High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicati...High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicating that this method is promising to synthesize high-purity CNCs on a large scale.It is considered that an appropriate proportion of Fe and Sn,proper particle size distribution,and a loose-porous aggregate structure of the catalyst are the key points to the high-purity growth of CNCs.Benefiting from the high-purity preparation,a CNC Buckypaper was successfully prepared and the electrical,mechanical,and electrochemical properties were investigated comprehensively.Furthermore,as one of the practical applications,the CNC Buckypaper was successfully utilized as an efficient adsorbent for the removal of methylene blue dye from wastewater with an adsorption efficiency of 90.9%.This study provides a facile and economical route for preparing high-purity CNCs,which is suitable for large-quantity production.Furthermore,the fabrication of macroscopic CNC Buckypaper provides promising alternative of adsorbent or other practical applications.展开更多
Recently,multilevel structural carbon aerogels are deemed as attractive candidates for microwave absorbing materials.Nevertheless,excessive stack and agglomeration for low-dimension carbon nanomaterials inducing imped...Recently,multilevel structural carbon aerogels are deemed as attractive candidates for microwave absorbing materials.Nevertheless,excessive stack and agglomeration for low-dimension carbon nanomaterials inducing impedance mismatch are significant challenges.Herein,the delicate“3D helix-2D sheet-1D fiber-0D dot”hierarchical aerogels have been successfully synthesized,for the first time,by sequential processes of hydrothermal self-assembly and in-situ chemical vapor deposition method.Particularly,the graphene sheets are uniformly intercalated by 3D helical carbon nanocoils,which give a feasible solution to the mentioned problem and endows the as-obtained aerogel with abundant porous structures and better dielectric properties.Moreover,by adjusting the content of 0D core-shell structured particles and the parameters for growth of the 1D carbon nanofibers,tunable electromagnetic properties and excellent impedance matching are achieved,which plays a vital role in the microwave absorption performance.As expected,the optimized aerogels harvest excellent performance,including broad effective bandwidth and strong reflection loss at low filling ratio and thin thickness.This work gives valuable guidance and inspiration for the design of hierarchical materials comprised of dimensional gradient structures,which holds great application potential for electromagnetic wave attenuation.展开更多
Armchair carbon nanocoils (CNCs) with different geometric parameters are constructed and optimized using a tight-binding (TB) total energy model. The quantum conductance of these nanocoils is simulated employing a π-...Armchair carbon nanocoils (CNCs) with different geometric parameters are constructed and optimized using a tight-binding (TB) total energy model. The quantum conductance of these nanocoils is simulated employing a π-orbital TB model incorporated with the non-equilibrium Green's function theory. Compared with the perfect armchair carbon nanotubes (CNTs) and armchair CNTs with only Stone-Wales (SW) defects, the quantum conductance spectra of the armchair CNCs present distinct gaps around the Fermi level, which are mainly originated from the existence of sp3 carbon in the three-dimensional spiral structures. Moreover, the detailed conductance spectra of the armchair CNCs depend sensitively on their geometric parameters, such as tubular diameter and block-block distance.展开更多
电催化反应过程涉及固、液、气传输以及电子和质子传导,为确保反应的顺利进行和提高催化剂中贵金属的利用率及延长催化剂的寿命,理想的电催化剂载体必须同时具备高比表面积、导电性好、合适的孔结构、耐腐蚀以及合适的表面基团等.为此,...电催化反应过程涉及固、液、气传输以及电子和质子传导,为确保反应的顺利进行和提高催化剂中贵金属的利用率及延长催化剂的寿命,理想的电催化剂载体必须同时具备高比表面积、导电性好、合适的孔结构、耐腐蚀以及合适的表面基团等.为此,碳载体的改性工作受到关注,常用的方法是通过酸、碱、氧化和高分子等手段改变载体的结构和表面性质,以期接近理想电催化剂载体的要求;同时在开发新型碳载体方面做了更大量的工作.本文简要评述了商品炭载体如碳黑Vulcan XC-72R以及其它的乙炔黑、黑珍珠-2000、Printex XE-2和Ketjen Black EC等碳材料在直接醇燃料电池中的应用,但对纳米碳纤维、碳纳米管、有序多孔碳、中间相碳小球、碳纳米角、碳纳米卷和碳气凝胶等新型碳载体则进行了较全面的评述.与商品碳载体相比,新型碳载体在一定程度上都表现出比XC-72R更优的性能,这主要是因为新型碳材料具有特殊的结构、更高的结晶性能(导电性)和更好的传质能力.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51661145025,51972039,and 51803018)
文摘High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicating that this method is promising to synthesize high-purity CNCs on a large scale.It is considered that an appropriate proportion of Fe and Sn,proper particle size distribution,and a loose-porous aggregate structure of the catalyst are the key points to the high-purity growth of CNCs.Benefiting from the high-purity preparation,a CNC Buckypaper was successfully prepared and the electrical,mechanical,and electrochemical properties were investigated comprehensively.Furthermore,as one of the practical applications,the CNC Buckypaper was successfully utilized as an efficient adsorbent for the removal of methylene blue dye from wastewater with an adsorption efficiency of 90.9%.This study provides a facile and economical route for preparing high-purity CNCs,which is suitable for large-quantity production.Furthermore,the fabrication of macroscopic CNC Buckypaper provides promising alternative of adsorbent or other practical applications.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51972039,51803018,and 51661145025)LiaoNing Revitalization Talents Program(No.XLYC1902122).
文摘Recently,multilevel structural carbon aerogels are deemed as attractive candidates for microwave absorbing materials.Nevertheless,excessive stack and agglomeration for low-dimension carbon nanomaterials inducing impedance mismatch are significant challenges.Herein,the delicate“3D helix-2D sheet-1D fiber-0D dot”hierarchical aerogels have been successfully synthesized,for the first time,by sequential processes of hydrothermal self-assembly and in-situ chemical vapor deposition method.Particularly,the graphene sheets are uniformly intercalated by 3D helical carbon nanocoils,which give a feasible solution to the mentioned problem and endows the as-obtained aerogel with abundant porous structures and better dielectric properties.Moreover,by adjusting the content of 0D core-shell structured particles and the parameters for growth of the 1D carbon nanofibers,tunable electromagnetic properties and excellent impedance matching are achieved,which plays a vital role in the microwave absorption performance.As expected,the optimized aerogels harvest excellent performance,including broad effective bandwidth and strong reflection loss at low filling ratio and thin thickness.This work gives valuable guidance and inspiration for the design of hierarchical materials comprised of dimensional gradient structures,which holds great application potential for electromagnetic wave attenuation.
基金supported by the Fundamental Research Funds for the Central Universities of China (Grant No. DUT10ZD211)the National Natural Science Foundation of China (Grant Nos. 51072027 and 40874039)
文摘Armchair carbon nanocoils (CNCs) with different geometric parameters are constructed and optimized using a tight-binding (TB) total energy model. The quantum conductance of these nanocoils is simulated employing a π-orbital TB model incorporated with the non-equilibrium Green's function theory. Compared with the perfect armchair carbon nanotubes (CNTs) and armchair CNTs with only Stone-Wales (SW) defects, the quantum conductance spectra of the armchair CNCs present distinct gaps around the Fermi level, which are mainly originated from the existence of sp3 carbon in the three-dimensional spiral structures. Moreover, the detailed conductance spectra of the armchair CNCs depend sensitively on their geometric parameters, such as tubular diameter and block-block distance.
文摘电催化反应过程涉及固、液、气传输以及电子和质子传导,为确保反应的顺利进行和提高催化剂中贵金属的利用率及延长催化剂的寿命,理想的电催化剂载体必须同时具备高比表面积、导电性好、合适的孔结构、耐腐蚀以及合适的表面基团等.为此,碳载体的改性工作受到关注,常用的方法是通过酸、碱、氧化和高分子等手段改变载体的结构和表面性质,以期接近理想电催化剂载体的要求;同时在开发新型碳载体方面做了更大量的工作.本文简要评述了商品炭载体如碳黑Vulcan XC-72R以及其它的乙炔黑、黑珍珠-2000、Printex XE-2和Ketjen Black EC等碳材料在直接醇燃料电池中的应用,但对纳米碳纤维、碳纳米管、有序多孔碳、中间相碳小球、碳纳米角、碳纳米卷和碳气凝胶等新型碳载体则进行了较全面的评述.与商品碳载体相比,新型碳载体在一定程度上都表现出比XC-72R更优的性能,这主要是因为新型碳材料具有特殊的结构、更高的结晶性能(导电性)和更好的传质能力.
