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Plasmon-enhanced Performance of Dye-sensitized Solar Cells Based on Electrodeposited Ag Nanoparticles

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Journal of Materials Science & Technology 2014年第1期30卷 1-7页

作者： Xinning luan Ying Wang Department of Mechanical & Industrial Engineering Louisiana State University

In the present work, pulse current deposition is used to deposit evenly distributed and uniformly sized Ag nanoparticles onto a TiO2 nanotube array as photoelectrode in dye-sensitized solar cells （DSSCs）, and the size and amount of loading Ag nanoparticles are controlled by the pulse deposition time. Due to the enhanced light absorption and electron-hole separation caused by plasmon effect, DSSCs based on Ag-modified TiO2 nanotube arrays show higher energy conversion efficiencies than those based on bare nanotubes with the same tube length. Particularly, DSSC based on nanotubes modified using pulse deposition time 1 s/3 s delivers the highest energy conversion efficiency of 1.68% and the largest short-circuit current of 4.37 mA/ cm2, while DSSC consisting of bare nanotubes exhibits efficiency of 1.20% and short-circuit current of 2.27 mA/cm2, which represents a 40% enhancement of cell efficiency in DSSC based on Ag-modified Ti02 nanotubes. It is also noted that overly long pulse deposition time will not further increase DSSC efficiency due to agglomeration of Ag particles. For example, when the pulse deposition time is increased to 2 s/6 s, DSSC based on Ag-modified nanotubes exhibits a lower efficiency of 1.42%. Moreover, high-concentration TiCI4 treatment on TiO2 nanotube arrays can further increase the energy conversion efficiencies to 3.82% and 2.61% for DSSC based on Ag-modified TiO2 nanotubes and DSSC based on bare TiO2 nanotubes, respectively, by significantly creating more surface area for dye loading.

关键词： TiO2 nanotube Dye-sensitized solar cell Pulse current deposition Ag nanoparticle TiCI4 treatment

Thermal Annealing and Graphene Modification of Exfoliated Hydrogen Titanate Nanosheets for Enhanced Lithium-ion Intercalation Properties

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Journal of Materials Science & Technology 2014年第9期30卷 839-846页

作者： Xinning luan Ying Wang Department of Mechanical and Industrial Engineering Louisiana State UniversityBaton Rouge LA 70803 USA

Hydrogen titanate has been considered as a promising lithium intercalation material due to its unique layered structure. In the present work, we fabricate 2D graphene/hydrogen titanate hybrid nanosheets for application as anode materials in lithium-ion batteries. H2Ti307 nanosheets are synthesized by exfoliation of a layered precursor via interacting bulky tetrabutylammonium （TBA＋） cations, followed by ion exchange with Na＋ ions and washing with water. The as-prepared hydrogen titanate nanosheets are well-dispersed exhibiting ultra-thin thickness with a lateral size up to a few micrometers. The sample is then annealed at 450, 650 Rnd 850 ℃, to optimize its Li＋-intercalation property. Heating at 450 ℃ leads to well-crystallized hydrogen titanate with a trace amount of TiO2. Heating at 650 and 850 ℃ results in mixed sodium titanates, since some sodium ions in the interlayer structure cannot be washed away and become chemically bonded to [TiO6] octahedra at high temperatures. Electrochemical properties of all the four samples are then evaluated by charged/discharged for 100 electrochemical cycles at 0.01-2.5 V vs. Li＋/Li at a specific current of 170 mA g-1. The unannealed hydrogen titanate delivers the highest initial discharge capacity of 130.5 mA h g-l, higher than 124.6 mA h g-1 from hydrogen titanate annealed at 450 ℃, as well as 101.3 and 63.8 mA h g-1 from hydrogen titanate annealed at 650 and 850℃, respectively, due to the high surface area from well-dispersed unannealed nanosheets. However, after 100 electrochemical cycles, well-crystallized hydrogen titanate annealed at 450 ℃ retain the highest charge capacity of 115.2 mA h g-1, corresponding to a capacity retention of 92.5%, while unannealed hydrogen titanate exhibits a final capacity of 72.1 mA h g-1 and a capacity retention of only 55.2%. To further improve energy density of lithium-ion battery, graphene/hydrogen titanate hybrid nanosheets are fabricated by adding graphene nanosheets into hydrogen titanates

关键词： Hydrogen titanate Sodium titanate Graphene nanosheets Exfoliation process Lithium-ion battery

Neural network-based H∞ filtering for nonlinear systems with time-delays

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Journal of Systems Engineering and Electronics 2008年第1期19卷 141-147页

作者： luan Xiaoli Liu Fei Inst. of Automation Jiangnan Univ. Wuxi 214122 P. R. China

A novel H∞ design methodology for a neural network-based nonlinear filtering scheme is addressed. Firstly, neural networks are employed to approximate the nonlinearities. Next, the nonlinear dynamic system is represented by the mode-dependent linear difference inclusion （LDI）. Finally, based on the LDI model, a neural network-based nonlinear filter （NNBNF） is developed to minimize the upper bound of H∞ gain index of the estimation error under some linear matrix inequality （LMI） constraints. Compared with the existing nonlinear filters, NNBNF is time-invariant and numerically tractable. The validity and applicability of the proposed approach are successfully demonstrated in an illustrative example.

关键词： H∞ filtering nonlinear system time-delay neural network linear matrix inequality

Synthesis, crystal structure, photodegradation kinetics and photocatalytic activity of novel photocatalyst ZnBiYO_4

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Journal of Environmental Sciences 2015年第3期27卷 51-61页

作者： Yanbing Cui Jingfei luan State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 A and c = 10.014323 A. The band gap of ZnBiYO4 was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiY04 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 rain-1 for ZnBiYO4 and N-doped TiO2, respectively. After visible hght irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO24- and NO3^-, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatog- raphy-mass spectrometry. The ZnBiYO4/（visible light） photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.

关键词： ZnBiYO4 and N-doped TiO2Methyl orangeVisible light irradiationPhotodegradation pathwayStructural properties

Chung＇s Law of the Iterated Logarithm for Subfractional Brownian Motion

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Acta Mathematica Sinica,English Series 2017年第6期33卷 839-850页

作者： Na Na luan School of Insurance and Economics University of International Business and Economics Beijing 100029 P. R. China

Let XH = {xH（t）,t ∈ R＋} be a subfractional Brownian motion in Rd. We provide asufficient condition for a self-similar Gaussian process to be strongly locally nondeterministic and show that XH has the property of strong local nondeterminism. Applying this property and a stochastic integral representation of XH, we establish Chung＇s law of the iterated logarithm for XH.

关键词： Subfractional Brownian motion self-similar Gaussian processes small ball probability,Chung's law of the iterated logarithm

SE Asian Cenozoic Larger Foraminifera:Taxonomic Questions,Apparent Radiation and Abrupt Extinctions

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Journal of Earth Science 2022年第6期33卷 1378-1399页

作者： Peter Lunt Xiwu luan College of Earth Science and Engineering Shandong University of Science and Technology(SDUST)Qingdao266579China Stratos Energy Advisors Kuala LumpurMalaysia

The Cenozoic larger foraminifera are important for biostratigraphy in SE *** review examines the taxonomic inconsistencies of this group and especially the confusion over concepts of evolution,migration,radiation and *** is proposed that from the Mediterranean to Indo-Pacific,Latest Eocene through Miocene,larger foraminifera populations were more homogenous than previously *** show a slow morphological radiation interrupted by several *** pattern is superimposed on a long-term decline in larger foraminiferal *** dating of the major biostratigraphic events are *** main lineages of larger foraminifera can be classified by their evolutionary *** classically“large”genera have highly peramorphic trends achieved through strong orthoselection,and these lineages were the most severely hit by a series of Mid-Eocene to Mid-Miocene extinction *** carbonate facies taxa that are traditionally grouped with the larger foraminifera are characterised by weak paramorphism,and these were much less affected by the extinction *** of these weakly peramorphic forms underwent Latest Miocene to recent radiation to and locally become rock-forming *** three major and one minor larger foraminiferal extinction events since the Mid Eocene coincide with abrupt tectonic events across SE ***,there are probably multiple causes for these extinctions,including global climatic changes.

关键词： larger foraminifera evolution biostratigraphy extinction

Catellani Reaction: An Enabling Technology for Vicinal Functionalization of Aryl Halides by Palladium(o)/Norbornene Cooperative Catalysis

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Chinese Journal of Chemistry 2021年第6期39卷 1690-1705页

作者： Sichan Dong Xinjun luan Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry&Materials ScienceNorthwest UniversityXi’anShaanxi 710127China

The Catellani reaction,originally discovered by Catellani in 1997,and further developed by Catellani,Lautens and others,has emerged as a powerful strategy for the synthesis of polysubstituted arenes,which would be difficult to access via traditional *** this process,both ortho-and/pso-positions of aryl halides could be functionalized simultaneously with different electrophiles and terminating agents under the cooperative catalysis of palladium and norbornene(NBE).This review focuses on the significant progress of such transformations,and the section of typical Catellani reactions is divided into five parts according to the functionalization mode of ortho-C-H bond:alkylation,arylation,amination,acylation or thiolation.

关键词： Catellani reaction Palladium Domino reaction C-H activation Vicinal functionalization

Nickel(hydro)oxide/graphdiyne Catalysts for Efficient Oxygen Production Reaction

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Chemical Research in Chinese Universities 2021年第6期37卷 1268-1274页

作者： luan Xiaoyu XUE Yurui Science Center for Material Creation and Energy Conversion School of Chemistry and Chemical EngineeringInstitute of Frontier and Interdisciplinary ScienceShandong UniversityJinan250100P.R.China

The transition metal-based materials have been regarded as promising electrocatalysts for oxygen evolution reaction(OER).However,achieving higher efficiency is largely limited by the valence states of metal ***,different graphdiyne(GDY)-nickel composites were designed and synthesized[Ni(OH)_(2)/GDY,NiOOH/GDY,and NiO_(x)/GDY]as the electrocatalysts for *** NiO_(x)/GDY possessing the mixed valence states can drive the OER more efficiently than Ni(OH)_(2)/GDY and NiOOH/***_(x)/GDY gives the smallest overpotential of 310 mV at 10 mA/cm^(2) for OER,which is even superior to commercial RuO_(2)*** results reveal that not only the fast charge transfer induced by GDY but also the prominent roles of mixed Ni^(2+)/Ni^(3+) valence states boost the OER electrocatalytic *** presence of the mixed valence state was demonstrated to be helpful for the charge transfer,resulting in the enhancement of the catalytic *** work may provide a new direction to design and fabricate high-performance materials for OER and beyond.

关键词： Graphdiyne Carbon material Heterojunction catalyst Oxygen evolution reaction Water splitting

Identifying Influential Spreaders in Complex Networks by Considering the Impact of the Number of Shortest Paths

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Journal of Systems Science & Complexity 2021年第6期34卷 2168-2181页

作者： luan Yangyang BAO Zhongkui ZHANG Haifeng School of Mathematical Science Anhui UniversityHefei 230601China

The study on how to identify influential spreaders in complex networks is becoming increasingly *** studies demonstrate that considering the shortest path length can improve the accuracy of identification,but which ignore the influence of the number of shortest *** many cases,even though the shortest path length of two nodes is rather larger,their interaction influence is also significant if the number of shortest paths between them is *** by this fact,the authors propose an improved centrality index(ICC)based on well-known closeness centrality and a semi-local iterative algorithm(semi-IA)to study the impact of the number of shortest paths on the identification of the influential *** comparing with several traditional centrality indices,such as degree centrality,k-shell decomposition,betweenness centrality and eigenvector centrality,the experimental results on real networks indicate that the ICC index and semi-IA have a better performance,regardless of the identification capability or the resolution.

关键词： Complex networks influential spreader number of shortest paths