementary technique to validatethe results. [ABSTRACT FROM AUTHOR]

Published
2014
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77. Rapid label-free detection of E. coliusing antimicrobial peptide assisted impedance spectroscopy

Author

Jiang, Keren, Etayash, Hashem, Azmi, Sarfuddin, Naicker, Selvaraj, Hassanpourfard, Mahtab, Shaibani, Parmiss Mojir, Thakur, Garima, Kaur, Kamaljit, and Thundat, Thomas

Abstract

There is an increasing demand for rapid detection of waterborne pathogens to monitor drinking water safety. We demonstrate a compact, label-free sensor array for rapid detection of Escherichia coli(E. coli) in contaminated water samples using antimicrobial peptide assisted impedimetric sensor platform. Interdigitated electrode arrays immobilized with the antimicrobial peptide Colicin V (ColV) were used to screen the affinity towards different bacterial strains by monitoring impedance variations in real-time. This ColV assisted impedance biosensor exhibited high selectivity towards Gram-negative strains particularly towards E. colistrains. This selective detection of E. colifrom other strains was observed at 102cfu mL−1, which is clinically relevant. The sensor can detect E. colifrom 102to 106cfu mL−1in water sample at pH 7 to 9. These results show that the antimicrobial peptide ColV assisted impedimetric array is capable of rapid, specific detection of E. coliin contaminated water samples.

Published
2015
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78. Boosting Electrochemical Nitrogen Reduction via Axial Coordination Engineering on Single‐Iron‐Atom Catalysts.

Author

Yang, Yang, Wang, Hanlin, Tan, Xuehai, Jiang, Keren, Zhai, Shengli, Li, Yifan, Xie, Xuesong, Chen, Ning, Zhang, Hao, and Li, Zhi

Abstract

Electrocatalytic nitrogen (N2) reduction reaction (NRR) presents a sustainable alternative to the Haber–Bosch process for ammonia (NH3) synthesis. Iron phthalocyanine (FePc) is demonstrated as a promising catalyst for the electrocatalytic NRR. However, FePc with planar symmetric Fe‐N4 sites exhibits poor N2 adsorption and activation capabilities, resulting in an unsatisfactory NRR performance. Herein, an axial oxygen coordination strategy is developed to optimize the local electron distribution on FePc for improving N2 adsorption and activation. The as‐obtained FePc‐O‐CP shows a superior NH3 yield rate (59.72 µg h−1 mg−1cat.) and a considerable Faradaic efficiency (13.76%) in 0.1 m HCl. Density functional theory (DFT) calculations verify that the axial oxygen ligand on FePc inhibits the adsorption of H+ and enhances the N2 adsorption and activation, thereby greatly promoting NH3 generation. This work reveals the significance of regulating the local coordination environment of single‐atom catalysts for improving electrocatalytic NRR performance and provides a feasible strategy for the rational design of atomic‐scale active sites. [ABSTRACT FROM AUTHOR]

Published
2024
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79. Fabrication and Catalytic Property of Cerium Oxide Nanomaterials

Author

Jiang, Keren

Subjects
Cerium Oxide, Anodization, Catalyst, CO Oxidation, Chemistry, Inorganic Chemistry, Materials Chemistry
Abstract

Cerium oxide, or ceria (CeOx: x = 1.5 to 2), has been widely used as a heterogeneous catalyst. Ceria has several properties make it high catalytic active: the fluctuating valence of cerium, the high oxygen storage capacity and high oxygen mobility in the nonstoichiometric ceria. With the high abundance of cerium on earth crust, ceria is a highly effective alternative of the noble metal catalysts. Research has been focused on designing nanostructured ceria and ceria related materials in recent years. The catalytic activity of ceria can be enhanced by the nanoscale effect which can be applied for various designs of catalysts with unique properties. In this thesis, I report two types of ceria-based nanomaterials fabricated by the electrochemical and dispersion-precipitation methods and our study of their physical and chemical properties. First, I discuss the fabrication of a ceria nanoporous membrane using a two-step method of anodization and subsequent calcination. A proposed anodization model involving the oxygen bubbles generation during the process for the growth of the nanoporous membranes is discussed. Second, I illustrate a new type of ceria-titania hybrid nanocomposites for oxidative catalysis. A dispersion-precipitation synthetic method for these catalysts and the evaluation of their oxidative catalytic activity are presented.  Finally, I discuss other potential synthetic methods to produce and further enhance the catalytic activity of these hybrid nanocomposite catalysts. Supervisor: Chin Li Cheung

Published
2011

80. Scaled-up Direct-Current Generation in MoS 2 Multilayer-Based Moving Heterojunctions.

Author

Liu J, Liu F, Bao R, Jiang K, Khan F, Li Z, Peng H, Chen J, Alodhayb A, and Thundat T

Abstract

Techniques for scaling-up the direct-current (dc) triboelectricity generation in MoS 2 multilayer-based Schottky nanocontacts are vital for exploiting the nanoscale phenomenon for real-world applications of energy harvesting and sensing. Here, we show that scaling-up the dc output can be realized by using various MoS 2 multilayer-based heterojunctions including metal/semiconductor (MS), metal/insulator (tens of nanometers)/semiconductor (MIS), and semiconductor/insulator (a few nanometers)/semiconductor (SIS) moving structures. It is shown that the tribo-excited energetic charge carriers can overcome the interfacial potential barrier by different mechanisms, such as thermionic emission, defect conduction, and quantum tunneling in the case of MS, MIS, and SIS moving structures. By tailoring the interface structure, it is possible to trigger electrical conduction resulting in optimized power output. We also show that the band bending in the surface-charged region of MoS 2 determines the direction of the dc power output. Our experimental results show that engineering the interface structure opens up new avenues for developing next-generation semiconductor-based mechanical energy conversion with high performance.

Published
2019
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