Publications by authors named "Rongyao Wang"

9 Publications

  • Page 1 of 1

Peroxydisulfate activation by LaNiO nanoparticles with different morphologies for the degradation of organic pollutants.

Water Sci Technol 2022 Jan;85(1):39-51

School of Water Conservancy and Environment, University of Jinan, Jinan 250022, China E-mail:

A series of LaNiO perovskite nanoparticles with different morphologies, such as spheres, rods and cubes, were prepared through co-precipitation and hydrothermal methods, and used as the catalysts for peroxydisulfate (PDS) activation. The physical and chemical characterization of LaNiO perovskites was performed, including X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen isotherm absorption (BET), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The LaNiO with different shapes showed different activities in Acid Orange 7 (AO7) degradation. Sphere-like LaNiO exhibited the highest catalytic activity, which is probably due to the largest specific surface area, higher proportion of reductive Ni and the higher electron transfer ability. The radical scavenging experiments and electron paramagnetic resonance (EPR) revealed the production of massive sulfate radicals (SO) and hydroxyl radicals (OH) during the oxidation. Finally, the possible mechanisms of PDS activation and AO7 degradation were proposed. The prepared LaNiO perovskites also showed excellent reusability and stability.
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http://dx.doi.org/10.2166/wst.2021.504DOI Listing
January 2022

Persulfate activation by ferrocene-based metal-organic framework microspheres for efficient oxidation of orange acid 7.

Environ Sci Pollut Res Int 2022 May 17;29(23):34464-34474. Epub 2022 Jan 17.

School of Water Conservancy and Environment, University of Jinan, Jinan, 250022, China.

Ferrocene-based metal-organic framework with different transition metals (M-Fc-MOFs, M = Fe, Mn, Co) was synthesized by a simple hydrothermal method and used as a heterogeneous catalyst for persulfate activation. The samples were characterized by X-ray diffraction, transmission electron microscopy, X-ray electron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Meanwhile, the influences of factors such as catalyst dosage, persulfate concentration, and pH on the degradation of acid orange 7 (AO7) were studied in detail. The results showed that hollow cobalt-based ferrocenyl metal-organic framework microspheres (Co-Fc-MOFs) exhibited the best catalytic performance, which is closely related to the synergy of Fc/Fc and Co(II)/Co(III) cycles in persulfate activation. Free radical quenching studies indicated that both sulfate and hydroxyl appeared to contribute to the degradation of AO7.
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http://dx.doi.org/10.1007/s11356-022-18669-2DOI Listing
May 2022

Vector Exceptional Points with Strong Superchiral Fields.

Phys Rev Lett 2020 Feb;124(8):083901

Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education, Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing 100081, China.

Exceptional points (EPs), branch points of complex energy surfaces at which eigenvalues and eigenvectors coalesce, are ubiquitous in non-Hermitian systems. Many novel properties and applications have been proposed around the EPs. One of the important applications is to enhance the detection sensitivity. However, due to the lack of single-handed superchiral fields, all of the proposed EP-based sensing mechanisms are only useful for the nonchiral discrimination. Here, we propose theoretically and demonstrate experimentally a new type of EP, which is called a radiation vector EP, to fulfill the homogeneous superchiral fields for chiral sensing. This type of EP is realized by suitably tuning the coupling strength and radiation losses for a pair of orthogonal polarization modes in the photonic crystal slab. Based on the unique modal-coupling property at the vector EP, we demonstrate that the uniform superchiral fields can be generated with two beams of lights illuminating the photonic crystal slab from opposite directions. Thus, the designed photonic crystal slab, which supports the vector EP, can be used to perform surface-enhanced chiral detection. Our findings provide a new strategy for ultrasensitive characterization and quantification of molecular chirality, a key aspect for various bioscience and biomedicine applications.
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http://dx.doi.org/10.1103/PhysRevLett.124.083901DOI Listing
February 2020

Amplification of the molecular chiroptical effect by low-loss dielectric nanoantennas.

Nanoscale 2017 May;9(17):5701-5707

School of Physics and Beijing Key Laboratory of Nanophotonics & Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, China.

We report here the chiroptical amplification effect occurring in the hybrid systems consisting of chiral molecules and Si nanostructures. Under resonant excitation of circularly polarized light, the hybrid systems show strong CD induction signals at the optical frequency, which arise from both the electric and magnetic responses of the Si nanostructures. More interestingly, the induced CD signals from Si-based dielectric nanoantennas are always larger than that from Au-based plasmonic counterparts. The related physical origin was disclosed. Furthermore, compared to the Au-based high-loss plasmonic nanoantennas, Si-based low-loss structures would generate negligible photothermal effect, which makes Si nanoantennas an optimized candidate to amplify molecular CD signals with ultralow thermal damage. Our findings may provide a guideline for the design of novel chiral nanosensors, which are applicable in the fields of biomedicine and pharmaceutics.
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http://dx.doi.org/10.1039/c7nr01527eDOI Listing
May 2017

A giant chiroptical effect caused by the electric quadrupole.

Nanoscale 2017 Apr;9(16):5110-5118

School of Physics and Beijing Key Laboratory of Nanophotonics & Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, 100081, China.

Recently, there has been great interest in studying ultrasensitive detection and characterization of biomolecules using plasmonic particles, because they are of considerable importance in biomedical science and pharmaceutics. So far, all the theories on plasmon-induced circular dichroism (CD) have been based on the dipole approximation; the electric quadrupolar contribution is generally considered to be relatively small and neglected. Here we demonstrate that the electric quadrupolar contribution not only cannot be ignored, but it also plays a key role in many cases. Particularly, for the chiral medium that possesses preferential molecular orientations and is located at the hotspot of plasmonic nanostructures, the plasmonic CD strength contributed by molecular electric quadrupoles (EQs) can be two orders of magnitude higher than that contributed by molecular electric/magnetic dipoles. Unlike the case of the dipole approximation, molecular EQ associated plasmonic CD activity appears mainly at the plasmonic resonance absorptions that facilitate the optically enhanced near-field with steep electric field gradients, and is correlated with the boosted emission rate of a molecular EQ. Based on such physical understandings, we can design nanostructures to realize a giant chiroptical effect using the EQ contribution according to the requirements, which provide a new strategy for ultrasensitive detection and quantification of molecular chirality.
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http://dx.doi.org/10.1039/c6nr09419hDOI Listing
April 2017

Plasmon-induced strong interaction between chiral molecules and orbital angular momentum of light.

Sci Rep 2015 Dec 14;5:18003. Epub 2015 Dec 14.

School of Physics and Beijing Key Laboratory of Nanophotonics &Ultrafine Optoelectronic Systems, Beijing Institute of Technology, 100081, Beijing, China.

Whether or not chiral interaction exists between the optical orbital angular momentum (OAM) and a chiral molecule remains unanswered. So far, such an interaction has not been observed experimentally. Here we present a T-matrix method to study the interaction between optical OAM and the chiral molecule in a cluster of nanoparticles. We find that strong interaction between the chiral molecule and OAM can be induced by the excitation of plasmon resonances. An experimental scheme to observe such an interaction has been proposed. Furthermore, we have found that the signal of the OAM dichroism can be either positive or negative, depending on the spatial positions of nanocomposites in the cross-sections of OAM beams. The cancellation between positive and negative signals in the spatial average can explain why the interaction has not been observed in former experiments.
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http://dx.doi.org/10.1038/srep18003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4677297PMC
December 2015

Giant circular dichroism enhancement and chiroptical illusion in hybrid molecule-plasmonic nanostructures.

Opt Express 2014 Feb;22(4):4357-70

Recently, there are great interest in studying the interaction between chiral molecules and plasmonic particles, because a weak circular dichroism (CD) signal in the ultraviolet (UV) region from chiral molecules can be both enhanced and transferred to the visible wavelength range by using plasmonic particles. Thus, ultrasensitive probe of tiny amounts of chiral substance by CD are worth waiting for. Here we present another way to strongly enhance CD of chiral molecules by using plasmonic particle cluster, which need not transfer to the visible wavelength. The method to calculate CD of chiral molecules in nanosphere clusters has been developed by means of multiple scattering of electromagnetic multipole fields. Our calculated results show that 2 orders of magnitude CD enhancement in the UV region for chiral molecules can be realized. Such a CD enhancement is very sensitive to the cluster structure. The cluster structure can cause chiroptical illusion in which a mirror symmetry in the CD spectra of opposite enantiomeric molecules is broken. The correction of quantum size effect on the phenomenon has also been considered. Our findings open up an alternative avenue for the ultrasensitive detection and illusion of chiral information.
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http://dx.doi.org/10.1364/OE.22.004357DOI Listing
February 2014

Giant optical activity from the radiative electromagnetic interactions in plasmonic nanoantennas.

Nanoscale 2013 May 26;5(9):3889-94. Epub 2013 Mar 26.

School of Physics, Key Laboratory of Cluster Science of Ministry of Education, Beijing Institute of Technology, Beijing, 100081, P R China.

We fabricate the linear chains of twisted gold nanorods by a facile chiral molecular templating method. In such a chiral plasmonic system, particle-particle separation distances are in the order of the light wavelength and are much larger than the sizes of individual particles. As a result, the inter-particle interactions in this chiral system are mediated mainly by a relatively weak far-field plasmonic coupling, rather than a strong near-field coupling. However, such a chiral system of twisted gold nanorods show a huge surface plasmon based circular dichroism response, with the highest anisotropy factor around 0.027. This is in contrast to the previous studies in which near-field plasmonic coupling is an indispensable prerequisite to obtain strong optical activity from a chiral plasmonic nanostructure. Our study demonstrates here an alternative strategy for achieving huge chiroptical response of a chiral plasmonic nanostructure based on far-field, radiative electromagnetic interactions of metallic nanoparticles. Theoretical simulations show a satisfactory agreement with the experimental results. This study may provide more flexible ways to design chiral plasmon nanostructures with strong CD responses for various applications.
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http://dx.doi.org/10.1039/c3nr00148bDOI Listing
May 2013

Real-time observation of fiber network formation in molecular organogel: supersaturation-dependent microstructure and its related rheological property.

J Phys Chem B 2006 Apr;110(14):7275-80

Biophysics and Micro/nanostructures Lab, Department of Physics, Blk. S12, National University of Singapore, 2 Science Drive 3, Singapore 117542.

Low-molecular mass organic gelators self-organizing into three-dimensional fiber networks within organic solvents have attracted much attention in recent years. However, to date, how the microstructure of fiber network is formed in a gelation process and the key factors that govern the topological structure of a gel network remain to be determined. In this work, we address these issues by investigating the in situ formation of the gel networks in the N-lauroyl-l-glutamic acid di-n-butylamide (GP-1)/propylene glycol (PG) system. By using optical microscopy, the time evolution of the gel network microstructure was investigated under various supersaturation conditions. It is found that supersaturation is one of the key factors that govern the topological structure of a gel network. In particular, the creation of the junctions turns out to be supersaturation-dependent. The rheological experiments further revealed the correlation between topological structure and mechanical properties. It suggests that the rheological properties can be effectively modified by tuning the microstructure topology of the gel network. Our results reported here provide new physical insight into the formation kinetics of a molecular gel. Furthermore, this work could be important in constructing and engineering a supramolecular structure for the purpose of applications.
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http://dx.doi.org/10.1021/jp054531rDOI Listing
April 2006
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