The practical applications of lithium-sulfur(Li-S)battery have been greatly hindered by the severe polysulfide shuttle at the cathode and rampant lithium dendrite growth at the anode.One of the effective solutions dea...The practical applications of lithium-sulfur(Li-S)battery have been greatly hindered by the severe polysulfide shuttle at the cathode and rampant lithium dendrite growth at the anode.One of the effective solutions deals with concurrent management of both electrodes.Nevertheless,this direction remains in a nascent stage due to a lack of material selection and mechanism exploration.Herein,we devise a temperature-mediated direct chemical vapor deposition strategy to realize the controllable synthesis of three-dimensional boron/nitrogen dual-doped graphene(BNG)particulated architectures,which is employed as a light-weighted and multi-functional mediator for both electrodes in Li-S batteries.Benefiting from the“sulfiphilic”and“lithiophilic”features,the BNG modified separator not only enables boosted kinetics of polysulfide transformation to mitigate the shuttle effect but also endows uniform lithium deposition to suppress the dendritic growth.Theoretical calculations in combination with electro-kinetic tests and operando Raman analysis further elucidate the favorable sulfur and lithium electrochemistry of BNG at a molecular level.This work offers direct insight into the mediator design via controllable synthesis of graphene materials to tackle the fundamental challenges of Li-S batteries.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
Recently,graphene has drawn considerable attention in the field of electronics,owing to its favorable conductivity and high carrier mobility.Crucial to the industrialization of graphene is its high-quality microfabric...Recently,graphene has drawn considerable attention in the field of electronics,owing to its favorable conductivity and high carrier mobility.Crucial to the industrialization of graphene is its high-quality microfabrication via chemical vapor deposition.However,many problems remain in its preparation,such as the not fully understood cracking mechanism of the carbon source,the mechanism of its substrate oxidation,and insufficient defect repair theory.To help close this capability gap,this study leverages density functional theory to explore the role of O in graphene growth.The effects of Cu substrate oxidation on carbon source cracking,nucleation barriers,crystal nucleus growth,and defect repairs are discussed.OCu was found to reduce energy change during dehydrogenation,rendering the process easier.Moreover,the adsorbed O in graphene or its Cu substrate can promote defect repair and edge growth.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
Carbon source precursor is a critical factor governing chemical vapor deposition growth of graphene films.Methane(CH4),has been the most commonly used precursor in the last decade,but it presents challenges in terms o...Carbon source precursor is a critical factor governing chemical vapor deposition growth of graphene films.Methane(CH4),has been the most commonly used precursor in the last decade,but it presents challenges in terms of decomposition efficiency and growth rate.Here we thoroughly evaluated acetylene(C2H_(2)),a precursor that is probably for providing carbon dimer(C2)species,for fast growth of large-scale graphene films.We find that the graphene growth behaviors fueled by C2H_(2) exhibit unconventional localized growth behavior with significant advantages in terms of high growth rate,which mainly ascribe to the as-decomposed C2 species.Therefore,a C2-fueled scanning growth strategy is proposed,and the fast scanning growth rate of 40 cm/min was experimentally demonstrated.This growth strategy is compatible with the approach of unidirectional growth of single-crystal graphene films,and the as-grown graphene films are of high-quality.This work demonstrates a reliable and promising strategy for the rapid synthesis of high-quality graphene film and may pave the avenue to cost-effective mass production of graphene materials in the roll-to-roll system.展开更多
By virtue of ultra-fexibility and non-inductive feature,fbrous electrode is an ideal platform for constructing wearable electronics and implantable electrodes for medical therapy.2D nanofuidic channels with tailored i...By virtue of ultra-fexibility and non-inductive feature,fbrous electrode is an ideal platform for constructing wearable electronics and implantable electrodes for medical therapy.2D nanofuidic channels with tailored ion transport dynamics enable minimized charge transfer resistance and efcient ion transport capability.Thus,combining the nanofuidic ion transport features and fbrous electrode advantages,2D nanofuidic fber electrode presents a series of extra advantages of unidirectional efcient ion transport and great biofriendliness.In this minireview,we frst elaborate the architecture characteristics of the emerging 2D nanofuidic fbers and highlight the intriguing features,such as tunable interlayer spacing,efcient ion transport and modifable channel surface.Conventional strategies for constructing 2D nanofuidic fbers have been systematically enumerated,including solvent volatilizing regulation,confnement triggered alignment,and fow-driven orientation.In addition,the promising applications of 2D nanofuidic fbers have been also summarized as well.Finally,we analyze the challenges and perspectives of fbrous 2D nanofuidic construction,ion transport mechanism study and potential application extension.展开更多
基金financially supported by the National Natural Science Foundation of China(51702225)the National Key Research and Development Program(2019YFA0708201)+3 种基金the Beijing Municipal Science and Technology Commission(Z161100002116020)the China Postdoctoral Science Foundation funded project(2020 M681704,2021 T140493)the support from Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies,Suzhou,Chinathe support from the Postdoctoral Research Foundation of Jiangsu Province。
文摘The practical applications of lithium-sulfur(Li-S)battery have been greatly hindered by the severe polysulfide shuttle at the cathode and rampant lithium dendrite growth at the anode.One of the effective solutions deals with concurrent management of both electrodes.Nevertheless,this direction remains in a nascent stage due to a lack of material selection and mechanism exploration.Herein,we devise a temperature-mediated direct chemical vapor deposition strategy to realize the controllable synthesis of three-dimensional boron/nitrogen dual-doped graphene(BNG)particulated architectures,which is employed as a light-weighted and multi-functional mediator for both electrodes in Li-S batteries.Benefiting from the“sulfiphilic”and“lithiophilic”features,the BNG modified separator not only enables boosted kinetics of polysulfide transformation to mitigate the shuttle effect but also endows uniform lithium deposition to suppress the dendritic growth.Theoretical calculations in combination with electro-kinetic tests and operando Raman analysis further elucidate the favorable sulfur and lithium electrochemistry of BNG at a molecular level.This work offers direct insight into the mediator design via controllable synthesis of graphene materials to tackle the fundamental challenges of Li-S batteries.
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 Natural Science Foundation of China(Nos.T2188101,52021006,and 52072042)the National Natural Science Foundation Youth Fund(Nos.22105006 and 52202033)+2 种基金Beijing National Laboratory for Molecular Science(No.BNLMS-CXTD-202001)the National Key R&D Program of China(Nos.2016YFA0200101,2016YFA0200103,and 2018YFA0703502)the Beijing Municipal Science&Technology Commission(Nos.Z191100000819005,Z191100000819007,and Z201100008720005).
文摘Recently,graphene has drawn considerable attention in the field of electronics,owing to its favorable conductivity and high carrier mobility.Crucial to the industrialization of graphene is its high-quality microfabrication via chemical vapor deposition.However,many problems remain in its preparation,such as the not fully understood cracking mechanism of the carbon source,the mechanism of its substrate oxidation,and insufficient defect repair theory.To help close this capability gap,this study leverages density functional theory to explore the role of O in graphene growth.The effects of Cu substrate oxidation on carbon source cracking,nucleation barriers,crystal nucleus growth,and defect repairs are discussed.OCu was found to reduce energy change during dehydrogenation,rendering the process easier.Moreover,the adsorbed O in graphene or its Cu substrate can promote defect repair and edge growth.
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the National Natural Science Foundation of China(No.T2188101)the Beijing National Laboratory for Molecular Science(No.BNLMS-CXTD-202001).
文摘Carbon source precursor is a critical factor governing chemical vapor deposition growth of graphene films.Methane(CH4),has been the most commonly used precursor in the last decade,but it presents challenges in terms of decomposition efficiency and growth rate.Here we thoroughly evaluated acetylene(C2H_(2)),a precursor that is probably for providing carbon dimer(C2)species,for fast growth of large-scale graphene films.We find that the graphene growth behaviors fueled by C2H_(2) exhibit unconventional localized growth behavior with significant advantages in terms of high growth rate,which mainly ascribe to the as-decomposed C2 species.Therefore,a C2-fueled scanning growth strategy is proposed,and the fast scanning growth rate of 40 cm/min was experimentally demonstrated.This growth strategy is compatible with the approach of unidirectional growth of single-crystal graphene films,and the as-grown graphene films are of high-quality.This work demonstrates a reliable and promising strategy for the rapid synthesis of high-quality graphene film and may pave the avenue to cost-effective mass production of graphene materials in the roll-to-roll system.
基金This project was fnancially supported by a startup research grant for a distinguished professor at Soochow University(Y.S.)the National Natural Science Foundation of China No.52003188(Y.S.)+2 种基金the Natural Science Foundation of Jiangsu Province No.BK20200871(Y.S.)the open research fund for Jiangsu Provincial Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies(Y.S.)the open research fund State Key Laboratory for Modifcation of Chemical Fibers and Polymer Materials,Donghua University No.KF2104(Y.S.).
文摘By virtue of ultra-fexibility and non-inductive feature,fbrous electrode is an ideal platform for constructing wearable electronics and implantable electrodes for medical therapy.2D nanofuidic channels with tailored ion transport dynamics enable minimized charge transfer resistance and efcient ion transport capability.Thus,combining the nanofuidic ion transport features and fbrous electrode advantages,2D nanofuidic fber electrode presents a series of extra advantages of unidirectional efcient ion transport and great biofriendliness.In this minireview,we frst elaborate the architecture characteristics of the emerging 2D nanofuidic fbers and highlight the intriguing features,such as tunable interlayer spacing,efcient ion transport and modifable channel surface.Conventional strategies for constructing 2D nanofuidic fbers have been systematically enumerated,including solvent volatilizing regulation,confnement triggered alignment,and fow-driven orientation.In addition,the promising applications of 2D nanofuidic fbers have been also summarized as well.Finally,we analyze the challenges and perspectives of fbrous 2D nanofuidic construction,ion transport mechanism study and potential application extension.