Vacancy zirconium oxide loaded nano ruthenium catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of electrocatalysts, in particular to a vacancy zirconium oxide loaded nano ruthenium catalyst as well as a preparation method and application thereof. Zirconium nitrate is used as a raw material and is fully mixed with a ruthenium chloride solution, hydrothermal treatment is performed to obtain a powder precursor, and then pyrolysis treatment is performed to form the hydrogen evolution reaction electrocatalyst of ruthenium powder loaded on ruthenium zirconium oxide rich in oxygen vacancies. The preparation method comprises the following steps: dissolving zirconium nitrate and ruthenium chloride in ethanol, carrying out atomic-level combination through hydrothermal reaction, and carrying out carbonization under low-temperature shielding gas to form a crystalline and amorphous zirconium oxide interface and a zirconium oxide and ruthenium interface. The raw materials mainly comprise zirconium nitrate and ruthenium chloride, the cost is low, large-scale preparation can be achieved, commercialization is facilitated, the catalyst can be used as an HER catalyst with excellent performance, and the catalyst has high catalytic activity and good stability and can be widely applied to water electrolysis devices.

Description

Technical Field

[0001] The invention relates to the technical field of electrocatalysts, and in particular to a vacancy zirconium oxide-loaded nano-ruthenium catalyst and a preparation method and application thereof. Background Art

[0002] Currently, alkaline water electrolysis is the most mature and commercialized technology, but it faces the problem of slow HER speed, resulting in low efficiency and proton adsorption capacity, which is crucial for HER activity. However, alkaline electrolytes require a prior water dissociation process to produce enough protons to participate in the reaction. This necessity makes the kinetics of alkaline HER very slow. Therefore, in addition to optimizing the adsorption strength of protons, it is also important to simultaneously reduce the energy barrier of water dissociation when designing HER electrocatalysts for alkaline media. Ruthenium has a similar proton binding energy to Pt and a lower price, and has been widely studied as a substitute metal for Pt in HER. Constructing a hydrogen spillover-based binary (HSBB) system by dispersing active materials on supports with water dissociation ability (such as metal oxides and hydroxides) has been proven to be an effective strategy to enhance alkaline HER activity. However, in such systems, hydrogen spillover from metal oxide / hydroxide supports to metal centers is a thermodynamically unfavorable process. In addition, the built-in electric field established between the metal and its support leads to the accumulation of charge at the interface, which gives the interface a strong proton capture ability, thereby increasing the barrier to hydrogen spillover. Therefore, accelerating hydrogen spillover in HSBB systems is a major challenge.

[0003] The work function difference (ΔΦ) between the metal and its support significantly affects the interfacial proton adsorption and thus the hydrogen spillover. Based on this theory, it is reasonable to tune the work function of the support to promote the energetically and kinetically favorable hydrogen spillover process. The d-band of the cations is considered to be completely empty oxides, such as ZrO2, TiO2, HfO2, and WO3, which are very suitable as supports with tunable work functions due to their tendency to form oxygen vacancies (Vo). This phenomenon leads to the appearance of d-band filling and occupied interstitial states, resulting in the modification of the Fermi level and work function. Vo can induce the reverse charge transfer from the support to the metal and promote hydrogen spillover. In addition, the amorphous nature of the support also significantly affects the catalytic activity. The disordered and loosely bonded amorphous phase produces abundant dangling bonds and unsaturated coordination configurations, which lead to more likely dd electron transfer and medium to long-range p-π orbital coupling, thereby promoting charge migration between active sites and enhancing HER activity. Herein, an amorphous / crystalline zirconia-supported nano-Ruthenium rich in oxygen vacancies is urgently needed as an efficient electrocatalyst for alkaline HER. Summary of the invention

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a vacancy zirconia-loaded nano-ruthenium catalyst and a preparation method and application thereof to solve the problems involved in the background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a vacancy zirconium oxide-supported nano-ruthenium catalyst, which uses zirconium nitrate as a raw material, is fully mixed with a ruthenium chloride solution and hydrothermally obtained to obtain a powder precursor, which is then pyrolyzed to form a ruthenium zirconium oxide-supported ruthenium powder rich in oxygen vacancies as a hydrogen evolution reaction electrocatalyst.

[0006] Preparation method of vacancy zirconium oxide supported nano ruthenium catalyst,

[0007] 1) adding ruthenium chloride RuCl3·xH2O and zirconium nitrate Zr(NO3)4·5H2O into ethanol, and stirring at room temperature to obtain an ethanol solution containing ruthenium and zirconium;

[0008] 2) pouring the formed ethanol solution containing ruthenium and zirconium into a polytetrafluoroethylene liner for hydrothermal reaction to obtain a precursor powder containing ruthenium and zirconium;

[0009] 3) The precursor powder is calcined in a tube furnace at 200-400° C. using a carbonization process to obtain ruthenium-doped zirconia powder.

[0010] Furthermore, the mass ratio of ruthenium chloride to zirconium nitrate in (1) is 1:3, the concentration of ruthenium chloride in the ethanol solution is 0.27 mg / ml, and the concentration of zirconium nitrate in the ethanol solution is 0.8 mg / ml.

[0011] Furthermore, the hydrothermal temperature in (2) is 200° C., and the hydrothermal time is 4 hours.

[0012] Furthermore, the calcination in (3) is carried out for 1 hour, and the calcination atmosphere is argon.

[0013] Application of vacant zirconia-loaded nano-ruthenium catalysts. Vacant zirconia-loaded nano-ruthenium catalysts are used as electrocatalysts in hydrogen evolution reactions.

[0014] Further, the application steps include:

[0015] (1) dispersing the catalyst and XC-72 powder in a mixed solution of nafion and ethanol;

[0016] (2) dropping the catalyst solution onto the glassy carbon electrode to obtain a working electrode;

[0017] (3) Graphite rod and standard hydrogen electrode were used as working electrode and reference electrode respectively in 1 M KOH electrolyte.

[0018] Furthermore, the mass ratio of the catalyst to XC-72 is 3:1.

[0019] Furthermore, the mass concentration of the nafion is 5 wt.%.

[0020] Furthermore, the volume ratio of the nafion to the ethanol is 1:10, and the mass volume ratio of the catalyst to the nafion is 1:10.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention first dissolves zirconium nitrate and ruthenium chloride in ethanol, combines them at the atomic level through hydrothermal reaction, and forms a crystalline and amorphous zirconium oxide interface and an interface between zirconium oxide and ruthenium after carbonization under low-temperature protective gas. The raw materials are mainly zirconium nitrate and ruthenium chloride, which have low cost, can be prepared in large quantities, are easy to commercialize, can be used as an excellent HER catalyst, have high catalytic activity and good stability, and can be widely used in water electrolysis devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a SEM image of the vacant zirconium oxide supported nano-ruthenium catalyst according to an embodiment of the present invention;

[0024] Figure 2 This is a TEM image of the vacant zirconium oxide-supported nano-ruthenium catalyst of an embodiment of the present invention;

[0025] Figure 3 This is a linear sweep voltammetric curve of the HER of the vacancy zirconium oxide supported nano-ruthenium catalyst in an alkaline electrolyte according to an embodiment of the present invention;

[0026] Figure 4 This is a Tafel slope diagram of the vacancy zirconium oxide supported nano-ruthenium catalyst in alkaline electrolyte according to an embodiment of the present invention;

[0027] Figure 5 This is a graph of the electrochemical activity area of ​​the vacant zirconium oxide-supported nano-ruthenium catalyst in an alkaline electrolyte according to an embodiment of the present invention;

[0028] Figure 6 This is a long-term stability diagram of the vacant zirconium oxide supported nano-ruthenium catalyst in an alkaline electrolyte according to an embodiment of the present invention; DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] A vacancy zirconium oxide supported nano-ruthenium catalyst is prepared by using zirconium nitrate as raw material, and is fully mixed with a ruthenium chloride solution and hydrothermally processed to obtain a powder precursor, which is then pyrolyzed to form a hydrogen evolution reaction electrocatalyst of ruthenium zirconium oxide supported ruthenium powder rich in oxygen vacancies.

[0032] Preparation method of vacancy zirconium oxide supported nano ruthenium catalyst,

[0033] 1) Add 20 mg of ruthenium chloride RuCl3·xH2O and 60 mg of zirconium nitrate Zr(NO3)4·5H2O into 75 mL of ethanol, and stir at room temperature to obtain an ethanol solution containing ruthenium and zirconium;

[0034] 2) Pour the formed ruthenium and zirconium ethanol solution into the polytetrafluoroethylene liner and heat it at 5℃min -1 The temperature is raised to 200-400° C. at a rate of 100° C. and maintained for 1 hour, and the calcination atmosphere is argon, to obtain a precursor powder containing ruthenium and zirconium;

[0035] 3) The precursor powder is calcined in a tube furnace at 200-400° C. using a carbonization process to obtain ruthenium-doped zirconia powder.

[0036] Figure 1 This is the SEM image of the vacant zirconium oxide supported nano-ruthenium catalyst;

[0037] Figure 2 TEM image of vacant zirconium oxide supported nano-ruthenium catalyst;

[0038] Embodiment 2:

[0039] Application of vacant zirconia-loaded nano-ruthenium catalyst: vacant zirconia-loaded nano-ruthenium catalyst is used as an electrocatalyst in hydrogen evolution reaction. The application steps include:

[0040] 3 mg of catalyst and 1 mg of XC-72 powder were dispersed in a mixed solution of 30 μL of 5 wt.% nafion and 300 μL of ethanol. After ultrasonication for 30 minutes, a homogeneous catalyst ink was obtained; 9 μL of the catalyst ink was dropped on a glassy carbon electrode and dried at room temperature to obtain a working electrode.

[0041] Performance Testing:

[0042] The graphite rod and standard hydrogen electrode (RHE) were used as the counter electrode and reference electrode respectively to test the HER catalytic activity of the above products in 1M KOH electrolyte. The test results are shown in Figure 3 As shown, in 1M KOH electrolyte, the current density of electrode sample No. 1 (heat treatment temperature = 300°C, red line in the figure) reaches 10 mA cm-2 When the overpotential is 14 mV, the overpotential of electrode sample No. 2 (heat treatment temperature = 200°C) and electrode sample No. 3 (heat treatment temperature = 400°C) reaches 51 mV and 31 mV; while the overpotential of commercial Pt / C is only 19 mV.

[0043] Depend on Figure 4 It can be seen that the Tafel slope of sample No. 1 is only 26.9mV dec -1 , while those of sample 2, sample 3 and commercial Pt / C are 40.6 mV dec -1 、36.1mV dec -1 and 35.4mV dec -1 , it can be concluded that sample No. 1 has good reaction kinetics.

[0044] Figure 5 The electrochemically active areas of samples 1, 2, and 3 were compared. Sample 1 was 28.4 mF cm -2 , sample No. 2 is 7.9mF cm -2 , sample No. 3 is 8.9mF cm -2 , from which it can be concluded that sample No. 1 has more active sites.

[0045] like Figure 6 As shown, the current density in 1 M KOH electrolyte is 10 mA cm -2 A 20-hour stability test was conducted, and the voltage hardly changed. The catalytic activity and stability were significantly better than those of commercial Pt / C.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A vacancy zirconium oxide supported nano-ruthenium catalyst, characterized in that: Zirconium nitrate is used as a raw material, and a powder precursor is obtained by fully mixing with a ruthenium chloride solution and hydrothermally treating the mixture. The precursor is then subjected to pyrolysis treatment to form a hydrogen evolution reaction electrocatalyst of ruthenium zirconium oxide loaded with ruthenium powder rich in oxygen vacancies.

2. The method for preparing the vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 1, characterized in that: 1) adding ruthenium chloride RuCl3·xH2O and zirconium nitrate Zr(NO3)4·5H2O into ethanol, and stirring at room temperature to obtain an ethanol solution containing ruthenium and zirconium; 2) pouring the formed ethanol solution containing ruthenium and zirconium into a polytetrafluoroethylene liner for hydrothermal reaction to obtain a precursor powder containing ruthenium and zirconium; 3) The precursor powder is calcined in a tube furnace at 200-400° C. using a carbonization process to obtain ruthenium-doped zirconia powder.

3. The method for preparing a vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 2, characterized in that: The mass ratio of ruthenium chloride to zirconium nitrate in (1) is 1:3, the concentration of ruthenium chloride in the ethanol solution is 0.27 mg / ml, and the concentration of zirconium nitrate in the ethanol solution is 0.8 mg / ml.

4. The method for preparing a vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 2, characterized in that: The hydrothermal temperature in (2) is 200° C. and the hydrothermal time is 4 h.

5. The method for preparing a vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 2, characterized in that: The calcination in (3) is carried out for 1 hour, and the calcination atmosphere is argon.

6. An application of the vacant zirconium oxide supported nano-ruthenium catalyst according to claim 1, wherein the catalyst is prepared according to the preparation method according to any one of claims 2 to 5, characterized in that: Vacancy zirconia-loaded nanoruthenium catalyst is used as an electrocatalyst in hydrogen evolution reaction.

7. The use of a vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 6, characterized in that: The application steps include: (1) dispersing the catalyst and XC-72 powder in a mixed solution of nafion and ethanol; (2) dropping the catalyst solution onto the glassy carbon electrode to obtain a working electrode; (3) Graphite rod and standard hydrogen electrode were used as working electrode and reference electrode respectively in 1 M KOH electrolyte.

8. The use of a vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 7, characterized in that: The mass ratio of the catalyst to XC-72 is 3:

1.

9. The use of a vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 7, characterized in that: The mass concentration of the nafion is 5 wt.%.

10. The use of a vacancy zirconium oxide supported nano-ruthenium catalyst according to claim 7, characterized in that: The volume ratio of the nafion to ethanol is 1:10, and the mass volume ratio of the catalyst to the nafion is 1:10.

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