CN107619042A - A kind of extensive method for preparing graphene nano wall - Google Patents

Abstract

A preparation method for large-scale preparation of graphene nanowalls, according to the following steps: (1) a quartz boat equipped with foamed nickel and ferrocene is placed in the heating zone of the quartz tube at the inflow end of the reaction gas, and the cleaned and dried A stainless steel sheet or a quartz boat with a steel mesh is placed in the heating zone of the quartz tube near the reaction gas outflow end; (2) under normal pressure, under the protection of an inert gas, the temperature is raised to 1000~1200°C, and the inert gas atmosphere is maintained, and then the volume The ratio of hydrogen and carbon source gas is 1:6~2:3, react for 1 minute to 3 hours; (3) turn off the carbon source gas and hydrogen, and lower the reaction furnace to room temperature under an inert gas atmosphere; the present invention has greater Excellent surface area to volume ratio, sharp outer edge, thin layer of transparency, and abundant surface defects; the preparation process is simple, the cost is low, and the control process is controllable. Compared with synthetic methods such as PECVD, it has the advantages of being simpler and can produce graphite on a large scale ene nanowalls.

Description

A method for large-scale preparation of graphene nanowalls

technical field

The invention belongs to the field of functional materials, and relates to a graphene nano wall and a preparation method thereof.

Background technique

In 1997, surface-bound graphene nanowalls were discovered in the fabrication of carbon nanotubes by evaporating graphite by direct current (DC) arc discharge in the presence of dilute hydrogen. Graphene nanowalls, as a new type of two-dimensional carbon nanomaterials, have shown interest in vertical structures with unique orientations, exposed sharp edges, non-stacked morphology, and large surface-to-volume ratios compared to conventional horizontally oriented graphite. There is great interest in the application of aligned graphene nanowalls (English full name Vertical AlignedGraphene nanowalls, hereinafter referred to as VG). So far, emerging applications of VG and its derivatives mainly include field emitters, atmospheric nanoscale corona discharge, gas sensors and biosensors, supercapacitors, lithium-ion batteries, fuel cells (catalyst support), and electrochemical sensor. At present, the methods for synthesizing graphene nanowalls mainly include microwave plasma enhanced chemical vapor deposition (English full name Plasma Enhanced Chemical Vapor Deposition, hereinafter referred to as PECVD) method and hot wire method. PECVD synthesis can obtain graphene nanowalls with non-agglomerated morphology and directional growth; However, it has disadvantages including low yield, relatively low growth rate, difficult control of electric and magnetic fields, expensive instruments, and complicated preparation conditions. However, few reports have used the traditional chemical vapor deposition method to directly synthesize graphene nanowalls. Due to the advantages of simple process, cheap raw materials, and easy control of growth conditions, chemical vapor deposition has great potential in the large-scale production of graphene nanowalls in the future.

Contents of the invention

The purpose of the present invention is to provide a method for large-scale preparation of graphene nanowalls, which is easy to operate, low in energy consumption, low in cost, and high in efficiency, and can directly grow graphene nanowalls on substrates such as stainless steel sheets and silk screens.

The present invention is achieved through the following technical solutions.

The large-scale preparation method for preparing graphene nano-walls according to the present invention follows the steps below.

(1) Put a quartz boat filled with nickel foam and ferrocene in the heating zone of the quartz tube at the inflow end of the reaction gas, and place a quartz boat with cleaned and dried stainless steel sheet or steel mesh on the quartz tube near the outflow end of the reaction gas. tube heating zone.

(2) Under normal pressure, raise the temperature to 1000~1200℃ under the protection of inert gas, maintain the inert gas atmosphere, and then introduce hydrogen and carbon source gas with a volume ratio of 1:6~2:3, and react for 1 minute to 3 hours .

(3) Turn off the carbon source gas and hydrogen, and lower the reaction furnace to room temperature under an inert gas atmosphere.

The inert gas is argon or nitrogen, argon is preferred, and the gas flow rate is 10-40 sccm. The carbon source gas is hydrocarbon, such as methane and acetylene, and the gas flow rate is 80~180 sccm.

The surface of the stainless steel sheet or wire mesh described in step (1) of the present invention is cleaned, respectively placed in acetone, 95% ethanol, and deionized water for 3-60 minutes, and then blown dry with nitrogen. The purpose is to remove impurities such as organic matter on the surface of the purchased stainless steel wire mesh.

The present invention has the following beneficial effects.

(1) The graphene nanowall prepared by the present invention is a two-dimensional carbon nanostructure perpendicular to the substrate, which has a large surface area to volume ratio, sharp outer edges, thin transparent layers, and abundant surface defects.

(2) The preparation process of the present invention is simple, the cost is low, and large-scale production is possible.

(3) The present invention can control various growth parameters such as growth time, carbon source gas flow, etc. to realize the growth of graphene nanowalls of various lengths and densities.

(4) The present invention discloses for the first time the use of chemical vapor deposition to grow graphene nanowalls, which can provide a window for people to better understand the growth mechanism of graphene nanowalls. Compared with synthetic methods such as PECVD, it has the advantage of being simpler and can produce graphene nanowalls on a large scale.

Description of drawings

Figure 1 is a schematic diagram of the experimental device for preparing graphene nanowalls.

Fig. 2 is the scanning electron micrograph of embodiment 1 preparation graphene nano wall magnification is 5000 times.

Fig. 3 is the scanning electron micrograph of embodiment 2 preparation graphene nano wall magnification is 24000 times.

Fig. 4 is the scanning electron micrograph of the graphene nanowall magnification of 12000 times for the preparation of embodiment 3.

Fig. 5 is the scanning electron micrograph of embodiment 3 preparation graphene nano wall magnification is 3000 times.

detailed description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The methods described in the following examples, unless otherwise specified, are conventional methods; the materials and reagents, unless otherwise specified, can be obtained from commercial sources.

Example 1.

The specific steps of growing graphene nanowalls by thermal chemical vapor deposition are as follows:

a. Place the substrates for growing graphene nanowalls in acetone, 95% ethanol, and deionized water for 3 minutes, and then dry them with nitrogen;

b. Place the stainless steel wire mesh in step a in three quartz boats respectively. Wherein the quartz boat near the end of the gas outflow heating furnace was put into 0.02 g of nickel foam, and the last two quartz boats were put into carbon paper respectively. In addition, a quartz boat containing 0.05 g of catalyst ferrocene and 0.025 g of nickel foam was placed in the heating zone where the reaction gas first flowed into the quartz tube.

c. Under normal pressure, feed 30 sccm of argon and raise the temperature of the furnace to 1100° C. at a rate of 27° C./min, adjust the argon to 15 sccm, and introduce 90 sccm of methane and 30 sccm of hydrogen. Move the quartz boat equipped with the catalyst to enter the furnace, and react under this condition for 5 minutes. After the reaction was completed, the quartz boat containing the catalyst was moved to expose the reaction gas into the heated part of the furnace, the methane and hydrogen were turned off and the argon was adjusted to 30 sccm to cool down to room temperature. The SEM images of the resulting graphene nanowalls are shown in Figure 2.

Example 2.

The difference from Example 1 is that the quartz tube was wiped dry with cotton soaked in ethanol. Then carry out the reaction according to the relevant conditions in Example 1, and graphene nanowalls can also be obtained, but only locally distributed. The resulting graphene nanowall SEM image is shown in Figure 3.

Example 3.

What is different from Example 1 is that the graphene nanowall can also be obtained by reacting under the same conditions as in Example 1, but at the same time, impurities such as carbon fibers are grown, and the obtained SEM images are shown in Figure 4 and Figure 5.

Claims (3)

1. A kind of 1. extensive preparation method for preparing graphene nano wall, it is characterized in that according to the following steps：

   （1）Flowed into reacting gas in the quartz ampoule heating zone of end and put the quartz boat equipped with nickel foam and ferrocene, and will be placed with Cleaning and the stainless steel substrates or the quartz boat of steel wire dried are placed in reacting gas outflow end quartz ampoule heating zone；

   （2）Under normal pressure, 1000 ~ 1200 DEG C are warming up under inert gas shielding, maintains inert gas atmosphere, then be passed through volume ratio Example is 1:6~2:3 hydrogen and carbon-source gas, react 1 minute ~ 3 hours；

   （3）Turn off carbon-source gas and hydrogen, reacting furnace is down to room temperature under inert gas atmosphere；

   Described inert gas is argon gas or nitrogen, and gas flow is 10 ~ 40sccm；Carbon-source gas are hydrocarbon, and gas flow is 80~180sccm。
2. A kind of 2. extensive preparation method for preparing graphene nano wall according to claim 1, it is characterized in that described Carbon-source gas are methane, acetylene.
3. A kind of 3. extensive preparation method for preparing graphene nano wall according to claim 1, it is characterized in that step（1） Described in stainless steel substrates or the surface clean of silk screen be：Be respectively placed in acetone, 95% ethanol, deionized water each ultrasonic 3 ~ 60min, then dried up with nitrogen.