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Ligand effect in surface atomic sites of group VI B transition metals on ultrathin Pt nanowires for enhanced oxygen reduction

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Nano Research 2024年第6期17卷 5298-5304页

作者： Yuwei He Yueguang chen Renjie Wu zhihe Xiao Mengxian Li Chunfeng Shi Leyu Wang State Key Laboratory of Chemical Resource Engineering College of ChemistryBeijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Petroleum Molecular and Process Engineering SINOPEC Research Institute of Petroleum Processing Co.Beijing 100083China

Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains challenging.Herein,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the surface.These NWs possess uniform sizes and well-controlled atomic arrangements.Compared to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based catalysts.Additionally,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/C.The ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.

关键词： ligand effect oxygen reduction reaction group VI B transition metal ultrathin nanowires multiple oxygen species

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Effects of dynamical spanwise retraction and stretch on flapping-wing forward flights

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Chinese Journal of Aeronautics 2024年第4期37卷 181-202页

作者： Kang LIU Bifeng SONG Ang chen zhihe WANG Dong XUE Wenqing YANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Intelligent Aircraft Research Center Chengdu Technological UniversityChengdu 610031China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China Harbin Institute of Technology Shenzhen 518055China

Birds and bats retract and stretch their wings dynamically during each flap in level flights, implying intriguing mechanisms for the aerodynamic performance improvement of flapping wings. A numerical investigation into the aerodynamic effects of such bio-inspired concept in forward flights has been performed based on a three-dimensional wing in plunging motion and a twosection wing in flapping motion. The currently considered Reynolds number and Strouhal number are Re=1.5×10^(5) and St=0.3, respectively. During the research, the mean angle of attack is varied in relatively wide ranges to achieve lift-thrust interconversion for the wings. The conclusive results show that dynamical spanwise retraction and stretch has induced three absolutely desirable scenarios for the oscillating wings in forward flights, namely producing more lift and consuming less power for a given thrust generation, producing more thrust and consuming less power for a given lift generation, and producing more lift and more thrust while consuming less power. Furthermore,the morphing wings have alleviated periodical aerodynamic load fluctuations compared with the non-morphing baseline. The mechanism of the aerodynamic effects of the bionic morphing mode is analyzed with the aid of field visualization. The current article is the first to reveal the absolute advantages of the bionic spanwise morphing. Hopefully, it may help comprehend the behaviors of natural fliers and provide inspirations for performance enhancement of micro artificial flappingwing vehicles.

关键词： Flapping wing Morphing wing Bionic Aerodynamics Vortex Flight

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OH regulator of highly dispersed Ru sites on host Pd nanocrystals for selective ethanol electro-oxidation

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Nano Research 2024年第5期17卷 3863-3871页

作者： zhihe Xiao Yueguang chen Renjie Wu Yuwei He Chunfeng Shi Leyu Wang State Key Laboratory of Chemical Resource Engineering College of ChemistryBeijing University of Chemical TechnologyBeijing 100029China Research Institute of Petroleum Processing SINOPECBeijing 100083China

The ethanol oxidation reaction(EOR)is crucial in direct alcohol fuel cells and chemical production.However,the electro-oxidation of ethanol molecules to produce acetaldehyde and carbon monoxide can poison the active sites of nanocatalysts,resulting in reduced performance and posing challenges in achieving high activity and selectivity for ethanol oxidation.In this study,we employed a dynamic seed-mediated method to precisely modify highly dispersed Ru sites onto well-defined Pd nanocrystals.The oxyphilic Ru sites serve as"OH valves",regulating water dissociation,while the surrounding Pd atomic arrangements control electronic states for the oxidation dehydrogenation of carbonaceous intermediates.Specifically,Ru0.040@Pd nanocubes(Ru:Pd=0.04 at.%),featuring(100)facets in Ru-Pd4 configurations,demonstrate an outstanding mass activity of 6.53 A·mgPd^(-1) in EOR under alkaline conditions,which is 6.05 times higher than that of the commercial Pd/C catalyst(1.08 A·mgPd-1).Through in-situ experiments and theoretical investigations,we elucidate that the hydrophilic Ru atoms significantly promote the dynamic evolution of H_(2)O dissociation into OHads species,while the electron redistribution from Ru to adjacent Pd concurrently adjusts the selective oxidation of C_(2) intermediates.This host-guest interaction accelerates the subsequent oxidation of carbonaceous intermediates(CH_(3)CO_(ads))to acetate,while preventing the formation of toxic*CHx and*CO species,which constitutes the rate-determining step.

关键词： OH regulator atomic sites ethanol electro-oxidation host-guest interaction

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Characterization of the micro-interfacial interactions of heterogeneous particulate matter(fine-grained sediment and microplastics) with copper ions

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International Journal of Sediment Research 2023年第6期38卷 871-879页

作者： Jing Ou zhihe chen Tung-Chiung Chang Civil Engineering School Sun Yat-sen University Engineering Research Center for Water Security Regulation in Southern China of Guangdong Province Department of Civil Engineering and Geomatics Cheng Shiu University

Particulate matter,such as sediment and microplastics(MPs),in aqueous environments has comparable micro-interfacial characteristics.However,the micro-interfacial characteristics of heterogeneous particulate matter are complex and are not fully understood.In this study,micro-interfacial kinetics and the interactions governing copper(Cu) ion adsorption to PP-sediment were investigated using microinterfacial characterization experiments and kinetic experiments for Cu ion absorption to sediment,polypropylene(PP),and PP-sediment particles.The results show that(1) a pseudo-second-order model can be used to accurately describe the micro-interfacial kinetics of Cu ion adsorption to PP-sediment,indicating that chemical adsorption dominates the process.For Cu,the adsorption capacity,qe,of PP-sediment is approximately 0.4808 mg/g,between that of sediment and PP.(2) Film diffusion is the rate-controlling process in the early adsorption stage.Intraparticle diffusion gradually becomes the controlling process as the film diffusion constant(kfd) decreases and the film diffusion model becomes less applicable,but intraparticle diffusion is weaker in the PP-sediment system than in the sedimentonly system.(3) The applicability of the intraparticle diffusion model for Cu ion adsorption to PP-sediment in the later stage of adsorption is between that of the sediment and PP systems.Furthermore,the heterogeneous aggregation of sediment and PP affects the micro-interfacial interactions of both types of particulate matter.The current study contributes to a better understanding of the microinterfacial interactions of heterogeneous particulate matter(such as fine-grained sediment and MPs)with heavy metal ions in aqueous environments.

关键词： Heterogeneous aggregation Kinetics Micro-interfacial interaction Microplastic (MP) Sediment

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Resilience patterns of human mobility in response to extreme urban floods

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National Science Review 2023年第8期10卷 121-133页

作者： Junqing Tang Pengjun Zhao Zhaoya Gong Hongbo Zhao Fengjue Huang Jiaying Li zhihe chen Ling Yu Jun chen School of Urban Planning and Design Shenzhen Graduate School Peking University 2. Key Laboratory of Earth Surface System and Human-Earth Relations of Ministry of Natural Resources of China Shenzhen Graduate SchoolPeking University School of Urban and Environmental Sciences Peking University Key Research Institute of Yellow River Civilization and Sustainable Development&Collaborative Innovation Center on Yellow River Civilization Henan Province and Ministry of Education Henan University 5. Key National Geomatics Center of China

Large-scale disasters can disproportionately impact different population groups, causing prominent disparity and inequality, especially for the vulnerable and marginalized. Here, we investigate the resilience of human mobility under the disturbance of the unprecedented ‘720’ Zhengzhou flood in China in 2021 using records of 1.32 billion mobile phone signaling generated by 4.35 million people. We find that although pluvial floods can trigger mobility reductions, the overall structural dynamics of mobility networks remain relatively stable. We also find that the low levels of mobility resilience in female, adolescent and older adult groups are mainly due to their insufficient capabilities to maintain business-as-usual travel frequency during the flood. Most importantly, we reveal three types of counter-intuitive, yet widely existing,resilience patterns of human mobility(namely, ‘reverse bathtub’, ‘ever-increasing’ and ‘ever-decreasing’ patterns), and demonstrate a universal mechanism of disaster-avoidance response by further corroborating that those abnormal resilience patterns are not associated with people’s gender or age. In view of the common association between travel behaviors and travelers’ socio-demographic characteristics, our findings provide a caveat for scholars when disclosing disparities in human travel behaviors during flood-induced emergencies.

关键词： disaster resilience urban flood human mobility Zhengzhou flood mobile phone data

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Experimental Study on the Effect of Increased Downstroke Duration for an FWAV with Morphing-coupled Wing Flapping Configuration

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Journal of Bionic Engineering 2024年第1期21卷 192-208页

作者： Ang chen Bifeng Song zhiheWang Kang Liu Dong Xue Xiaojun Yang School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Harbin Institute of Technology Shenzhen 518055China

This paper is based on a previously developed bio-inspired Flapping Wing Aerial Vehicle(FWAV),RoboFalcon,which can fly with a morphing-coupled flapping pattern.In this paper,a simple flapping stroke control system based on Hall effect sensors is designed and applied,which is capable of assigning different up-and down-stroke speeds for the RoboFalcon platform to achieve an adjustable downstroke ratio.The aerodynamic and power characteristics of the morphing-coupled flapping pattern and the conventional flapping pattern with varying downstroke ratios are measured through a wind tunnel experiment,and the corresponding aerodynamic models are developed and analyzed by the nonlinear least squares method.The relatively low power consumption of the slow-downstroke mode of this vehicle is verified through outdoor flight tests.The results of wind tunnel experiments and flight tests indicate that increased downstroke duration can improve aerodynamic and power performance for the RoboFalcon platform.

关键词： Flapping wing aerial vehicle(FWAV) Downstroke ratio Bio-inspired design Morphing-coupled flapping

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Hydroxylated metal–organic-layer nanocages anchoring single atomic cobalt sites for robust photocatalytic CO_(2) reduction

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Nano Research 2024年第4期17卷 2410-2419页

作者： Weiyi Pan zhihe Wei Yanhui Su Yuebin Lian Zhangyi Zheng Huihong Yuan Yongze Qin Xulan Xie Qianqian Bai Zhenyang Jiao Wei Hua Jinzhou chen Wenjun Yang Zhao Deng Yang Peng Soochow Institute for Energy and Materials Innovations College of EnergySoochow UniversitySuzhou 215006China Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province Soochow UniversitySuzhou 215006China School of Photoelectric Engineering Changzhou institute of technologyChangzhou 213032China Jiangsu Key Laboratory for Advanced Negative Carbon Technologies Soochow UniversitySuzhou 215123China

Assembly of two-dimensional(2D)metal–organic layers(MOLs)based on the hard and soft acid–base theorem represents an exquisite strategy for the construction of photocatalytic platforms in virtue of the highly exposed active sites,much improved mass transport,and greatly elevated stability.Herein,nanocages composed of MOLs are produced for the first time through a cosolvent approach utilizing zirconium-based UiO-66-(OH)2 as the structural precursor.To endow the catalytic activity for CO_(2) conversion,single atomic Co^(2+)sites are appended to the Zr-oxo nodes of the MOL cages,demonstrating a remarkable CO yield of 7.74 mmol·g^(-1)·h^(-1) and operational stability of 97.1%product retention after five repeated cycles.Such an outstanding photocatalytic performance is mainly attributed to the unique nanocage morphology comprising enormous 2D nanosheets for augmented Co^(2+)exposure and the abundant surface hydroxyl groups for local CO_(2) enrichment.This work underlines the tailoring of both metal–organic framework(MOF)morphology and functionality to boost the turnover rate of photocatalytic CO_(2) reduction reaction(CO_(2)RR).

关键词： photocatalytic CO_(2) reduction metal–organic layer nanocage single-atom catalyst co-catalyst

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Freezing-directed construction of enzyme/nano interfaces:Reagentless conjugation,superior activity,and better stability

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Chinese Chemical Letters 2024年第1期35卷 471-474页

作者： Ke Quan Jiajie Tong Lifang chen Shuyao Fang Mengjiao Li Linlin Wu zhihe Qing Hunan Provincial Key Laboratory of Cytochemistry School of Food and BioengineeringSchool of Chemistry and Chemical EngineeringChangsha University of Science and TechnologyChangsha 410114China Department of Oncology Tengzhou Central People’s Hospital Affiliated Xuzhou Medical UniversityTengzhou 277500China

Immobilizing enzyme to nano interfaces has demonstrated to be a favorable strategy for prompting the industrialized application of enzyme.Despite tremendous endeavor has been devoted to using gold nanoparticles(AuNPs)as conjugation matrix due to its fascinating physico-chemical properties,maintaining enzymatic activity while circumventing cumbersome modification remains a formidable challenge.Herein,the freezing-directed conjugation of enzyme/nano interfaces was constructed without extra reagent.As the proof of concept,glucose oxidase(GOx)was chosen as model enzyme.The one-pot conjugation process can be facilely completed at−20°C under aqueous solution.Moreover,with the loading of GOx on AuNP at freezing,the enzyme exhibited superior catalytic activity and stability upon thermal and pH perturbation.The mechanism of boosted activity was then discussed in detail.It was found that higher loading density under freezing condition and more enzyme tending to bind AuNPs via Au-S bond were the main factors for the superior activity.More importantly,this methodology was universal and can also be applied to other enzyme which contains natural cysteine,such as horseradish peroxidase(HRP)and papain.This facile conjugation strategy accompanied by remarkable bioactivity expand the possibilities for enzymatic biosensing,microdevice and even drug delivery.

关键词： Enzyme conjugation Freezing AuNPs Catalytic activity

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Characteristics of micro-interface adsorption kinetics between sediments and Cu ions

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International Journal of Sediment Research 2017年第1期32卷 82-89页

作者： zhihe chen Bingchuan Zeng Department of Water Resources and Environment Geography and Planning School of Sun Yat-sen University Key Laboratory of Water Cycle and Water Security in Southern China of Guangdong High Education Institute

This work investigates the adsorption of Cu ions in sediments by conducting batch experiments,including isothermal experiments and adsorption kinetics experiments.Data from isothermal experiments were analyzed using the Langmuir,Freundlich and Temkin models,and the experimental kinetic data were fit using pseudo-first-order,pseudo-second-order,Elovich,liquid film diffusion and intra-particle diffusion models.The Langmuir model resulted in the best fit for the equilibrium data,which indicated that the adsorption capacity of Cu ions on the sediment was1.0403 mggwith a Kvalue of 4.2877 L mgThe Freundlich and Temkin models also provided good fits,and the nand A values were 3.8565 and 66.9964 L mg,respectively,indicating stronger adsorption intensities and adsorption energies between the Cu ions and the sediment.Compared with the pseudo-first-order and Elovich models,the pseudo-second-order model was more appropriate for describing the adsorption kinetics,indicating the chemisorption nature of adsorption.The adsorption kinetic process can be divided into film diffusion,pore diffusion and adsorption reactions.The controlling step for the adsorption kinetics changed with the development of the adsorption process.The entire adsorption process took 180 min.Film diffusion was the controlling step for the first 20 min.During the 20 to 60 min period,the pore diffusion gradually increased and the film diffusion decreased so that both phenomena coexisted.Pore diffusion was the controlling step during the 60-180 min period.

关键词： Sediments Cu ions Adsorption Isotherms Kinetics

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Comparison of Pb(Ⅱ) and Cd(Ⅱ) micro-interfacial adsorption on ?ne sediment in the Pearl River Basin, China

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International Journal of Sediment Research 2021年第3期36卷 401-418页

作者： Qunsheng Fang zhihe chen Jianpeng Zheng Zhihua Zhu Geography and Planning School Sun Yat-sen University Key Laboratory of Water Cycle and Water Security in Southern China of Guangdong High Education Institute Engineering Research Center for Water Security Regulation in Southern China of Guangdong Province Civil Engineering School Sun Yat-sen University Institute of Environmental and Ecological Engineering Guangdong University of Technology

The complex micro-interfacial interaction theories of heavy metal ions such as Pb(II) and Cd(II)adsorption on fine sediment in aqueous solution were not systematically investigated. The aim of this work was to reflect the micro-interfacial adsorption characteristics. Sediment samples were collected from an estuary. The Isothermal and kinetics adsorption experiment were done to acquire the data.Isothermal, kinetics, film diffusion and intraparticle diffusion models were adopted to fit the adsorption experimental data. The results indicated that the Langmuir, Freundlich and Temkin models were suitable for analyzing the isothermal experimental data. The maximum adsorption capacities of Pb(II) and Cd(II)on the sediment were 1.1377 and 0.9821 mg·g-1, respectively. The qmand KLof the Langmuir model, Kfand nFof the Freundlich model, and b and A of the Temkin model all exhibited a power function relationship with the initial adsorbate concentration. The pseudo-second-order model provided a better fit for the experimental kinetics data compared with the fit of the pseudo-first-order and Elovich models.The pseudo-second-order parameters k2and qeof Pb(II) and qeof Cd(II) both had a power function relationship with adsorption time, additionally, the k2of Cd(II) had an exponential function relationship with adsorption time. The liquid-film diffusion parameters kfdof Pb(II) and Cd(II) were 0.0569 and 0.1806 min-1, respectively. The intraparticle diffusion parameter kidvalues of Pb(II) and Cd(II) were0.0055 mg·g-1·min1/2and 0.0049 mg·g-1min1/2, respectively. The physical significance of the model parameters showed that Pb(II) adsorption on sediment was stronger than Cd(II). The results of this study provided a theoretical reference for the micro-interfacial mechanism of heavy metal ion adsorption on sediment.

关键词： Sediment Heavy metal ions Micro-interfacial interaction Isotherms Kinetics Model parameters

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