阅读说明：本技术 一种银耳制备碳基过渡金属纳米复合催化剂的方法 (Method for preparing carbon-based transition metal nano composite catalyst from tremella ) 是由 何纯挺 章佳 孙榕智 杨莉 丁立稳 于 2021-06-16 设计创作，主要内容包括：本发明公开了一种利用银耳合成生物质碳纳米复合材料的方法及其在能源催化领域的应用。本发明首次利用银耳作为前驱体,通过先浸渍金属盐水溶液中再浸渍KOH溶液,真空冷冻干燥后在惰性氛围下热解的方式得到碳基过渡金属纳米复合材料X/NPC-Tfu。制备的生物质碳纳米复合材料拥有约0.3wt％的高磷含量,形貌为厚度2～3nm的超薄纳米片,比表面积高于300m～(2)/g,负载的金属纳米颗粒高度均匀分布,平均粒径小于10nm。该碳基纳米复合催化剂的制备方法简单、成本较低,且可以大批量合成,在能源催化领域具有高度潜在的工业应用价值,可用于电催化水分解,氧还原反应,二氧化碳还原反应以及多种有机催化反应。(The invention discloses a method for synthesizing a biomass carbon nano composite material by utilizing tremella and application of the biomass carbon nano composite material in the field of energy catalysis. According to the invention, tremella is used as a precursor for the first time, and the carbon-based transition metal nanocomposite material X/NPC-Tfu is obtained by firstly soaking in a metal salt aqueous solution and then soaking in a KOH solution, carrying out vacuum freeze drying, and then pyrolyzing in an inert atmosphere. The prepared biomass carbon nano composite material has high phosphorus content of about 0.3 wt%, is an ultrathin nanosheet with the thickness of 2-3 nm, and has the specific surface area higher than 300m 2 And/g, the supported metal nanoparticles are highly uniformly distributed, and the average particle size is less than 10 nm. The preparation method of the carbon-based nano composite catalyst is simple, has low cost and canThe large-scale synthesis has high potential industrial application value in the field of energy catalysis, and can be used for electrocatalytic water decomposition, oxygen reduction reaction, carbon dioxide reduction reaction and various organic catalytic reactions.)

1. A method for synthesizing a carbon-based nano composite material by utilizing tremella is characterized by comprising the following steps: preparing a metal salt aqueous solution, soaking dried tremella in the metal salt aqueous solution to enrich metal ions, then transferring the tremella into a KOH solution for secondary soaking, performing vacuum freeze drying treatment after soaking is completed, and then pyrolyzing the tremella in an inert atmosphere to obtain the carbon-based nanocomposite material X/NPC-Tfu, wherein X is Fe, Co, Ni, Cu or Mo transition metal.

2. The method for synthesizing carbon-based nanocomposite according to claim 1, wherein the metal is enriched by a method of immersion in an aqueous metal salt solution involving a metal salt species comprising a metal nitrate, a metal acetate or a metal chloride.

3. The method for synthesizing a carbon-based nanocomposite according to claim 1, wherein the concentration of the aqueous metal salt solution is 0.1 to 0.5 mol/L; the soaking time is 1-2 days.

4. The method for synthesizing a carbon-based nanocomposite according to claim 1, wherein the concentration of the KOH solution is 0.1 to 0.5 mol/L; the soaking time is 1-2 days.

5. The method for synthesizing the carbon-based nanocomposite material according to claim 1, wherein the vacuum freeze-drying treatment time is 1 to 2 days.

6. The process for the synthesis of carbon-based nanocomposites according to claim 1, wherein the specific steps of pyrolysis in an inert atmosphere are: and (3) heating the freeze-dried sample to 800-1000 ℃ at a heating rate of 5 ℃/min in the inert atmosphere of a tube furnace, keeping the temperature for 2 hours, naturally cooling to room temperature, and carrying out pyrolysis annealing to obtain the carbon-based transition metal nanocomposite X/NPC-Tfu with uniform distribution of biomass carbon load and small size.

7. The method for synthesizing the carbon-based nanocomposite material according to claim 1, wherein the prepared carbon-based nanocomposite material has ultrathin nanosheets with high phosphorus content and morphology of about 2-3 nm and specific surface area higher than 300m²(iv)/g, and the metal nanoparticles are highly uniformly distributed with an average particle size of less than 10 nm.

8. The application of the carbon-based nano composite material prepared by the method of claim 1, wherein the synthesized Co/NPC-Tfu is used as an anode catalyst, and Ni/NPC-Tfu is used as a cathode catalyst, so that the carbon-based nano composite material has excellent electrocatalytic full water decomposition performance.

9. The application of the carbon-based nanocomposite prepared by the method according to claim 1 in the field of energy catalysis, which is characterized by comprising the application in water decomposition, oxygen reduction reaction, carbon dioxide reduction reaction and various organic catalytic reactions.

Technical Field

The invention relates to the field of nano material preparation and energy catalysis, in particular to synthesis of a biomass-derived carbon-based nano composite material and application of the biomass-derived carbon-based nano composite material as an electrocatalytic water decomposition catalyst.

Background

The nano material has an ultra-high specific surface area and an obvious size effect, can provide sufficient surface reaction active sites for catalytic reaction, and is beneficial to the adsorption of reactants and the desorption of intermediate products and final products in the reaction process, so that the nano material is widely applied to the field of catalysis, such as thermal catalysis, electrocatalysis, photocatalysis, photoelectrocatalysis and the like. The carbon-based nano material has the advantages of low cost, abundant and easily available raw material sources, good conductivity, large specific surface area, stable chemical performance and the like, and is always a hot spot of current basic and application research. Since the 21 st century, most of the carbon-based materials are synthesized from fossil fuels such as methane, asphalt and ethanol, and the synthesis process requires harsh or expensive experimental conditions or experimental equipment (such as chemical vapor deposition, arc discharge technology, etc.), or toxic and harmful reagents are added in the process of synthesizing the carbon-based materials.

In recent years, research to develop and utilize biomass to produce carbon-based composites has received increasing attention due to the abundant carbon content and unique microstructure of biomass. The biomass carbon-based composite material is applied to the fields of energy, environment, catalysis and the like, so that biomass resources can be effectively utilized, and the economic added value of the biomass can be improved. Compared with the traditional carbon material preparation method, the method for directly preparing the nano catalyst by using the biomass has the following advantages: rich resources, low cost, green and simple synthesis method and contribution to large-scale production. In the process of preparing the biomass carbon, the original special microstructure of the biomass can be reserved, and meanwhile, heteroatoms such as nitrogen, phosphorus and the like can be introduced in situ when the biomass is used for synthesizing the carbon material, so that the electronic structure and the physical and chemical properties of the carbon material can be effectively regulated and controlled. Therefore, the biomass-derived carbon-based nano composite catalyst with practical value is prepared by applying the new technology and the new method and utilizing the advantages of the interdisciplinary disciplines and screening proper biomass as a precursor, the cost of the catalyst is reduced, and the catalyst has inexplicable practical significance for promoting industrial production in the field of energy catalysis.

The smaller the size of the nanomaterial, the higher the dispersion of the material, and the higher its catalytic activity tends to be. However, the existing biomass-derived carbon-based metal composite material is often loaded with metal particles with large sizes (larger than 50nm) and insufficient uniform distribution, which directly influences the performance of the material.

Disclosure of Invention

The invention aims to provide a method for synthesizing biomass-derived carbon-based transition metal nanocomposite by using tremella.

The purpose of the invention is realized by the following technical scheme:

a method for synthesizing carbon-based transition metal nanocomposite by using tremella comprises the following steps of soaking dried tremella in 0.1-0.5 mol/L metal salt solution for 1-2 days to enrich metal ions in the tremella; cleaning and airing the surface of the tremella rich in metal ions, soaking the tremella in 0.1-0.5 mol/L potassium hydroxide solution for 1-2 days, quickly freezing the tremella in liquid nitrogen, and freeze-drying the tremella in a vacuum freeze dryer for 1-2 days; and finally, heating the freeze-dried sample to 800-1000 ℃ at a heating rate of 5 ℃/min in the inert atmosphere of a tube furnace, keeping the temperature for 2h, naturally cooling to room temperature, and carrying out pyrolysis annealing to obtain the metal composite nano material X/NPC-Tfu (X ═ Fe, Co, Ni, Cu, Mo and the like) with uniform distribution and small size loaded by biomass carbon.

Preferably, the metal salt solution contains metal nitrate, metal acetate or metal chloride.

Preferably, the metal species involved in the metal salt solution comprises Fe, Co, Ni, Cu or Mo transition metals.

Hair brushThe other purpose of the invention is to provide the application of the carbon-based transition metal nano composite material prepared by the method in the field of energy catalysis; including water decomposition, oxygen reduction (ORR), carbon dioxide reduction (CO)₂RR) and various organic catalytic reactions.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, tremella is selected as a precursor for preparing the biomass carbon material for the first time;

(2) the biomass carbon nanocomposite prepared by the invention has a high phosphorus content of about 0.3 wt%;

(3) the biomass carbon nanocomposite prepared by the method is an ultrathin nanosheet with the shape of about 3 nm;

(4) the specific surface area of the biomass carbon nano composite material prepared by the invention is higher than 300m²/g；

(5) The biomass carbon nano composite material prepared by the invention has uniformly distributed nano particles loaded, and the average particle size is less than 10 nm;

(6) the preparation method is simple and can be used for mass preparation;

(7) the preparation cost of the invention is low, taking Co/NPC-Tfu as an example, the cost of Co/NPC-Tfu is only 3.5 yuan/gram, which is about the RuO of the current commercial catalyst₂One two hundredth of the price, and has high potential industrial application value;

(8) the Co/NPC-Tfu prepared by the method shows excellent OER catalytic performance, and in a classical three-electrode system with 1.0M KOH electrolyte, a sample can drive 10 mA-cm on a glassy carbon electrode only by 254mV overpotential^-2The current density of (1) is that only 198mV of overpotential is needed on the copper foam carrier electrode to drive 10mA cm^-2Current density of (d);

(9) the nickel nano material Ni/NPC-Tfu prepared by the method has good HER electrocatalytic performance, and can drive 10mA cm in 1.0M KOH on a glassy carbon electrode by only 198mV overpotential^-2Current density of (d);

(10) Co/NPC-Tfu is used as an anode catalyst, Ni/NPC-Tfu is used as a cathode catalyst, and electrocatalytic water decomposition can be realized by only 1.56V10mA·cm^-2Current density of (d);

(11) the biomass carbon nano composite material prepared by the invention has high potential application value in the field of energy catalysis, and can be used for other materials such as ORR and CO₂RR and various organic catalytic reactions.

Drawings

FIG. 1 is an X-ray powder diffraction pattern of Co/NPC-Tfu of the present invention.

FIG. 2 is a scanning electron microscope photograph of Co/NPC-Tfu of the present invention.

FIG. 3 is an atomic force microscope image of Co/NPC-Tfu of the present invention.

FIG. 4 is a transmission electron microscope photograph of Co/NPC-Tfu according to the present invention.

FIG. 5 is a graph showing the adsorption curve and pore size distribution of Co/NPC-Tfu nitrogen gas according to the present invention.

FIG. 6 is a graph of OER linear sweep voltammetry for Co/NPC-Tfu of the present invention on glassy carbon and copper foam, respectively, and copper foam.

FIG. 7 is a graph of Co/NPC-Tfu Tafel of the present invention.

FIG. 8 shows that Co/NPC-Tfu of the present invention is present at 10mA · cm^-2Constant current electrowinning at current density.

FIG. 9 is a diagram of the electrochemical specific surface area of Co/NPC-Tfu of the present invention.

FIG. 10 is a Co/NPC-Tfu electrochemical impedance spectroscopy of the present invention.

FIG. 11 is an X-ray powder diffraction pattern of Ni/NPC-Tfu of the present invention.

FIG. 12 is a transmission electron microscope photograph of Ni/NPC-Tfu of the present invention.

FIG. 13 is a graph of HER linear sweep voltammetry on glassy carbon for Ni/NPC-Tfu of the invention.

FIG. 14 is a plot of linear sweep voltammetry for electrocatalytic total hydrolysis using Co/NPC-Tfu as the anode OER electrocatalyst and Ni/NPC-Tfu as the cathode HER electrocatalyst according to the present invention.

Detailed Description

Example 1 preparation of Co/NPC-Tfu

Soaking dried tremella in 0.1-0.5 mol/L cobalt nitrate solution for 1-2 days, taking out tremella, wiping off surface water, and soaking in 500mL of 0.1-0.5 mol/L potassium hydroxide solution for 1-2 days. Taking out and wiping off water, quickly freezing in liquid nitrogen, and freeze-drying in a freeze dryer for 1-2 days. And finally, heating the freeze-dried sample to 800-1000 ℃ in a tube furnace at a heating rate of 5 ℃/min, keeping the temperature for 2 hours, and naturally cooling to room temperature to obtain the sample Co/NPC-Tfu. The X-ray diffraction pattern of the product is shown in figure 1; FIG. 2 shows a scanning electron microscope; FIG. 3 is an atomic force microscope image; transmission electron microscopy is shown in FIG. 4; the nitrogen adsorption curve and pore size distribution are shown in FIG. 5.

EXAMPLE 2 electro-catalytic OER Performance testing of Co/NPC-Tfu

The Co/NPC-Tfu obtained in example 1 is subjected to an electrochemical test by adopting a classical three-electrode system at normal temperature on a CHI760E electrochemical workstation. The electrolyte was a 1.0M KOH solution. Hg/HgO and Pt sheets were used as reference and counter electrodes. 10mg of Co/NPC-Tfu is taken, 400uL of water, 200uL of n-propanol and 30uL of Nafion are added, and the mixture is dripped on a platinum carbon electrode and foam copper as a working electrode after 2 hours of ultrasonic treatment. The linear sweep voltammetry plot shown in FIG. 6 was obtained at a sweep rate of 5mV/s, where Co/NPC-Tfu was driven at 10mA cm on a platinum carbon electrode and copper foam^-2The overpotentials required for the current densities were 254mV and 198mV, respectively. The Tafel plot shown in FIG. 7 was calculated from FIG. 6, and it was found that the Tafel slope of Co/NPC-Tfu on a platinum-carbon electrode was 68.6mV dec^-1. The Co/NPC-Tfu shown in the figure 8 is electrolyzed for 25 hours, the performance is only reduced by 3.2 percent, and the stability of the Co/NPC-Tfu is proved to be good.

Example 3Co/NPC-Tfu electrochemical specific surface area test

To determine the electrochemical surface area (ECSA), Cyclic Voltammetry (CV) measurements were used to explore the electrochemical double layer capacitance (C) of the fabricated electrodes_dl). CV was performed in a range of non-faradaic (0.93-1.03V vs RHE) sweep rates of 60, 80, 100, 120, 140 and 160mV s^-1. A linear plot was obtained by plotting the current density at 0.98V vs RHE versus scan rate. C_dlIs half the slope of the line graph and is used to represent ECSA. The electrochemical specific surface area is shown in FIG. 9.

Example 4Co/NPC-Tfu electrochemical impedance Spectroscopy testing

Electrochemical Impedance Spectroscopy (EIS) measurements were made in the frequency range of 0.01Hz to 100 kHz. The electrochemical impedance spectrum is shown in FIG. 10.

Example 5 electrocatalytic HER Performance testing of Ni/NPC-Tfu

The synthesis method of Ni/NPC-Tfu is similar to that of Co/NPC-Tfu obtained in example 1, except that the cobalt nitrate solution is replaced by a nickel nitrate solution, and other conditions are not changed. The X-ray diffraction pattern of Ni/NPC-Tfu is shown in FIG. 11, and the transmission electron microscopy pattern is shown in FIG. 12. The electrocatalytic HER performance test of Ni/NPC-Tfu also adopts a classical three-electrode system on a CHI760E electrochemical workstation at normal temperature, and carries out electrochemical test on a glassy carbon electrode. The sample preparation method and test conditions on the glassy carbon electrode were the same as in example 2. FIG. 13 is a corresponding linear sweep voltammetry plot showing that Ni/NPC-Tfu is driven at 10mA cm on a platinum carbon electrode^-2The overpotential required for the current density was 198 mV.

Example 6 electrocatalytic Total Water splitting Performance test of Co/NPC-Tfu and Ni/NPC-Tfu

Co/NPC-Tfu and Ni/NPC-Tfu were loaded onto copper foam in the manner described in example 2. An electrocatalytic total hydrolysis test was performed in a 1.0M KOH solution of electrolyte using Co/NPC-Tfu as the anode OER electrocatalyst and Ni/NPC-Tfu as the cathode HER electrocatalyst, respectively. The test result is shown in FIG. 14, and only 1.56V is needed to reach 10mA cm^-2The current density of (1).

According to the invention, tremella with high phosphorus content is selected as a biomass precursor for the first time, and the tremella with high phosphorus content (about 0.3 wt%), ultra-thin size (2-3 nm) and high specific surface area (more than 300 m) can be prepared in a large scale by simple dipping, drying and pyrolysis methods²(ii)/g) carbon-based transition metal nanocomposite material X/NPC-Tfu (X ═ transition metal such as Fe, Co, Ni, Cu, Mo, etc., in which metal nanoparticles are highly uniformly distributed and the average particle diameter is less than 10 nm; NPC: nitrogen-phosphorus doped carbon; tfu: latin name Tremella fuciformis (Tremella fuciformis) abbreviation). The preparation method of the carbon-based nano composite catalyst is simple, has low cost, is suitable for large-scale synthesis, has high potential industrial application value in the field of energy catalysis, and can be used for electrocatalytic water decomposition reactionOxygen Reduction Reaction (ORR), carbon dioxide reduction reaction (CO)₂RR) and various organic catalytic reactions.

Taking electrocatalytic water decomposition as an example, the technology for preparing hydrogen by electrocatalytic water decomposition has wide application prospect because hydrogen has higher energy density and is clean and environment-friendly. Water splitting involves both the Hydrogen Evolution Reaction (HER) on the cathode and the Oxygen Evolution Reaction (OER) on the anode, both of which require the introduction of a catalyst to reduce the reaction overpotential in the electrocatalytic reaction and increase the reaction efficiency. Some noble metals and their oxides are currently recognized as excellent performance catalysts for electrolysis of water. However, due to the scarcity and high cost of such catalysts, their commercial application has been greatly limited. The Co/NPC-Tfu has excellent OER electro-catalytic performance which is superior to that of the RuO serving as the current commercial catalyst₂And cost only about RuO₂1/200 for price. Co/NPC-Tfu is used as anode OER electrocatalyst, Ni/NPC-Tfu is used as cathode HER electrocatalyst, and electrocatalytic total moisture decomposition can reach 10mA cm only by 1.56V voltage^-2The current density of (1).