boron-doped diamond-loaded metal monoatomic atom and preparation method and application thereof
阅读说明：本技术 硼掺杂金刚石负载金属单原子及其制备方法和应用 (boron-doped diamond-loaded metal monoatomic atom and preparation method and application thereof ) 是由 杨扬 唐永炳 徐梦琦 胡渊 张文军 于 2019-08-30 设计创作，主要内容包括：本发明提供了一种硼掺杂金刚石负载金属单原子,所述硼掺杂金刚石负载金属单原子包括基底,设置在所述基底一侧或两侧的硼掺杂金刚石薄膜,以及均匀负载在所述硼掺杂金刚石薄膜表面的催化剂,所述催化剂包括金属单原子。制备得到硼掺杂金刚石负载金属单原子的电极具有宽的电化学窗口、高的稳定性、高的催化活性以及产物选择性,大幅提高催化过程的选择性和效率。(The invention provides a boron-doped diamond-loaded metal monoatomic atom, which comprises a substrate, a boron-doped diamond film and a catalyst, wherein the boron-doped diamond film is arranged on one side or two sides of the substrate, the catalyst is uniformly loaded on the surface of the boron-doped diamond film, and the catalyst comprises the metal monoatomic atom. The prepared boron-doped diamond-loaded metal monatomic electrode has a wide electrochemical window, high stability, high catalytic activity and product selectivity, and the selectivity and efficiency of the catalytic process are greatly improved.)
1. A boron-doped diamond-supported metal monoatomic atom includes a substrate, a boron-doped diamond film disposed on one or both sides of the substrate, and a catalyst uniformly supported on a surface of the boron-doped diamond film, the catalyst including a metal monoatomic atom.
2. The boron doped diamond loaded metal monatomic of claim 1, wherein the metal monatomic is selected from any of the transition metals, the p-zone metals.
3. The boron-doped diamond supported metal monatomic according to claim 1, wherein the ratio of the supported area of the catalyst to the area of the boron-doped diamond layer is 0.01% to 10%.
4. The boron-doped diamond supported metal monoatomic compound according to any one of claims 1 to 3, wherein the particle size of the catalyst is 0.1 to 80 nm.
5. The boron-doped diamond loaded metal monoatomic film according to any one of claims 1 to 3, wherein the thickness of the boron-doped diamond thin film is 500nm to 10 μm.
6. A preparation method of boron-doped diamond loaded metal monoatomic ions is characterized by comprising the following steps:
Providing a boron-doped diamond carrier, wherein the boron-doped diamond carrier comprises a substrate and a boron-doped diamond film arranged on one side or two sides of the substrate;
Providing a metal salt solution, taking the boron-doped diamond carrier as a working electrode, a Pt electrode as a counter electrode, a saturated silver/silver chloride electrode as a reference electrode, taking the metal salt solution as electroplating solution, performing electrochemical deposition under magnetic stirring by adopting a three-electrode system, and depositing metal monoatomic atoms on the boron-doped diamond film; and then, carrying out dispersion treatment on the metal atoms deposited on the boron-doped diamond film by adopting an annealing method to obtain the boron-doped diamond loaded metal monoatomic atoms.
7. The method for producing a boron-doped diamond-loaded metal monoatomic solution according to claim 6, wherein the metal salt solution is selected from any one of a transition metal and a p-region metal; and the concentration of the metal salt solution is 0.5-5 x 10- 3mol/L; and/or the presence of a gas in the gas,
before the step of performing electrochemical deposition by using a three-electrode system under magnetic stirring, the method further comprises the following steps: and pretreating the metal salt solution, wherein the pretreatment step is to introduce inert gas into the metal salt solution for treatment for more than 30 minutes.
8. the method for preparing the boron-doped diamond-loaded metal monoatomic according to any one of claims 6 to 7, wherein in the electrochemical deposition process, the voltage of the electrochemical deposition is-0.50V to-0.20V, the step number is 10 to 12, and the pulse width is 8 to 10 s.
9. an electrocatalytic reduction reaction electrode, wherein the electrocatalytic reduction reaction electrode is made of the boron-doped diamond-supported metal monoatomic atom according to any one of claims 1 to 5 or the boron-doped diamond-supported metal monoatomic atom prepared by the method according to any one of claims 6 to 8.
10. Use of an electrode comprising a boron doped diamond supported metal monatomic according to any one of claims 1 to 5 or produced by the method according to any one of claims 6 to 8 for electrocatalytic reduction reactions.
Technical Field
The invention relates to the field of catalytic electrodes, in particular to a boron-doped diamond-loaded metal monoatomic atom and a preparation method and application thereof.
Background
With the increasing global population, the depletion of fossil fuels and the global environmental problems become more serious, and the search for new fuels that can replace the traditional fossil fuels and reduce the environmental burden and realize the sustainable utilization of energy is urgent. The ammonia gas is mainly used for producing chemical fertilizers in chemical engineering processes, plays an important role in solving global grain problems, is also a green energy carrier and is a potential energy transmission fuel.
The ammonia gas generated by nitrogen reduction mainly plays a role in chemical production, and the synthetic ammonia has great significance for the growth of crops and the solution of global grain problems. At present, the main method for preparing ammonia gas by nitrogen reduction in industrial production is to use the Haber-Bosch method, the process conditions required by the Haber-Bosch method are harsh, the reaction temperature needs to be kept within the range of 400-650 ℃, the pressure needs to be kept between 150-300atm, hydrogen is one of indispensable raw materials, and energy required by the reaction is derived from the combustion of fossil fuel, so a large amount of carbon dioxide is generated, and the environmental burden is increased. Compared with the traditional haber-bosch method, the electrochemical catalytic reduction of nitrogen to generate ammonia has the following advantages: (1) the electrocatalytic reduction technology has mild conditions; (2) a large amount of energy is not consumed, and the carbon footprint is reduced; (3) the equipment is simple, and the complex reaction equipment is prevented from being built in a factory.
The technology of generating ammonia gas (NRR) by electrocatalysis Nitrogen Reduction has been studied by scientists as early as the sixties of the last century, but is limited by the lack of knowledge on material design, lagging characterization and testing means and not achieving good results. Whether or not electrocatalytic reduction can be performed efficiently depends to a large extent on the design of the catalytic electrode. Electrocatalytic NRR requires overcoming a very high energy barrier to achieve N2This places high demands on the catalytic activity of the catalyst. In an aqueous solution, a Hydrogen Evolution Reaction (HER) has a lower reduction potential than that of NRR, and thus, the progress of the Hydrogen Evolution Reaction is not efficient and is not favorable for the NRR Reaction; meanwhile, the selectivity of catalytic reaction is poor, a large amount of byproducts are often generated along with side reaction in NRR reaction, and in addition, the electrocatalytic NRR at the present stage has poor stability and catalysis of electrode materialsThe development of this technique has been inhibited by the defects such as low activity of the catalyst and low Faraday efficiency due to ammonia gas generation.
Disclosure of Invention
The invention aims to provide a boron-doped diamond-loaded metal monoatomic atom and a preparation method and application thereof, and aims to solve the problems of poor stability and low catalytic activity of an electrocatalytic reaction electrode material.
In order to achieve the purpose, the invention adopts the following technical scheme:
a boron-doped diamond-supported metal monoatomic film includes a substrate, a boron-doped diamond film disposed on one or both sides of the substrate, and a catalyst uniformly supported on a surface of the boron-doped diamond film, the catalyst including a metal monoatomic film.
And a method for preparing the boron-doped diamond-loaded metal monoatomic ions, which comprises the following steps:
Providing a boron-doped diamond carrier, wherein the boron-doped diamond carrier comprises a substrate and a boron-doped diamond film arranged on one side or two sides of the substrate;
Providing a metal salt solution, taking the boron-doped diamond carrier as a working electrode, a Pt electrode as a counter electrode, a saturated silver/silver chloride electrode as a reference electrode, taking the metal salt solution as electroplating solution, performing electrochemical deposition under magnetic stirring by adopting a three-electrode system, and depositing metal monoatomic atoms on the boron-doped diamond film; and then, carrying out dispersion treatment on the metal atoms deposited on the boron-doped diamond film by adopting an annealing method to obtain the boron-doped diamond loaded metal monoatomic atoms.
And the material of the electrocatalytic reduction reaction electrode is the boron-doped diamond-loaded metal monoatomic atom or the boron-doped diamond-loaded metal monoatomic atom prepared by the method.
And the application of the electrode containing the boron-doped diamond-loaded metal monoatomic atom or the boron-doped diamond-loaded metal monoatomic atom prepared by the method in electrocatalytic reduction reaction.
Compared with the prior art, the boron-doped diamond-loaded metal monoatomic ring provided by the invention comprises a substrate, a boron-doped diamond film arranged on one side or two sides of the substrate, and a catalyst uniformly loaded on the surface of the boron-doped diamond film, wherein the catalyst comprises metal monoatomic rings. The boron-doped diamond film is used as a carrier and has a wide electrochemical window and high stability, so that the hydrogen evolution reaction can be effectively inhibited, and the Faraday efficiency of ammonia gas generation is improved; secondly, the catalyst is loaded on the surface of the boron-doped diamond film, the catalyst comprises metal monoatomic atoms, and the metal monoatomic atoms and the boron-doped diamond film are interacted, so that the metal atoms have low coordination and maximum atom utilization efficiency, the prepared boron-doped diamond-loaded metal monoatomic atoms have high catalytic activity, stability and selectivity in an electrochemical process, and the selectivity and efficiency in the catalytic process are greatly improved.
the invention provides a preparation method of boron-doped diamond loaded metal monoatomic atoms, which comprises the following steps of firstly providing a boron-doped diamond carrier, wherein the boron-doped diamond carrier comprises a substrate and boron-doped diamond films arranged on one side or two sides of the substrate; and then carrying out electrochemical deposition by taking the boron-doped diamond as a working electrode and taking the pretreated metal salt solution as electroplating solution, and then carrying out dispersion treatment on metal atoms deposited on the boron-doped diamond film by adopting an annealing method to obtain the boron-doped diamond loaded metal monoatomic atoms. The method for loading the metal monoatomic atoms on the boron-doped diamond carrier by adopting the electrochemical deposition method is rapid, efficient and low in pollution, and controllably and uniformly and independently deposits the metal monoatomic atoms on the surface of the boron-doped diamond carrier. The preparation method is simple and quick, and is beneficial to industrial application.
According to the electrocatalytic reduction reaction electrode provided by the invention, the material of the electrocatalytic reduction reaction electrode is the boron-doped diamond-loaded metal monoatomic atom or the boron-doped diamond-loaded metal monoatomic atom prepared by the method, and in the process of carrying out electrocatalytic reaction by taking the boron-doped diamond-loaded metal monoatomic atom as the material of the working electrode, the electrocatalytic reaction has high catalytic activity, and the catalytic rate of the electrode reaches a high level.
the application of the electrode containing the boron-doped diamond-loaded metal monoatomic atom or the boron-doped diamond-loaded metal monoatomic atom prepared by the method in the electrocatalytic reduction reaction comprises electrochemical reactions such as electrocatalytic nitrogen reduction to ammonia gas, electrocatalytic carbon dioxide reduction, electrocatalytic oxygen reduction, electrocatalytic methanol oxidation and the like.
Drawings
Fig. 1 is a schematic illustration of a boron doped diamond loaded metal monatomic provided by embodiments of the present invention.
FIG. 2 shows NH of a boron-doped diamond-loaded metal bismuth monatomic electrode provided in example 2 of the present invention under different voltage conditions in an electrocatalytic reduction reaction3Analytical figures for yield and faradaic efficiency.
fig. 3 is an analysis diagram of a current time curve of the electrocatalytic reduction reaction of the boron-doped diamond-loaded metal bismuth monatomic electrode provided in example 2 of the present invention under different voltage conditions.
Detailed Description
In order to make the objects, technical solutions and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
an example of the present invention provides a boron-doped diamond supported metal monoatomic atom, as shown in fig. 1, including a substrate, a boron-doped diamond film disposed on one or both sides of the substrate, and a catalyst uniformly supported on a surface of the boron-doped diamond film, the catalyst including a metal monoatomic atom.
Specifically, the boron-doped diamond-loaded metal monoatomic layer comprises a substrate, and preferably, the substrate is made of any one material selected from a titanium mesh, a carbon cloth, a silicon wafer and a molybdenum mesh. In a preferred embodiment of the invention, a titanium mesh is selected as the substrate for subsequent processing.
Specifically, the boron-doped diamond film is arranged on one side or two sides of the substrate, can be used as a carrier for subsequent treatment, and has a wide electrochemical window and high stability by using the boron-doped diamond film as the carrier, so that the hydrogen evolution reaction can be effectively inhibited, and the Faraday efficiency of ammonia gas generation is improved. Preferably, the thickness of the boron-doped diamond film is 500nm to 10 μm. If the thickness of the obtained boron-doped diamond film is too thin, the diamond film has poor stability and uneven deposition; if the thickness of the obtained boron-doped diamond film is too thick, the boron-doped diamond film is easy to fall off, and the subsequent use is influenced. In the most preferred embodiment of the present invention, the boron-doped diamond film has a thickness of 10 μm.
Specifically, the catalyst is uniformly loaded on the surface of the boron-doped diamond film and comprises metal single atoms. The catalyst is uniformly dispersed on the surface of the boron-doped diamond film, so that most of catalyst particles are exposed to realize the catalytic property. The catalyst is uniformly dispersed on the surface of the boron-doped diamond film, so that the catalytic active sites are uniformly dispersed, specifically, the catalyst comprises metal monoatomic atoms, and the metal monoatomic atoms and the boron-doped diamond film interact with each other, so that the metal atoms have low coordination and maximum atom utilization efficiency, the prepared boron-doped diamond-loaded metal monoatomic atoms have high catalytic activity, high stability and high selectivity in an electrochemical process, and the selectivity and the efficiency of the catalytic process are greatly improved. Preferably, the metal monoatomic atom is selected from any one of transition metals and p-block metals. The metal monoatomic atom is p-region metal, the electronic configuration of a p-region metal valence layer is nsnp, and the p-region metal valence layer has a low valence state and is not easy to form an inert electron pair effect with a highest valence tendency. When the electrocatalytic reduction reaction is carried out, the catalyst has higher catalytic activity and can greatly improve the catalytic efficiency.
Preferably, the catalyst comprises a metal single atom; further preferably, the catalyst further comprises particles in which metal monoatomic groups are aggregated. Among them, the size of the catalyst particles is an important factor affecting the catalytic activity. When the catalyst particles are present in the form of blocks, their catalytic performance depends on their exposed surface, and the catalytic effect is poor; when the particle size is reduced to the nanometer size range, non-metallic properties, including some new reaction properties and higher catalytic properties, are created. Preferably, the particle size of the catalyst is 0.1-80 nm. If the particle size of the catalyst particles is too small, a large amount of aggregation is easily caused, and the catalytic effect is poor; if the particle diameter of the catalyst particles is too large, the catalytic effect is not obtained.
Preferably, the proportion of the supported area of the catalyst to the area of the boron-doped diamond layer is 0.01 to 10%. If the loading amount of the catalyst is too much, the metal monoatomic atoms are too much and cannot be uniformly dispersed in the boron-doped diamond film, so that the catalytic effect is influenced; if the load of the catalyst is too small, the load of the metal monoatomic atom is too small, the catalytic efficiency is not high enough, and the catalytic effect is poor.
The boron-doped diamond-loaded metal monoatomic ion provided by the invention comprises a substrate, a boron-doped diamond film arranged on one side or two sides of the substrate, and a catalyst uniformly loaded on the surface of the boron-doped diamond film, wherein the catalyst comprises metal monoatomic atoms. The boron-doped diamond film is used as a carrier and has a wide electrochemical window and high stability, so that the hydrogen evolution reaction can be effectively inhibited, and the Faraday efficiency of ammonia gas generation is improved; secondly, the catalyst is loaded on the surface of the boron-doped diamond film, the catalyst comprises metal monoatomic atoms, and the metal monoatomic atoms and the boron-doped diamond film are interacted, so that the metal atoms have low coordination and maximum atom utilization efficiency, the prepared boron-doped diamond-loaded metal monoatomic atoms have high catalytic activity, stability and selectivity in an electrochemical process, and the selectivity and efficiency in the catalytic process are greatly improved.
The boron-doped diamond-loaded metal monoatomic layer is prepared by the following preparation method.
Correspondingly, the embodiment of the invention also provides a preparation method of the boron-doped diamond-loaded metal monoatomic atom. The method comprises the following steps:
S01, providing a boron-doped diamond carrier, wherein the boron-doped diamond carrier comprises a substrate and boron-doped diamond films arranged on one side or two sides of the substrate;
S02, providing a metal salt solution, taking the boron-doped diamond carrier as a working electrode, taking a Pt electrode as a counter electrode, taking a saturated silver/silver chloride electrode as a reference electrode, taking the metal salt solution as an electroplating solution, performing electrochemical deposition by adopting a three-electrode system under magnetic stirring, and depositing metal monoatomic atoms on the boron-doped diamond film; and then, carrying out dispersion treatment on the metal atoms deposited on the boron-doped diamond film by adopting an annealing method to obtain the boron-doped diamond loaded metal monoatomic atoms.
Specifically, in S01, providing a boron-doped diamond carrier, wherein the boron-doped diamond carrier comprises a substrate and a boron-doped diamond film disposed on one side or both sides of the substrate;
Preferably, the material of the substrate is selected from any one of titanium mesh, carbon cloth, silicon wafer and molybdenum mesh. In the preferred embodiment of the invention, the base material is titanium mesh. Preferably, the area of the substrate material is 4 multiplied by 4 to 10 multiplied by 10cm2The thickness is 0.5 mm.
Preferably, the substrate is subjected to pretreatment, wherein the pretreatment is ultrasonic treatment by adopting an organic solvent, and then the substrate is placed in nano diamond powder suspension for ultrasonic treatment for 1-3 hours. Further preferably, in the step of performing ultrasonic treatment on the substrate by using an organic solvent, the substrate is firstly cleaned by ultrasonic using acetone, and is treated by using acetone, so that organic impurities on the surface of the substrate material can be dissolved and cleaned by using acetone which has good fat solubility and water solubility. Preferably, the addition amount of the acetone is 50mL, and the ultrasonic cleaning time is 10-20 minutes.
After the acetone is ultrasonically cleaned, the ethanol is used for ultrasonic cleaning, and the ethanol is further used for cleaning, so that impurities which are not cleaned and residual acetone solution can be removed, the surface of the substrate material is ensured to be free of impurities, and meanwhile, a rugged micro surface structure is formed on the substrate material; the rugged microscopic surface structure is a crystal planting site which is a position where the diamond seed crystals are stably adsorbed. Facilitating subsequent processing of the substrate material. Preferably, the addition amount of the ethanol is 50mL, and the ultrasonic cleaning time is 10-20 minutes.
Further preferably, the substrate is subjected to ultrasonic treatment by using an organic solvent, and then is placed in the nano-diamond powder suspension for ultrasonic treatment for 1-3 hours, and preferably, the preparation method of the nano-diamond powder suspension comprises the following steps: providing 1-5mL of purchased diamond solution, and adding 100-400mL of deionized water. The particle size of the prepared nano diamond powder suspension is 1-100 nm. The solution is added while ensuring that the substrate material is submerged. And implanting diamond seed crystals on the surface of the substrate material to prepare for subsequent deposition treatment. If the ultrasonic treatment time is too short, the nano-diamond cannot be uniformly implanted into the surface of the substrate material, and if the ultrasonic treatment time is too long, the number of implanted diamond seeds is large, so that the surface seeds fall off, and the subsequent deposition treatment is also influenced.
Preferably, the substrate is placed in the nano-diamond powder suspension for ultrasonic treatment for 1-3 hours, and then dried in inert gas flow at room temperature, so that impurities cannot exist in the subsequent deposition treatment process. In a preferred embodiment of the invention, the inert gas stream is selected from a nitrogen stream and treated in a nitrogen stream to avoid introducing other impurities during the preparation process.
Preferably, a boron-doped diamond film is prepared on one or both sides of the substrate using a hot wire vapor chemical deposition process. The specific operation method of the hot wire vapor phase chemical deposition method is as follows:
s11, placing the pretreated titanium mesh substrate on a base table of a hot wire vapor deposition device, and keeping the titanium mesh in the middle of a hot wire and parallel to the hot wire; the distance between the hot wire and the surface of the titanium mesh is 20 mm.
S12, pumping the pressure in the furnace to be below 0.1Pa, and then introducing reaction gas to perform a deposition reaction.
In step S11, preferably, the hot wires are tantalum wires with a diameter of 0.5 to 0.6mm, and the number of the hot wires is 9 to 10 hot wires. Further preferably, the titanium mesh is kept in the middle of the hot wire and parallel to the hot wire, wherein the distance between the hot wire and the surface of the titanium mesh is 6-25 mm, the temperature of the hot wire is 2000-2400 ℃, the power of the hot wire is 5000-7000W, and the temperature of the titanium mesh substrate is 500-850 ℃. In the preferred embodiment of the invention, 9 tantalum wires with the diameter of 0.5mm are selected as the hot wires, and the distance between the hot wires and the surface of the titanium mesh is kept to be 20 mm; the temperature of the hot wire is kept at 2000 ℃, the power of the hot wire is 6900W, and the temperature of the titanium mesh substrate is 500 ℃.
In the step S12, it is preferable that the total pressure of the introduced reaction gas is 1000 to 5000Pa, and the total flow rate is 500 sccm. More preferably, the reaction gas is an inert gas or CH4、H2Mixed gas of gas and Trimethyl borane (TMB), wherein CH4As a carbon source for diamond deposition, CH4The concentration is 1.5-5%; the trimethylborane is used as a boron doping source for BDD deposition and is a mixed gas of the trimethylborane and hydrogen, and the concentration of the trimethylborane in the mixed gas is 0.1-1%. H2The function is to etch the non-diamond carbon and remove impurities; the function of the inert gas is to keep the total gas flow constant, and in a preferred embodiment of the invention, the inert gas is argon. In a preferred embodiment of the present invention, note that the reactive gas isAr、CH4、H2And Trimethylborane (TMB). In one embodiment of the present invention, the total gas flow rate is set to 500sccm, wherein the reactive gas ensures each gas CH4、H2The flow rates of Ar and TMB are 10sccm, 100sccm, 370sccm and 20 sccm.
Preferably, after the gas is introduced, the deposition pressure is adjusted to 1500 Pa; preferably, in the step of preparing the boron-doped diamond film on one side or both sides of the substrate by using a hot wire vapor chemical deposition method, the deposition time of the hot wire vapor chemical deposition method is 8-10 hours, so that the diamond film starts to nucleate and grow, and the boron-doped diamond film is prepared. In the most preferred embodiment of the invention, after the gas is introduced, the deposition pressure is adjusted to 1500Pa, and the deposition time is set to 10 hours, so as to obtain the boron-doped diamond film with the thickness of about 10 μm, namely the boron-doped diamond carrier.
Specifically, in step S02, providing a metal salt solution, using the boron-doped diamond carrier as a working electrode, a Pt electrode as a counter electrode, a saturated silver/silver chloride electrode as a reference electrode, and the metal salt solution as an electroplating solution, performing electrochemical deposition under magnetic stirring by using a three-electrode system, and depositing metal monoatomic atoms on the boron-doped diamond film; and then, carrying out dispersion treatment on the metal atoms deposited on the boron-doped diamond film by adopting an annealing method to obtain the boron-doped diamond loaded metal monoatomic atoms.
Preferably, the metal salt solution is selected from any one of transition metal and p-block metal salt solution. In a specific embodiment of the invention, bismuth nitrate and antimony chloride solutions are used as the metal salt solutions for the reaction.
Preferably, the concentration of the metal salt solution is 0.5-5 multiplied by 10-3And M. If the concentration of the metal salt solution is too high, the number of metal single atoms loaded on the boron-doped diamond carrier in unit area is large, and the metal single atoms are not favorable for playing a catalytic role; if the metal salt concentration is too low, this will result in a single atomic number of metal being supported on a unit area of boron-doped diamond carrierMore, the catalytic efficiency is poorer.
Preferably, before the step of performing electrochemical deposition by using a three-electrode system under magnetic stirring, the method further comprises the following steps: and pretreating the metal salt solution, wherein the pretreatment step is to introduce inert gas into the metal salt solution for treatment for more than 30 minutes. In a preferred embodiment of the invention, the inert gas is nitrogen, and the metal salt solution is treated by introducing nitrogen for 30-40 minutes to remove oxygen dissolved in the solution.
Specifically, the boron-doped diamond carrier is used as a working electrode, a Pt electrode is used as a counter electrode, a saturated silver/silver chloride electrode is used as a reference electrode, the metal salt solution is electroplating solution, and electrochemical deposition is carried out by adopting a three-electrode system under magnetic stirring. Preferably, the electrochemical deposition method can be selected from pulse plating, direct current plating, square wave pulse method and differential pulse method. Further preferably, in the electrochemical deposition process, the deposition voltage is-0.50V to-0.20V, the step number is 10 to 12, and the pulse width is 8 to 10 s. In the preferred embodiment of the invention, during the electrochemical deposition process, the deposition voltage is-0.50V to-0.20V, the step number is 112, and the pulse width is 10 s.
Preferably, a magnetic stirring method is adopted during electrochemical deposition, and the stirring speed of the magnetic stirring is 500-2000 r/min.
Specifically, depositing metal single atoms on the boron-doped diamond film; and then, carrying out dispersion treatment on the metal atoms deposited on the boron-doped diamond film by adopting an annealing method to obtain the boron-doped diamond loaded metal monoatomic atoms. Preferably, the annealing method adopts annealing by a tube furnace treatment. The specific operation steps are as follows: placing the boron-doped diamond-loaded metal monoatomic atoms into a porcelain boat, then placing the porcelain boat into a tube furnace, and annealing under the protection of inert gas. Preferably, the annealing temperature is 100-300 ℃, and the annealing time is 1-3 h.
preferably, the deposited metal atoms are dispersed by a tube furnace annealing method, and then acid-washed in a sulfuric acid solution with a certain concentration to remove excess metal atoms. Preferably, the treatment temperature of the acid washing treatment is 60-80 ℃, and the treatment time is 5-20 min.
The invention provides a preparation method of boron-doped diamond loaded metal monoatomic atoms, which comprises the following steps of firstly providing a boron-doped diamond carrier, wherein the boron-doped diamond carrier comprises a substrate and boron-doped diamond films arranged on one side or two sides of the substrate; and then carrying out electrochemical deposition by taking the boron-doped diamond as a working electrode and the pretreated metal salt solution as electroplating solution to obtain the boron-doped diamond loaded metal monoatomic. The method for loading the metal monoatomic atoms on the boron-doped diamond carrier by adopting the electrochemical deposition method is rapid, efficient and low in pollution, and controllably and uniformly and independently deposits the metal monoatomic atoms on the surface of the boron-doped diamond carrier. The preparation method is simple and quick, and is beneficial to industrial application.
Correspondingly, the embodiment of the invention also provides an electrocatalytic reduction reaction electrode, and the material of the electrocatalytic reduction reaction electrode is the boron-doped diamond-loaded metal monoatomic atom or the boron-doped diamond-loaded metal monoatomic atom prepared by the method.
Preferably, the electrocatalytic reaction includes electrochemical reactions such as electrocatalytic reduction of nitrogen into ammonia, electrocatalytic reduction of carbon dioxide, electrocatalytic reduction of oxygen, electrocatalytic oxidation of methanol, and the like.
In a preferred embodiment of the invention, the boron-doped diamond loaded metal monoatomic layer prepared by the method is used as a working electrode for carrying out electrocatalytic reduction on nitrogen. The specific operation is as follows: providing a closed H-shaped double-tank reactor, and isolating an anode chamber and a cathode chamber by using a proton exchange membrane; adopting a three-cell system, taking the prepared boron-doped diamond-loaded metal monoatomic layer as a working electrode, a graphite rod as a counter electrode, Ag/AgCl as a reference electrode, and enabling the distance between the working electrode and the counter electrode to be 2cm, wherein the reference electrode is close to the working electrode; then, 0.1M saturated Na was added to the cathode chamber2SO4Adding equal volume of 0.1M Na into the anode chamber2SO4Solution, carrying out electrocatalytic reduction on N at constant voltage of-1.5V to-1.0V2and (4) reacting.
the boron-doped diamond-loaded metal monoatomic layer is used as a working electrode for electrocatalytic reduction reaction, and in the process of electrocatalytic reaction by using the boron-doped diamond-loaded metal monoatomic layer as the working electrode, the electrocatalytic reaction has high catalytic activity, and the catalytic rate of the electrode reaches a high level.
Preferably, the electrode containing the boron-doped diamond-supported metal monoatomic atom or the boron-doped diamond-supported metal monoatomic atom prepared by the method is applied to electrocatalytic reduction reaction.
the application of the electrode containing the boron-doped diamond-loaded metal monoatomic atom or the boron-doped diamond-loaded metal monoatomic atom prepared by the method in the electrocatalytic reduction reaction comprises electrochemical reactions such as electrocatalytic nitrogen reduction to ammonia gas, electrocatalytic carbon dioxide reduction, electrocatalytic oxygen reduction, electrocatalytic methanol oxidation and the like.
The present invention will now be described in further detail by taking, as examples, boron-doped diamond-loaded metal monoatomic ions, a method for producing the same, and an electrocatalytic nitrogen reduction reaction.