Dimethylamine modified tetranuclear hetero-metal cluster compound as well as preparation method and application thereof

Abstract

The invention discloses a dimethylamine modified tetranuclear hetero-metal cluster compound as well as a preparation method and application thereof, belongs to the field of electrocatalytic oxygen evolution, and relates to a compound as well as a preparation method and application thereof. The invention aims to solve the problem of hydrogen energy shortage. The molecular formula of the dimethylamine modified tetranuclear hetero-metal cluster compound is [(CH3) 2NH2] [Ni (H2O) 6] [{NaNiSbW (OH) 4 (H2O) 6} {SbW8O30}]. 2H2O, and the molecular weight of the dimethylamine modified tetranuclear hetero-metal cluster compound is 2861.62. The method is used for alkaline electro-catalysis oxygen production. The preparation method comprises the following steps: preparing a Na9 [SbW9O33] precursor; the preparation method comprises the following steps: dissolving a Na9 [SbW9O33] precursor in deionized water, adding nickel nitrate, stirring, adding terephthalic acid, stirring, dropwise adding a NaOH solution, reacting for 2 hours, cooling, filtering, adding dimethylamine hydrochloride, evaporating and crystallizing at room temperature, and obtaining a hexagonal yellow crystal after three days. The overpotential of the dimethylamine modified tetranuclear hetero-metal cluster compound disclosed by the invention can reach 39.7 mV. The slope of Tafel is 19.75 mV / dec. And the slope of the fitted straight line is 4.51 mF / cm < 2 >. And the electrochemical transfer resistance is 1.9 ohm.

Description

Technical Field

[0001] The invention is used in the field of electrocatalytic oxygen evolution and relates to a compound, a preparation method and an application thereof. Background Art

[0002] With the deterioration of the environment and the depletion of carbon-based fuels, it has become increasingly urgent to explore an environmentally friendly energy source to replace traditional fuels. Hydrogen is considered to be an alternative to fossil fuels due to its high energy density, renewable nature, and environmental friendliness. Water electrolysis has attracted much attention for its stable output, high energy conversion efficiency, and high product purity. Water electrolysis is divided into two half reactions, namely hydrogen evolution reaction and oxygen evolution reaction, of which the oxygen evolution reaction is the anode reaction in water decomposition. However, the oxygen evolution reaction (OER) is a multi-electron and multi-proton reaction process with slow kinetics and usually requires a high overpotential to proceed. Although considerable efforts have been made, the cyclic stability and poor electronic conductivity of these catalysts still hinder their practical application in the future hydrogen economy. Therefore, the need to develop catalysts with excellent and stable OER catalytic performance is imminent. Summary of the invention

[0003] The purpose of the present invention is to solve the problem of hydrogen energy shortage, and provides a dimethylamine-modified tetranuclear heterometallic cluster compound, and a preparation method and application thereof.

[0004] The molecular formula of the tetranuclear heterometallic cluster compound modified by dimethylamine is [(CH3)2NH2][Ni(H2O)6][{NaNiSbW(OH)4(H2O)6}{SbW8O 30}]·2H2O, molecular weight is 2861.62.

[0005] The preparation method of the dimethylamine-modified tetranuclear heterometallic cluster compound is as follows:

[0006] 1. Na9[SbW9O 33 ]Precursor preparation: 40.0 g of sodium tungstate was dissolved in 80 mL of deionized water, stirred and heated to 90°C to obtain solution A;

[0007] Dissolve 1.96 g of antimony oxide in 13 mL of hydrochloric acid to obtain solution B;

[0008] After solution A was heated to 90°C, solution B was added to solution A and reacted for 1 hour. After the solution was cooled, it was filtered to obtain a clear and transparent solution. After seven days, transparent crystals were obtained, namely Na9[SbW9O 33 ]precursor;

[0009] 2. Na9[SbW9O 33 ] precursor was dissolved in deionized water, {NaSbW9O 33The mass ratio of the precursor to deionized water is 0.68-0.69 g: 20-40 mL. Add 0.29-0.3 g of nickel nitrate and stir for 15 minutes. Add 0.11-0.12 g of terephthalic acid and stir for 10 minutes. Then, add 1 mol / L NaOH solution until the terephthalic acid is completely dissolved. The process lasts for 30 minutes. React for 2 hours at a pH of 6-7 and a temperature of 85-95°C. After cooling, filter and add 0.25 g of dimethylamine hydrochloride. Evaporate and crystallize at room temperature. Hexagonal yellow crystals appear after three days to obtain a dimethylamine-modified tetranuclear heterometallic cluster compound.

[0010] The dimethylamine-modified tetranuclear heterometallic cluster compound is used for alkaline electrocatalytic oxygen production.

[0011] The tetranuclear heterometallic cluster compound modified by dimethylamine is mainly composed of {B-β-SbW8}, a unique tetranuclear heterometallic unit {NaNiSbW(OH)4(H2O)6}, and free (CH3)2NH2 and Ni(H2O)6. The unique tetranuclear heterometallic unit is composed of sodium, nickel, antimony, and tungsten metal ions, and the sandwich position is a parallelogram structure formed by two symmetrical tetranuclear heterometallics. The two polymerized anions {SbW8O 30} 9- The β-type sandwich structure is formed by connecting Sb(1), W(1) and Ni(2) in the tetranuclear heterometallic unit. Among them, Sb(2) in the polyacid anion {B-β-SbW8} is connected to the surrounding oxygen atoms to form a tetrahedral structure, which is further surrounded by eight WO6 octahedra. Each structural unit is connected by Na(1) to form a one-dimensional chain structure. The one-dimensional chain structure forms a two-dimensional planar structure through hydrogen bond supramolecular action. The planes are connected by hydrogen bonds between Ni(1) and {B-β-SbW8}.

[0012] The overpotential of the dimethylamine-modified tetranuclear heterometallic cluster compound of the present invention can reach 39.7 mV. The Tafel slope is 19.75 mV / dec. The slope of the fitted straight line is 4.51 mF / cm 2 The electrochemical transfer resistance is 1.9Ω. The curve remains constant over a period of 15 hours, indicating that the electrocatalytic oxygen evolution material of the present invention has significant stability under alkaline conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the monomer structure diagram of the tetranuclear heterometallic cluster compound modified by dimethylamine in Experiment 1;

[0014] Figure 2 Polyhedral diagram of the tetranuclear heterometallic cluster compound modified with dimethylamine in Experiment 1;

[0015] Figure 3The one-dimensional structure of the tetranuclear heterometallic cluster compound modified by dimethylamine in Experiment 1;

[0016] Figure 4 The two-dimensional structure of the tetranuclear heterometallic cluster compound modified by dimethylamine in Experiment 1;

[0017] Figure 5 The three-dimensional structure of the tetranuclear heterometallic cluster compound modified by dimethylamine in Experiment 1;

[0018] Figure 6 Infrared spectrum of tetranuclear heterometallic cluster compound modified by dimethylamine in experiment 1;

[0019] Figure 7 UV-visible absorption spectrum of tetranuclear heterometallic cluster compound modified by dimethylamine in experiment 1;

[0020] Figure 8 Linear sweep voltammetry (LSV) test diagram of tetranuclear heterometallic cluster compounds modified with dimethylamine in experiment 1;

[0021] Fig. 9 Tafel slope (Tafel) curve of tetranuclear heterometallic cluster compound modified by dimethylamine in experiment 1;

[0022] Fig.10 Cyclic voltammetry curves of tetranuclear heterometallic cluster compounds modified with dimethylamine in experiment 1;

[0023] Fig.11 Electrochemical impedance spectroscopy (EIS) spectrum of tetranuclear heterometallic cluster compounds modified with dimethylamine in experiment 1;

[0024] Fig.12 The current-time curve of the 15-hour electrolysis of the tetranuclear heterometallic cluster compound modified with dimethylamine in Experiment 1. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0026] Specific embodiment 1: The molecular formula of the tetranuclear heterometallic cluster compound modified by dimethylamine in this embodiment is [(CH3)2NH2][Ni(H2O)6][{NaNiSbW(OH)4(H2O)6}{SbW8O 30}]·2H2O, molecular weight is 2861.62.

[0027] Specific embodiment 2: Specific embodiment 1 The preparation method of the dimethylamine modified tetranuclear heterometallic cluster compound is as follows:

[0028] 1. Na9[SbW9O 33]Precursor preparation: 40.0 g of sodium tungstate was dissolved in 80 mL of deionized water, stirred and heated to 90°C to obtain solution A;

[0029] Dissolve 1.96 g of antimony oxide in 13 mL of hydrochloric acid to obtain solution B;

[0030] After solution A was heated to 90°C, solution B was added to solution A and reacted for 1 hour. After the solution was cooled, it was filtered to obtain a clear and transparent solution. After seven days, transparent crystals were obtained, namely Na9[SbW9O 33 ]precursor;

[0031] 2. Na9[SbW9O 33 ] precursor was dissolved in deionized water, {NaSbW9O 33 The mass ratio of the precursor to deionized water is 0.68-0.69 g: 20-40 mL. Add 0.29-0.3 g of nickel nitrate and stir for 15 minutes. Add 0.11-0.12 g of terephthalic acid and stir for 10 minutes. Then, add 1 mol / L NaOH solution until the terephthalic acid is completely dissolved. The process lasts for 30 minutes. React for 2 hours at a pH of 6-7 and a temperature of 85-95°C. After cooling, filter and add 0.25 g of dimethylamine hydrochloride. Evaporate and crystallize at room temperature. Hexagonal yellow crystals appear after three days to obtain a dimethylamine-modified tetranuclear heterometallic cluster compound.

[0032] Specific implementation method three: This implementation method is different from the specific implementation method two in that {NaSbW9O 33 The mass ratio of the precursor to the volume of deionized water is 0.6888 g:40 mL. The rest is the same as the second embodiment.

[0033] Specific embodiment 4: This embodiment is different from specific embodiments 2 to 3 in that the amount of nickel nitrate added in step 2 is 0.2928 g, and the amount of terephthalic acid added is 0.1166 g. The rest is the same as specific embodiments 2 to 3.

[0034] Specific embodiment 5: This embodiment is different from specific embodiments 2 to 4 in that in step 2, the pH value is kept at 6.4 and the temperature is heated to 90° C. The rest is the same as specific embodiments 2 to 4.

[0035] Specific embodiment 6: The tetranuclear heterometallic cluster compound modified with dimethylamine described in this embodiment and in any one of specific embodiments 1 to 4 is used for alkaline electrocatalytic oxygen production.

[0036] The following experiments were used to verify the effect of the present invention:

[0037] Experiment 1:

[0038] The preparation method of the tetranuclear heterometallic cluster compound modified by dimethylamine is as follows:

[0039] 1. Na9[SbW9O 33 ]Precursor preparation: 40.0 g of sodium tungstate was dissolved in 80 mL of deionized water, stirred and heated to 90°C to obtain solution A;

[0040] Dissolve 1.96 g of antimony oxide in 13 mL of hydrochloric acid to obtain solution B;

[0041] After solution A was heated to 90°C, solution B was added to solution A and reacted for 1 hour. After the solution was cooled, it was filtered to obtain a clear and transparent solution. After seven days, transparent crystals were obtained, namely Na9[SbW9O 33 ]precursor;

[0042] 2. Na9[SbW9O 33 ] precursor was dissolved in deionized water, {NaSbW9O 33 The mass ratio of the precursor to the volume of deionized water is 0.68-0.69 g: 20-40 mL. Add 0.2928 g of nickel nitrate and stir for 15 minutes. Add 0.1166 g of terephthalic acid and stir for 10 minutes. Then, add 1 mol / L NaOH solution until the terephthalic acid is completely dissolved. The process lasts for 30 minutes. At a pH of 6.4 and a temperature of 90°C, react for 2 hours. After cooling, filter and add 0.25 g of dimethylamine hydrochloride. Evaporate and crystallize at room temperature. Hexagonal yellow crystals appear after three days to obtain a dimethylamine-modified tetranuclear heterometallic cluster compound.

[0043] The compound is mainly composed of {B-β-SbW8}, a unique tetranuclear heterometallic unit {NaNiSbW(OH)4(H2O)6}, and free (CH3)2NH2 and Ni(H2O)6. The unique tetranuclear heterometallic unit is composed of sodium, nickel, antimony, and tungsten metal ions, and the sandwich position is a parallelogram structure formed by two symmetrical tetranuclear heterometallics. The two polymerized anions {SbW8O 30} 9- The β-type sandwich structure is formed by connecting Sb(1), W(1) and Ni(2) in the tetranuclear heterometallic unit. Among them, Sb(2) in the polyacid anion {B-β-SbW8} is connected to the surrounding oxygen atoms to form a tetrahedral structure, which is further surrounded by eight WO6 octahedra. Each structural unit is connected by Na(1) to form a one-dimensional chain structure. The one-dimensional chain structure forms a two-dimensional planar structure through hydrogen bonding. The planes are connected by hydrogen bonds between Ni(1) and {B-β-SbW8}.

[0044] The electrochemical performance of the prepared dimethylamine-modified tetranuclear heterometallic cluster catalytic oxygen evolution material was tested:

[0045] Electrode fabrication:

[0046] Grind the sample with carbon black at a mass ratio of 2:1 for 30 minutes, weigh 0.005g of the ground sample in a centrifuge tube, add 150μL of anhydrous ethanol and 50μL of deionized water, and ultrasonicate for 30 minutes. Spread the obtained slurry evenly on a 1*1cm 2 After drying at room temperature, evenly apply a thin film on the carbon cloth, and then test the electrocatalytic performance after drying.

[0047] 1. Overpotential test of electrocatalytic oxygen evolution materials

[0048] The oxygen evolution linear sweep voltammetry (LSV) curve of the tetranuclear heterometallic cluster compound modified by dimethylamine of the present invention is as follows: Figure 8 The electrochemical oxygen production activity of the electrode in alkaline solution was studied using a standard three-electrode electrochemical device (0.5 mol / L KOH solution), with a standard mercury electrode as the reference electrode, a platinum electrode as the negative electrode, and a working electrode as the positive electrode.

[0049] The electrolyte is 0.5 mol / L KOH solution, the voltage test range is 0-0.65 V, and the scanning speed is 0.005 V / s. There is an initial oxidation peak at 16 mV, which can be attributed to the oxidation peak of Ni. The overpotential of the oxygen evolution material is 39.7 mV.

[0050] 2. Tafel slope test of electrocatalytic oxygen evolution materials

[0051] The Tafel slope curve of the tetranuclear heterometallic cluster compound modified by dimethylamine of the present invention is as follows: Fig. 9 The polarization curves were performed at a scan rate of 5 mV / s. The Tafel slope obtained from the kinetic analysis of OER was 19.75 mV / dec.

[0052] 3. Test of electrochemical active surface area of ​​electrocatalytic oxygen evolution materials

[0053] The cyclic voltammetry curve of the tetranuclear heterometallic cluster compound modified by dimethylamine of the present invention is as follows: Fig.10 (a) is shown. The test conditions are as follows: the electrolyte solution is 0.5 mol / L KOH solution, and the scan rate is 10-80 mV / s. It can be seen from the figure that the test curves at different scan rates are all parallelograms, and there is not much change with the increase of the scan rate. Fig.10 (b) is the Δj / 2 (Δj=j a -j c ) is a linear fit of the scan rate at a potential of 0.1 V, where J a is the anode current density, j cis the cathode current density. The slope of the fitted straight line is 4.51mF / cm 2 .

[0054] 4. Impedance of electrocatalytic oxygen evolution materials

[0055] The impedance spectroscopy (EIS) spectrum of the tetranuclear heterometallic cluster compound modified by dimethylamine of the present invention is as follows: Fig.11 As shown, the electrochemical transfer resistance of the electrode material can be obtained to be 1.9Ω.

[0056] 5. Electrochemical stability test of electrocatalytic oxygen evolution materials

[0057] The current-time curve of the 15-hour electrolysis of the tetranuclear heterometallic cluster compound modified by dimethylamine of the present invention is as follows: Fig.12 As shown, under given working conditions (E=0.83V, 0.5mol / L KOH solution), using the chronoamperometry, the curve remained constant over a period of 15 hours, highlighting the remarkable stability of the electrocatalytic oxygen evolution material of the present invention under alkaline conditions.

[0058] The crystallographic data of the tetranuclear heterometallic cluster compound modified by dimethylamine described in this experiment are shown in Table 1:

[0059] Table 1 Crystallographic parameters

[0060]

[0061]

[0062] The partial bond length table of the tetranuclear heterometallic cluster compound modified by dimethylamine described in this experiment is shown in Table 2:

[0063] Table 2 Key length table

[0064]

[0065]

[0066] The bond angle table of the tetranuclear heterometallic cluster compound modified by dimethylamine described in this experiment is shown in Table 3:

[0067] Table 3 Bond angle table

[0068]

[0069]

[0070]

[0071] The hydrogen bond table of the dimethylamine-modified tetranuclear heterometallic cluster compound described in this experiment is shown in Table 4:

[0072] Table 4

[0073]

[0074]

[0075] The infrared absorption spectrum of the tetranuclear heterometallic cluster compound modified by dimethylamine in this experiment is shown in Figure 6 As shown. Figure 6 It can be seen that 3227.771cm -1 and 1627.626cm -1 The peak at 3130.61cm is attributed to the HO vibration absorption peak in water molecules. -1 and 1412.12cm -1 The peaks at 1020.641, 932.8958, 863.471, 679.7845cm are attributed to the vibration absorption peaks of dimethylamine NH and CN. -1 The peaks at υ(W=Ot) and υ(WO b -W)、υ(WO c -W) and υ(Sb-O) vibration absorption peaks.

[0076] The UV-visible absorption spectra of the tetranuclear heterometallic cluster compound modified by dimethylamine in this experiment vary with illumination time. Figure 7 As shown. Figure 7 It can be observed that with the increase of illumination time, a new broad absorption band is observed starting from 454nm, and its absorption intensity is strongest near 410nm.

Claims

1. A tetranuclear heterometallic cluster compound modified with dimethylamine, characterized in that The molecular formula of the tetranuclear heterometallic cluster compound modified by dimethylamine is [(CH3)2NH2][Ni(H2O)6][{NaNiSbW(OH)4(H2O)6}{SbW8O 30 }]·2H2O, molecular weight is 2861.

62.

2. The method for preparing the tetranuclear heterometallic cluster compound modified by dimethylamine according to claim 1, characterized in that The preparation method of the dimethylamine-modified tetranuclear heterometallic cluster compound is as follows:

1. Na9[SbW9O 33 ]Precursor preparation: 40.0 g of sodium tungstate was dissolved in 80 mL of deionized water, stirred and heated to 90°C to obtain solution A; Dissolve 1.96 g of antimony oxide in 13 mL of hydrochloric acid to obtain solution B; After solution A was heated to 90°C, solution B was added to solution A and reacted for 1 hour. After the solution was cooled, it was filtered to obtain a clear and transparent solution. After seven days, transparent crystals were obtained, namely Na9[SbW9O 33 ]precursor; 2. Na9[SbW9O 33 ] precursor was dissolved in deionized water, {NaSbW9O 33 The mass ratio of the precursor to deionized water is 0.68-0.69 g: 20-40 mL. Add 0.29-0.3 g of nickel nitrate and stir for 15 minutes. Add 0.11-0.12 g of terephthalic acid and stir for 10 minutes. Then, add 1 mol / L NaOH solution until the terephthalic acid is completely dissolved. The process lasts for 30 minutes. React for 2 hours at a pH of 6-7 and a temperature of 85-95°C. After cooling, filter and add 0.25 g of dimethylamine hydrochloride. Evaporate and crystallize at room temperature. Hexagonal yellow crystals appear after three days to obtain a dimethylamine-modified tetranuclear heterometallic cluster compound.

3. The method for preparing the tetranuclear heterometallic cluster compound modified by dimethylamine according to claim 2, characterized in that In step 2 33 The mass ratio of the precursor to the volume of deionized water is 0.6888 g:40 mL.

4. The method for preparing the tetranuclear heterometallic cluster compound modified by dimethylamine according to claim 2, characterized in that In step 2, the amount of nickel nitrate added is 0.2928 g, and the amount of terephthalic acid added is 0.1166 g.

5. The method for preparing the tetranuclear heterometallic cluster compound modified by dimethylamine according to claim 2, characterized in that In step 2, the pH value is maintained at 6.4 and heated to 90°C.

6. The use of the tetranuclear heterometallic cluster compound modified by dimethylamine according to claim 1, characterized in that The dimethylamine-modified tetranuclear heterometallic cluster compound is used for alkaline electrocatalytic oxygen production.

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