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H2-Induced coalescence of Pt nanoparticles for the preparation of ultrathin Pt nanowires with high-density planar defects

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NANOSCALE 2019年第31期11卷 14828-14835页

作者： Liu, Yaming Wang, Chaoqi Wang, Weicong Guo, Ruiyun Bi, Wei Guo, Yanjun Jin, Mingshang Xi An Jiao Tong Univ Frontier Inst Sci & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Construction of planar defects within a metallic catalyst can significantly improve its catalytic performance. However, it remains a huge challenge to introduce planar defects during the synthesis of metallic catalysts. In this work, we have reported an effective approach for the preparation of Pt nanowires with high-density planar defects. The success of the approach mainly relies on the attaching and merging of small Pt nanoparticles at low temperatures with the assistance of H-2. By comparing the catalytic activities of Pt nanowires with high-density planar defects and commercial Pt/C catalysts toward methanol oxidation reactions, we show that the existence of planar defects can markedly enhance the electrocatalytic performance of the Pt nanowires. The Pt nanowires of 2.0 nm in diameter show a factor of 6.1 enhancement in specific activity and a factor of 5.4 enhancement in mass activity, respectively, for this reaction, compared to the commercial Pt/C catalyst. The method developed in this work could be an effective route to introduce planar defects within Pt catalysts, endowing them with much enhanced catalytic properties.

关键词： Catalyst activity

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MHD Simulations Preliminarily Predict The Habitability and Radio Emission of TRAPPIST-1e

arXiv

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arXiv 2025年

作者： Wang, BoRui Ye, ShengYi Varela, J. Luo, XinYi Department of Earth and Space Sciences Southern University of Science and Technology Shenzhen518055 China Institute for Fusion Studies University of Texas AustinTX78712 United States State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Context. As the closest Earth-like exoplanet within the habitable zone of the M-dwarf star TRAPPIST-1, TRAPPIST-1e exhibits a magnetic field topology that is dependent on space weather conditions. Variations in these conditions influence its habitability and contribute to its radio emissions. Aims. Our objective is to analyze the response of different terrestrial magnetosphere structures of TRAPPIST-1e to various space weather conditions, including events analogous to coronal mass ejections (CMEs). We assess its habitability by computing the magnetopause standoff distance and predict the resulting radio emissions using scaling laws. This study provides some priors for future radio observations. Methods. We perform three-dimensional magnetohydrodynamic (MHD) simulations of the TRAPPIST-1e system using the PLUTO code in spherical coordinates. Assuming TRAPPIST-1e possesses various Earth-like magnetospheres, we analyze the impact of four distinct space weather conditions on its magnetospheric topology. The space weather parameters range from sub-Alfvénic conditions to CMEs. Results. Our analysis indicates that the predicted habitability and radio emission of TRAPPIST-1e strongly depend on the planet’s magnetic field intensity and magnetic axis inclination. Within sub-Alfvénic, super-Alfvénic, and transitional stellar wind regimes, the radio emission intensity positively correlates with both planetary magnetic field strength and axial tilt, while planetary habitability, quantified by the magnetopause standoff distance, shows a positive correlation with magnetic field strength and a negative correlation with magnetic axis tilt. If TRAPPIST-1e possesses a magnetic field strength and axial tilt comparable to Earth’s (∼ 0.32G and ∼ 23.5◦). its magnetosphere can effectively shield the planetary surface from stellar wind erosion even under severe space weather conditions (e.g., CME events). However, for larger axial tilts (∼ 45◦), a stronger planetary magnetic field would be

关键词： Plasma magnetohydrodynamic waves

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Enhanced Nucleate Pool Boiling by Coupling the Pinning Act and Cluster Bubble Nucleation of Micro-nano Composited Surfaces

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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2020年 157卷 119979-119979页

作者： Liu, Bin Yu, Lingmin Zhang, Yonghai Di Marco, Paolo Wei, Jinjia Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Peoples R China Xian Technol Univ Sch Mat & Chem Engn 2 Xuefu Rd Xian 710021 Peoples R China Univ Pisa Dept Energy Syst Construct & Terr Engn I-56122 Pisa Italy Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

A new idea by coupling the pinning act of the micro-pin-fins and the cluster bubble nucleation of nonuniform nanowalls, was proposed to improve the boiling performance on micro-nano composited surface in the low surface tension liquid. To realize this idea, the uniform/nonuniform nanowalls were composited on the smooth surface and micro-pin-finned surfaces. The pool boiling performance of a smooth surface, the uniform/nonuniform nanowall surfaces, micro-pin-finned surface, and micro-nano composited surfaces with uniform/nonuniform nanowalls were tested and compared with each other. Both the heat transfer coefficient (HTC) and critical heat flux (CHF) of the micro-nano composited surface with nonuniform nanowalls (named PFNW2) are significantly increased compared to the micro-pin-finned surface. In addition, small bubble departure diameters, high bubble departure frequency and velocity were also found on PFNW2. A unique bubble behavior, named microbubble explosive emission, was observed, which provides a strong evidence for the effectiveness of the method to enhance boiling heat transfer by coupling the pinning act of the micro-pin-fins and the cluster bubble nucleation. It is suggested that high liquid subcooling and modulated nanostructures for bubble departure promotion are both indispensable for further enhancement of HTC and CHF in low surface tension liquid. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Nanowall micro-pin-fin enhanced nucleate boiling microbubble explosive emission pinning act bubble dynamics

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Entropy generation analysis of different solar thermal systems

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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH 2020年第17期27卷 20699-20724页

作者： Rashidi, Saman Yang, Liu Khoosh-Ahang, Ali Jing, Dengwei Mahian, Omid Semnan Univ Fac New Sci & Technol Dept Energy Semnan Iran Southeast Univ Sch Energy & Environm Key Lab Energy Thermal Convers & Control Minist Educ Nanjing Peoples R China Islamic Azad Univ Dept Mech Engn Semnan Branch Semnan Iran Xi An Jiao Tong Univ Int Res Ctr Renewable Energy State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Peoples R China

The entropy generation analysis is an approach to optimize the performance of different thermal systems by investigating the related irreversibilities of the system. This paper provides a concise review of the entropy generation analysis performed for different solar thermal energy systems including solar collectors, solar heaters, solar heat exchangers, and solar stills. The mathematical formulation and the equations for calculating the entropy generation are briefly presented. Moreover, main passive techniques including the usage of nanofluids, porous materials, and inserts which are used to improve the efficiency of different solar systems are discussed. It is shown that using entropy generation minimization method is an efficient tool to find the optimal design of solar systems. The current review aims to motivate researchers in the field of solar energy for using entropy generation analysis to reduce the lost work and consequently improving the system performance.

关键词： Entropy generation Solar thermal energy systems Irreversibilities Optimization

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Recent advancement in induced-charge electrokinetic phenomena and their micro- and nano-fluidic applications

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ADVANCES IN COLLOID AND INTERFACE SCIENCE 2020年 280卷 102159-102159页

作者： Feng, Huicheng Chang, Honglong Zhong, Xin Wong, Teck Neng Northwestern Polytech Univ Unmanned Syst Res Inst Xian 710072 Peoples R China Northwestern Polytech Univ MOE Key Lab Micro & Nano Syst Aerosp Xian 710072 Peoples R China Northwestern Polytech Univ Yangtze River Delta Res Inst Taicang 215400 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Nanyang Technol Univ Sch Mech & Aerosp Engn 50 Nanyang Ave Singapore 639798 Singapore

Induced-charge electrokinetics (ICEK) remains a hot topic due to its promising applications in micro- and nanofluidics. Over the past decade, researchers have made a great advancement in both fundamental studies and application developments. They captured (I) a flow reversal in induced-charge electroosmosis (ICEO) and attributed it to the phase delay effect of ions, (II) a chaotic ICED and attributed it to the concentration polarization in the bulk solution, (III) a non-quadratic correlation for ICEO of non-Newtonian fluids and attributed it to the power-law viscosity, (IV) an induced-charge electrophoretic (ICEP) rotation of Janus doublets, etc. Furthermore, various ICEK-based micro- and nano-fluidic devices have been developed, namely, micropumps, particle focusers, trappers, sorters, and nanopore ion diodes. The present article provides a comprehensive review on the recent advancement of ICEK. Firstly, the fundamental studies of ICEK are introduced;then the micro- and nano-fluidic applications based on ICEK are presented;lastly, promising future directions for both fundamental and applications are discussed. This review presents the basic framework of ICEK, and can facilitate the development of ICEK-based applications. (C) 2020 Elsevier B.V. AU rights reserved.

关键词： Induced-charge electrokinetics Microlluidics nanofluidics

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Mechanistic Study on Adsorption Desulfurization Using Modified Graphene

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INDUSTRIAL & engineering CHEMISTRY RESEARCH 2019年第24期58卷 10589-10598页

作者： Zhang, Peng Mao, Xiangyang Yang, Bolun Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

To enhance the adsorption desulfurization performance of graphene, graphene oxide was first hydrophobically modified by using dodecylamine and then reduced. Adsorption desulfurization experiments were performed on graphene with different degrees of reduction, where dibenzothiophene (DBT) was selected as thiophenic sulfur. FTIR, XRD, SEM, EDS, XPS, contact angle test, and elemental analysis showed that dodecylamine was successfully grafted onto a graphene surface, which could enhance the hydrophobic properties of graphene and effectively prevent the agglomeration of graphene sheets during the reduction process. Adsorption experiments showed that graphene with a higher degree of reduction had a larger DBT adsorption capacity. Density functional theory plus dispersion force correction calculation results showed that graphene with intact pi-conjugated structure had the highest adsorption energy for DBT. Further population analysis showed that this pi-pi interaction was mainly caused by the dispersion force. The modification process can effectively recover the pi-conjugated structure of graphene and enhance the pi-pi interaction with the thiophenic sulfur.

关键词： Thiophenes Redox reactions Adsorption Two dimensional materials Chemical structure

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Intelligent recognition of severe slugging in a long-distance pipeline-riser system

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EXPERIMENTAL THERMAL AND FLUID SCIENCE 2020年 113卷 110022-000页

作者： Xu, Qiang Li, Wensheng Liu, Weizhi Zhang, Xuemei Yang, Chenyu Guo, Liejin Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China CNPC Tubular Goods Res Inst State Key Lab Performance & Struct Safety Petr Tu Xian 710077 Peoples R China

In this work, experiments on flow regimes during two-phase flow in a long-distance pipeline-riser system were carried out. The test loop with inner diameter 46 mm consists of a long horizontal pipeline with length 1657 m, followed by a 30 in downward inclined section, and ended at an S-shaped riser with height 11.2 m. A simple method utilizing pressure signals and artificial neural networks is proposed to identify the flow regimes. Firstly, characteristic parameters of pressure signals in time-domain and frequency-domain are extracted, then they are reduced by principal component analysis, and finally flow regimes are recognized by artificial neural networks. The influence of pressure signals at different positions along the pipeline, which includes the horizontal section, the inclined section, the riser section and the separator, on the overall recognition rate is discussed. Higher recognition rates can be achieved by using pressure signals at and near the bottom of the riser rather than pressure signals at other locations along the pipeline. Additionally, a higher recognition rate can be obtained using the pressure difference of the riser instead of the pressure signal. Based on pressure signals at and near the bottom of the riser, when flow regimes are divided into two categories, a satisfactory recognition rate of 93% can be obtained with the signal length of 60 s;When the signal length exceeds 120 s, the recognition rate is about 96%, and it remains unchanged as the signal length increases;When flow regimes are classified into four categories, the recognition rate is about 90% if the signal length exceeds 120 s and remains unchanged as the signal length increases.

关键词： Two-phase flow flow regime Regime recognition Pressure oscillation Pipeline-riser

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Heat transfer characteristics of subcooled water in a hypervapotron under high mass fluxes and high heat fluxes

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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2019年 129卷 580-590页

作者： Zhu, Ge Bi, Qincheng Yan, Jianguo Wang, Teng Zhao, Jinle Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Xian Univ Technol Inst Water Resources & Hydroelect Engn Xian 710048 Shaanxi Peoples R China

In order to investigate the heat transfer characteristics of hypervatron in the divertor dome of the International Thermonuclear Experimental Reactor (ITER), the off-center electrically heating method was used simulate the one-side heating condition in the engineering application. The heat transfer experiments of subcooled water were carried out in a vertically upward hypervapotron under the system parameters as follows: system pressure P = 2.7, 3.2, 3.7 MPa, mass flux G = 2000-5000 kg.m(-2).s(-1), and equivalent one-side radiating heat flux q(e) = 2-5 MW.m(-2). The effects of parameters on heat transfer were discussed in detail. The results show that the heat transfer coefficient h is significantly affected by G in the single phase (SP) region;the h is synthetically influenced by P, G, q in the partially boiling (PB) region;the h is only affected by q in the fully developed boiling (FDB) region. The experimental data were compared with the typical correlations in single phase region and subcooled boiling region, respectively. The results show that the Dittus-Boelter correlation and the modified Shah correlation have good agreement with the experimental data. The typical CHF correlations for smooth tubes were assessed by the CHF data, the results indicate that experimental Bo(cr) are overpredicted by most CHF correlations, so it can be speculated that the hypervapotron can obtain higher CHF values than smooth tubes. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Hypervapotron Subcooled flow boiling High heat flux CHF ITER

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Unveiling micro- and nanoscale bubble dynamics for enhanced electrochemical water splitting

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Advances in Colloid and Interface Science 2025年 343卷 103544页

作者： Lu, Xinlong Yadav, Devendra He, Baichuan Zhou, Yu Zhou, Liwu Zeng, Zilong Ma, Lijing Jing, Dengwei International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Department of Chemical Engineering Technion - Israel Institute of Technology Haifa3200003 Israel College of Mechanical Engineering Xi'an Shiyou University Shaanxi Xi'an710065 China

Bubbles generated during electrochemical and photoelectrochemical water splitting critically influence efficiency through complex factors, including chemical reactions, species transport, mass transfer at the three-phase interface, and bubble coverage. A detailed understanding of the nucleation, growth, coalescence, and detachment of micro- and nanoscale bubbles is vital for advancing water splitting technologies. Surface-attached bubbles significantly reduce the electrocatalytically active area of electrodes, leading to increased surface overpotential at a given current density. Consequently, their effective removal is pivotal for optimizing the electrolysis process. However, the intricate interplay among single bubble evolution, mass transport, bubble coverage, and overpotential remain inadequately understood. This review explores the fundamental mechanisms underpinning bubble evolution, with an emphasis on the Marangoni effect and its influence on bubble dynamics. Furthermore, recent advancements in understanding individual bubbles on micro and nano-electrodes are highlighted, offering valuable insights into scale-dependent bubble behavior. These findings enrich our knowledge of gas-liquid interfacial phenomena and underscore their industrial significance, presenting opportunities to enhance water splitting performance through optimized bubble dynamics. © 2025

关键词： Electrolysis

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Solar Hydrocarbons: Single-Step, Atmospheric-Pressure Synthesis of C2-C4 Alkanes and Alkenes from CO2

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ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 2023年第27期62卷 e202304470-e202304470页

作者： Song, Rui Li, Zhao Guo, Jiuli Duchesne, Paul N. Qiu, Chenyue Mao, Chengliang Jia, Jia Tang, Sanli Xu, Yang-Fan Zhou, Wenzhe Wang, Lu Sun, Wei Yan, Xiaoliang Guo, Liejin Jing, Dengwei Ozin, Geoffrey A. Xi An Jiao Tong Univ Int Res Ctr Renewable Energy Xian 710049 Shaanxi Peoples R China XianJiaotong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Univ Toronto Dept Chem Solar Fuels Grp 80 St George St Toronto ON M5S 3H6 Canada Anyang Normal Univ Sch Chem & Chem Engn Anyang 455000 Henan Peoples R China Univ Toronto Dept Mat Sci & Engn Toronto ON M5S 3E4 Canada Zhejiang Univ State Key Lab Silicon Mat Hangzhou 310058 Zhejiang Peoples R China Zhejiang Univ Sch Mat Sci & Engn Hangzhou 310058 Zhejiang Peoples R China

Cobalt ferrite (CoFe2O4) spinel has been found to produce C-2-C-4 hydrocarbons in a single-step, ambient-pressure, photocatalytic hydrogenation of CO2 with a rate of 1.1 mmol g(-1) h(-1), selectivity of 29.8 % and conversion yield of 12.9 %. On stream the CoFe2O4 reconstructs to a CoFe-CoFe2O4 alloy-spinel nanocomposite which facilitates the light-assisted transformation of CO2 to CO and hydrogenation of the CO to C-2-C-4 hydrocarbons. Promising results obtained from a laboratory demonstrator bode well for the development of a solar hydrocarbon pilot refinery.

关键词： C-2-C-4 Hydrocarbons CO2 Hydrogenation Cobalt Ferrite Photocatalysis

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