Direct synthesis of layer-tunable and transfer-free graphene on technologically important substrates is highly valued for various electronics and device applications.State of the art in the field is currently a two-st...Direct synthesis of layer-tunable and transfer-free graphene on technologically important substrates is highly valued for various electronics and device applications.State of the art in the field is currently a two-step process:a high-quality graphene layer synthesis on metal substrate through chemical vapor deposition(CVD)followed by delicate layer transfer onto device-relevant substrates.Here,we report a novel synthesis approach combining ion implantation for a precise graphene layer control and dual-metal smart Janus substrate for a diffusion-limiting graphene formation to directly synthesize large area,high quality,and layer-tunable graphene films on arbitrary substrates without the post-synthesis layer transfer process.Carbon(C)ion implantation was performed on Cu-Ni film deposited on a variety of device-relevant substrates.A well-controlled number of layers of graphene,primarily monolayer and bilayer,is precisely controlled by the equivalent fluence of the implanted C-atoms(1 monolayer~4×10^(15)C-atoms/cm^(2)).Upon thermal annealing to promote Cu-Ni alloying,the pre-implanted C-atoms in the Ni layer are pushed toward the Ni/substrate interface by the top Cu layer due to the poor C-solubility in Cu.As a result,the expelled C-atoms precipitate into a graphene structure at the interface facilitated by the Cu-like alloy catalysis.After removing the alloyed Cu-like surface layer,the layer-tunable graphene on the desired substrate is directly realized.The layer-selectivity,high quality,and uniformity of the graphene films are not only confirmed with detailed characterizations using a suite of surface analysis techniques but more importantly are successfully demonstrated by the excellent properties and performance of several devices directly fabricated from these graphene films.Molecular dynamics(MD)simulations using the reactive force field(ReaxFF)were performed to elucidate the graphene formation mechanisms in this novel synthesis approach.With the wide use of ion implantation technology in the microelectronics industry,this novel graphene synthesis approach with precise layer-tunability and transfer-free processing has the promise to advance efficient graphene-device manufacturing and expedite their versatile applications in many fields.展开更多
Chemical vapor deposition(CVD)graphene film is a promising electrode-modifying material for fabricating high-performance glucose sensor due to its high electrical conductivity and two-dimensional structure over large ...Chemical vapor deposition(CVD)graphene film is a promising electrode-modifying material for fabricating high-performance glucose sensor due to its high electrical conductivity and two-dimensional structure over large area.However,the use of typical metal-based CVD graphene suffers from the residue contamination of polymer transfer-support and heavy metal ions.In this work,we directly grew fewlayer graphene on the SiO2/Si substrate without transfer process and then fabricated graphene-based glucose sensors by sequentially immobilizing glucose oxidase and depositing Nafion layer on its surface that was functionalized by oxygen-plasma treatment.Our transfer-and metal-free process shows distinct advantage over the common metal-CVD method in improving the electrochemical performance by eliminating the contamination of transfer-residue.Thus-obtained glucose sensor shows a high sensitivity(16.16μA mM-1cm-2)with a detection limit of 124.19μM.This method is simple and promising for the development of highly sensitive glucose sensors.展开更多
Graphene, a two-dimensional material with outstanding electrical and mechanical properties, has attracted considerable attention in the field of semiconductor technologies due to its potential use as a buffer layer fo...Graphene, a two-dimensional material with outstanding electrical and mechanical properties, has attracted considerable attention in the field of semiconductor technologies due to its potential use as a buffer layer for the epitaxial Ⅲ-nitride growth. In recent years, significant progress has been made in the chemical vapor deposition growth of graphene on various insulating substrates for the nitride epitaxy, which offers a facile, inexpensive, and easily scalable methodology. However, certain challenges are still present in the form of producing high-quality graphene and achieving optimal interface compatibility with Ⅲ-nitride materials.In this review, we provide an overview of the bottlenecks associated with the transferred graphene fabrication techniques and the state-of-the-art techniques for the transfer-free graphene growth. The present contribution highlights the current progress in the transfer-free graphene growth on different insulating substrates, including sapphire, quartz, SiO_(2)/Si, and discusses the potential applications of transfer-free graphene in the Ⅲ-nitride epitaxy. Finally, it includes the prospects of the transfer-free graphene growth for the Ⅲ-nitride epitaxy and the challenges that should be overcome to realize its full potential in this field.展开更多
Gaseous promotors have readily been adopted during the direct synthesis of graphene over insulators to enhance the growth quality and/or boost the growth rate.The understanding of the real functions of carbon-containi...Gaseous promotors have readily been adopted during the direct synthesis of graphene over insulators to enhance the growth quality and/or boost the growth rate.The understanding of the real functions of carbon-containing promotors has still remained elusive.In this study,we identify the critical roles of a representative CO_(2)promotor played in the direct growth of graphene.The comparative experimental trials validate CO_(2)as an effective modulator to decrease graphene nucleation density,improve growth kinetics,mitigate adlayer formation.The first-principles calculations illustrate that the generation of gas-phase OH species in CO_(2)-assisted system helps decrease the energy barriers of CH4 decomposition and carbon attachment to the growth front,which might be the key factor to allow high-quality direct growth.Such a CO_(2)-promoted strategy enables the conformal coating of graphene film over curved insulators,where the sheet resistance of grown graphene on quartz reaches as low as 1.26 kΩ·sq^(−1)at an optical transmittance of~95.8%.The fabricated endoscope lens based on our conformal graphene harvests an apoptosis of 82.8%for noninvasive thermal therapy.The work presented here is expected to motivate further investigations in the controllable growth of high-quality graphene on insulating substrates.展开更多
Graphene meshes(GMs)have attracted considerable attention as advanced materials for high-performance gas sensing due to their high-density active edge sites and excellent electronic properties.However,the contaminatio...Graphene meshes(GMs)have attracted considerable attention as advanced materials for high-performance gas sensing due to their high-density active edge sites and excellent electronic properties.However,the contamination-free preparation of GMs remains a challenge.Herein,we present a dewdrop-templated chemical vapor deposition approach to directly grow clean and intact graphene micromeshes(GMM)on SiO_(2)/Si substrates.The self-assembled micrometer-sized dewdrops from controlled water vapor condensation serve as a residue-free template for directing the growth of GMM with tunable hole sizes from submicrons to tens of microns.Density functional theory(DFT)calculations reveal that carbon species preferentially adsorb on pristine SiO_(2) regions to form a mesh structure.Contamination-free GMM gas sensors were fabricated using a simple transfer-free process,demonstrating a record-high sensitivity of 7.25%·ppm−1 and an ultra-low detection limit of 1.18 ppb for NO_(2) at room temperature.Complementary DFT studies elucidate that NO_(2) molecules adsorb more strongly on the edges of GMM,leading to a high response of the sensor.This work offers profound insights into dewdrop-templated graphene growth mechanisms and establishes a simple yet effective approach for fabricating high-performance transfer-free GMM sensors,thus paving the way for their practical applications in environmental monitoring and industrial safety fields.展开更多
采用密度泛函理论的M06-2X和MN15方法,研究了生理环境(水液相、1.013×10^(5)Pa、310.15 K)下双丙氨酸螯合二价钙[α-Ala_(2)→Ca^(2+),缩写:α-A_(2)→Ca^(2+)]消除羟基自由基(OH)的反应机理.研究发现,α-A_(2)→Ca^(2+)与OH的反...采用密度泛函理论的M06-2X和MN15方法,研究了生理环境(水液相、1.013×10^(5)Pa、310.15 K)下双丙氨酸螯合二价钙[α-Ala_(2)→Ca^(2+),缩写:α-A_(2)→Ca^(2+)]消除羟基自由基(OH)的反应机理.研究发现,α-A_(2)→Ca^(2+)与OH的反应有抽氢、加成和电子转移3个通道.势能面研究表明:OH与α-A2→Ca^(2+)的抽H反应自由能垒在13.2至56.8 k J/mol之间;OH与α-A_(2)→Ca^(2+)的加成反应自由能垒在61.0至66.2 kJ/mol之间;电子从α-A_(2)→Ca^(2+)向OH转移反应的自由能垒是179.0 k J/mol.结果表明,在生命体内α-A_(2)→Ca^(2+)可通过向OH提供H原子以及OH与C的加成过程消除OH,双丙氨酸螯合钙具有较好的清除羟自由基能力.展开更多
近年来,氢硅烷参与的光催化自由基反应是有机合成领域的研究热点.文章系统综述了可见光催化下氢硅烷作为硅源合成有机硅化合物及作为卤原子转移(halogen atom transfer,XAT)试剂的自由基反应.研究表明,可见光催化下,氢硅烷能在温和条件...近年来,氢硅烷参与的光催化自由基反应是有机合成领域的研究热点.文章系统综述了可见光催化下氢硅烷作为硅源合成有机硅化合物及作为卤原子转移(halogen atom transfer,XAT)试剂的自由基反应.研究表明,可见光催化下,氢硅烷能在温和条件下产生硅自由基,通过加成、取代等反应途径,高效构建了碳硅键.氢硅烷能与卤代烷烃发生单电子转移反应,生成烷基自由基中间体,并与烯烃、芳烃等富电子底物发生加成、取代等反应,最终实现交叉偶联这一重要转化过程.文章也对未来研究方向进行了展望:1)深入探索氢硅烷与羰基化合物的反应体系,解决该领域研究匮乏的问题;2)开发兼具高选择性、优异稳定性且经济的新型光催化剂;3)将光催化与过渡金属催化相结合,添加手性配体,实现不对称自由基反应的突破性进展.展开更多
基金supported by the National Key R&D Program of China(No.2022YFA1203400)the National Natural Science Foundation of China under Grant(Nos.62174093 and 12075307)+7 种基金the Ningbo Youth Science and Technology Innovation Leading Talent Project under Grant(No.2023QL006)the Open Research Fund of China National Key Laboratory of Materials for Integrated Circuits(No.NKLJC-K2023-01)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515110628)the support by LDRD Seedling ER project at Los Alamos National Laboratory,NM,USA(No.20210867ER)partially supported by Guangdong Provincial Key Laboratory of Computational Science and Material Design(No.2019B030301001)supported by Center for Computational Science and Engineering at Southern University of Science and TechnologyShanghai Rising-Star Program(No.21QA1410900)the support from the Youth Innovation Promotion Association CAS
文摘Direct synthesis of layer-tunable and transfer-free graphene on technologically important substrates is highly valued for various electronics and device applications.State of the art in the field is currently a two-step process:a high-quality graphene layer synthesis on metal substrate through chemical vapor deposition(CVD)followed by delicate layer transfer onto device-relevant substrates.Here,we report a novel synthesis approach combining ion implantation for a precise graphene layer control and dual-metal smart Janus substrate for a diffusion-limiting graphene formation to directly synthesize large area,high quality,and layer-tunable graphene films on arbitrary substrates without the post-synthesis layer transfer process.Carbon(C)ion implantation was performed on Cu-Ni film deposited on a variety of device-relevant substrates.A well-controlled number of layers of graphene,primarily monolayer and bilayer,is precisely controlled by the equivalent fluence of the implanted C-atoms(1 monolayer~4×10^(15)C-atoms/cm^(2)).Upon thermal annealing to promote Cu-Ni alloying,the pre-implanted C-atoms in the Ni layer are pushed toward the Ni/substrate interface by the top Cu layer due to the poor C-solubility in Cu.As a result,the expelled C-atoms precipitate into a graphene structure at the interface facilitated by the Cu-like alloy catalysis.After removing the alloyed Cu-like surface layer,the layer-tunable graphene on the desired substrate is directly realized.The layer-selectivity,high quality,and uniformity of the graphene films are not only confirmed with detailed characterizations using a suite of surface analysis techniques but more importantly are successfully demonstrated by the excellent properties and performance of several devices directly fabricated from these graphene films.Molecular dynamics(MD)simulations using the reactive force field(ReaxFF)were performed to elucidate the graphene formation mechanisms in this novel synthesis approach.With the wide use of ion implantation technology in the microelectronics industry,this novel graphene synthesis approach with precise layer-tunability and transfer-free processing has the promise to advance efficient graphene-device manufacturing and expedite their versatile applications in many fields.
基金financially supported by the Ministry of Science and Technology of China(Nos.2016YFA0200101 and 2016YFB04001104)the National Natural Science Foundation of China(Nos.51325205,51290273,51521091,51272256,61422406,51802317 and 61574143)+5 种基金the Chinese Academy of Sciences(Nos.KGZD-EW-303-1,KGZD-EW-303-3,KGZD-EW-T06 and XDPB06)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB30000000)the Liaoning Revitalization Talents Program(No.XLYC1808013)the Liaoning Key R&D Programthe Program for Guangdong Introducing Innovative and Enterpreneurial Teamsthe Development and Reform Commission of Shenzhen Municipality for the development of the“Low-Dimensional Materials and Devices”discipline.
文摘Chemical vapor deposition(CVD)graphene film is a promising electrode-modifying material for fabricating high-performance glucose sensor due to its high electrical conductivity and two-dimensional structure over large area.However,the use of typical metal-based CVD graphene suffers from the residue contamination of polymer transfer-support and heavy metal ions.In this work,we directly grew fewlayer graphene on the SiO2/Si substrate without transfer process and then fabricated graphene-based glucose sensors by sequentially immobilizing glucose oxidase and depositing Nafion layer on its surface that was functionalized by oxygen-plasma treatment.Our transfer-and metal-free process shows distinct advantage over the common metal-CVD method in improving the electrochemical performance by eliminating the contamination of transfer-residue.Thus-obtained glucose sensor shows a high sensitivity(16.16μA mM-1cm-2)with a detection limit of 124.19μM.This method is simple and promising for the development of highly sensitive glucose sensors.
基金supported by the National Key R&D Program of China(2019YFA0708204)National Natural Science Foundation of China(T2188101)+1 种基金Science Fund for Distinguished Young Scholars of Jiangsu Province(BK20211503)Jiangsu Funding Program for Excellent Postdoctoral Talent(2022ZB595)。
文摘Graphene, a two-dimensional material with outstanding electrical and mechanical properties, has attracted considerable attention in the field of semiconductor technologies due to its potential use as a buffer layer for the epitaxial Ⅲ-nitride growth. In recent years, significant progress has been made in the chemical vapor deposition growth of graphene on various insulating substrates for the nitride epitaxy, which offers a facile, inexpensive, and easily scalable methodology. However, certain challenges are still present in the form of producing high-quality graphene and achieving optimal interface compatibility with Ⅲ-nitride materials.In this review, we provide an overview of the bottlenecks associated with the transferred graphene fabrication techniques and the state-of-the-art techniques for the transfer-free graphene growth. The present contribution highlights the current progress in the transfer-free graphene growth on different insulating substrates, including sapphire, quartz, SiO_(2)/Si, and discusses the potential applications of transfer-free graphene in the Ⅲ-nitride epitaxy. Finally, it includes the prospects of the transfer-free graphene growth for the Ⅲ-nitride epitaxy and the challenges that should be overcome to realize its full potential in this field.
基金the National Key R&D Program of China(Nos.2019YFA0708201 and 2019YFA0708204)the National Natural Science Foundation of China(Nos.T2188101,61527814,and 22179089)+3 种基金the Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXTD-202001)the Beijing Municipal Science and Technology Planning Project(No.Z191100000819004)the Science Fund for Distinguished Young Scholars of Jiangsu Province(No.BK20211503)the Suzhou Science and Technology Project-Prospective Application Research Program(No.SYG202038).
文摘Gaseous promotors have readily been adopted during the direct synthesis of graphene over insulators to enhance the growth quality and/or boost the growth rate.The understanding of the real functions of carbon-containing promotors has still remained elusive.In this study,we identify the critical roles of a representative CO_(2)promotor played in the direct growth of graphene.The comparative experimental trials validate CO_(2)as an effective modulator to decrease graphene nucleation density,improve growth kinetics,mitigate adlayer formation.The first-principles calculations illustrate that the generation of gas-phase OH species in CO_(2)-assisted system helps decrease the energy barriers of CH4 decomposition and carbon attachment to the growth front,which might be the key factor to allow high-quality direct growth.Such a CO_(2)-promoted strategy enables the conformal coating of graphene film over curved insulators,where the sheet resistance of grown graphene on quartz reaches as low as 1.26 kΩ·sq^(−1)at an optical transmittance of~95.8%.The fabricated endoscope lens based on our conformal graphene harvests an apoptosis of 82.8%for noninvasive thermal therapy.The work presented here is expected to motivate further investigations in the controllable growth of high-quality graphene on insulating substrates.
基金supported by the National Natural Science Foundation of China(Nos.52188101,52272051,52122202,12174086,and 12404009)High-level Talent Research Start-up Project Funding of Henan Academy of Sciences(No.231820055)+2 种基金the Fundamental Research Fund of Henan Academy of Sciences(No.240620057)the Scientific and Technological Research Project of Henan(No.242102230153)Cultivation and Enhancement Project of Technology Innovation Platform of Henan Academy of Sciences(No.241020004).
文摘Graphene meshes(GMs)have attracted considerable attention as advanced materials for high-performance gas sensing due to their high-density active edge sites and excellent electronic properties.However,the contamination-free preparation of GMs remains a challenge.Herein,we present a dewdrop-templated chemical vapor deposition approach to directly grow clean and intact graphene micromeshes(GMM)on SiO_(2)/Si substrates.The self-assembled micrometer-sized dewdrops from controlled water vapor condensation serve as a residue-free template for directing the growth of GMM with tunable hole sizes from submicrons to tens of microns.Density functional theory(DFT)calculations reveal that carbon species preferentially adsorb on pristine SiO_(2) regions to form a mesh structure.Contamination-free GMM gas sensors were fabricated using a simple transfer-free process,demonstrating a record-high sensitivity of 7.25%·ppm−1 and an ultra-low detection limit of 1.18 ppb for NO_(2) at room temperature.Complementary DFT studies elucidate that NO_(2) molecules adsorb more strongly on the edges of GMM,leading to a high response of the sensor.This work offers profound insights into dewdrop-templated graphene growth mechanisms and establishes a simple yet effective approach for fabricating high-performance transfer-free GMM sensors,thus paving the way for their practical applications in environmental monitoring and industrial safety fields.
文摘采用密度泛函理论的M06-2X和MN15方法,研究了生理环境(水液相、1.013×10^(5)Pa、310.15 K)下双丙氨酸螯合二价钙[α-Ala_(2)→Ca^(2+),缩写:α-A_(2)→Ca^(2+)]消除羟基自由基(OH)的反应机理.研究发现,α-A_(2)→Ca^(2+)与OH的反应有抽氢、加成和电子转移3个通道.势能面研究表明:OH与α-A2→Ca^(2+)的抽H反应自由能垒在13.2至56.8 k J/mol之间;OH与α-A_(2)→Ca^(2+)的加成反应自由能垒在61.0至66.2 kJ/mol之间;电子从α-A_(2)→Ca^(2+)向OH转移反应的自由能垒是179.0 k J/mol.结果表明,在生命体内α-A_(2)→Ca^(2+)可通过向OH提供H原子以及OH与C的加成过程消除OH,双丙氨酸螯合钙具有较好的清除羟自由基能力.
文摘近年来,氢硅烷参与的光催化自由基反应是有机合成领域的研究热点.文章系统综述了可见光催化下氢硅烷作为硅源合成有机硅化合物及作为卤原子转移(halogen atom transfer,XAT)试剂的自由基反应.研究表明,可见光催化下,氢硅烷能在温和条件下产生硅自由基,通过加成、取代等反应途径,高效构建了碳硅键.氢硅烷能与卤代烷烃发生单电子转移反应,生成烷基自由基中间体,并与烯烃、芳烃等富电子底物发生加成、取代等反应,最终实现交叉偶联这一重要转化过程.文章也对未来研究方向进行了展望:1)深入探索氢硅烷与羰基化合物的反应体系,解决该领域研究匮乏的问题;2)开发兼具高选择性、优异稳定性且经济的新型光催化剂;3)将光催化与过渡金属催化相结合,添加手性配体,实现不对称自由基反应的突破性进展.
