Supported platinum-based electrocatalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, and discloses a supported platinum-based electrocatalyst as well as a preparation method and application thereof. The catalyst comprises a carrier and an active component, the carrier is a TiO2-RuO2 composite metal oxide nanosheet doped with an Nb element, and a metal element in the active component is Pt; metal elements in the active component are dispersed on the carrier in the form of nanoparticles; the specific surface area of the carrier is 30-100m < 2 > / g; on the basis of the total mass of the catalyst, the content of the Nb element is 0.8 wt%-4 wt%, the content of the Ti element is 10 wt%-20.6 wt%, the content of the Ru element is 17 wt%-37 wt%, and the content of the Pt is 20 wt%-60 wt%. The supported platinum-based catalyst provided by the invention has excellent hydrogen peroxide inhibition capability and oxygen reduction activity, and has excellent stability when being applied to alkaline membrane fuel cells.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a supported platinum-based electrocatalyst and a preparation method and application thereof. Background Art

[0002] Alkaline membrane fuel cells (HEMFCs) have a similar structure to proton exchange membrane fuel cells (PEMFCs). The mild alkaline working environment makes it possible to use low-cost non-platinum group metal catalysts and cheap bipolar plates, making them a potential alternative to proton exchange membrane fuel cells and attracting widespread attention.

[0003] However, HEMFC currently has serious operational stability issues, often losing most of its performance within hundreds of hours of operation. This is because the inadequate reduction of oxygen in the cathode oxygen reduction (ORR) process during fuel cell operation will produce a small amount of hydrogen peroxide that accumulates and destroys the chemical structure of the ion exchange membrane, thus greatly shortening the operating life of the alkaline membrane fuel cell. In addition, the cathode catalyst also has the problem of reduced catalytic performance due to electrochemical corrosion due to the high potential environment in which it is located, which further affects the stability of the battery and increases the cost.

[0004] At present, there is a wide range of cathode catalysts for alkaline membrane fuel cells. Non-precious metal catalysts that have the potential to replace platinum metal have the problems of high hydrogen peroxide yield and poor stability, which seriously affects their practicality. Platinum metal catalysts are still the most reliable choice. Although platinum-carbon catalysts are the most advanced alkaline redox catalysts, some of the oxygen in the reaction process is still insufficiently reduced to form hydrogen peroxide, which affects the durability of the ion exchange membrane. At the same time, the catalyst itself will undergo structural collapse of the carbon carrier after undergoing an electrochemical reaction and affect the catalytic activity. These factors have led to poor stability of alkaline membrane fuel cells and increased costs.

[0005] Therefore, developing oxygen reduction catalysts with strong hydrogen peroxide inhibition, high stability and high activity to improve the operating life of alkaline membrane fuel cells is a key goal to promote the sustainable development of this industry. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the supported Pt-based catalyst in the prior art has a high hydrogen peroxide yield after being applied to a battery, which leads to a reduction in the battery operating life.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a supported platinum-based electrocatalyst, which comprises a carrier and an active component; the carrier is a TiO2-RuO2 composite metal oxide nanosheet doped with Nb element, the metal element in the active component is Pt; the metal element in the active component is dispersed on the carrier in the form of nanoparticles; the specific surface area of ​​the carrier is 30-100m 2 / g;

[0008] Based on the total mass of the catalyst, the content of the Nb element is 0.8-4wt%, the content of the Ti element is 10-20.6wt%, the content of the Ru element is 17-37wt%, and the content of the Pt is 20-60wt%.

[0009] A second aspect of the present invention provides a method for preparing a supported platinum-based electrocatalyst, the method comprising:

[0010] (1) subjecting a mixed solution containing a Ti source, a Ru source, and a Nb source to alkaline precipitation to obtain a solid phase material I, thereby first calcining the solid phase material I to obtain a carrier;

[0011] (2) in the presence of a solvent, bringing a Pt source into first contact with the carrier to obtain a first material;

[0012] (3) bringing the reducing agent into second contact with the first material to obtain a second solid-liquid mixed material;

[0013] (4) subjecting the second material to a second calcination to obtain the solid-liquid separation of the solid phase material II, thereby obtaining the supported platinum-based electrocatalyst.

[0014] The third aspect of the present invention provides a supported platinum-based electrocatalyst prepared by the method described in the second aspect.

[0015] The fourth aspect of the present invention provides the use of the supported platinum-based electrocatalyst described in the first aspect and the third aspect in an alkaline membrane fuel cell.

[0016] The supported platinum-based catalyst provided by the present invention has excellent hydrogen peroxide inhibition ability, oxygen reduction activity and stability. The alkaline membrane fuel cell constructed by using the catalyst of the present invention as a cathode catalyst has excellent stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is an XRD diagram of the electrocatalyst obtained in Example 1 provided by the present invention;

[0018] Figure 2 is an XPS graph of the electrocatalyst obtained in Example 1 provided by the present invention;

[0019] Figure 3 is a TEM image of the electrocatalyst obtained in Example 1 provided by the present invention;

[0020] Figure 4 is an EDS mapping diagram of the electrocatalyst obtained in Example 1 provided by the present invention;

[0021] Figure 5 is a comparison diagram of polarization curves of the electrocatalyst obtained in Example 1 and the Pt / C catalyst provided by the exemplary embodiment of the present invention;

[0022] Figure 6 : is a comparison chart of hydrogen peroxide yields of the electrocatalyst obtained in Example 1 and the Pt / C catalyst provided by the exemplary embodiment of the present invention;

[0023] Figure 7 This is a stability test of the electrocatalysts and Pt / C catalysts obtained in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 provided by the present invention after being applied to batteries. DETAILED DESCRIPTION

[0024] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0025] As mentioned above, the first aspect of the present invention provides a supported platinum-based electrocatalyst, which includes a carrier and an active component; the carrier is a TiO2-RuO2 composite metal oxide nanosheet doped with Nb element, and the metal element in the active component is Pt; the metal element in the active component is dispersed on the carrier in the form of nanoparticles; the specific surface area of ​​the carrier is 30-100m 2 / g;

[0026] Based on the total mass of the catalyst, the content of the Nb element is 0.8-4wt%, the content of the Ti element is 10-20.6wt%, the content of the Ru element is 17-37wt%, and the content of the Pt is 20-60wt%.

[0027] Preferably, based on the total mass of the catalyst, the content of the Nb element is 1-3wt%, the content of the Ti element is 12-15wt%, and the content of the Ru element is 21-25wt%. The inventors found that the electrocatalyst obtained under this preferred embodiment can significantly reduce the hydrogen peroxide yield and increase the service life of the battery.

[0028] Preferably, based on the total mass of the catalyst, the content of Pt is 35-42 wt%.

[0029] More preferably, the metal element in the active component is in the form of nanoparticles with an average diameter of 4-6 nm.

[0030] As mentioned above, the second aspect of the present invention provides a method for preparing a supported platinum-based electrocatalyst, the method comprising:

[0031] (1) subjecting a mixed solution containing a Ti source, a Ru source, and a Nb source to alkaline precipitation to obtain a solid phase material I, thereby first calcining the solid phase material I to obtain a carrier;

[0032] (2) in the presence of a solvent, bringing a Pt source into first contact with the carrier to obtain a first material;

[0033] (3) bringing the reducing agent into second contact with the first material to obtain a second solid-liquid mixed material;

[0034] (4) subjecting the second material to a second calcination to obtain the solid-liquid separation of the solid phase material II, thereby obtaining the supported platinum-based electrocatalyst.

[0035] Preferably, in step (1), the molar ratio of the Nb source calculated as Nb element, the Ti source calculated as Ti element and the Ru source calculated as Ru element in the mixed solution is 1:10-42:10-42; preferably 1:18-22:18-22.

[0036] In the present invention, there is no special requirement for the preparation method of the mixed solution containing Ti source, Ru source and Nb source, as long as the raw materials are evenly mixed; illustratively, the preparation method includes: dispersing Ti source, Ru source and Nb source in water, ultrasonicating for 20-40 minutes, and obtaining a mixed solution; the present invention will not be elaborated here, and those skilled in the art should not understand it as a limitation of the present invention.

[0037] Preferably, the Nb source is selected from at least one of niobium pentachloride, niobium oxytrichloride and niobium pentoxide.

[0038] More preferably, the Nb source is niobium pentachloride; the present invention has found through creative research that the electrocatalyst obtained under this preferred specific embodiment can more significantly reduce the hydrogen peroxide yield and increase the service life of the battery.

[0039] Preferably, the Ti source is selected from titanium-containing compounds, preferably titanium dioxide; the Ru source is selected from Ru-containing compounds, preferably hydrated ruthenium chloride.

[0040] Preferably, in step (1), the alkali precipitation step comprises: stirring and mixing a mixed solution containing a Ti source, a Ru source and a Nb source with an alkali solution and then letting it stand; the amount of the alkali solution used is such that the pH value of the system after stirring and mixing is 7-10.

[0041] More preferably, the alkaline solution is a potassium hydroxide aqueous solution with a concentration of 0.1-1 mol / L and / or a sodium hydroxide aqueous solution with a concentration of 0.1-1 mol / L.

[0042] More preferably, the static time is 8-20 min.

[0043] Preferably, in step (1), the first calcination is carried out in an air atmosphere, and the conditions of the first calcination include: a temperature of 500-900°C and a time of 2-10 hours. The present invention has found through creative research that under the preferred calcination conditions, the crystal form of ruthenium oxide can be promoted to change while increasing the bonding strength between different components of the carrier, which is beneficial to improving the transfer efficiency and enhancing the stability of the carrier structure; the prepared electrocatalyst can significantly reduce the hydrogen peroxide yield and increase the service life of the battery.

[0044] More preferably, the conditions for the first calcination also include: a heating rate of 6-12° C. / min.

[0045] Preferably, the solid phase material I is dried before the first calcination.

[0046] Preferably, in step (2), based on the total mass of the Pt source and the carrier in terms of Pt element, the amount of the Pt source used is 20-60 wt %, preferably 35-42 wt %.

[0047] More preferably, the Pt source is selected from an aqueous solution of chloroplatinic acid with a concentration of 80-120 mg / mL.

[0048] Preferably, in step (2), the solvent is water.

[0049] More preferably, the amount of the solvent used is 80-120 mL per 100 g of the carrier.

[0050] Preferably, the first contact is performed under ultrasonic conditions, and the conditions for the first contact include: temperature of 15-35°C, time of 0.5-2h, and ultrasonic frequency of 30-50kHz.

[0051] Preferably, in step (3), the reducing agent is selected from formic acid and sodium borohydride.

[0052] It should be noted that, in the present invention, there is no special requirement for the amount of the reducing agent, as long as the amount is sufficient to reduce all the platinum sources; the present invention will not be elaborated here, and those skilled in the art should not regard it as a limitation of the present invention.

[0053] Preferably, the second contact is carried out under stirring conditions, and the conditions for the second contact include: a stirring speed of 200-2000 rpm, a time of 1-8 h, and a temperature of 70-90°C.

[0054] In the present invention, in step (4), there is no particular requirement for the specific operation method of solid-liquid separation, which may be illustratively suction filtration, filtration, centrifugation, etc. The present invention will not be elaborated here, and those skilled in the art should not understand it as a limitation of the present invention.

[0055] Preferably, in step (4), the second calcination is carried out in the presence of an air atmosphere, and the conditions of the second calcination include: a temperature of 150-250° C. and a time of 2-10 hours. The present invention has found through creative research that under this preferred embodiment, the interaction between the metal oxide support and the platinum component can be significantly enhanced, thereby improving the activity and stability of the catalyst.

[0056] More preferably, the second calcination conditions also include: a heating rate of 6-12°C / min.

[0057] Preferably, the first calcination and the second calcination are each independently performed in a tube furnace.

[0058] Preferably, the solid phase material II is washed and dried before the second calcination.

[0059] As mentioned above, the third aspect of the present invention provides a supported platinum-based electrocatalyst prepared by the method described in the second aspect.

[0060] As mentioned above, the fourth aspect of the present invention provides the use of the supported platinum-based electrocatalyst described in the first aspect and the third aspect in an alkaline membrane fuel cell.

[0061] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials used are purchased from commercial sources.

[0062] Example 1

[0063] This example is used to illustrate that the supported platinum-based electrocatalyst provided by the present invention is prepared by the following method:

[0064] (1) dissolving titanium dioxide, hydrated ruthenium chloride and 0.05 mmol of niobium pentachloride in 100 mL of deionized water to obtain a mixed solution; stirring the mixed solution with a 0.5 M potassium hydroxide solution, allowing the solution to stand for 10 min, and then filtering the solution to obtain a solid phase material I; the solid phase material I is subjected to a first calcination to obtain a carrier; the amount of the 0.5 M sodium hydroxide solution is such that the pH value of the system after stirring and mixing is 7;

[0065] The molar ratio of niobium pentachloride calculated as Nb element, titanium dioxide calculated as Ti element and hydrated ruthenium chloride calculated as Ru element is 1:20:20;

[0066] The first calcination is carried out in an air atmosphere, and the conditions of the first calcination are: temperature of 500° C., time of 3 hours, and heating rate of 5° C. / min.

[0067] (2) a Pt source (100 mg / mL chloroplatinic acid aqueous solution) is first contacted with 60 mg of a carrier in 50 mL of deionized water to obtain a first material; the first contact is performed under ultrasonic conditions, and the conditions of the first contact include: a temperature of 25° C., a time of 0.5 h, and an ultrasonic frequency of 50 kHz;

[0068] Based on the total mass of the Pt source and the carrier calculated as the Pt element, the amount of the Pt source is 40wt%;

[0069] (3) contacting the first material with 4 mL of formic acid for a second time to obtain a second solid-liquid mixed material; the second contact is carried out under stirring conditions, and the conditions of the second contact include: a stirring speed of 200 rpm, a time of 8 hours, and a temperature of 80° C.;

[0070] (4) The solid phase material II obtained after the second material is filtered is washed with water three times, dried (temperature is 80° C., time is 12 h), and calcined for the second time to obtain the supported platinum-based electrocatalyst S1;

[0071] The second calcination is carried out in an air atmosphere, and the conditions of the first calcination are: temperature of 150° C., time of 2 h, and heating rate of 10° C. / min.

[0072] Example 2

[0073] (1) dissolving titanium dioxide, hydrated ruthenium chloride and 0.05 mmol of niobium pentachloride in 100 mL of deionized water to obtain a mixed solution; stirring the mixed solution with a 0.5 M potassium hydroxide solution, allowing the mixture to stand for 10 min, and then filtering to obtain a solid phase material I; the solid phase material I is subjected to a first calcination to obtain a carrier; the amount of the 0.5 M sodium hydroxide solution is such that the pH value of the system after stirring and mixing is 8;

[0074] The molar ratio of niobium pentachloride calculated as Nb element, titanium dioxide calculated as Ti element and hydrated ruthenium chloride calculated as Ru element is 1:21:19;

[0075] The first calcination is carried out in an air atmosphere, and the conditions of the first calcination are: temperature of 700° C., time of 3 hours, and heating rate of 10° C. / min.

[0076] (2) a Pt source (100 mg / mL chloroplatinic acid aqueous solution) is first contacted with 60 mg of a carrier in 50 mL of deionized water to obtain a first material; the first contact is performed under ultrasonic conditions, and the conditions of the first contact include: a temperature of 25° C., a time of 0.5 h, and an ultrasonic frequency of 40 kHz;

[0077] Based on the total mass of the Pt source and the carrier calculated as the Pt element, the amount of the Pt source is 42 wt%;

[0078] (3) contacting the first material with 4 mL of formic acid for a second time to obtain a second solid-liquid mixed material; the second contact is carried out under stirring conditions, and the conditions of the second contact include: a stirring speed of 200 rpm, a time of 8 hours, and a temperature of 80° C.;

[0079] (4) The solid phase material II obtained after the second material is filtered is washed with water three times, dried (temperature is 80° C., time is 12 h), and calcined for the second time to obtain the supported platinum-based electrocatalyst S1;

[0080] The second calcination is carried out in an air atmosphere, and the conditions of the first calcination are: temperature of 250° C., time of 10 h, and heating rate of 10° C. / min.

[0081] Example 3

[0082] This embodiment is carried out using a process similar to that of Embodiment 1, except that, in this embodiment, the total amount of niobium pentachloride, titanium dioxide and hydrated ruthenium chloride is controlled to remain unchanged, but the molar ratio of niobium pentachloride calculated as Nb element, titanium dioxide calculated as Ti element and hydrated ruthenium chloride calculated as Ru element is 1:12:12.

[0083] The rest are the same as in Example 1.

[0084] The electrocatalyst S3 was prepared.

[0085] Example 4

[0086] This embodiment is carried out using a process similar to that of Embodiment 1, except that, in this embodiment, the total amount of niobium pentachloride, titanium dioxide and hydrated ruthenium chloride is controlled unchanged, but the molar ratio of niobium pentachloride calculated as Nb element, titanium dioxide calculated as Ti element and hydrated ruthenium chloride calculated as Ru element is 1:40:40.

[0087] The rest are the same as in Example 1.

[0088] The electrocatalyst S4 was prepared.

[0089] Example 5

[0090] This example is carried out using a process similar to that of Example 1, except that, in this example, niobium oxytrichloride of equal mass is used to replace niobium pentachloride in Example 1.

[0091] The rest are the same as in Example 1.

[0092] Electrocatalyst S5 was prepared.

[0093] Example 6

[0094] This example is carried out using a process similar to that of Example 1, except that in this example, the temperature of the first calcination is 450°C.

[0095] The rest are the same as in Example 1.

[0096] Electrocatalyst S6 was prepared.

[0097] Example 7

[0098] This example is carried out using a process similar to that of Example 1, except that in this example, the temperature of the first calcination is 950°C.

[0099] The rest are the same as in Example 1.

[0100] Electrocatalyst S7 was prepared.

[0101] Example 8

[0102] This example is carried out using a process similar to that of Example 1, except that in this example, the temperature of the second calcination is 100°C.

[0103] The rest are the same as in Example 1.

[0104] The electrocatalyst S8 was prepared.

[0105] Example 9

[0106] This example is carried out using a process similar to that of Example 1, except that in this example, the temperature of the second calcination is 300°C.

[0107] The rest are the same as in Example 1.

[0108] The electrocatalyst S9 was prepared.

[0109] Comparative Example 1

[0110] This comparative example was carried out using a process similar to that of Example 1, except that, in this comparative example, an equal molar amount of cerium chloride hexahydrate was used to replace the niobium pentachloride in Example 1.

[0111] The rest are the same as in Example 1.

[0112] The electrocatalyst DS1 was prepared.

[0113] Comparative Example 2

[0114] This comparative example was carried out using a process similar to that of Example 1, except that in this comparative example, tantalum pentachloride of equal mass was used to replace niobium pentachloride in Example 1.

[0115] The rest are the same as in Example 1.

[0116] The electrocatalyst DS2 was prepared.

[0117] Comparative Example 3

[0118] This comparative example was carried out using a process similar to that of Example 1, except that in this comparative example, niobium pentachloride was not added. That is, in step (1), the same amount of titanium dioxide and hydrated ruthenium chloride as in Example 1 were dissolved in deionized water to obtain a mixed solution.

[0119] The rest are the same as in Example 1.

[0120] The electrocatalyst DS3 was prepared.

[0121] Comparative Example 4

[0122] This comparative example is carried out using a process similar to that of Example 1, except that in this comparative example, niobium pentachloride and titanium dioxide are not added. That is, in step (1), the same amount of hydrated ruthenium chloride as in Example 1 is dissolved in deionized water to obtain a mixed solution.

[0123] The rest are the same as in Example 1.

[0124] The electrocatalyst DS4 was prepared.

[0125] Comparative Example 5

[0126] This comparative example was carried out using a process similar to that of Example 1, except that in this comparative example, niobium pentachloride and hydrated ruthenium chloride were not added. That is, in step (1), the same amount of titanium dioxide as in Example 1 was dissolved in deionized water to obtain a mixed solution.

[0127] The rest are the same as in Example 1.

[0128] The electrocatalyst DS5 was prepared.

[0129] Comparative Example 6

[0130] This comparative example is carried out using a process similar to that of Example 1, except that niobium pentachloride is not added in this comparative example. The specific steps are as follows:

[0131] (1) The same amount of titanium dioxide and hydrated ruthenium chloride as in Example 1 was dissolved in deionized water to obtain a mixed solution; the mixed solution was then stirred and mixed with a 0.5 M potassium hydroxide solution and allowed to stand for 10 min, and then filtered to obtain a solid phase material I. The solid phase material I was subjected to a first calcination to obtain a carrier; the amount of the 0.5 M sodium hydroxide solution was such that the pH value of the system after the stirring and mixing was 7;

[0132] The first calcination is carried out in an air atmosphere, and the conditions of the first calcination are: temperature of 450° C., time of 3 hours, and heating rate of 5° C. / min.

[0133] (2) a Pt source (100 mg / mL chloroplatinic acid aqueous solution) is first contacted with 60 mg of a carrier in 50 mL of deionized water to obtain a first material; the first contact is performed under ultrasonic conditions, and the conditions of the first contact include: a temperature of 25° C., a time of 0.5 h, and an ultrasonic frequency of 50 kHz;

[0134] Based on the total mass of the Pt source and the carrier calculated as the Pt element, the amount of the Pt source is 40wt%;

[0135] (3) contacting the first material with 4 mL of formic acid for a second time to obtain a second solid-liquid mixed material; the second contact is carried out under stirring conditions, and the conditions of the second contact include: a stirring speed of 200 rpm, a time of 2 h, and a temperature of 80° C.;

[0136] (4) The solid phase material II obtained after filtering the second material was washed with water three times and dried (temperature was 80° C., time was 12 h) to obtain the supported platinum-based electrocatalyst DS6.

[0137] The composition and parameter characteristics of the catalysts prepared in each example are shown in Table 1;

[0138] The element content was quantitatively detected by inductively coupled plasma emission spectrometry, and the specific surface area was tested by a fully automatic physical adsorption instrument.

[0139] Table 1

[0140]

[0141] Table 1 (Continued)

[0142] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Nb element content (wt%) / / / / / / Ce content (wt%) 2.8 / / / / / Ta content (wt%) / 2.8 / / / / Ti element content (wt%) 12.7 13.9 13.5 / 35.2 13.8 Ru content (wt%) 24.5 26.2 28.5 40.2 / 28.9 Pt element content (wt%) 39.2 39.6 39.4 39.2 39.4 39.5 <![CDATA[Specific surface area (m 2 / g)]]> 52 55 49 32 72 59 name DS1 DS2 DS3 DS4 DS5 DS6

[0143] The present invention also exemplarily provides the XRD ( Figure 1 ) and XPS images ( Figure 2 ),from Figure 1 and Figure 2 The results show that the electrocatalyst provided by the present invention contains Nb-doped TiO2-RuO2 composite metal oxide and Pt metal element. Figure 2 It can also be seen that the Nb element exists in the form of niobium pentoxide.

[0144] The present invention also exemplarily provides a TEM image of the electrocatalyst obtained in Example 1 ( Figure 3 ) and EDS mapping, from Figure 3 It can be clearly seen that the Pt metal element is dispersed on the carrier in the form of nanoparticles, with an average particle diameter of 5nm; Figure 4 It can be clearly seen that the Nb element, Ti element, Ru element and Pt element in the electrocatalyst provided by the present invention are in a uniformly dispersed state.

[0145] Test Example 1

[0146] The electrocatalyst provided in the above example was tested for its electrocatalytic oxygen reduction performance and hydrogen peroxide yield.

[0147] The test method is: the above sample (electrocatalyst obtained in the above example) is tested using a three-electrode system, with a saturated calomel electrode (SCE) as the reference electrode, a carbon rod electrode as the counter electrode, and a 0.1M potassium hydroxide solution saturated with O2 as the electrolyte. The working electrode uses a rotating ring disk electrode coated with catalyst ink.

[0148] (1) Take 1 mg of sample powder, 5 μL of 5 wt% Nafion solution (perfluorinated resin solution), add 895 μL of anhydrous ethanol and 100 μL of aqueous solution, and after ultrasonic dispersion, a uniformly dispersed catalytic ink can be obtained;

[0149] (2) Take 12.5 μL of the catalyst ink obtained in step 1 and apply it on the glassy carbon electrode twice. Use the rotating disk electrode method to test and keep the rotation speed at 1600 rpm. Use the linear voltammetry method to collect the oxygen reduction polarization curve in the oxygen saturated 0.1 M KOH solution. Control the disk electrode potential to scan from 0.05 V to 1.05 V at a scan rate of 5 mV / s. The ring electrode potential is kept at 1.2 V.

[0150] Hydrogen peroxide yield %: Hydrogen peroxide yield was calculated according to the following formula:

[0151]

[0152] Among them, I d is the disk current, I r is the ring current and N is the current collection efficiency of the platinum ring, which is 0.37 in this formula.

[0153] The test results are shown in Table 2.

[0154] Table 2

[0155]

[0156]

[0157] From the results in Table 2, it can be seen that the supported platinum-based catalyst provided by the present invention has an excellent effect of inhibiting hydrogen peroxide production as an oxygen reduction catalyst.

[0158] The present invention also provides a comparison diagram of polarization curves of the electrocatalyst obtained in Example 1 and the Pt / C catalyst ( Figure 5 ) and hydrogen peroxide yield comparison chart ( Figure 6 ),from Figure 5 It can be seen that the electrocatalyst provided by the present invention has similar oxygen reduction activity to commercially available Pt / C (Pt content 40wt%; model: Pt / C; manufacturer: Johnson Matthey, USA), but the disk current is significantly lower than that of Pt / C, indicating that the electrocatalyst obtained by the present invention has better oxygen reduction catalytic activity and lower hydrogen peroxide yield. Figure 6 It can be more clearly seen that the electrocatalyst obtained in the present invention has a hydrogen peroxide yield significantly lower than that of commercially available Pt / C.

[0159] Test Example 2

[0160] This test example is used to illustrate the actual operation stability test of the electrocatalyst provided in the previous example after being applied to the battery.

[0161] Membrane electrode preparation method:

[0162] (1) The electrocatalyst obtained in the above examples (S1, S2, DS1, DS2) was used as the cathode catalyst. 10 mg of the catalyst was weighed and dissolved in 1 mL of isopropanol and 50 μL of aqueous solution. 96 μL of 5% PAP-TP-100 ethanol solution of the ionomer solution was added. After strong ultrasonication for 1 min, the mixture was ultrasonicated in an ice bath for 2 h.

[0163] (2) Using commercially available Pt / C (Pt content 40 wt%; model: Pt / C; manufacturer: Johnson Matthey, USA) as the anode catalyst, 10 mg of Pt / C was weighed and dissolved in 1 mL of isopropanol and 50 μL of aqueous solution, 96 μL of 5% PAP-TP-100 ethanol solution was added, and strong ultrasound was performed for 1 min and then ice bath ultrasound was performed for 2 h;

[0164] (3) The catalyst slurry prepared by ultrasonic dispersion in the above steps 1 and 2 is sprayed symmetrically on both sides of the alkaline membrane in succession, and the alkaline membrane sprayed with the catalyst is soaked in a 3M NaOH solution overnight. Then, the residual NaOH on the surface of the alkaline membrane is replaced with ultrapure water, and the water on the surface of the alkaline membrane is gently absorbed with dust-free paper.

[0165] (4) Two gas diffusion layers (SGL28BC) were sandwiched between the two sides of the alkaline membrane to form a membrane electrode (MEA), and the prepared membrane electrode was placed on a 5 cm 2 The membrane electrode is clamped in the graphite flow field plate with three snake flow channels.

[0166] Alkaline membrane fuel cell test method:

[0167] The battery fixture with MEA installed was heated to 80°C, hydrogen was introduced into the anode at a flow rate of 400 sccm, humidification temperature of 78°C, and back pressure of 150 kPa; oxygen was introduced into the cathode at a flow rate of 400 sccm, humidification temperature of 79°C, and back pressure of 150 kPa. The battery was kept at 0.5 A cm 2 The test was carried out at a constant current density and the loss of operating voltage was calculated to evaluate the actual operating stability of the catalyst.

[0168] Test results see Figure 7 It can be clearly seen from the figure that the electrocatalyst provided by the present invention remains stable under long-term testing conditions, showing a significant stability advantage over commercially available products.

[0169] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A supported platinum-based electrocatalyst, characterized in that: The catalyst comprises a carrier and an active component; the carrier is a TiO2-RuO2 composite metal oxide nanosheet doped with Nb element, the metal element in the active component is Pt; the metal element in the active component is dispersed on the carrier in the form of nanoparticles; the specific surface area of ​​the carrier is 30-100m 2 / g; Based on the total mass of the catalyst, the content of the Nb element is 0.8-4wt%, the content of the Ti element is 10-20.6wt%, the content of the Ru element is 17-37wt%, and the content of the Pt is 20-60wt%.

2. The electrocatalyst according to claim 1, characterized in that Based on the total mass of the catalyst, the content of the Nb element is 1-3wt%, the content of the Ti element is 12-15wt%, and the content of the Ru element is 21-25wt%.

3. The electrocatalyst according to claim 1 or 2, characterized in that Based on the total mass of the catalyst, the content of Pt is 35-42wt%; And / or, the metal element in the active component is in the form of nanoparticles with an average diameter of 4-6 nm.

4. A method for preparing a supported platinum-based electrocatalyst, characterized in that: The method includes: (1) subjecting a mixed solution containing a Ti source, a Ru source, and a Nb source to alkaline precipitation to obtain a solid phase material I, thereby first calcining the solid phase material I to obtain a carrier; (2) in the presence of a solvent, bringing a Pt source into first contact with the carrier to obtain a first material; (3) bringing the reducing agent into second contact with the first material to obtain a second material mixed with solid and liquid; (4) subjecting the second material to a second calcination to obtain the solid-liquid separation of the solid phase material II, thereby obtaining the supported platinum-based electrocatalyst.

5. The method according to claim 4, characterized in that In step (1), the molar ratio of the Nb source calculated as Nb element, the Ti source calculated as Ti element and the Ru source calculated as Ru element in the mixed solution is 1:10-42:10-42; preferably 1:18-22:18-22.

6. The method according to claim 4 or 5, characterized in that: In step (1), the alkali precipitation step comprises: stirring and mixing a mixed solution containing a Ti source, a Ru source and a Nb source with an alkali solution and then standing the mixture; the amount of the alkali solution is such that the pH value of the system after stirring and mixing is 7-10; Preferably, the alkaline solution is a potassium hydroxide aqueous solution with a concentration of 0.1-1 mol / L and / or a sodium hydroxide aqueous solution with a concentration of 0.1-1 mol / L; And / or, in step (1), the first calcination is carried out in an air atmosphere, and the conditions of the first calcination include: a temperature of 500-900° C. and a time of 2-10 h.

7. The method according to any one of claims 4 to 6, characterized in that: In step (2), based on the total mass of the Pt source and the carrier in terms of Pt element, the amount of the Pt source is 20-60 wt %, preferably 35-42 wt %; And / or, the first contact is performed under ultrasonic conditions, and the conditions for the first contact include: temperature of 15-35°C, time of 0.5-2h, and ultrasonic frequency of 30-50kHz.

8. The method according to any one of claims 4 to 7, characterized in that: In step (3), the reducing agent is selected from formic acid and sodium borohydride; And / or, the second contact is carried out under stirring conditions, and the conditions of the second contact include: a stirring speed of 200-2000 rpm, a time of 1-8 hours, and a temperature of 70-90° C.; And / or, in step (4), the second calcination is carried out in the presence of an air atmosphere, and the conditions of the second calcination include: a temperature of 150-250° C. and a time of 2-10 hours.

9. A supported platinum-based electrocatalyst prepared by the method according to any one of claims 4 to 8.

10. Use of the supported platinum-based electrocatalyst according to any one of claims 1 to 3 and 9 in an alkaline membrane fuel cell.

Images