Touch-sensitive screens are crucial components of wearable devices.Materials such as reduced graphene oxide(rGO),carbon nanotubes(CNTs),and graphene offer promising solutions for flexible touch-sensitive screens.Howev...Touch-sensitive screens are crucial components of wearable devices.Materials such as reduced graphene oxide(rGO),carbon nanotubes(CNTs),and graphene offer promising solutions for flexible touch-sensitive screens.However,when stacked with flexible substrates to form multilayered capacitive touching sensors,these materials often suffer from substrate delamination in response to deformation;this is due to the materials having different Young’s modulus values.Delamination results in failure to offer accurate touch screen recognition.In this work,we demonstrate an induced charge-based mutual capacitive touching sensor capable of high-precision touch sensing.This is enabled by electron trapping and polarization effects related to mixed-coordinated bonding between copper nanoparticles and vertically grown graphene nanosheets.Here,we used an electron cyclotron resonance system to directly fabricate graphene-metal nanofilms(GMNFs)using carbon and copper,which are firmly adhered to flexible substrates.After being subjected to 3000 bending actions,we observed almost no change in touch sensitivity.The screen interaction system,which has a signal-to-noise ratio of 41.16 dB and resolution of 650 dpi,was tested using a handwritten Chinese character recognition trial and achieved an accuracy of 94.82%.Taken together,these results show the promise of touch-sensitive screens that use directly fabricated GMNFs for wearable devices.展开更多
The electronic properties of graphene are very sensitive to its dielectric environment.The coupling to a metal substrate can give rise to many novel quantum effects in graphene,such as band renormalization and plasmon...The electronic properties of graphene are very sensitive to its dielectric environment.The coupling to a metal substrate can give rise to many novel quantum effects in graphene,such as band renormalization and plasmons with unusual properties,which are of high technological interest.Infrared nanoimaging are very suitable for exploring these effects considering their energy and length scales.Here,we report near-field infrared nanoimaging studies of graphene on copper synthesized by chemical vapor deposition.Remarkably,our measurements reveal three different types of near-field optical responses of graphene,which are very distinct from the near-field edge fringes observed in the substrate.These results can be understood from the modification of optical conductivity of graphene due to its coupling with the substrate.Our work provides a framework for identifying the near-field response of graphene in graphene/metal systems and paves the way for studying their novel physics and potential applications.展开更多
Though it is well recognized that the space between graphene cover and the metal substrate canact as a two-dimensional(2D)nanoreactor,several issues are still unresolved,including the role of the metal substrate,the m...Though it is well recognized that the space between graphene cover and the metal substrate canact as a two-dimensional(2D)nanoreactor,several issues are still unresolved,including the role of the metal substrate,the mechanisms ruling water intercalation and the identification ofsites at which water is decomposed.Here,we solve these issues by means of density functional theory and high-resolution electron energyloss spectroscopy experiments carried out on graphene grown on(111)-oriented Cu foils.Specifically,we observe decomposition of H2O atroom temperature with only H atoms forming bonds with graphene and with buried OH groups underneath the graphene cover.Ourtheoretical model discloses physicochemical mechanisms ruling the migration and decomposition of water on graphene/Cu.We discover thatthe edge of graphene can be easily saturated by H through decomposition of H2O,which allows H2O to migrate in the subsurface region from thedecoupled edge,where H2O decomposes at room temperature.Hydrogen atoms produced by the decomposition of H2O initially form a chemicalbond with graphene for the lower energy barrier compared with other routes.These findings are essential to exploit graphene/Cu interfaces incatalysis and in energy-related applications.展开更多
The dynamic behavior of the interface between few layer graphene(FLG) and tungsten metal tips under Joule heating has been studied by in-situ transmission electron microscopy(TEM) method. High-resolution and real-time...The dynamic behavior of the interface between few layer graphene(FLG) and tungsten metal tips under Joule heating has been studied by in-situ transmission electron microscopy(TEM) method. High-resolution and real-time observations show the tungsten tip ‘swallow' carbon atoms of the FLG and ‘spit' graphite shells at its surface. The tip was carbonized to tungsten carbide(WC, W_2 C and WC_x) after this process. A carbon diffusion mechanism has been proposed based on the diffusion of carbon atoms through the tungsten tip and separation from the surface of the tip. After Joule heating, the initial FLG-metal mechanical contact was transformed to FLG-WCx-W contact, which results in significant improvement on electrical conductivity at the interface.展开更多
The x wt%graphene-Ti composites（x = 0,0.2,0.3 and 0.4） were obtained using the powder metallurgy method.The X-ray diffraction results demonstrated that the peak intensity of graphene increased monotonically with inc...The x wt%graphene-Ti composites（x = 0,0.2,0.3 and 0.4） were obtained using the powder metallurgy method.The X-ray diffraction results demonstrated that the peak intensity of graphene increased monotonically with increasing graphene content.Furthermore,the number of grain boundary and interface between graphene and matrix increased as graphene increased,which led to a sharp rise of thermal resistances.The thermal conductivity and specific heat capacity of composites initially decreased drastically with addition of graphene,but then increased with increasing graphene content from 0.2 to 0.4 wt%.This phenomenon was connected with the graphene content and the characteristics of Ti matrix（pores,grain boundary and interface between graphene and matrix）.The variation of the compressive strength of composites was attributed to the interaction effects of the average grain size of the Ti matrix（d_m） and the volume fraction（V_f） and aspect ratio（A） of graphene.展开更多
Normal levels of oxygen free radicals play an important role in cellular signal transduction, redox homeostasis, regulatory pathways, and metabolic processes. However, radiolysis of water induced by high-energy radiat...Normal levels of oxygen free radicals play an important role in cellular signal transduction, redox homeostasis, regulatory pathways, and metabolic processes. However, radiolysis of water induced by high-energy radiation can produce excessive amounts of exogenous oxygen free radicals, which cause severe oxidative damages to all cellular components, disrupt cellular structures and signaling pathways, and eventually lead to death. Herein, we show that hybrid nanoshields based on single-layer graphene encapsulating metal nanoparticles exhibit high catalytic activity in scavenging oxygen superoxide （·O2^-）, hydroxyl （·OH）, and hydroperoxyl （HO2·） free radicals via electron transfer between the single-layer graphene and the metal core, thus achieving biocatalytic scavenging both in vitro and in vivo. The levels of the superoxide enzyme, DNA, and reactive oxygen species measured in vivo dearly show that the nanoshields can efficiently eliminate harmful oxygen free radicals at the cellular level, both in organs and circulating blood. Moreover, the nanoshields lead to an increase in the overall survival rate of gamma ray-irradiated mice to up to 90%, showing the great potential of these systems as protective agents against ionizing radiation.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52275565,52105593,and 62104155)the Natural Science Foundation of Guangdong Province,China(No.2022A1515011667)+2 种基金the Shenzhen Foundation Research Key Project(No.JCYJ20200109114244249)the Youth Talent Fund of Guangdong Province,China(No.2023A1515030292)the Shenzhen Excellent Youth Basic Research Fund(No.RCYX20231211090249068).
文摘Touch-sensitive screens are crucial components of wearable devices.Materials such as reduced graphene oxide(rGO),carbon nanotubes(CNTs),and graphene offer promising solutions for flexible touch-sensitive screens.However,when stacked with flexible substrates to form multilayered capacitive touching sensors,these materials often suffer from substrate delamination in response to deformation;this is due to the materials having different Young’s modulus values.Delamination results in failure to offer accurate touch screen recognition.In this work,we demonstrate an induced charge-based mutual capacitive touching sensor capable of high-precision touch sensing.This is enabled by electron trapping and polarization effects related to mixed-coordinated bonding between copper nanoparticles and vertically grown graphene nanosheets.Here,we used an electron cyclotron resonance system to directly fabricate graphene-metal nanofilms(GMNFs)using carbon and copper,which are firmly adhered to flexible substrates.After being subjected to 3000 bending actions,we observed almost no change in touch sensitivity.The screen interaction system,which has a signal-to-noise ratio of 41.16 dB and resolution of 650 dpi,was tested using a handwritten Chinese character recognition trial and achieved an accuracy of 94.82%.Taken together,these results show the promise of touch-sensitive screens that use directly fabricated GMNFs for wearable devices.
基金supported by the National Natural Science Foundation of China(Grant No.11874271).
文摘The electronic properties of graphene are very sensitive to its dielectric environment.The coupling to a metal substrate can give rise to many novel quantum effects in graphene,such as band renormalization and plasmons with unusual properties,which are of high technological interest.Infrared nanoimaging are very suitable for exploring these effects considering their energy and length scales.Here,we report near-field infrared nanoimaging studies of graphene on copper synthesized by chemical vapor deposition.Remarkably,our measurements reveal three different types of near-field optical responses of graphene,which are very distinct from the near-field edge fringes observed in the substrate.These results can be understood from the modification of optical conductivity of graphene due to its coupling with the substrate.Our work provides a framework for identifying the near-field response of graphene in graphene/metal systems and paves the way for studying their novel physics and potential applications.
基金This work was supported by the National Natural Science Foundation of China(Nos.21676232 and 21673206).A.P.thanks Danil W.Boukhvalov for scientific discussions and Vito Fabio for technical support for the HREELS experiments.D.F.acknowledges financial support from the Spanish Ministry of Economy and Competitiveness,through the Maria de Maeztu Programme for Units of Excellence in R&D(No.MDM-2014-0377)and MINECO project MAT2015-65356-C3-3-R.
文摘Though it is well recognized that the space between graphene cover and the metal substrate canact as a two-dimensional(2D)nanoreactor,several issues are still unresolved,including the role of the metal substrate,the mechanisms ruling water intercalation and the identification ofsites at which water is decomposed.Here,we solve these issues by means of density functional theory and high-resolution electron energyloss spectroscopy experiments carried out on graphene grown on(111)-oriented Cu foils.Specifically,we observe decomposition of H2O atroom temperature with only H atoms forming bonds with graphene and with buried OH groups underneath the graphene cover.Ourtheoretical model discloses physicochemical mechanisms ruling the migration and decomposition of water on graphene/Cu.We discover thatthe edge of graphene can be easily saturated by H through decomposition of H2O,which allows H2O to migrate in the subsurface region from thedecoupled edge,where H2O decomposes at room temperature.Hydrogen atoms produced by the decomposition of H2O initially form a chemicalbond with graphene for the lower energy barrier compared with other routes.These findings are essential to exploit graphene/Cu interfaces incatalysis and in energy-related applications.
基金supported by the Program from Ministry of Science and Technology(Grant Nos.2012CB933003,2013CB932600,2013CB934500&2013YQ16055107)the National Natural Science Foundation of China(Grant Nos.11474337,221322304,51172273&51421002)Strategic Priority Research Program B of the Chinese Academy of Sciences of China(Grant No.XDB07030100)
文摘The dynamic behavior of the interface between few layer graphene(FLG) and tungsten metal tips under Joule heating has been studied by in-situ transmission electron microscopy(TEM) method. High-resolution and real-time observations show the tungsten tip ‘swallow' carbon atoms of the FLG and ‘spit' graphite shells at its surface. The tip was carbonized to tungsten carbide(WC, W_2 C and WC_x) after this process. A carbon diffusion mechanism has been proposed based on the diffusion of carbon atoms through the tungsten tip and separation from the surface of the tip. After Joule heating, the initial FLG-metal mechanical contact was transformed to FLG-WCx-W contact, which results in significant improvement on electrical conductivity at the interface.
基金Ministry of Science&Technology of China:Sino-Italy International Cooperation on Innovation(2016YFE0104000)International Cooperation and Exchanges(NSFC,51561145007)National Energy Novel Materials Center(NENMC-Ⅱ-1705)
基金supported by the Chinese Postdoctoral Science Foundation(No.2014M561795)the Postdoctoral Scientific Research Project of Zhejiang Province,China(No.BSH1401037)
文摘The x wt%graphene-Ti composites（x = 0,0.2,0.3 and 0.4） were obtained using the powder metallurgy method.The X-ray diffraction results demonstrated that the peak intensity of graphene increased monotonically with increasing graphene content.Furthermore,the number of grain boundary and interface between graphene and matrix increased as graphene increased,which led to a sharp rise of thermal resistances.The thermal conductivity and specific heat capacity of composites initially decreased drastically with addition of graphene,but then increased with increasing graphene content from 0.2 to 0.4 wt%.This phenomenon was connected with the graphene content and the characteristics of Ti matrix（pores,grain boundary and interface between graphene and matrix）.The variation of the compressive strength of composites was attributed to the interaction effects of the average grain size of the Ti matrix（d_m） and the volume fraction（V_f） and aspect ratio（A） of graphene.
基金We gratefully acknowledge the financial support from the Ministry of Science and Technology of China （Nos. 2016YFA0204100 and 2016YFA0200200）, the National Natural Science Foundation of China （Nos. 81471786, 21573220, and 21303191）, the strategic Priority Research Program of the Chinese Academy of Sciences （No. XDA09030100）, Natural Science Foundation of Tianjin （No. 13JCQNJC13500）.
文摘Normal levels of oxygen free radicals play an important role in cellular signal transduction, redox homeostasis, regulatory pathways, and metabolic processes. However, radiolysis of water induced by high-energy radiation can produce excessive amounts of exogenous oxygen free radicals, which cause severe oxidative damages to all cellular components, disrupt cellular structures and signaling pathways, and eventually lead to death. Herein, we show that hybrid nanoshields based on single-layer graphene encapsulating metal nanoparticles exhibit high catalytic activity in scavenging oxygen superoxide （·O2^-）, hydroxyl （·OH）, and hydroperoxyl （HO2·） free radicals via electron transfer between the single-layer graphene and the metal core, thus achieving biocatalytic scavenging both in vitro and in vivo. The levels of the superoxide enzyme, DNA, and reactive oxygen species measured in vivo dearly show that the nanoshields can efficiently eliminate harmful oxygen free radicals at the cellular level, both in organs and circulating blood. Moreover, the nanoshields lead to an increase in the overall survival rate of gamma ray-irradiated mice to up to 90%, showing the great potential of these systems as protective agents against ionizing radiation.
