Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing t...Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems.展开更多
Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal s...Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C-H bond in CH_(4)and hence accelerate CH_(4) coupling performance.As an example,the synthetic Au/ZnO porous nanosheets exhibit the C_(2)H_(6) photosynthetic rate of 1,121.6μmol g^(-1)_(cat)h^(-1)and the CH_(4) conversion rate of 2,374.6μmol g^(-1)_(cat)h^(-1) under oxygen-free system,2 orders of magnitude higher than those of previously reported photocatalysts.By virtue of several in situ spectroscopic techniques,it is established that the generated Au^(δ-)and O^-species together polarized the C-H bond,while the Au^(δ-)and O^-species jointly stabilized the CH_(3) intermediates,which favored the coupling of CH_(3) intermediate to photosynthesize C_(2)H_(6) instead of overoxidation into CO_(x).Thus,the design of dual active species is beneficial for achieving high-efficient CH_(4)-to-C_(2)H_(6) photoconversion.展开更多
CO_(2)photoreduction to high-valued CH_(4)is highly attractive,whereas the CH_(4)selectivity and activity,especially under atmospheric CO_(2),is still unsatisfying.Here,we design spatially-separated redox sites on two...CO_(2)photoreduction to high-valued CH_(4)is highly attractive,whereas the CH_(4)selectivity and activity,especially under atmospheric CO_(2),is still unsatisfying.Here,we design spatially-separated redox sites on two-dimensional heterostructured nanosheets with loaded metal oxides,thus achieving high reactivity and selectivity of photocatalytic atmospheric CO_(2)reduction to CH_(4).Taking the synthetic In_(2)O_(3)/In_(2)S_(3)nanosheets with loaded PdO quantum dots as a prototype,quasi in-situ X-ray photoelectron spectra reveal the Pd sites accumulate photogenerated holes for dissociating H_(2)O and the In sites accept photoexcited electrons to activate CO_(2).Moreover,the Pd-OD bond is confirmed by in-situ Fourier-transform infrared spectra during the D2O labeling experiment,indicating the PdO quantum dots participate in H_(2)O oxidation to supply hydrogen species for CO_(2)methanation.As a result,in a simulated air atmosphere,the PdO-In_(2)O_(3)/In_(2)S_(3)nanosheets enable favorable atmospheric CO_(2)-to CH_(4)photoreduction with nearly 100%selectivity and ultralong stability of 240 h as well as CO_(2)conversion of 48.2%.This study opens an approach towards designing photocatalysts with spatially-separated redox sites to achieve efficient oxidation and reduction of CO_(2)photocatalysis to CH_(4).展开更多
High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and l...High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.展开更多
Analysis of the atomic structure of monoclinic BiVO4 reveals its fascinating structure-related dual response to visible light and temperature.Although there have been a few reported studies of its responses to visible...Analysis of the atomic structure of monoclinic BiVO4 reveals its fascinating structure-related dual response to visible light and temperature.Although there have been a few reported studies of its responses to visible light and temperature,an understanding of the effects of quantum size,particle shape or specific exposed facets on its dual responsive properties remains elusive;this is primarily due to the limited availability of high-quality monodisperse nanocrystals with extremely small sizes and specific_(4)exposed facets.Herein,we describe a novel assembly-fusion strategy for the synthesis of mesostructured monoclinic BiVO_(4)quantum tubes with ultranarrow diameter of 5 nm,ultrathin wall thickness down to 1 nm and exposed{020}facets,via a convenient hydrothermal method at temperatures as low as 100℃.Notably,the resulting high-quality quantum tubes possess significantly superior dual-responsive properties compared with bulk BiVO_(4)or even BiVO4 nanoellipsoids,and thus,show high promise for applications as visible-light photocatalysts and temperature indicators offering improved environmental quality and safety.This mild and facile methodology should be capable of extension to the preparation of other mesostructured inorganic quantum tubes with similar characteristics,giving a range of materials with enhanced dual-responsive properties.展开更多
Sluggish separation and migration kinetics of the photogenerated carriers account for the low-efficiency of CO_(2) photoreduction into CH_(4). Design and construction two-dimensional (2D) in-plane heterostructures dem...Sluggish separation and migration kinetics of the photogenerated carriers account for the low-efficiency of CO_(2) photoreduction into CH_(4). Design and construction two-dimensional (2D) in-plane heterostructures demonstrate to be an appealing approach to address above obstacles. Herein, we fabricate 2D in-plane heterostructured Ag_(2)S-In_(2)S_(3) atomic layers via an ion-exchange strategy. Photoluminescence spectra, time-resolved photoluminescence spectra, and photoelectrochemical measurements firmly affirm the optimized carrier dynamics of the In_(2)S_(3) atomic layers after the introduction of in-plane heterostructure. In-situ Fourier transform infrared spectroscopy spectra and density functional theory (DFT) calculations disclose the in-plane heterostructure contributes to CO_(2) activation and modulates the adsorption strength of CO* intermediates to facilitate the formation of CHO* intermediates, which are further protonated to CH4. In consequence, the in-plane heterostructure achieves the CH_(4) evolution rate of 20 µmol·g^(−1)·h^(−1), about 16.7 times higher than that of the In2S3 atomic layers. In short, this work proves construction of in-plane heterostructures as a promising method for obtaining high-efficiency CO_(2)-to-CH_(4) photoconversion properties.展开更多
To create a harmonious society and mitigate fossil economy,efficient CO_(2)reducing is a critical step and is urgently needed.CO_(2)electroreduction (ECO_(2)RR) technology,which converts greenhouse CO_(2)to chemical f...To create a harmonious society and mitigate fossil economy,efficient CO_(2)reducing is a critical step and is urgently needed.CO_(2)electroreduction (ECO_(2)RR) technology,which converts greenhouse CO_(2)to chemical feedstocks and liquid fuels with renewable electricity,is a promising answer to "Carbon Neutrality" and "Paris Agreement"[1].Despite the great potential of CO_(2)electroreduction for energy and environment issues,it is still challenging of this technology.展开更多
CO_(2)electroreduction to formate is technically feasible and economically viable,but still suffers from low selectivity and high overpotential at industrial current densities.Here,lattice-distorted metallic nanosheet...CO_(2)electroreduction to formate is technically feasible and economically viable,but still suffers from low selectivity and high overpotential at industrial current densities.Here,lattice-distorted metallic nanosheets with disorder-engineered metal sites are designed for industrial-current-density CO_(2)-to-formate conversion at low overpotentials.As a prototype,richly lattice-distorted bismuth nanosheets are first constructed,where abundant disorder-engineered Bi sites could be observed by high-angle annular dark-field scanning transmission electron microscopy image.In-situ Fourier-transform infrared spectra reveal the CO_(2)•−*group is the key intermediate,while theoretical calculations suggest the electron-enriched Bi sites could effectively lower the CO_(2)activation energy barrier by stabilizing the CO_(2)•−*intermediate,further affirmed by the decreased formation energy from 0.49 to 0.39 eV.As a result,the richly lattice-distorted Bi nanosheets exhibit the ultrahigh current density of 800 mA·cm^(−2)with 91%Faradaic efficiencies for CO_(2)-to-formate electroreduction,and the formate selectivity can reach nearly 100%at the current density of 200 mA·cm^(−2)with a very low overpotential of ca.570 mV,outperforming most reported metal-based electrocatalysts.展开更多
Carbon dioxide electroreduction usually suffers from low catalytic activities and debatable reaction mechanisms at present. That may be primarily ascribed to the high energy barrier for carbon dioxide activation over ...Carbon dioxide electroreduction usually suffers from low catalytic activities and debatable reaction mechanisms at present. That may be primarily ascribed to the high energy barrier for carbon dioxide activation over the conventionally fabricated catalysts and the infeasibility of traditional characterization techniques for unveiling the evolution of active sites and reactive intermediates. Two-dimensional(2 D) materials, which possess the active sites with high proportion, high activity and high uniformity, can act as ideal models to manipulate the active sites and understand structure-property relationship. In this review, we overview the boosted carbon dioxide activation by the intrinsic peculiar electronic states of 2D catalysts and the charge localization effect induced by chemical modification of two-dimensional catalysts. We also summarize the recognition of the structural evolutions for active sites in two-dimensional catalysts by means of in situ X-ray diffraction pattern and in situ X-ray absorption spectroscopy. Moreover, we emphasize the detection of the reactive intermediates on active sites in two-dimensional catalysts via in situ Raman spectroscopy and in situ Fourier transform infrared spectroscopy. Finally, we end this review with an outlook on the unresolved issues and future development of carbon dioxide electroreduction.展开更多
Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utili...Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utilize in-situ spectral techniques to unveil the H2O-mediated HCHO photooxidation mechanism.As an example,the synthetic defective Bi2WO6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H2O at room temperature.In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of•OH radicals,possibly stemmed from H2O oxidation by the photoexcited holes.Synchrotron-radiation vacuum ultraviolet photoionization mass spectroscopy and H218O isotope-labeling experiment directly evidence the formed•OH radicals as the source of oxygen atoms,trigger HCHO photooxidation to produce CO2,while in-situ Fourier transform infrared spectroscopy discloses the HCOO*radical is the main photooxidation intermediate.Density-functional-theory calculations further reveal the•OH formation process is the rate-limiting step,strongly verifying the critical role of H2O in promoting HCHO photooxidation.This work first clearly uncovers the H2O-mediated HCHO photooxidation mechanism,holding promise for high-efficiency indoor HCHO removal at ambient conditions.展开更多
The major obstacle for selective CO_(2)photoreduction to C_(2)hydrocarbons lies in the difficulty of C–C coupling,which is usually restrained by the repulsive dipole–dipole interaction between adjacent carbonaceous ...The major obstacle for selective CO_(2)photoreduction to C_(2)hydrocarbons lies in the difficulty of C–C coupling,which is usually restrained by the repulsive dipole–dipole interaction between adjacent carbonaceous intermediates.Herein,we first construct semiconducting atomic layers featuring abundant Metal^(n+)-Metal^(δ+)pair sites(0<δ<n),aiming to tailor asymmetric charge distribution on the carbonaceous intermediates and hence trigger their C–C coupling for selectively yielding C_(2)hydrocarbons.As an example,we first fabricate Co-doped NiS2 atomic layers possessing abundant Ni^(2+)-Ni^(δ+)(0<δ<2)pairs,where Co doping strategy can ensure higher amount of Ni^(2+)-Ni^(δ+)pair sites.In-situ Fourier-transform infrared spectroscopy,quasi in-situ Raman spectroscopy and density-functional-theory calculations disclose the Ni^(2+)-Ni^(δ+)pair sites endow the adjacent CO intermediates with distinct charge densities,thus decreasing their dipole–dipole repulsion and hence lowering the rate-limiting C–C coupling reaction barrier.As a result,in simulated flue gas(10%CO_(2)balance 90%N_(2)),the ethylene selectivity for Co-doped NiS_(2)atomic layers reaches up to 74.3%with an activity of 70μg·g^(−1)·h^(−1),outperforming previously reported photocatalysts under similar operating conditions.展开更多
To realize efficient atmospheric CO_(2) chemisorption and activation,abundant Ti^(3+) sites and oxygen vacancies in TiO_(2) ultrathin layers were designed.Positron annihilation lifetime spectroscopy and theoretical ca...To realize efficient atmospheric CO_(2) chemisorption and activation,abundant Ti^(3+) sites and oxygen vacancies in TiO_(2) ultrathin layers were designed.Positron annihilation lifetime spectroscopy and theoretical calculations first unveil each oxygen vacancy is associated with the formation of two Ti^(3+)sites,giving a Ti^(3+)-V_(o)-Ti^(3+) configuration.The Ti^(3+)-V_(o)-Ti^(3+) sites could bond with CO_(2) molecules to form a stable configuration,which converted the endoergic chemisorption step to an exoergic process,verified by in-situ Fourier-transform infrared spectra and theoretical calculations.Also,the adjacent Ti^(3+)sites not only favor CO_(2) activation into COOH*via forming a stable Ti^(3+)–C–O–Ti^(3+) configuration,but also facilitate the rate-limiting COOH^(*)scission to CO^(*)by reducing the energy barrier from 0.75 to 0.45 e V.Thus,the Ti^(3+)-V_(o)-TiO_(2) ultrathinlayers could directly capture and photofix atmospheric CO_(2) into near-unity CO,with the corresponding CO_(2)-to-CO conversion ratio of ca.20.2%.展开更多
Natural bio-enzyme catalysts usually exhibit unexpected performances for many significant reactions,which are worthy of reference.Here we report artificial metal-sulfur-carbon(M-S-C)mimic-enzyme catalysts based on bio...Natural bio-enzyme catalysts usually exhibit unexpected performances for many significant reactions,which are worthy of reference.Here we report artificial metal-sulfur-carbon(M-S-C)mimic-enzyme catalysts based on bionic design.The catalysts combine metal centers and functional ligands,which realize the universal fabrication of phase and adjustable dimension.The synthesized catalysts inherit the highly active and selective feature of bio-enzyme catalysts.When directly used for carbon dioxide electroreduction reaction,the Sn-S-C catalyst exhibits high selectivity for formate(Faradaic efficiency>95%),as well as a continuous stability over 120 h at a high current density of 740 m A cm^(-2),greatly outperforming the reported catalysts for formate formation.The catalytic sites and pathways are probed with in-situ Fourier transform infrared(FTIR)spectra,in-situ Raman spectra and synchrotron-radiation X-ray photoelectron spectra.These results break the inherent conundrum that it is impossible to simultaneously realize activity and durability under high selectivity.Our findings offer a versatile strategy to inherit from nature and integrate different components,thus designing efficient catalysts for various challenging reactions and energy conversions via a natural sustainable way.展开更多
1 Project profile The Qinghai–Tibet Railway(Fig.1),which extends from Golmud to Lhasa,has a total length of 1142 km.A 960 km section of its total length is over 4000 m above sea level,and the highest point on Tanggul...1 Project profile The Qinghai–Tibet Railway(Fig.1),which extends from Golmud to Lhasa,has a total length of 1142 km.A 960 km section of its total length is over 4000 m above sea level,and the highest point on Tanggula Mountains is 5072 m above sea level.This railway is known as the“Heavenly Road”and the highest and longest highland railway in the world.The project began on June 29,2001,and the railway operated on July 1,2006,with a total investment of 33.09 billion yuan.The frail ecology environment with severe high-altitude anoxia and widespread permafrost was the primary challenge to the construction of the Qinghai–Tibet Railway.A vast number of railway construction personnel achieved technological breakthroughs and innovations.In 2008,the Qinghai–Tibet Railway project won the National Science&Technology Progress Award(special).展开更多
In recent years,with the development of road and railway transportation industries,a variety of complicated decisionmaking problems have emerged in real-world applications.It is urgent to analyze these problems from t...In recent years,with the development of road and railway transportation industries,a variety of complicated decisionmaking problems have emerged in real-world applications.It is urgent to analyze these problems from the perspective of theoretical and methodological innovations,and provide methods in management,decision-making and application so as to achieve efficient operations of traffic and transportation systems.These problems have展开更多
基金supported by the 2021 Chinese Academy of Engineering(CAE)International Top-level Forum on Engineering Science and Technology,“Safety and Governance of the High-Speed Railway”。
文摘Safety is essential when building a strong transportation system.As a key development direction in the global railway system,the intelligent railway has safety at its core,making safety a top priority while pursuing the goals of efficiency,convenience,economy,and environmental friendliness.This paper describes the state of the art and proposes a system architecture for intelligent railway systems.It also focuses on the development of railway safety technology at home and abroad,and proposes the active safety method and technology system based on advanced theoretical methods such as the in-depth integration of cyber–physical systems(CPS),data-driven models,and intelligent computing.Finally,several typical applications are demonstrated to verify the advancement and feasibility of active safety technology in intelligent railway systems.
基金supported by the National Key R&D Program of China(2019YFA0210004,2022YFA1502904,2021YFA1501502)the National Natural Science Foundation of China(22125503,21975242,U2032212,21890754,22002148)+1 种基金2023 Synchrotron Radiation Joint Fund of USTCthe Youth Innovation Promotion Association of CAS(CX2340007003)。
文摘Photocatalytic CH_(4) coupling into high-valued C_(2)H_(6) is highly attractive,whereas the photosynthetic rate,especially under oxygen-free system,is still unsatisfying.Here,we designed the negatively charged metal supported on metal oxide nanosheets to activate the inert C-H bond in CH_(4)and hence accelerate CH_(4) coupling performance.As an example,the synthetic Au/ZnO porous nanosheets exhibit the C_(2)H_(6) photosynthetic rate of 1,121.6μmol g^(-1)_(cat)h^(-1)and the CH_(4) conversion rate of 2,374.6μmol g^(-1)_(cat)h^(-1) under oxygen-free system,2 orders of magnitude higher than those of previously reported photocatalysts.By virtue of several in situ spectroscopic techniques,it is established that the generated Au^(δ-)and O^-species together polarized the C-H bond,while the Au^(δ-)and O^-species jointly stabilized the CH_(3) intermediates,which favored the coupling of CH_(3) intermediate to photosynthesize C_(2)H_(6) instead of overoxidation into CO_(x).Thus,the design of dual active species is beneficial for achieving high-efficient CH_(4)-to-C_(2)H_(6) photoconversion.
基金supported by the National Key Research and Development Program of China(2022YFA1502904,2019YFA0210004,2021YFA1501502)the National Natural Science Foundation of China(22125503,21975242,U2032212,21890754,22002148)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)the Youth Innovation Promotion Association of Chinese Academy of Sciences(CX2340007003)the University Synergy Innovation Program of Anhui Province(GXXT-2020-001)
文摘CO_(2)photoreduction to high-valued CH_(4)is highly attractive,whereas the CH_(4)selectivity and activity,especially under atmospheric CO_(2),is still unsatisfying.Here,we design spatially-separated redox sites on two-dimensional heterostructured nanosheets with loaded metal oxides,thus achieving high reactivity and selectivity of photocatalytic atmospheric CO_(2)reduction to CH_(4).Taking the synthetic In_(2)O_(3)/In_(2)S_(3)nanosheets with loaded PdO quantum dots as a prototype,quasi in-situ X-ray photoelectron spectra reveal the Pd sites accumulate photogenerated holes for dissociating H_(2)O and the In sites accept photoexcited electrons to activate CO_(2).Moreover,the Pd-OD bond is confirmed by in-situ Fourier-transform infrared spectra during the D2O labeling experiment,indicating the PdO quantum dots participate in H_(2)O oxidation to supply hydrogen species for CO_(2)methanation.As a result,in a simulated air atmosphere,the PdO-In_(2)O_(3)/In_(2)S_(3)nanosheets enable favorable atmospheric CO_(2)-to CH_(4)photoreduction with nearly 100%selectivity and ultralong stability of 240 h as well as CO_(2)conversion of 48.2%.This study opens an approach towards designing photocatalysts with spatially-separated redox sites to achieve efficient oxidation and reduction of CO_(2)photocatalysis to CH_(4).
基金the National Key R&D Program of China(2022YFA1502904,2019YFA0210004,2021YFA1501502)National Natural Science Foundation of China(22125503,21975242,U2032212,21890754)+1 种基金Youth Innovation Promotion Association of CAS(CX2340007003)Technical Talent Promotion Plan(TS2021002).
文摘High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.
基金This work was financially supported by the National Basic Research Program of China(No.2009CB939901)the National Natural Science Foundation of China(Nos.90922016 and 10979047)the Innovative Project of Chinese Academy of Sciences(No.KJCX2-YW-H2O).
文摘Analysis of the atomic structure of monoclinic BiVO4 reveals its fascinating structure-related dual response to visible light and temperature.Although there have been a few reported studies of its responses to visible light and temperature,an understanding of the effects of quantum size,particle shape or specific exposed facets on its dual responsive properties remains elusive;this is primarily due to the limited availability of high-quality monodisperse nanocrystals with extremely small sizes and specific_(4)exposed facets.Herein,we describe a novel assembly-fusion strategy for the synthesis of mesostructured monoclinic BiVO_(4)quantum tubes with ultranarrow diameter of 5 nm,ultrathin wall thickness down to 1 nm and exposed{020}facets,via a convenient hydrothermal method at temperatures as low as 100℃.Notably,the resulting high-quality quantum tubes possess significantly superior dual-responsive properties compared with bulk BiVO_(4)or even BiVO4 nanoellipsoids,and thus,show high promise for applications as visible-light photocatalysts and temperature indicators offering improved environmental quality and safety.This mild and facile methodology should be capable of extension to the preparation of other mesostructured inorganic quantum tubes with similar characteristics,giving a range of materials with enhanced dual-responsive properties.
基金Acknowledgements This study is supported by the Marine Public Welfare Industry Program of State Oceanic Administration （Grant No. 201005005）. Yan LI from the First Institute of Oceanography, SOA, is appreciated for her work on partial calculations. Dr. Yu LIU, School of Marine Sciences, Nanjing University of Information Science ＆ Technology, is appreciated for his valuable help in coordinating the running of ROMS. Thanks to Philipp Wu from the University of California, Berkeley for his help in proofreading the manuscript. CD appreciates the support from the National Natural Science Foundation of China （Grant Nos. 41476022, 41490643, and 91128204）, Startup Foundation for Introducing Talent of Nanjing University of Information Science ＆ Technology （2013r121and 2014r072）, Program for Innovation Research and Entrepreneurship team in Jiangsu Province, National Basic Research Program of China （No. 2014CB745000）, and National Programme on Global Change and Air-Sea Interaction （No. GASI- 03-IPOVAI-05）.
基金This work was financially supported by the National Key R&D Program of China(Nos.2019YFA0210004,2017YFA0207301,and 2017YFA0303500)the National Natural Science Foundation of China(Nos.21975242,U2032212,21890754,and 21805267)+7 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-SLH011)the Fok Ying-Tong Education Foundation(No.161012)the University Synergy Innovation Program of Anhui Province(GXXT-2020-001)Users with Excellence Program of Hefei Science Center CAS(2020HSC-UE001)Supercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘Sluggish separation and migration kinetics of the photogenerated carriers account for the low-efficiency of CO_(2) photoreduction into CH_(4). Design and construction two-dimensional (2D) in-plane heterostructures demonstrate to be an appealing approach to address above obstacles. Herein, we fabricate 2D in-plane heterostructured Ag_(2)S-In_(2)S_(3) atomic layers via an ion-exchange strategy. Photoluminescence spectra, time-resolved photoluminescence spectra, and photoelectrochemical measurements firmly affirm the optimized carrier dynamics of the In_(2)S_(3) atomic layers after the introduction of in-plane heterostructure. In-situ Fourier transform infrared spectroscopy spectra and density functional theory (DFT) calculations disclose the in-plane heterostructure contributes to CO_(2) activation and modulates the adsorption strength of CO* intermediates to facilitate the formation of CHO* intermediates, which are further protonated to CH4. In consequence, the in-plane heterostructure achieves the CH_(4) evolution rate of 20 µmol·g^(−1)·h^(−1), about 16.7 times higher than that of the In2S3 atomic layers. In short, this work proves construction of in-plane heterostructures as a promising method for obtaining high-efficiency CO_(2)-to-CH_(4) photoconversion properties.
基金financially supported by the National Key R&D Program of China (2019YFA0210004, 2017YFA0207301)Strategic Priority Research Program of Chinese Academy of Sciences (XDB36000000)+6 种基金the National Natural Science Foundation of China (22125503, 21975242, U2032212, 21890754)Youth Innovation Promotion Association of CAS (CX2340007003)Major Program of Development Foundation of Hefei Center for Physical Science and Technology (2020HSC-CIP003)Key Research Program of Frontier Sciences of CAS (QYZDYSSW-SLH011)the Fok Ying-Tong Education Foundation (161012)Users with Excellence Program of Hefei Science Center (2020HSC-UE001)the University Synergy Innovation Program of Anhui Province (GXXT-2020-001)。
文摘To create a harmonious society and mitigate fossil economy,efficient CO_(2)reducing is a critical step and is urgently needed.CO_(2)electroreduction (ECO_(2)RR) technology,which converts greenhouse CO_(2)to chemical feedstocks and liquid fuels with renewable electricity,is a promising answer to "Carbon Neutrality" and "Paris Agreement"[1].Despite the great potential of CO_(2)electroreduction for energy and environment issues,it is still challenging of this technology.
基金the National Key Research and Development Program of China(No.2019YFA0210004)the National Natural Science Foundation of China(Nos.22125503,21975242,U2032212,and 21890754)+5 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)the Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-SLH011)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Users with Excellence Program of Hefei Science Center CAS(No.2020HSC-UE001)the University Synergy Innovation Program of Anhui Province(No.GXXT-2020-001)。
文摘CO_(2)electroreduction to formate is technically feasible and economically viable,but still suffers from low selectivity and high overpotential at industrial current densities.Here,lattice-distorted metallic nanosheets with disorder-engineered metal sites are designed for industrial-current-density CO_(2)-to-formate conversion at low overpotentials.As a prototype,richly lattice-distorted bismuth nanosheets are first constructed,where abundant disorder-engineered Bi sites could be observed by high-angle annular dark-field scanning transmission electron microscopy image.In-situ Fourier-transform infrared spectra reveal the CO_(2)•−*group is the key intermediate,while theoretical calculations suggest the electron-enriched Bi sites could effectively lower the CO_(2)activation energy barrier by stabilizing the CO_(2)•−*intermediate,further affirmed by the decreased formation energy from 0.49 to 0.39 eV.As a result,the richly lattice-distorted Bi nanosheets exhibit the ultrahigh current density of 800 mA·cm^(−2)with 91%Faradaic efficiencies for CO_(2)-to-formate electroreduction,and the formate selectivity can reach nearly 100%at the current density of 200 mA·cm^(−2)with a very low overpotential of ca.570 mV,outperforming most reported metal-based electrocatalysts.
基金financially supported by the National Key R&D Program of China (2019YFA0210004)the National Natural Science Foundation of China (22125503, 21975242, U2032212)+7 种基金the Strategic Priority Research Program of Chinese Academy of Sciences (XDB36000000)the Youth Innovation Promotion Association of CAS (CX2340007003)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology (2020HSC-CIP003)the Fok Ying-Tong Education Foundation (161012)Users with Excellence Program of Hefei Science Center (2020HSC-UE001)the University Synergy Innovation Program of Anhui Province (GXXT-2020-001)the Anhui Provincial Natural Science Foundation of China (2108085QB69)the Fundamental Research Funds for the Central Universities (WK2060000006)。
文摘Carbon dioxide electroreduction usually suffers from low catalytic activities and debatable reaction mechanisms at present. That may be primarily ascribed to the high energy barrier for carbon dioxide activation over the conventionally fabricated catalysts and the infeasibility of traditional characterization techniques for unveiling the evolution of active sites and reactive intermediates. Two-dimensional(2 D) materials, which possess the active sites with high proportion, high activity and high uniformity, can act as ideal models to manipulate the active sites and understand structure-property relationship. In this review, we overview the boosted carbon dioxide activation by the intrinsic peculiar electronic states of 2D catalysts and the charge localization effect induced by chemical modification of two-dimensional catalysts. We also summarize the recognition of the structural evolutions for active sites in two-dimensional catalysts by means of in situ X-ray diffraction pattern and in situ X-ray absorption spectroscopy. Moreover, we emphasize the detection of the reactive intermediates on active sites in two-dimensional catalysts via in situ Raman spectroscopy and in situ Fourier transform infrared spectroscopy. Finally, we end this review with an outlook on the unresolved issues and future development of carbon dioxide electroreduction.
基金This work was financially supported by National Key R&D Program of China(Nos.2019YFA0210004 and 2017YFA0207301)the National Natural Science Foundation of China(Nos.21975242 and 21890754)+5 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Key Research Program of Frontier Sciences of CAS(No.QYZDYSSW-SLH011)the Fok Ying-Tong Education Foundation(No.161012)Supercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utilize in-situ spectral techniques to unveil the H2O-mediated HCHO photooxidation mechanism.As an example,the synthetic defective Bi2WO6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H2O at room temperature.In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of•OH radicals,possibly stemmed from H2O oxidation by the photoexcited holes.Synchrotron-radiation vacuum ultraviolet photoionization mass spectroscopy and H218O isotope-labeling experiment directly evidence the formed•OH radicals as the source of oxygen atoms,trigger HCHO photooxidation to produce CO2,while in-situ Fourier transform infrared spectroscopy discloses the HCOO*radical is the main photooxidation intermediate.Density-functional-theory calculations further reveal the•OH formation process is the rate-limiting step,strongly verifying the critical role of H2O in promoting HCHO photooxidation.This work first clearly uncovers the H2O-mediated HCHO photooxidation mechanism,holding promise for high-efficiency indoor HCHO removal at ambient conditions.
基金National Key R&D Program of China(Nos.2019YFA0210004 and 2017YFA0207301)National Natural Science Foundation of China(Nos.21975242,U2032212,21890754,and 21805267)+4 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-SLH011)the Fok Ying-Tong Education Foundation(No.161012).
文摘The major obstacle for selective CO_(2)photoreduction to C_(2)hydrocarbons lies in the difficulty of C–C coupling,which is usually restrained by the repulsive dipole–dipole interaction between adjacent carbonaceous intermediates.Herein,we first construct semiconducting atomic layers featuring abundant Metal^(n+)-Metal^(δ+)pair sites(0<δ<n),aiming to tailor asymmetric charge distribution on the carbonaceous intermediates and hence trigger their C–C coupling for selectively yielding C_(2)hydrocarbons.As an example,we first fabricate Co-doped NiS2 atomic layers possessing abundant Ni^(2+)-Ni^(δ+)(0<δ<2)pairs,where Co doping strategy can ensure higher amount of Ni^(2+)-Ni^(δ+)pair sites.In-situ Fourier-transform infrared spectroscopy,quasi in-situ Raman spectroscopy and density-functional-theory calculations disclose the Ni^(2+)-Ni^(δ+)pair sites endow the adjacent CO intermediates with distinct charge densities,thus decreasing their dipole–dipole repulsion and hence lowering the rate-limiting C–C coupling reaction barrier.As a result,in simulated flue gas(10%CO_(2)balance 90%N_(2)),the ethylene selectivity for Co-doped NiS_(2)atomic layers reaches up to 74.3%with an activity of 70μg·g^(−1)·h^(−1),outperforming previously reported photocatalysts under similar operating conditions.
基金This work was supported by the National Key R&D Program of China(2019YFA0210004,2017YFA0207301,2017YFA0303500)the National Natural Science Foundation of China(21975242,U2032212,21890754,21805267,21703222,11975225)+7 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)Youth Innovation Promotion Association of CAS(CX2340007003)Key Research Program of Frontier Sciences of CAS(QYZDY-SSW-SLH011)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(2020HSC-CIP003)Users with Excellence Program of Hefei Science Center CAS(2020HSCUE001)The University Synergy Innovation Program of Anhui Province(GXXT-2020-001)the Fok Ying-Tong Education Foundation(161012)Supercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘To realize efficient atmospheric CO_(2) chemisorption and activation,abundant Ti^(3+) sites and oxygen vacancies in TiO_(2) ultrathin layers were designed.Positron annihilation lifetime spectroscopy and theoretical calculations first unveil each oxygen vacancy is associated with the formation of two Ti^(3+)sites,giving a Ti^(3+)-V_(o)-Ti^(3+) configuration.The Ti^(3+)-V_(o)-Ti^(3+) sites could bond with CO_(2) molecules to form a stable configuration,which converted the endoergic chemisorption step to an exoergic process,verified by in-situ Fourier-transform infrared spectra and theoretical calculations.Also,the adjacent Ti^(3+)sites not only favor CO_(2) activation into COOH*via forming a stable Ti^(3+)–C–O–Ti^(3+) configuration,but also facilitate the rate-limiting COOH^(*)scission to CO^(*)by reducing the energy barrier from 0.75 to 0.45 e V.Thus,the Ti^(3+)-V_(o)-TiO_(2) ultrathinlayers could directly capture and photofix atmospheric CO_(2) into near-unity CO,with the corresponding CO_(2)-to-CO conversion ratio of ca.20.2%.
基金supported by the National Key R&D Program of China(2019YFA0210004,2017YFA0207301)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)+7 种基金the National Natural Science Foundation of China(22125503,21975242,U2032212,21890754,2212500041)the Youth Innovation Promotion Association of CAS(CX2340007003)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology(2020HSC-CIP003)the Key Research Program of Frontier Sciences of CAS(QYZDYSSW-SLH011)the Fok Ying-Tong Education Foundation(161012)Users with Excellence Program of Hefei Science Center(2020HSC-UE001)the University Synergy Innovation Program of Anhui Province(GXXT-2020-001)。
文摘Natural bio-enzyme catalysts usually exhibit unexpected performances for many significant reactions,which are worthy of reference.Here we report artificial metal-sulfur-carbon(M-S-C)mimic-enzyme catalysts based on bionic design.The catalysts combine metal centers and functional ligands,which realize the universal fabrication of phase and adjustable dimension.The synthesized catalysts inherit the highly active and selective feature of bio-enzyme catalysts.When directly used for carbon dioxide electroreduction reaction,the Sn-S-C catalyst exhibits high selectivity for formate(Faradaic efficiency>95%),as well as a continuous stability over 120 h at a high current density of 740 m A cm^(-2),greatly outperforming the reported catalysts for formate formation.The catalytic sites and pathways are probed with in-situ Fourier transform infrared(FTIR)spectra,in-situ Raman spectra and synchrotron-radiation X-ray photoelectron spectra.These results break the inherent conundrum that it is impossible to simultaneously realize activity and durability under high selectivity.Our findings offer a versatile strategy to inherit from nature and integrate different components,thus designing efficient catalysts for various challenging reactions and energy conversions via a natural sustainable way.
文摘1 Project profile The Qinghai–Tibet Railway(Fig.1),which extends from Golmud to Lhasa,has a total length of 1142 km.A 960 km section of its total length is over 4000 m above sea level,and the highest point on Tanggula Mountains is 5072 m above sea level.This railway is known as the“Heavenly Road”and the highest and longest highland railway in the world.The project began on June 29,2001,and the railway operated on July 1,2006,with a total investment of 33.09 billion yuan.The frail ecology environment with severe high-altitude anoxia and widespread permafrost was the primary challenge to the construction of the Qinghai–Tibet Railway.A vast number of railway construction personnel achieved technological breakthroughs and innovations.In 2008,the Qinghai–Tibet Railway project won the National Science&Technology Progress Award(special).
文摘In recent years,with the development of road and railway transportation industries,a variety of complicated decisionmaking problems have emerged in real-world applications.It is urgent to analyze these problems from the perspective of theoretical and methodological innovations,and provide methods in management,decision-making and application so as to achieve efficient operations of traffic and transportation systems.These problems have
