Single Carbon Fibers with a Macroscopic‐Thickness, 3D Highly Porous Carbon Nanotube Coating

Abstract

Carbon fiber (CF) grafted with a layer of carbon nanotubes (CNTs) plays an important role in composite materials and other fields; to date, the applications of CNTs@CF multiscale fibers are severely hindered by the limited amount of CNTs grafted on individual CFs and the weak interfacial binding force. Here, monolithic CNTs@CF fibers consisting of a 3D highly porous CNT sponge layer with macroscopic-thickness (up to several millimeters), which is directly grown on a single CF, are fabricated. Mechanical tests reveal high sponge-CF interfacial strength owing to the presence of a thin transitional layer, which completely inhibits the CF slippage from the matrix upon fracture in CNTs@CF fiber-epoxy composites. The porous conductive CNTs@CF hybrid fibers also act as a template for introducing active materials (pseudopolymers and oxides), and a solid-state fiber-shaped supercapacitor and a fiber-type lithium-ion battery with high performances are demonstrated. These CNTs@CF fibers with macroscopic CNT layer thickness have many potential applications in areas such as hierarchically reinforced composites and flexible energy-storage textiles.

Three‐Dimensional Interconnected Porous Nitrogen‐Doped Carbon Hybrid Foam for Notably Promoted Direct Dehydrogenation of Ethylbenzene to Styrene

“…As shown in Figure 4a and Figure S5a, all catalysts exhibit two broad diffraction peaks occurring at around 26°and 44°, which can be indexed as (002) and (100) planes of graphitic structure, respectively. [53] Compared with other four catalysts, NC MS @NC Glu-NH4Cl exhibits weakest peak, which indicates that the decline of crystallinity of the microstructures, because of the strengthened bubbling effect of NH 3 and HCl from NH 4 Cl in breaking the continuity of the ordered structures [49,54] and this agrees well with SEM results that the introduction of NH 4 Cl leads to the appearance of porous structure. [53] Compared with other four catalysts, NC MS @NC Glu-NH4Cl exhibits weakest peak, which indicates that the decline of crystallinity of the microstructures, because of the strengthened bubbling effect of NH 3 and HCl from NH 4 Cl in breaking the continuity of the ordered structures [49,54] and this agrees well with SEM results that the introduction of NH 4 Cl leads to the appearance of porous structure.…”

“…From Figure 1b, the as-prepared nitrogen-doped carbon (NC MS , 3.49 of C/N atomic ratio) by annealing pristine melamine sponge keeps the original network structure but smaller grid mesh (20-50 μm) and thinner skeleton (1-5 μm). It has been widely reported that NH 4 Cl can create porous structure and introduce more defects due to the bubbling effect of the released NH 3 and HCl from NH 4 Cl at high temperature and achieve nitrogen-doped carbon materials. [34,49] Owing to the released NH 3 diffusing into melamine sponge skeleton, hopefully we would produce porous network structured nitrogen-doped carbon by annealing the freeze-dried NH 4 Cl-loaded melamine sponge.…”

“…[1] Various strategies have been adopted to prepare 3D carbon materials, such as self-assemble method, [2] direct-templated chemical vapor deposition (CVD) [3] and carbonization of 3D organic templates [4] , and the fruitful 3D structured carbon matrix has been fabricated (e. g., 3D graphene aerogel, [5] carbon foam [6] and 3D CNTs foam [7] ). [1] Various strategies have been adopted to prepare 3D carbon materials, such as self-assemble method, [2] direct-templated chemical vapor deposition (CVD) [3] and carbonization of 3D organic templates [4] , and the fruitful 3D structured carbon matrix has been fabricated (e. g., 3D graphene aerogel, [5] carbon foam [6] and 3D CNTs foam [7] ).…”

“…3D hierarchical carbon materials provide a versatile platform for various applications such as catalysis, adsorption, supercapacitor and separation. [1] Various strategies have been adopted to prepare 3D carbon materials, such as self-assemble method, [2] direct-templated chemical vapor deposition (CVD) [3] and carbonization of 3D organic templates [4] , and the fruitful 3D structured carbon matrix has been fabricated (e. g., 3D graphene aerogel, [5] carbon foam [6] and 3D CNTs foam [7] ). Despite the recent achievements in 3D carbon nanomaterials fabrication, there are still many challenges to overcome: Firstly, unstable pristine graphene network results in poor mechanical stability.…”

“…In this process, each of melamine sponge, NH4Cl, glucose, and freeze-drying operation is indispensable. The melamine sponge acts as both 3D template and nitrogen-doped carbon precursor, the added NH 4 Cl serves as both gas template and nitrogen source regarding the formation of porous nitrogen-doped carbon, and the NH 3 and HCl gases released from NH 4 Cl blew the carbon skeleton and etched the skeleton into porous structure, and the added glucose acts as three roles including the oxygen dopant to increase oxygen content of the carbon materials, the carbon source to form nitrogen-doped carbon layer and the upholder to inhibit the crash of porous carbon skeleton resulting from the collision of NH 3 and HCl gases pyrolyzed from NH 4 Cl. The developed NC MS @NC Glu-NH4Cl hybrid foam featuring with the interconnected nitrogen-doped carbon foam coated by porous nitrogen-doped carbon shows 1.6 times high steady-state styrene rate (4.77 mmol g À 1 h À 1 ) with 96.4 % of selectivity for direct dehydrogenation of ethylbenzene to styrene as compared to the well-established nanodiamond, ascribed to the promoted mass transfer and the accessibility of active sites led by its unique 3D interconnected porous hybrid foam structure, relatively increased surface kenotic carbonyl group and structural defects, promoted nucleophilicity by nitrogen-doping.…”