CN117888142A

CN117888142A - Amorphous oxide-coated noble metal nanoparticle catalytic material, and preparation method and application thereof

Info

Publication number: CN117888142A
Application number: CN202410116464.2A
Authority: CN
Inventors: 黄振峰; 邹吉军; 高睿杰; 宁博; 潘伦; 张香文; 马智德
Original assignee: Qinghai Provincial Quality Certification Consulting And Inspection Center Co ltd; Tianjin University
Current assignee: Qinghai Provincial Quality Certification Consulting And Inspection Center Co ltd; Tianjin University
Priority date: 2024-01-29
Filing date: 2024-01-29
Publication date: 2024-04-16

Abstract

The invention discloses a catalytic material, which comprises: a carrier; noble metal nanoparticles anchored on the support surface; and an amorphous oxide layer coated on the surface of the noble metal nanoparticle. The invention also discloses a preparation method of the catalytic material and application of the electrode material for hydrogen evolution and oxygen evolution of electrolyzed water. The catalytic material of the invention is used as an electrolyzed water hydrogen evolution catalyst or an electrolyzed water oxygen evolution catalyst material, and has excellent catalytic activity and stability under normal temperature and acidic conditions.

Description

Amorphous oxide-coated noble metal nanoparticle catalytic material, and preparation method and application thereof

Technical Field

The invention belongs to the technical field of catalysts for producing hydrogen by water electrolysis, and particularly relates to an amorphous oxide-coated noble metal nanoparticle catalytic material, a preparation method thereof and application thereof in the field of hydrogen production by water electrolysis.

Background

With the continuous consumption of fossil energy and the continuous growth of social energy demands, the energy problem of human society is becoming more and more remarkable. In addition, combustion of fossil fuels also contributes to the exacerbation of environmental problems such as greenhouse effect and acid rain. Therefore, it is urgent to find renewable energy sources to replace fossil fuels. Hydrogen is a green energy carrier with a high combustion heating value and the combustion products are free of carbon dioxide, and is considered to be an ideal renewable energy source. There are many methods for producing hydrogen, such as methane reforming, natural gas reforming, biological methods, photodecomposition, and the like. Among them, the electrolytic water hydrogen production is the hydrogen production method with the most development prospect. If the electric energy is derived from renewable energy sources such as solar energy, wind energy and the like, the whole process is zero-carbon emission. The technology of hydrogen production by water electrolysis mainly comprises the technology of hydrogen production by alkaline water electrolysis, the technology of water electrolysis by proton exchange membrane and the technology of water electrolysis by solid oxide. The solid oxide electrolysis water technology requires working temperatures as high as 600 ℃, which requires that both the electrolysis cell and the electrode material have good high temperature resistance, and thus is still in the research and development stage at present. The alkaline water electrolysis technology has the advantages of mature process, various electrode materials in alkaline environment, low electrolysis current density and poor product purity. The proton exchange membrane water electrolysis technology has high product purity, compact structure and quick response, and is a development trend of the water electrolysis technology in the future; however, the acidic working environment has high requirements on the acid resistance and corrosion resistance of the electrode material; the catalytic materials used at present mostly contain noble metals such as Pt, ir, ru and the like, and the cost is high; in addition, the commercial electrode material has poor stability due to weak metal carrier effect between the noble metal nano-particles and the carrier, and is easy to fall off and agglomerate. Therefore, it is important to develop an electrode material for proton exchange membrane water electrolysis technology which has high activity, long-term stability and low noble metal consumption.

In order to develop new low cost, high activity electrode materials that can replace commercial catalysts, some techniques have been applied such as particle morphology regulation, alloying, and metal-metal oxide bonding. Among them, coupling noble metals with transition metals can effectively improve the stability of electrode materials, and is expected to replace commercial materials. However, the synthesis conditions of the related materials reported at present are harsh, the synthesis process is complex, and the industrial amplification is not facilitated. Meanwhile, certain metal oxides have poor conductivity, so that the material impedance is increased, and further, the reaction energy consumption is increased, which is unfavorable for industrial application. Therefore, searching for a suitable material to synthesize a stable and efficient electrolyzed water catalyst is a current research hotspot.

The invention is proposed for this purpose.

Disclosure of Invention

Aiming at the defects of the current catalyst in design and application, the invention provides an amorphous oxide-coated noble metal nanoparticle catalytic material and a preparation method thereof. The catalytic material prepared by the preparation method provided by the invention has excellent performance and low noble metal consumption, and is used for electrolytic water hydrogen evolution and oxygen evolution electrode materials, and has excellent catalytic activity and stability.

The technical scheme of the invention is as follows:

in a first aspect, the present invention discloses a catalytic material comprising:

A carrier;

noble metal nanoparticles anchored on the support surface;

and an amorphous oxide layer coated on the surface of the noble metal nanoparticle.

Preferably, the amorphous oxide layer has a composition MO _x; m is one of Mo, W and V; the noble metal nano-particles are Pt, pd, ru, rh or Ir nano-particles; the particle size of the nano particles is not more than 4nm.

Preferably, the carrier comprises: carbon black, titanium dioxide, tin dioxide, molybdenum trioxide, tin antimony oxide, indium tin oxide, fluorine tin oxide, tungsten dioxide, tungsten trioxide, or the like.

Preferably, the mass ratio of the carrier, the noble metal nanoparticles and the amorphous oxide is (10-20): (1-3): (2-4), more preferably 15:2:3.

The invention discloses a preparation method of the catalytic material, which comprises the following steps:

(1) Preparing polyoxometalates;

(2) Dissolving the polyoxometallate prepared in the step (1) in water and mixing with a carrier;

(3) Roasting the mixture obtained in the step (2) to obtain the catalytic material.

Preferably, the preparation method of the polyoxometalate in the step (1) comprises the following steps: the mixed solution of metal salts comprising noble metal and amorphous oxide metal is regulated to a certain pH value and then evaporated, concentrated and crystallized to obtain the polyoxometalate; the noble metal is one of Pt, pd, ru, rh or Ir; the amorphous oxide metal is one of Mo, W and V.

Preferably, the polyoxometalate of step (2) is mixed with the carrier for a time not less than 8 hours; the carrier comprises: carbon black, titanium dioxide, tin dioxide, molybdenum trioxide, tin antimony oxide, indium tin oxide, fluorine tin oxide, tungsten dioxide, tungsten trioxide, and the like.

Preferably, the roasting temperature in the step (3) is 200-400 ℃, the roasting time is 2-4h, and the roasting atmosphere is inert atmosphere.

In a third aspect, the invention discloses the use of the catalytic material for an electrode material for hydrogen evolution and oxygen evolution of electrolyzed water.

Preferably, the conditions for electrolysis of water are: the electrolyte is acidic and the temperature is normal temperature; the term "normal temperature" herein generally means a temperature in the range of 0 to 40 ℃.

The invention has the following beneficial effects:

1. The amorphous oxide-coated noble metal nanoparticle catalytic material has strong metal-carrier interaction with the noble metal nanoparticle coated inside, adjusts the electronic structure of the noble metal nanoparticle, enables the noble metal nanoparticle to show a valence state closer to zero-valent metal, is used for an electrolytic water hydrogen evolution oxygen evolution electrode material, and is favorable for reaction. The noble metal nano particles are uniformly anchored on the surface of the carrier, and the coating of the amorphous oxide layer plays a role in protecting the noble metal nano particles, so that the noble metal nano particles cannot fall off or agglomerate in the reaction process, and the long-term stability of the catalytic material is improved. The catalytic material of the invention is used as an electrolyzed water hydrogen evolution catalyst or an electrolyzed water oxygen evolution catalyst material, and has excellent catalytic activity and long-term stability under normal temperature and acidic conditions.

2. The noble metal nano-particle catalytic material coated by the amorphous oxide takes the carrier as a substrate, the noble metal nano-particle coated by the amorphous oxide is taken as a catalytic active substance, and the overall catalytic material has good conductivity and low impedance, and is beneficial to the electrocatalytic reaction.

3. The preparation method of the invention uses polyoxometallate. The molecular structure of the polyoxometalate is that an octahedron formed by six or more transition metal atoms and oxygen atoms surrounds an octahedron formed by one or more noble metal atoms and oxygen atoms; the molecular structure is favorable for forming a structure that the amorphous transition metal oxide layer is coated on the surface of the noble metal nano-particles, avoids the use of various metal precursors, and simplifies the preparation process of the catalytic material. After the polyoxometalate is dissolved in water, the charge is opposite to that of the carrier, so that the polyoxometalate is anchored on the surface of the carrier. In the catalytic material prepared by the method, the noble metal nano particles are coated by the amorphous oxide layer, and the amorphous oxide layer and the noble metal nano particles in the amorphous oxide layer have strong metal-carrier interaction, so that the electronic structure of the noble metal nano particles is regulated, the noble metal nano particles are in a valence state closer to zero-valent metal, and the catalytic material is used for the electrolytic water hydrogen evolution oxygen evolution electrode material, and is beneficial to the reaction; meanwhile, in the catalytic material, the noble metal nano-particles are anchored on the surface of the carrier, and the existence of the amorphous oxide layer plays a role in protecting the noble metal nano-particles, so that the noble metal nano-particles cannot fall off or agglomerate in the reaction process, and the long-term stability of the catalytic material is improved. The catalytic material of the invention is used as an electrolyzed water hydrogen evolution catalyst or an electrolyzed water oxygen evolution catalyst material, and has excellent catalytic activity and stability under normal temperature and acidic conditions.

4. The preparation method of the catalytic material is simple, can be obtained only through two steps of dipping and roasting, is beneficial to amplification and is particularly suitable for mass production.

Drawings

FIG. 1 is a scanning electron microscope image of the carbon black support of example 1.

Fig. 2 is a scanning electron microscope image of the amorphous oxide coated noble metal nanoparticle catalytic material prepared in example 1.

FIG. 3 is an X-ray diffraction pattern of catalyst particles of the catalytic material prepared in example 1.

Fig. 4 is a spherical aberration correcting transmission electron microscope image of amorphous oxide coated noble metal nanoparticles of the catalytic material prepared in example 1.

Fig. 5 is a transmission electron microscope image of the catalytic material prepared in example 1.

FIG. 6 is a graph showing the activity of the catalyst of example 1 in the three-electrode system at room temperature.

FIG. 7 is a graph showing the stability of the electrolytic water hydrogen evolution reaction tested in a three-electrode system at normal temperature of the catalyst in example 1.

Detailed Description

The present invention will now be described more fully hereinafter with reference to the accompanying drawings and specific embodiments, which are given by way of illustration only, and are not to be construed as limiting the scope of the invention.

Example 1: preparation of noble metal Pt particle catalytic material coated by amorphous Mo oxide. The method comprises the following steps:

1. Synthesis of polyoxometallate: 343mg of Na ₂Pt(OH)₆ and 1.5g of Na ₂MoO₄·2H₂ O were dissolved in hot water and stirred for half an hour; then, the pH value of the mixed solution is adjusted to 6.5 by using HNO ₃ with the concentration of 1M, and the mixed solution is stirred for half an hour; the pH of the solution was again adjusted to 1.6 using 1M HNO ₃ and stirred for half an hour; heating, evaporating, cooling and crystallizing the obtained solution to obtain polyoxometallate;

2. Dissolving the obtained polyoxometallate in water, adding 2g of carbon black into the water, stirring for 8 hours, and evaporating the solvent from the obtained slurry by a rotary evaporator to obtain powder;

3. And roasting the obtained powder for 2 hours at 300 ℃ in an argon atmosphere to obtain the noble metal Pt particle catalytic material wrapped by the amorphous Mo oxide.

FIG. 1 is a scanning electron microscope image of a carbon black carrier used, and FIG. 2 is a scanning electron microscope image of an amorphous oxide coated noble metal nanoparticle catalytic material prepared; it can be seen from fig. 1 and 2 that the morphology of the carbon black support is not changed after loading the noble metal nanoparticles coated with the amorphous oxide.

FIG. 3 is an X-ray diffraction pattern of the catalyst particles of the prepared catalytic material, as can be seen from FIG. 3, with no other XRD signals except for the peaks of the carbon material and Pt; the oxide coated on the surface of the Pt nano particle is amorphous.

FIG. 4 is a transmission electron microscope image of spherical aberration correction of amorphous oxide coated noble metal nanoparticles of the catalytic material prepared; the presence of an amorphous oxide coated noble metal nanoparticle structure can be illustrated by fig. 4. FIG. 5 is a transmission electron microscope image of the catalytic material prepared; as can be seen from fig. 5, noble metal particles in the catalytic material are uniformly distributed on the surface of the carbon black carrier, and the particle size of the noble metal nanoparticles is about 2 nm.

FIGS. 6 and 7 are graphs showing the hydrogen evolution reaction activity and stability of electrolyzed water at room temperature in a three-electrode system of the catalytic material obtained in this example; as can be seen from FIG. 6, the electrocatalytic hydrogen evolution activity of the catalytic material is excellent, and the current density of 10mA cm ^-2 can be achieved only by 11mV, and the current density of 100mA cm ^-2 can be achieved only by 97 mV; as can be seen from fig. 7, the catalyst was stable at a current density of 10mA cm ^-2 in the first 37 hours and 100mA cm ^-2 in the latter 63 hours; the electrocatalytic hydrogen evolution stability of the catalytic material is excellent.

Example 2: preparation of noble metal Pt particle catalytic material coated by amorphous Mo oxide. The method comprises the following steps:

Step1 and step2 are the same as in example 1;

3. and roasting the powder for 2 hours at 200 ℃ in an argon atmosphere to obtain the noble metal nano-particle catalytic material coated by the amorphous oxide.

The electrochemical activity data of the amorphous oxide coated noble metal nanoparticle catalytic material obtained in this example are shown in table 1.

Example 3: preparation of noble metal Pt particle catalytic material coated by amorphous Mo oxide.

Step1 and step2 are the same as in example 1;

3. And roasting the powder at 400 ℃ for 2 hours in an argon atmosphere to obtain the noble metal nanoparticle catalytic material coated by the amorphous oxide.

Example 4: preparation of noble metal Pt particle catalytic material coated by amorphous Mo oxide.

Step1 and step2 are the same as in example 1;

3. And roasting the powder for 3 hours at 300 ℃ in an argon atmosphere to obtain the noble metal nano-particle catalytic material coated by the amorphous oxide.

Example 5: preparation of noble metal Pt particle catalytic material coated by amorphous Mo oxide.

Step1 and step2 are the same as in example 1;

3. and roasting the powder for 4 hours at 300 ℃ in an argon atmosphere to obtain the noble metal nano-particle catalytic material coated by the amorphous oxide.

Example 6: preparation of noble metal Pt particle catalytic material coated by amorphous W oxide layer. The method comprises the following steps:

step 1, step 2 and step 3 are the same as in example 1, wherein in step 1, na ₂MoO₄·2H₂ O is replaced with Na ₂WO₄·2H₂ O;

Example 7: preparation of noble metal Pt particle catalytic material wrapped by amorphous V oxide layer. The method comprises the following steps:

step 1, step 2 and step 3 are the same as in example 1, wherein in step 1 Na ₂MoO₄·2H₂ O is replaced with Na ₃VO₄;

Example 8: preparation of noble metal Pd particle catalytic material coated by amorphous Mo oxide layer. The method comprises the following steps:

1. Synthesis of polyoxometallate: 326mg of K ₂[PdCl₄ and 1.5g of Na ₂MoO₄·2H₂ O are dissolved in hot water and stirred for half an hour; then, the pH value of the mixed solution is adjusted to 4.5 by using 0.1M H ₂SO₄, and the mixed solution is stirred for half an hour; heating, evaporating, cooling and crystallizing the obtained solution to obtain polyoxometallate;

Step2 and step3 are the same as in example 1.

The electrochemical activity data of the amorphous oxide coated noble metal nanoparticle catalytic material obtained in this example are shown in table 2.

Example 9: and (3) preparing the noble metal Ru particle catalytic material wrapped by the amorphous Mo oxide layer. The method comprises the following steps:

1. synthesis of polyoxometallate: 1.5g of Na ₂MoO₄·2H₂ O and 612mg of [ Ru (p-cym) Cl ₂]₂ were dissolved in hot water, stirred for 4h and extracted with dichloromethane to give the polyoxometalate.

Step2 and step3 are the same as in example 1.

Example 10: preparation of noble metal Rh particle catalytic material coated by amorphous Mo oxide layer. The method comprises the following steps:

1. Synthesis of polyoxometallate: dropwise adding an aqueous solution containing 1.5g of Na ₂MoO₄·2H₂ O into an aqueous solution containing 925mg of [ RhCp x Cl ₂]₂ ] dropwise, stirring at room temperature for 3h, and recrystallizing to obtain the polyoxometallate.

Step2 and step3 are the same as in example 1.

Example 11: preparation of noble metal Ir particle catalytic material coated by amorphous Mo oxide layer. The method comprises the following steps:

1. Synthesis of polyoxometallate: dropwise adding an aqueous solution containing 1.5g of Na ₂MoO₄·2H₂ O into an aqueous solution containing 701mg of [ IrCp x Cl ₂]₂ ] at 100 ℃ under reflux for 1h, and recrystallizing to obtain polyoxometalate.

Step2 and step3 are the same as in example 1.

Example 12: in this example, the carbon black support was replaced with a titania support.

The preparation method of the catalytic material is basically the same as in example 1, except that: the carrier is titanium dioxide.

Example 13: in this example, the carbon black support was replaced with a fluorine tin oxide support. The preparation method of the catalytic material is basically the same as in example 1, except that: the carrier is fluorine tin oxide.

Example 14: in this example, the carbon black support was replaced with a tungsten dioxide support. The preparation method of the catalytic material is basically the same as in example 1, except that: the carrier is tungsten dioxide.

Example 15: in this example, the carbon black support was replaced with a tin antimony oxide support. The preparation method of the catalytic material is basically the same as in example 11, except that: the carrier is tin antimony oxide.

Comparative example 1: the comparative example is free of precious metal nanoparticles.

1. 1.2G of ammonium heptamolybdate was dissolved in water, 2g of carbon black was added thereto, and stirred for 8 hours, and the obtained slurry was evaporated to dryness of the solvent by a rotary evaporator to obtain powder.

2. The powder was calcined at 300 ℃ for 2 hours in an argon atmosphere to obtain an amorphous oxide catalytic material dispersed on a carbon black support.

The electrochemical activity data of the amorphous oxide-coated noble metal nanoparticle catalytic material obtained in this comparative example are shown in tables 1 and 2.

Comparative example 2: the catalyst used in this comparative example was a commercial noble metal catalyst of 20wt% Pt/C. The electrochemical activity data of the catalysts in this comparative example are shown in Table 1.

Comparative example 3: the catalyst used in this comparative example was a commercial noble metal catalyst, irO ₂. The electrochemical activity data of the catalysts in this comparative example are shown in Table 2.

Comparative example 4: in this comparative example, a noble metal salt and an amorphous oxide-forming salt were added separately to prepare a substituted polyoxometalate.

The preparation method of the catalytic material is the same as in example 1, except that: platinum acetylacetonate was used as a source of formation of platinum nanoparticles and ammonium heptamolybdate was used as a source of formation of an amorphous molybdenum oxide layer.

Comparative example 5: the present comparative example does not contain an amorphous oxide.

The preparation method of the catalytic material is the same as in example 1, except that: platinum acetylacetonate was used as a source of formation of platinum nanoparticles, and no amorphous oxide was contained.

The catalytic materials of examples 1 to 7 and examples 12 to 14 and comparative examples 1,2,4 and 5 were subjected to an electrolyzed water hydrogen evolution reaction activity test, and the test results are shown in table 1.

Table 1: test result of activity of hydrogen evolution reaction of electrolyzed water by different catalytic materials

As can be seen from Table 1, the activity of the amorphous oxide coated noble metal Pt nanoparticle catalytic material of the present invention was much higher than that of the carbon black supported amorphous oxide catalytic material (comparative example 1) in electrolyzed water (electrolyte pH 0.25), and also superior to that of the commercial Pt carbon catalyst (comparative example 2). The catalytic material activity was similar to that of carbon black and superior to that of commercial Pt carbon catalyst (comparative example 2) by changing the carrier to titanium dioxide, tin antimony oxide, fluorine tin oxide, tungsten dioxide, etc. Meanwhile, the preparation of substituted polyoxometalates by adding noble metal salts and amorphous oxide-forming salts respectively gives a catalytic material having poor activity (comparative example 4); and the catalytic material obtained without the coating of the amorphous oxide was also inferior in activity (comparative example 5).

The catalytic materials of examples 8 to 11 and 15 and comparative examples 1 and 3 were subjected to an electrolytic water (electrolyte pH 1) oxygen evolution reaction activity test, and the test results are shown in Table 2.

Table 2: results of testing activities of electrolytic water oxygen evolution reactions by different catalytic materials

Examples	Electrolyte pH	Electrolyte temperature (. Degree. C.)	Overpotential (mV) at 10mA/cm ^-2
				Example 8	1	25	295
Example 9	1	25	298
				Example 10	1	25	301
Example 11	1	25	300
				Example 15	1	25	299
Comparative example 1	1	25	NA
				Comparative example 3	1	25	350

As can be seen from table 2, the activity of the amorphous oxide coated noble metal nanoparticle catalytic material of the present invention was much higher than that of the amorphous oxide supported carbon black catalytic material without noble metal nanoparticles (comparative example 1, without noble metal nanoparticles) in electrolyzed water (electrolyte pH 1), and also superior to that of the commercial iridium dioxide catalyst (comparative example 3).

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalytic material, comprising:

A carrier;

noble metal nanoparticles anchored on the support surface;

2. The catalytic material of claim 1, wherein the amorphous oxide layer has a composition MO _x, and M is one of MO, W, V; the noble metal nano-particles are Pt, pd, ru, rh or Ir nano-particles, and the particle size of the nano-particles is not more than 4nm.

3. The catalytic material of claim 1, wherein the support comprises: carbon black, titanium dioxide, tin dioxide, molybdenum trioxide, tin antimony oxide, indium tin oxide, fluorine tin oxide, tungsten dioxide or tungsten trioxide.

4. The catalytic material of claim 1, wherein the mass ratio of the support, noble metal nanoparticles, and amorphous oxide is (10-20): (1-3): (2-4).

5. The method for preparing a catalytic material according to claims 1-4, comprising the steps of:

(1) Preparing polyoxometalates;

6. The method of claim 5, wherein the method of preparing the polyoxometalate of step (1) comprises: the mixed solution of metal salts comprising noble metal and amorphous oxide metal is regulated to a certain pH value and then evaporated, concentrated and crystallized to obtain the polyoxometalate; the noble metal is one of Pt, pd, ru, rh or Ir; the amorphous oxide metal is one of Mo, W and V.

7. The method of claim 5, wherein the polyoxometalate of step (2) is mixed with the carrier for a period of not less than 8 hours; the carrier comprises: carbon black, titanium dioxide, tin dioxide, molybdenum trioxide, tin antimony oxide, indium tin oxide, fluorine tin oxide, tungsten dioxide or tungsten trioxide.

8. The method according to claim 5, wherein the baking temperature in the step (3) is 200-400 ℃, the baking time is 2-4 hours, and the baking atmosphere is an inert atmosphere.

9. Use of a catalytic material according to any one of claims 1-4 for the electrolysis of water to hydrogen and oxygen evolution electrode materials.

10. Use according to claim 9, characterized in that the conditions of electrolysis of water are: the electrolyte is acidic and the temperature is normal temperature.