CN101191204A - Preparation method of network interpenetrating diamond-coated porous electrode - Google Patents

Abstract

The preparation method of the network interpenetrating diamond-coated porous electrode of the present invention adopts the porous activated carbon material made of carbonaceous material interphase and different fillers as the matrix, liquid acetone as the carbon source, hydrogen as the carrier, and microwave plasma chemical gas phase Deposition (MPCVD) process prepares honeycomb diamond-coated porous electrodes on porous activated carbon substrates; the reaction chamber is evacuated and filled with reaction gas, and after adjusting the pressure of the reaction chamber, chemical vapor deposition (CVD) begins to deposit diamond coatings, process parameters It is: the pressure is 2-4kPa, the total gas flow is 90-120 ml/min, and the acetone/hydrogen is 1-3% (volume ratio). The invention solves the problems of high preparation cost, complex process and limited electrode area of the diamond porous electrode.

Description

Preparation method of network interpenetrating diamond-coated porous electrode

【Technical field】

The invention relates to the technical field of new materials, in particular to a method for preparing a diamond-coated porous electrode with a network interpenetrating structure on an activated carbon substrate by using microwave plasma chemical vapor deposition (MPCVD) technology.

【Background technique】

As a new carbon functional electrode material, boron-doped diamond coated electrode has extremely low background current, and the electrostatic capacitance on the electrode surface is only a few microfarads/square centimeter (μf/cm ² ), which is smaller than carbon electrode materials such as glassy carbon. 2 orders of magnitude, so that the signal-to-noise ratio generated by the redox of reactants on the electrode surface is much higher than that of other electrode materials. The diamond-coated electrode has a wide electrochemical potential window (3-5V) in the electrolyte, which can study electrochemical reactions that can only occur at high overpotentials, and realize material analysis, synthesis, and decomposition that are impossible for conventional electrodes. The surface of diamond-coated electrodes has a very good "self-cleaning" ability, while traditional graphite electrodes, platinum electrodes and other electrode materials are very easy to absorb a layer of impurities on the surface or self-oxidize to cause electrode pollution and increase surface resistance. Diamond-coated electrodes also have excellent properties in terms of hardness and strength, can withstand the strong impact of ultrasonic waves on the electrode surface, and have a long service life. However, the relatively low capacitance of diamond electrodes seriously affects its applications in electrochemical capacitors, energy storage and generation devices (batteries and fuel cells). For example, energy supply electric double layer capacitors used as memory backup devices usually work in the potential range of 0.8-3.0V, which requires electrode materials to have both a wide potential window and high capacitance. In this regard, the porosity of the diamond electrode is an effective way to solve the problem. Electrode porosity can achieve the purpose of increasing the surface area, improving surface activity and improving the charge storage capacity of the electrode, and can reduce the requirements for the size of the electrode in practical applications.

According to the literature search, boron-doped porous diamond has been prepared by oxygen plasma etching and chemical vapor deposition (CVD). Its porous structure makes the diamond-coated electrode possess the characteristics of high capacitance and wide potential window. However, this method is expensive and is currently limited to laboratory research.

【Content of invention】

The purpose of the present invention is to overcome the deficiencies of the prior art, and propose a method for preparing a network interpenetrating structure diamond-coated porous electrode with an activated carbon material as a matrix by using chemical vapor deposition technology, so as to solve the problem of high preparation cost of diamond porous electrodes and poor process technology. complex and limited electrode area.

The preparation method of the network interpenetrating diamond-coated porous electrode of the present invention is realized through the following technical scheme. The present invention adopts porous activated carbon materials with different pore structures and properties made of carbonaceous material interphase and different fillers as the matrix, liquid acetone as the carbon source, hydrogen as the carrier, and microwave plasma chemical vapor deposition (MPCVD) process Fabrication of interpenetrating network diamond-coated porous electrodes on porous activated carbon substrates. After the reaction chamber is evacuated, it is filled with reaction gas. The reaction gas generates a sufficient concentration of active hydrogen atoms and carbon-containing active groups under the excitation of the plasma. After adjusting the pressure of the reaction chamber, the diamond coating is deposited by chemical vapor deposition (CVD). , the process parameters are: pressure 0.5-5 kPa (kPa), total gas flow rate 90-120 ml/min, acetone/hydrogen 1-3% (volume ratio).

In the present invention, after the reaction chamber in the device is evacuated, a certain amount of hydrogen is charged, the background vacuum degree of the reaction chamber is higher than 1× ^10-3 Pa (Pa), and the pressure of filling hydrogen is 2 to 4 kilopascals (kPa). ); its function is: the generated hydrogen plasma bombards and cleans the surface of the active carbon substrate, and the active hydrogen atoms are accelerators for diamond growth.

The reaction gases mentioned above are hydrogen and acetone. Acetone was carried into the reaction chamber by bubbling hydrogen gas.

The activated carbon matrix described above is made of a good self-sintering carbonaceous mesophase mixed with different fillers.

【Detailed ways】

Three embodiments of the preparation method of the network interpenetrating diamond-coated porous electrode of the present invention are provided below.

Example 1

The self-sintering carbonaceous mesophase and apple carbon filler powder are mixed to make sheet-like porous activated carbon, and the sheet-like porous activated carbon is ultrasonically cleaned in acetone solution, dried and placed in the reaction chamber after cleaning, and microwaved. The chamber is evacuated to 1×10 ^-3 Pa (Pa), filled with hydrogen gas at a pressure of 2 kilopascal (kPa), and the microwave source with a power of 1000W is turned on. After the hydrogen plasma is ignited, the temperature rises to 750°C within 10 seconds. , keep the temperature for 1 minute; feed the reaction gas, the reaction gas is hydrogen and acetone, start to deposit the diamond coating with chemical vapor deposition (CVD) after adjusting the pressure of the reaction chamber, the process parameters are: pressure 2 kilopascals (kPa), total gas The flow rate is 90 ml/min, and the acetone/hydrogen is 1% (volume ratio).

Example 2

The self-sintering carbonaceous mesophase and carbon fiber filler are mixed to make sheet-like porous activated carbon, and the sheet-like porous activated carbon is subjected to ultrasonic vibration in 0.5 μm (micromolecular) diamond sand acetone solution, and then deionized water After cleaning and drying, put it into the reaction chamber, evacuate the microwave reaction chamber to 1×10 ³ Pa (Pa), fill it with hydrogen gas at a pressure of 2 kilopascal (kPa), turn on the microwave source with a power of 1000 watts, and the hydrogen plasma After glowing, the temperature rises to 750°C within 10 seconds, and the temperature is kept constant for 1 minute; the reaction gas is hydrogen and acetone, and the chemical vapor deposition (CVD) is used to deposit the diamond coating after adjusting the pressure of the reaction chamber. The parameters are: the pressure is 3 kilopascals (kPa), the total gas flow is 100 ml/min, and the acetone/hydrogen is 2% (volume ratio).

Example 3

The self-sintering carbonaceous mesophase and apple pomace filler are mixed to make sheet-like porous activated carbon, and the sheet-like porous activated carbon is ultrasonically cleaned with deionized water, dried and put into the reaction chamber, and the microwave reaction chamber is pumped Vacuum to 1×10 ^-3 Pa (Pa), fill with hydrogen gas at a pressure of 2 kilopascal (kPa), turn on the microwave source with a power of 1000 watts, and the temperature will rise to 750°C within 10 seconds after the hydrogen plasma is ignited. Keep the temperature constant for 1 minute; feed the reaction gas, the reaction gas is hydrogen and acetone, and start to deposit the diamond coating by chemical vapor deposition (CVD) after adjusting the pressure of the reaction chamber. The process parameters are: pressure 4 kilopascals (kPa), total gas flow 120 ml/min, acetone/hydrogen is 3% (volume ratio).

Claims (6)

1. A method for preparing a network interpenetrating diamond-coated porous electrode, characterized in that, ——Using porous activated carbon material as the substrate, liquid acetone as the carbon source, and hydrogen as the carrier, the honeycomb diamond-coated porous electrode is prepared on the porous activated carbon substrate by microwave plasma chemical vapor deposition process; ——The reaction chamber is evacuated and filled with reaction gases hydrogen and acetone. After adjusting the pressure of the reaction chamber, the diamond coating is deposited by chemical vapor deposition. The process parameters are: pressure 0.5-5 kPa, total gas flow 90-120 ml/ Minutes, the volume ratio of acetone/hydrogen is 1-3%. 2. The preparation method of network interpenetrating diamond-coated porous electrode according to claim 1, characterized in that, after the reaction chamber is evacuated, the reaction gas is filled, and the background vacuum degree of the reaction chamber is higher than 1×10 ³ Pa, the pressure of the reaction gas charged is 2-4 kPa. 3. according to the preparation method of the described network interpenetrating diamond coating porous electrode of claim 1 or 2, it is characterized in that, with liquid acetone as carbon source, it is carried into reaction chamber with hydrogen bubbling method, in microwave plasma Under the action of the body, active hydrogen atoms and carbon-containing active groups are generated. 4. The preparation method of the network interpenetrating diamond-coated porous electrode according to claim 1 or 2, wherein the porous activated carbon matrix is made by mixing carbonaceous mesophase and apple carbon filler powder. 5. The method for preparing a network interpenetrating diamond-coated porous electrode according to claim 1 or 2, wherein the porous activated carbon matrix is made by mixing carbonaceous mesophase and carbon fiber filler. 6. The method for preparing a network interpenetrating diamond-coated porous electrode according to claim 1 or 2, wherein the porous activated carbon matrix is made by mixing a carbonaceous mesophase and an apple pomace filler.