Search

Your search keyword '"Xia, Xing-Hua"' showing total 1,325 results
Start Over Author "Xia, Xing-Hua"
1,325 results on '"Xia, Xing-Hua"'

3. Antenna enhanced infrared photoinduced force imaging in aqueous environment with super-resolution and hypersensitivity

Author

Li, Jian, Pang, Jie, Yan, Zhen-dong, Jahng, Junghoon, Li, Jin, Morrison, William, Liang, Jing, Zhang, Qing-Ying, and Xia, Xing-Hua

Subjects
Physics - Optics
Abstract

Tip enhanced IR spectra and imaging have been widely used in cutting-edge studies for the in-depth understanding of the composition, structure and function of interfaces at the nanoscale. However, molecular monolayer sensitivity has only been demonstrated on solid/gas interfaces. In aqueous environment, the reduced sensitivity due to strong damping of the cantilever oscillation and background IR absorption extremely limits the practical applications of tip enhanced IR nanospectroscopy. Here, we demonstrate hypersensitive nanoscale IR spectra and imaging in aqueous environment with the combination of photoinduced force (PiF) microscopy and resonant antennas. The highly confined electromagnetic field inbetween the tip end and antenna extremely amplifies the photoinduced force to the detectable level, while the excitation via plasmon internal reflection mode minimizes the environmental absorption. A polydimethylsiloxane (PDMS) layer (~1-2 nm thickness) functionalized on the AFM tip has been successfully identified in water with antennas of different sizes. Sampling volume of ~604 chemical bonds from PDMS was demonstrated with sub-10 nm spatial resolution confirmed by electric (E) field distribution mapping on antennas, which strongly suggests the desired requirements for interfacial spectroscopy. This platform demonstrates for the first time the application of photoinduced force microscopy in aqueous environments, providing a brand-new configuration to achieve highly enhanced nanoscale IR signals, which is extremely promising for future research of interfaces and nanosystems in aqueous environments.

Published
2020
Full Text
View/download PDF

6. Tip enhanced IR imaging with sub-10 nm resolution and hypersensitivity

Author

Li, Jian, Jahng, Junghoon, Pang, Jie, Morrison, William, Li, Jin, Lee, Eun Seong, Xu, Jing-Juan, Chen, Hong-Yuan, and Xia, Xing-Hua

Subjects
Physics - Optics, Physics - Instrumentation and Detectors
Abstract

IR spectroscopy has been widely used for chemical identification and quantitative analysis of reactions occurring in a specific time and space domains by measuring an average signal of the entire system1. Achieving IR measurements with nanometer-scale spatial resolution is highly desirable to obtain a detailed understanding of the composition, structure and function of interfaces2-5. The challenges in IR nanoscopy yet exist owing to the small molecular cross section and pristine optical diffraction limit. Although atomic force microscopy (AFM) based techniques, such as scattering-type scanning near-field optical microscopy and photothermal-induced resonance microscopy (PTIR), can acquire IR spectroscopy in a few tens of nanometer scale resolution6-9, IR measurements with monolayer level sensitivity remains elusive and can only be realized under critical conditions10,11. Herein, we demonstrate sub-10 nm spatial resolution sampling a volume of ~360 molecules with a strong field enhancement at the sample-tip junction by implementing noble metal substrates (Au, Ag, Pt) in photo-induced force microscopy (PiFM). This technique shows versatility and robustness of PiFM, and is promising for application in interfacial studies with hypersensitivity and super spatial resolution., Comment: 9 pages;4 figures

Published
2019
Full Text
View/download PDF

12. Molecular Engineering of a Tumor‐Targeting Thione‐Derived Diketopyrrolopyrrole Photosensitizer to Attain NIR Excitation Over 850 nm for Efficient Dual Phototherapy.

Author

Xu, Gang, Song, Yunxia, Jin, Haifeng, Shi, Pengmin, Jiao, Yubo, Cao, Fangzhou, Pang, Jie, Sun, Yanyan, Fang, Lei, Xia, Xing‐Hua, and Zhao, Jian

Subjects
FRONTIER orbitals, REORGANIZATION energy, PHOTODYNAMIC therapy, SULFURATION, REACTIVE oxygen species
Abstract

Photosensitizers with near‐infrared (NIR) excitation, especially above 800 nm which is highly desired for phototherapy, remain rare due to the fast nonradiative relaxation process induced by exciton‐vibration coupling. Here, a diketopyrrolopyrrole‐derived photosensitizer (DTPA‐S) is developed via thionation of carbonyl groups within the diketopyrrolopyrrole skeleton, which results in a large bathochromic shift of 81 nm, endowing the photosensitizer with strong NIR absorption at 712 nm. DTPA‐S is then introduced with a functional biomolecule (N3‐PEG2000‐RGD) via click reaction for the construction of integrin αvβ3 receptor‐targeted nano‐micelles (NanoDTPA‐S/RGD), which endows the photosensitizer with a further superlarge absorption redshift of 138 nm, thus extending the absorption maxima to ≈850 nm. Remarkably, thiocarbonyl substitution increases the nonbonding characters in frontier molecular orbitals, which can effectively suppress the nonradiative vibrational relaxation process via reducing the reorganization energy, enabling efficient reactive oxygen species (ROS) generation under 880 nm excitation. Screened by in vitro and in vivo assays, NanoDTPA‐S/RGD with high water solubility, excellent tumor‐targeting ability, and photodynamic/photothermal therapy synergistic effect exhibits satisfactory phototherapeutic performance. Overall, this study demonstrates a new design of efficient NIR‐triggered diketopyrrolopyrrole photosensitizer with facile installation of functional biomolecules for potential clinical applications. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

15. Key Structure Parameters for Designing High-Performance Substrates of Surface-Enhanced Infrared Absorption Spectroelectrochemistry

Author

Li, Jin, Zhang, Qing-Ying, Yan, Zhendong, Li, Jian, and Xia, Xing-Hua

Abstract

Attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) plays a crucial role in understanding the interfacial reaction mechanisms at the molecular level, achieving an enhancement factor (EF) of up to 103. However, when this technique is integrated with electrochemistry (EC-ATR-SEIRAS), the EF is significantly reduced by ten- to hundred-fold. Thus, understanding of the key parameters that contribute to the EF is of great importance in designing high-performance substrates and extending the application for EC-SEIRAS. In this study, we propose that the structure of the substrate for EC-ATR-SEIRAS consists of an enhancement unit (EU) supported on a conductivity unit (CU). The CU will screen the incident IR light reaching and interacting with the EU, resulting in a smaller EF as the CU thickness increases. Then, we introduce a strategy to optimize the performance of the EC-SEIRAS substrate by assembling a plasmonic antenna array as the EU that is supported on IR-transparent and conductive monolayer graphene as the CU. The established plasmon-enhanced EC-SEIRAS substrate demonstrates much higher IR enhancement, repeatability, and stability.

Published
2024
Full Text
View/download PDF

16. Beta-Cyclodextrin-Modified Covalent Organic Framework Nanochannel for Electrochemical Chiral Recognition of Amino Acids

Author

Wu, Ming-Yang, Mo, Ri-Jian, Chen, Shuang, Rafique, Saima, Bian, Si-Jia, Tang, You-Jie, Li, Zhong-Qiu, and Xia, Xing-Hua

Abstract

The chiral recognition and separation of enantiomers are of great importance for biological research and the pharmaceutical industry. Preparing homochiral materials with adjustable size and chiral binding sites is beneficial for achieving an efficient chiral recognition performance. Here, a homochiral covalent organic framework membrane modified with β-cyclodextrin (CD-COF) was constructed, which was subsequently utilized as an electrochemical sensor for the enantioselective sensing of tryptophan (Trp) molecules. The preferential adsorption of l-Trp over d-Trp at the β-CD sites can enhance the surface charge density and hydrophilicity of the CD-COF membrane, resulting in an increased transmembrane ionic current. Trp enantiomers with concentrations down to 0.28 nM can be effectively discriminated. The l-/d-Trp recognition selectivity increases with the Trp concentration and reaches a value of 19.2 at 1 mM. The selective adsorption of l-Trp to the CD-COF membrane will also hinder its transport, resulting in a l-/d-Trp permeation selectivity of 15.3. This study offers a new strategy to construct homochiral porous membranes and achieve efficient chiral sensing and separation.

Published
2024
Full Text
View/download PDF

21. Nanometer‐Resolved Mapping of Organic Cation Migration Behavior in Methylammonium Lead Halide Perovskites.

Author

Liang, Jing, Lan, Mu‐Hao, Pang, Jie, Xia, Xing‐Hua, and Li, Jian

Subjects
ORGANIC conductors, CRYSTAL grain boundaries, DIFFUSION kinetics, OPTOELECTRONIC devices, CRYSTAL lattices
Abstract

The performance and stability of organic metal halide perovskite (OMHP) optoelectronic devices have been associated with ion migration. Understanding of nanoscale resolved organic cation migration mechanism would facilitate structure engineering and commercialization of OMHP. Here, we report a three‐dimensional approach for in situ nanoscale infrared imaging of organic ion migration behavior in OMHPs, enabling to distinguish migrations along grain boundary and in crystal lattice. Our results reveal that organic cation migration along OMHP film surface and grain boundaries (GBs) occurs at lower biases than in crystal lattice. We visualize the transition of organic cation migration channels from GBs to volume upon increasing electric field. The temporal resolved results demonstrate the fast MA+ migration kinetics at GBs, which is comparable to diffusivity of halide ions. Our findings help understand the role of organic cations in the performance of OMHP devices, and the proposed approach holds broad applicability for revealing migration mechanisms of organic ions in OMHPs based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

46. Synergistic Al−Al Dual‐Atomic Site for Efficient Artificial Nitrogen Fixation.

Author

Biswas, Sudip, Zhou, Jingwen, Chen, Xue‐Lu, Chi, Chen, Pan, Yi‐An, Cui, Peixin, Li, Jian, Liu, Chungen, and Xia, Xing‐Hua

Subjects
HABER-Bosch process, NITROGEN, CHARGE exchange, ACTIVATION energy, NITROGEN fixation, ELECTROLYTIC reduction, DOPING agents (Chemistry), CATALYSTS
Abstract

Synthesis of ammonia by electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the Haber–Bosch process. However, it is commonly obstructed by the high activation energy. Here, we report the design and synthesis of an Al−Al bonded dual atomic catalyst stabilized within an amorphous nitrogen‐doped porous carbon matrix (Al2NC) with high NRR performance. The dual atomic Al2‐sites act synergistically to catalyze the complex multiple steps of NRR through adsorption and activation, enhancing the proton‐coupled electron transfer. This Al2NC catalyst exhibits a high Faradaic efficiency of 16.56±0.3 % with a yield rate of 29.22±1.2 μg h−1 mgcat−1. The dual atomic Al2NC catalyst shows long‐term repeatable, and stable NRR performance. This work presents an insight into the identification of synergistic dual atomic catalytic site and mechanistic pathway for the electrochemical conversion of N2 to NH3. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results