Preparation method and application of monatomic alloy catalyst
阅读说明：本技术 一种单原子合金催化剂的制备方法及应用 (Preparation method and application of monatomic alloy catalyst ) 是由 张伟 庞贝贝 姚涛 于 2021-08-05 设计创作，主要内容包括：本发明涉及合金催化剂领域,公开了一种单原子合金催化剂的制备方法及应用,方法包括以下步骤：S1、将碳纳米管加入浓硝酸中,置于油浴环境中冷凝回流反应一端时间,产物自然冷却至室温,离心洗涤至溶液呈中性,最后置于真空冷冻干燥箱中烘干,制得酸化处理的碳纳米管；S2、将酸化处理的碳纳米管粉末加入无水乙醇中超声分散,然后向分散液中滴加两种或两种以上不同的金属前驱体溶液,搅拌的同时利用激光平行照射,反应一端时间后将得到的溶液离心洗涤,真空干燥后即得单原子合金催化剂。本发明通过一种激光辐照的方法制备出了分散均匀、形貌一致、大小均一的单原子铂钌合金纳米催化剂,所获得的催化剂在全pH范围内均表现出了优异的电解水制氢的活性。(The invention relates to the field of alloy catalysts, and discloses a preparation method and application of a monatomic alloy catalyst, wherein the method comprises the following steps: s1, adding the carbon nano tube into concentrated nitric acid, placing the carbon nano tube in an oil bath environment for a period of time for condensation reflux reaction, naturally cooling a product to room temperature, centrifugally washing the product until the solution is neutral, and finally placing the product in a vacuum freeze drying oven for drying to obtain the carbon nano tube subjected to acidification treatment; and S2, adding the acidified carbon nanotube powder into absolute ethyl alcohol for ultrasonic dispersion, then dropwise adding two or more different metal precursor solutions into the dispersion liquid, stirring and parallelly irradiating by using laser, centrifugally washing the obtained solution after reacting for a period of time, and drying in vacuum to obtain the monatomic alloy catalyst. The monoatomic platinum-ruthenium alloy nano-catalyst with uniform dispersion, consistent appearance and size is prepared by a laser irradiation method, and the obtained catalyst shows excellent activity of hydrogen production by water electrolysis in the full pH range.)
1. A preparation method of a monatomic alloy catalyst is characterized by comprising the following steps:
s1, adding the carbon nano tube into concentrated nitric acid, placing the carbon nano tube in an oil bath environment for a period of time for condensation reflux reaction, naturally cooling a product to room temperature, centrifugally washing the product until the solution is neutral, and finally placing the product in a vacuum freeze drying oven for drying to obtain the carbon nano tube subjected to acidification treatment;
and S2, adding the acidified carbon nanotube powder into absolute ethyl alcohol for ultrasonic dispersion, then dropwise adding two or more different metal precursor solutions into the dispersion liquid, stirring and parallelly irradiating by using laser, centrifugally washing the obtained solution after reacting for a period of time, and drying in vacuum to obtain the monatomic alloy catalyst.
2. The method for preparing the monatomic alloy catalyst according to claim 1, wherein the ratio of the carbon nanotubes to the acid solution in step S1 is 100-110 ℃, and the oil bath time is 4-8 hours.
3. The method of claim 1, wherein the mass ratio of the carbon nanotubes to the metallic Pt precursor to the Ru precursor is about 100: 0.4-0.7: 10-14.
4. The method of claim 1, wherein the metal precursor is one of chloroplatinic acid hexahydrate, chloroauric acid, palladium chloride, iridium chloride, rhodium chloride, ruthenium acetate, silver chloride, copper chloride, nickel chloride, iron chloride, or cobalt chloride.
5. The method for preparing the monatomic alloy catalyst according to claim 1, wherein the laser parallel irradiation in step S2 uses a laser wavelength of 355nm, a frequency of 1 to 50Hz, a single pulse energy of 1 to 500mJ, and a laser parallel irradiation time of 1 to 120 min.
6. The method for preparing a monatomic alloy catalyst according to claim 1, wherein the metal precursor solution includes a ruthenium chloride solution and a chloroplatinic acid hexahydrate solution, the concentration of the ruthenium chloride solution is 0.01 to 0.03mol/L, the concentration of the chloroplatinic acid hexahydrate solution is 0.03 to 0.05mol/L, and the volume ratio of the ruthenium chloride solution to the chloroplatinic acid hexahydrate solution is 1:0.1 to 10.
7. Use of a monatomic alloy catalyst, prepared according to the method of any of claims 1-6, having a high efficiency full pH universal HER activity, in a hydrogen evolution reaction.
Technical Field
The invention relates to the field of alloy catalysts, in particular to a preparation method and application of a monatomic alloy catalyst.
Background
The hydrogen is regarded as the 'ultimate energy' of the twenty-first century as a renewable energy with high energy density, cleanness and no pollution, the source of the hydrogen is wide, and compared with the traditional 'methane steam reforming', the electrocatalytic hydrogen evolution is regarded as a new energy technology with the most development potential in the future due to the advantages of high conversion efficiency, high hydrogen purity, no pollution and the like. However, the slow kinetic rate of the Hydrogen Evolution Reaction (HER) under alkaline and neutral conditions and the instability of the catalyst under acidic environment have become bottlenecks that restrict the wide application of the electrocatalytic hydrogen evolution technology, and therefore, there is a need to design a highly efficient and stable full-pH universal hydrogen evolution electrocatalyst to improve the efficiency of electrocatalytic hydrogen production.
Currently, the existing commercial hydrogen evolution electrocatalyst is mainly a platinum/carbon (Pt/C) catalyst, which mainly uses a noble metal Pt, and the price is high, and the activity and the stability of long-term operation still need to be further improved. The use amount of noble metal platinum can be effectively reduced by utilizing a metal alloying method, and the stability and the activity of the catalyst can be simultaneously improved by the interaction of the alloy. Most of the existing methods for preparing the alloy are solvothermal methods, specific organic solvents are needed, the morphology and the size of the prepared catalyst are difficult to control, and ligand residues exist on the surface. The laser irradiation method can be carried out in the absence of chemical reagents or organic solvents, and the prepared nano material has a clean surface and does not contain any ligand, so that the method is a simpler and green nano material synthesis method at normal temperature and normal pressure.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a preparation method and application of a monatomic alloy catalyst.
The purpose of the invention can be realized by the following technical scheme:
the invention provides a preparation method of a monatomic alloy catalyst, which comprises the following steps:
s1, adding the carbon nano tube into concentrated nitric acid, placing the carbon nano tube in an oil bath environment for a period of time for condensation reflux reaction, naturally cooling a product to room temperature, centrifugally washing the product until the solution is neutral, and finally placing the product in a vacuum freeze drying oven for drying to obtain the carbon nano tube subjected to acidification treatment;
and S2, adding the acidified carbon nanotube powder into absolute ethyl alcohol for ultrasonic dispersion, then dropwise adding two or more different metal precursor solutions into the dispersion liquid, stirring and parallelly irradiating by using laser, centrifugally washing the obtained solution after reacting for a period of time, and drying in vacuum to obtain the monatomic alloy catalyst.
Further preferably, the ratio of the carbon nanotubes to the acid solution in step S1 is 100-110 ℃, and the oil bath time is 4-8 h.
Further preferably, the mass ratio of the carbon nanotubes to the metallic Pt precursor to the Ru precursor is about 100: 0.4-0.7: 10-14.
Further preferably, the metal precursor is one of chloroplatinic acid hexahydrate, chloroauric acid, palladium chloride, iridium chloride, rhodium chloride, ruthenium acetate, silver chloride, copper chloride, nickel chloride, ferric chloride, or cobalt chloride.
Further preferably, the laser wavelength used for the laser parallel irradiation in step S2 is 355nm, the frequency is 1-50Hz, the single pulse energy is 1-500mJ, and the laser parallel irradiation time is 1-120 min.
Further preferably, the metal precursor solution comprises a ruthenium chloride solution and a chloroplatinic acid hexahydrate, the concentration of the ruthenium chloride solution is 0.01-0.03mol/L, the concentration of the chloroplatinic acid hexahydrate is 0.03-0.05mol/L, and the volume ratio of the ruthenium chloride solution to the chloroplatinic acid hexahydrate is 1:0.1-10
The monatomic alloy catalyst is prepared according to the method, and has high-efficiency full-pH general HER activity.
The invention has the beneficial effects that:
the invention provides a preparation method of a monatomic alloy catalyst with ultrahigh HER activity, the PtRu monatomic alloy catalyst prepared by the method has high-efficiency full-pH general HER activity, the activity of the catalyst is obviously improved by introducing platinum elements, and compared with a commercial PtC (20%) catalyst, the monatomic alloy catalyst not only improves the utilization rate of platinum atoms, but also reduces the cost of the catalyst. Meanwhile, the monatomic alloy catalyst has higher activity and stability, and is a potential electro-catalytic hydrogen production catalyst substitute.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is an X-ray diffraction pattern of examples 1, 2, 3;
FIG. 2 is a transmission electron microscope photograph of examples 1, 2 and 3;
FIG. 3 is a scanning transmission electron microscope photograph of the high angle annular dark field image of example 2;
FIG. 4 is an X-ray absorption near-edge structure map and corresponding Fourier transform map of example 2;
FIG. 5 shows examples 1, 2 and 3 at N2Saturated 0.1mol/L KOH, 0.5mol/L H2SO4And a linear sweep voltammogram in 1mol/L PBS solution at a sweep rate of 5 mV/s;
FIG. 6 is a graph of mass activity of examples 1, 2, 3 at different overpotentials.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "opening," "upper," "lower," "thickness," "top," "middle," "length," "inner," "peripheral," and the like are used in an orientation or positional relationship that is merely for convenience in describing and simplifying the description, and do not indicate or imply that the referenced component or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present invention.
Example 1
600 mg of carbon nano tube is weighed and placed in a round-bottom flask, 100 ml of concentrated nitric acid is added, the round-bottom flask is placed in an oil bath pan with the temperature of 105 ℃ for acidification for 6 hours, and a condenser tube is placed above the round-bottom flask for condensation reflux. Naturally cooling to room temperature, centrifugally washing until the solution is neutral, and then placing in a vacuum freeze drying oven for drying for later use.
Ultrasonically dispersing 5mg of acidified carbon nanotube carrier in 15mL of ethanol, dropwise adding 0.4mL of ruthenium trichloride solution and 0.01mL of chloroplatinic acid hexahydrate solution, and stirring for 1 hour in the dark. The solution was irradiated with parallel light from a Nd: YAG laser having a wavelength of 355nm, a frequency of 20Hz, an energy of 10mJ and a spot diameter of 6mm for 1 hour. And ultrasonically washing the centrifuged powder sample with deionized water and absolute ethyl alcohol for three times, and then placing the powder sample in a vacuum drying oven at 60 ℃ for drying overnight to obtain the low PtRu monatomic alloy catalyst loaded by the acidified carbon nano tube.
Example 2
600 mg of carbon nano tube is weighed and placed in a round-bottom flask, 100 ml of concentrated nitric acid is added, the round-bottom flask is placed in an oil bath pan with the temperature of 105 ℃ for acidification for 6 hours, and a condenser tube is placed above the round-bottom flask for condensation reflux. Naturally cooling to room temperature, centrifugally washing until the solution is neutral, and then placing in a vacuum freeze drying oven for drying for later use.
Ultrasonically dispersing 5mg of acidified carbon nanotube carrier in 15mL of ethanol, dropwise adding 0.4mL of ruthenium trichloride solution and 0.05mL of chloroplatinic acid hexahydrate solution, and stirring for 1 hour in the dark. The solution was irradiated with parallel light from a Nd: YAG laser having a wavelength of 355nm, a frequency of 20Hz, an energy of 10mJ and a spot diameter of 6mm for 1 hour. And ultrasonically washing the centrifuged powder sample with deionized water and absolute ethyl alcohol for three times, and then placing the powder sample in a vacuum drying oven at 60 ℃ for drying overnight to obtain the acidified carbon nanotube-loaded medium PtRu monatomic alloy catalyst.
Example 3
600 mg of carbon nano tube is weighed and placed in a round-bottom flask, 100 ml of concentrated nitric acid is added, the round-bottom flask is placed in an oil bath pan with the temperature of 105 ℃ for acidification for 6 hours, and a condenser tube is placed above the round-bottom flask for condensation reflux. Naturally cooling to room temperature, centrifugally washing until the solution is neutral, and then placing in a vacuum freeze drying oven for drying for later use.
Ultrasonically dispersing 5mg of acidified carbon nanotube carrier in 15mL of ethanol, dropwise adding 0.4mL of ruthenium trichloride solution and 0.4mL of chloroplatinic acid hexahydrate solution, and stirring for 1 hour in the dark. The solution was irradiated with parallel light from a Nd: YAG laser having a wavelength of 355nm, a frequency of 20Hz, an energy of 10mJ and a spot diameter of 6mm for 1 hour. And ultrasonically washing the centrifuged powder sample with deionized water and absolute ethyl alcohol for three times, and then placing the powder sample in a vacuum drying oven at 60 ℃ for drying overnight to obtain the high PtRu monatomic alloy catalyst loaded by the acidified carbon nano tube.
Structure detection
From the XRD results of fig. 1, it can be seen that the acidified carbon nanotube supported PtRu monatomic alloy catalyst mainly maintains the original carbon nanotube structure, but a distinct diffraction peak corresponding to the Ru (111) crystal plane appears, and in the samples of examples 1 and 2, no diffraction peak of any Pt species appears, indicating that the introduction of Pt atoms does not change the crystal structure of Ru nanoparticles, and as the Pt content increases, a distinct diffraction peak of Pt species appears in example 3, indicating that the excessive Pt content changes the crystal structure of Ru nanoparticles. The TEM (fig. 2) of the lower and higher magnifications shows that the PtRu monatomic alloys of the embodiment examples 1, 2 and 3 with different platinum contents were uniformly supported on the carbon nanotubes mainly in a spherical grain structure with average grain diameters of 2.09, 2.29 and 2.16nm, without any aggregation, and the interplanar spacing of the PtRu alloy with a smaller platinum content in the embodiment examples 1 and 2 corresponded to Ru (111), while the interplanar spacing of the PtRu alloy in the embodiment example 3 corresponded to Pt (111) as the platinum content increased. Meanwhile, Mapping (FIG. 3a) and Line-scanning (FIG. 3b) images corresponding to the HAADF-STEM plots of the sample of example 2 also indicate that a proper amount of Pt atoms can be successfully incorporated into the Ru matrix without changing the lattice parameter of Ru. To further confirm that Pt in example 2 is present in the Ru nanoparticles in a monoatomic dispersion form, we characterized the material using an X-ray absorption near edge structure map (XANES, FIG. 4a) and a corresponding Fourier transform map (FT-EXAFS, FIG. 4b), and it can be seen that the Pt-Pt metal coordination peak in the PtRu alloy is significantly different from Pt-Pt in Pt foil, which is Pt-Ru coordination, confirming the monoatomic dispersion of Pt. Finally, the above analysis results correspond to XRD results, and the successful synthesis of the carbon nanotube-supported PtRu monatomic alloy in example 2 is explained.
Performance detection
To evaluate the HER activity of the PtRu monatomic alloy catalysts of examples 1, 2, 3 at full pH, we utilized a commercial PtC (20%) catalyst as a performance control, with the following specific test procedures and results:
(1) 5mg of the PtRu monatomic alloy catalyst in examples 1, 2 and 3, the acidified carbon nanotube in the examples and the commercial PtC catalyst were ultrasonically dispersed in a mixed solution of water and absolute ethyl alcohol in a volume ratio of 3:1, 100. mu.L of perfluorosulfonic acid (0.5 wt%) was added as a binder, and the ultrasonic treatment was continued for 60 minutes to obtain a uniformly mixed suspension. Accurately transferring 6 μ L of suspension by using a pipette, and uniformly dripping the suspension on the surface of a clean glassy carbon electrode, wherein the diameter of the electrode is 3mm, and the loading amount of a catalyst on the electrode is 0.386mg cm-2And naturally drying the test sample to be tested.
(2) At 0.1mol/L KOH, 0.5mol/L H2SO4And 1mol/LPBS solution with graphite rod as counter electrode, saturated Ag/AgCl as reference electrode, measured in three electrode mode and all potentials converted to reversible hydrogen electrode potential (RHE). During the test, high-purity N is continuously introduced into the electrolyte solution2The scanning speed of cathode linear volt-ampere is controlled to be 5mV s-1. As shown in FIG. 5, it is apparent that the PtRu monatomic alloy catalyst of example 2 has the best HER activity and the current density reaches 10mA cm-2The required overpotentials were 13, 28 and 15mV, far exceeding the commercial PtC catalyst and the PtRu atom alloy catalyst in example 1 and example 3, respectively.
(3) To further compare the amounts of noble metals Pt and Ru, we normalized HER activity to the unit mass of Pt and Ru. From the figureAs is clear from the results shown in FIG. 6, the mass activities at an overpotential of 100mV of the PtRu monatomic alloy catalyst and the commercial PtC catalyst in examples 1, 2 and 3 under alkaline conditions were 2.69, 3.35, 2.37 and 0.49A mg, respectively-1It can be seen that example 2 has the highest mass activity, also far beyond commercial PtC catalysts, and is 7 times its mass activity.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.