Heater‐Free and Substrate‐Independent Growth of Vertically Standing Graphene Using A High‐Flux Plasma‐Enhanced Chemical Vapor Deposition

Abstract

Graphene, a typical 2D nanostructure comprising of sp 2hybridized carbon atoms offers not only superior electron mobility and mechanical strength, but also huge specific surface area and facile functionalization. [4,5] All these merits render the vast utilizations of graphene in optoelectronics, [6,7] FETs, [8,9] sensors, [10] catalysts [11] and energy storage devices. [12,13] Compared with the laid-down graphene, vertically standing graphene (VSG) is composed of folded graphene petals with seamless edges [14] growing nearly perpendicularly to the substrate regardless of catalyst surface. [15-17] The tremendous interests toward VSG stem from its unique properties, such as large surface to volume ratio, nonaggregation morphology, and abundance of exposed and ultrathin edges. [18,19] Along with the excellent intrinsic properties of graphene, VSG exhibits its indispensable roles especially in the fields of emitters, [20] supercapacitors, [21] and fuel cells. [22] Notably, the morphologies and structural features of VSG significantly influences such applications. [12,21] However, conventional deposition processes for VSG are usually carried out above 500 °C [15,21,23-25] with the usual drawback of poor scalability, [26,27] which hampers both scientific research and large scale fabrication. Therefore, an efficient and facile strategy for convenient tuning of VSG morphologies and structures, particularly at significantly reduced temperatures, is of vital importance for practical applications at lowered cost. To date, impressive improvements have been made to reduce fabrication temperature and realize an efficient control of structure and morphology of VSG via sputtering, [28] thermal chemical vapor deposition (TCVD), [23] and plasma enhanced chemical vapor deposition (PECVD). [16] Compared with other techniques, PECVD offers the advantages of low substrate temperature, fast growth, substrate independence and good feasibility in controlling morphologies and structures. [18] In a typical PECVD system, the nonequilibrium plasma dissociates the carbon related gaseous precursors to produce reactive radicals as the building blocks for VSG and the generated energetic electrons boost the reaction kinetics of the growth process at low substrate temperature. We note that the electric field from the plasma sheath perpendicular to the substrate affects the growth Vertically standing graphene (VSG) films have demonstrated various appealing functionalities on the basis of excellent electrical/thermal conductivity and electrochemical/catalytic properties, owing to their unique morphology, preferable orientation of the basal planes, and adequate defects as effective catalytic sites. Most fabrication processes for VSG suffer from the disadvantage of high processing temperature, difficulty in structural control, or poor scalability, which limits their many potential applications. Herein, a scalable high-flux plasma-enhanced chemical vapor deposition system is designed, with streamlined magnetic field to enable high and uniform ion densi...

A flexible metallic TiC nanofiber/vertical graphene 1D/2D heterostructured as active electrocatalyst for advanced Li–S batteries

“…A way forward lies in significant enlargement in the specific interfacial area with electrocatalysts, so that Li 2 S could be spread over a large surface to reduce overall film thickness and avoid local aggregation. Conducting two‐dimensional (2D) materials such as low‐defect graphene would be an additive material of choice, so that its effective coupling with nanoelectrocatalysts could enable the best use of the surficial area of the catalysts while providing an electric highway for charge and ion transportation 17,46–50 …”

Atomic Layer Coated Al2O3 on Nitrogen Doped Vertical Graphene Nanosheets for High Performance Sodium Ion Batteries

“…[15,30,31] Our previous work has demonstrated the potential application of vertically standing graphene films (VSG) directly as the anode in a sodium-ion battery. [22] In order to obtain defective, porous, and vertically aligned graphene nanosheets with a compact arrangement for an enhancement of sodium storage capability, we introduced and modulate the nitrogen plasma via varying the nitrogen gas flow rate from 0 sccm to 10 sccm during the fabrication process in our laboratory-built H-PECVD system, as shown in step 1 in Figure 1a. The fabricated NVG shows apparently different morphology as seen in Figure S1.…”

“…pathway of ions; thus, it has been introduced as support backbone for active materials [18][19][20] or directly used as anode for batteries. [21,22] However, the defective and porous structure with large specific surface area (SSA) of these carbon materials always suffer from extremely low initial Coulombic efficiency (ICE), low reversible capacity, and unsatisfied cycling stability due to uncontrollable decomposition of the electrolyte and poor interface construction between electrolyte and electrode. [23,24] Therefore, it is highly desired to deactivate the surface defects while maintain the sodium storage capacity of vertically oriented structure.…”

Effects of Substrates on Nucleation, Growth and Electrical Property of Vertical Few-Layer Graphene

“…VFLG can be prepared on different substrates with or without catalysts at a low temperature through plasma-enhanced chemical vapor deposition (PECVD) [ 10 , 11 , 12 , 13 , 14 ]. The impact factors of VFLG growth, such as plasma power, gas ratio, pressure, growth time, temperature and so on, have been studied in detail for the controllable growth of VFLG regarding growth rate, morphology and density of VFLG [ 15 , 16 , 17 , 18 ].…”