A kind of preparation method of palladium hydride

Abstract

The invention discloses a preparation method of palladium hydride, comprising the following steps: using metal palladium as a precursor, carrying out a hydrothermal reaction with an alcohol compound, the reaction temperature being 100-200 DEG C, the reaction time being 0.5-12 hours, and washing and drying after the reaction to obtain palladium hydride; the method uses alcohol as a hydrogenating agent, which is low in price, easy to obtain, environmentally friendly, non-toxic and pollution-free compared with traditional hydrogenating agents; the palladium hydride is prepared by a one-step hydrothermal method, the process is simple and easy to operate, and the method is convenient for operation.

Description

Technical Field

[0001] The invention relates to a method for preparing a metal hydride, in particular to a method for preparing a palladium hydride. Background Art

[0002] Pd hydride refers to metal Pd containing a large number of H atoms in the lattice, and is an alloy of Pd and metal H. Pd-based catalysts are potential substitutes for Pt-based catalysts; in the regulation of the structure and composition of Pd-based catalysts, it is found that palladium hydride is a very good active substance for electrocatalytic reactions. Literature research shows that: (1) H can evenly penetrate into the metal lattice, and because of its small atomic size, the Pd lattice expands; (2) Depending on the difference in electronegativity, significant electron transfer occurs between the doped H atoms and the adjacent Pd atoms; (3) Different from the dd orbital hybridization in traditional Pd-based catalysts, the orbital hybridization mode in Pd non-metallic alloys is s, pd orbital hybridization between H elements and Pd atoms, which can effectively change the charge distribution of Pd atoms, improve the adsorption free energy of the catalytic site, and thus significantly change the electrocatalytic performance of traditional Pd-based catalysts.

[0003] The reported methods for preparing Pd hydrides are relatively limited. Usually, Pd-based nanocatalysts are directly exposed to H under certain conditions. 2 atmosphere. Commonly used H sources include H 2 Gas, DMF, NaBH 4 、N 2 H 4 , HCHO, CH 3 CHO, and -NH 2 Base molecules (such as oleylamine and n-butylamine), etc. However, the operation process is complicated, the raw materials are expensive, and some raw materials are even not environmentally friendly. Summary of the invention

[0004] Purpose of the invention: The present invention aims to provide a method for preparing palladium hydride which is simple in process, low in price, environmentally friendly and non-toxic.

[0005] Technical solution: The method for preparing palladium hydride of the present invention comprises the following steps: using metal palladium as a precursor, carrying out a hydrothermal reaction with an alcohol compound, the reaction temperature is 100-200° C., and the reaction time is 0.5-12 hours; after the reaction, washing and drying are performed to obtain palladium hydride.

[0006] Alcohol compounds are both hydrogenating agents and solvents. Alcohol compounds decompose on the surface of palladium catalysts to produce H 2 , H 2 Adsorbing and dissociating on the palladium surface, H atoms penetrate the palladium surface and dissolve in the interstitial positions of the palladium lattice to form palladium hydride.

[0007] Preferably, the alcohol compound is methanol, ethanol, propanol, n-butanol, n-octanol or isobutanol. Preferably, the ratio of the metal palladium to the alcohol compound is (0.01-100) mg: (1-100) mL.

[0008] Preferably, the palladium metal is palladium nanodendrites. The preparation method of palladium nanodendrites is simple, and they can be prepared in large quantities, with a particle size of less than 5 nm and abundant reactive active sites.

[0009] The preparation method of the palladium nanodendrites comprises the following steps: taking 0.5 ml of 0.5 M palladium acetate acetic acid solution, adding 3 ml of water, mixing well, placing in a 60 degree water bath for 5 minutes, adding 0.5 ml of newly prepared 0.5 M 1-naphthol solution, mixing well, and standing at a constant temperature for 2 hours; after the reaction is completed, centrifuging the black product, washing with ethanol three times, and vacuum drying at room temperature for 6 hours to obtain palladium nanodendrites.

[0010] If the reaction temperature is too low, hydrogenation cannot be achieved. The higher the reaction temperature, the shorter the time required to reach the maximum degree of hydrogenation. Preferably, the reaction temperature is 160-200°C and the reaction time is 6-12 hours.

[0011] Preferably, the drying temperature is 20-25° C. The drying temperature should not be too high, otherwise the precious metals are prone to agglomeration.

[0012] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The present method uses alcohols as hydrogenating agents, which are inexpensive, easily available, environmentally friendly, non-toxic and pollution-free compared to traditional hydrogenating agents. Palladium hydride is prepared by a one-step hydrothermal method, and the process is simple and easy to operate; (2) The palladium hydride prepared by the present method using palladium nanodendrites can maintain the morphology of the Pd nanodendrite precursor; (3) The electrocatalytic activity of palladium hydride in the acidic hydrogen evolution reaction is significantly improved compared to before hydrogenation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 HRTEM images of the palladium hydride and palladium nanodendrites prepared in Example 2;

[0014] Figure 2 The XPS graph of the palladium hydride and palladium nanodendrites prepared in Example 2;

[0015] Figure 3 XRD patterns of palladium hydrides prepared with different alcohol molecules as hydrogenating agents;

[0016] Figure 4 The palladium hydride and palladium nanodendrites prepared in Example 2 were heated to 0.5 MH 2 SO 4 Comparison of electrocatalytic activity of hydrogen evolution reaction in solution. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below in conjunction with embodiments.

[0018] Example 1

[0019] The preparation method of palladium hydride of the present invention comprises the following steps:

[0020] Take 5 mg of palladium nanodendrites, add them to 15 mL of methanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200 ° C, and maintain it for 12 hours. After the reaction is completed, the black product is centrifuged, washed with ethanol three times, and vacuum dried at room temperature for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0021] The preparation method of the palladium nanodendrites comprises the following steps: taking 0.5 ml of 0.5 M palladium acetate acetic acid solution, adding 3 ml of water, mixing thoroughly, placing in a 60 degree water bath for 5 minutes, adding 0.5 ml of newly prepared 0.5 M 1-naphthol solution, mixing evenly, and standing at a constant temperature for 2 hours; after the reaction is completed, centrifuging the black product, washing with ethanol three times, and vacuum drying at 25° C. for 6 hours to obtain palladium nanodendrites.

[0022] The preparation method of palladium nanocrystals used in the following examples is the same as that in Example 1.

[0023] Example 2

[0024] The preparation method of palladium hydride of the present invention comprises the following steps:

[0025] Take 5 mg of palladium nanodendrites, add them to 15 mL of ethanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200°C, and maintain it for 12 hours. After the reaction is completed, centrifuge the black product, wash it three times with ethanol, and vacuum dry it at 25°C for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0026] The preparation method of palladium nanodendrites is the same as that in Example 1.

[0027] Example 3

[0028] The preparation method of palladium hydride of the present invention comprises the following steps:

[0029] Take 5 mg of palladium nanodendrites, add them to 15 mL of n-propanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200°C, and maintain it for 12 hours. After the reaction is completed, centrifuge the black product, wash it three times with ethanol, and vacuum dry it at 25°C for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0030] The preparation method of palladium nanodendrites is the same as that in Example 1.

[0031] Example 4

[0032] The preparation method of palladium hydride of the present invention comprises the following steps:

[0033] Take 5 mg of palladium nanodendrites, add them to 15 mL of n-butanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200 ° C, and maintain it for 12 hours. After the reaction is completed, the black product is centrifuged, washed with ethanol three times, and vacuum dried at room temperature for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0034] The preparation method of palladium nanodendrites is the same as that in Example 1.

[0035] Example 5

[0036] The preparation method of palladium hydride of the present invention comprises the following steps:

[0037] Take 5 mg of palladium nanodendrites, add them to 15 mL of n-octanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200°C, and maintain it for 12 hours. After the reaction is completed, centrifuge the black product, wash it three times with ethanol, and dry it in vacuum at 25°C for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0038] Example 6

[0039] The preparation method of palladium hydride of the present invention comprises the following steps:

[0040] Take 5 mg of palladium nanodendrites, add them to 15 mL of isobutanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200°C, and maintain it for 12 hours. After the reaction is completed, centrifuge the black product, wash it three times with ethanol, and dry it in vacuum at 25°C for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0041] Example 7

[0042] The preparation method of palladium hydride of the present invention comprises the following steps:

[0043] Take 0.01 mg of palladium nanodendrites, add them to 1 mL of ethanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200°C, and maintain it for 12 hours. After the reaction is completed, centrifuge the black product, wash it three times with ethanol, and dry it in vacuum at 20°C for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0044] Example 8

[0045] The preparation method of palladium hydride of the present invention comprises the following steps:

[0046] Take 100 mg of palladium nanodendrites, add them to 100 mL of ethanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200 ° C, and maintain it for 12 hours. After the reaction is completed, the black product is centrifuged, washed with ethanol three times, and vacuum dried at room temperature for 6 hours to obtain a Pd-based hydride nanocatalyst.

[0047] Example 9

[0048] The preparation method of palladium hydride of the present invention comprises the following steps:

[0049] Take 5 mg of palladium nanodendrites, add them to 15 mL of ethanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 100 ° C, and maintain it for 12 hours. After the reaction is completed, the black product is centrifuged, washed with ethanol three times, and vacuum dried at room temperature for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0050] Example 10

[0051] The preparation method of palladium hydride of the present invention comprises the following steps:

[0052] Take 5 mg of palladium nanodendrites, add them to 15 mL of ethanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 160°C, and maintain it for 12 hours. After the reaction is completed, centrifuge the black product, wash it with ethanol three times, and vacuum dry it at room temperature for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0053] Embodiment 11

[0054] The preparation method of palladium hydride of the present invention comprises the following steps:

[0055] Take 5 mg of palladium nanodendrites, add them to 15 mL of ethanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200 ° C, and maintain it for 0.5 h. After the reaction is completed, the black product is centrifuged, washed with ethanol three times, and vacuum dried at room temperature for 6 h to obtain the Pd-based hydride nanocatalyst.

[0056] Example 12

[0057] The preparation method of palladium hydride of the present invention comprises the following steps:

[0058] Take 5 mg of palladium nanodendrites, add them to 15 mL of ethanol, and mix them thoroughly by ultrasonication. Place the resulting reaction solution in a reactor, heat it to 200 ° C, and maintain it for 6 hours. After the reaction is completed, the black product is centrifuged, washed with ethanol three times, and vacuum dried at room temperature for 6 hours to obtain the Pd-based hydride nanocatalyst.

[0059] Structural characterization

[0060] The palladium hydride prepared in Example 2 and the corresponding precursor palladium nanodendrites were physically characterized and compared using HRTEM. Figure 1 As shown (Figures a and b are HRTEM images of palladium hydride, and Figures c and d are HRTEM images of palladium nanodendrites). Figure 1 By comparing a and c, we can see that the prepared palladium hydride can still maintain the morphology and structure of palladium nanodendrites well. Figure 1 Comparing b and d, it can be seen that the lattice fringe spacing of Pd hydride is 0.230nm, corresponding to the (111) crystal plane of palladium hydride. Compared with the lattice spacing of 0.223nm on the (111) crystal plane of Pd nanodendrite, the lattice has expanded significantly, proving the successful doping of H atoms.

[0061] XPS was used to compare the physical characterization of the palladium hydride prepared in Example 2 and the corresponding precursor palladium nanodendrites. Figure 3 As shown, by comparison, it can be found that after the palladium nanodendrites were doped with H to form hydrides, the valence band was significantly narrowed, which also proves the formation of hydrides.

[0062] XRD was used to characterize the palladium hydrides prepared by using different alcohol molecules as hydrogenating agents. Figure 3 As shown. It can be seen that the selected multiple types of alcohol molecules can all obtain Pd hydrides, proving the universality of preparing palladium hydrides through alcohol molecules.

[0063] Performance Characterization

[0064] The hydrogen evolution electrocatalytic activity of the palladium hydride prepared in Example 2 and the corresponding precursor palladium nanodendrites was tested. The test method was as follows: using a standard three-electrode system, a Shanghai Chenhua CHI 760e electrochemical analyzer was used at 25°C, a catalyst-modified glassy carbon electrode (d = 3 mm) was used as the working electrode, a graphite rod was used as the auxiliary electrode, and a saturated calomel reference electrode (SCE) was used as the reference electrode. 2 SO 4 The hydrogen evolution electrocatalytic activity of palladium hydride and palladium nanodendrites was tested in solution.

[0065] Test results such as Figure 4 As shown in the figure, it can be seen that the catalytic performance of palladium nanodendrites has been significantly improved after hydrogenation. -2 The overpotential of palladium hydride is 44mV, and the overpotential of palladium nanodendrites is 73mV, which is an increase of 29mV.

Claims

1. A method for preparing palladium hydride, It is characterized in that The following steps are involved: Using metal palladium as a precursor, mixing it with an alcohol compound, placing the obtained reaction solution in a reactor for reaction at a reaction temperature of 100-200°C and a reaction time of 0.5-12 hours; washing and drying after the reaction to obtain palladium hydride; the palladium metal is palladium nanodendrites; the alcohol compound is methanol, ethanol, propanol, n-butanol, n-octanol or isobutanol; The preparation method of the palladium nanodendrites comprises the following steps: taking 0.5 ml of 0.5 M palladium acetate acetic acid solution, adding 3 ml of water, mixing well, placing in a 60 degree water bath for 5 minutes, adding 0.5 ml of newly prepared 0.5 M 1-naphthol solution, mixing well, and standing at a constant temperature for 2 hours; after the reaction is completed, centrifuging the black product, washing with ethanol three times, and vacuum drying at room temperature for 6 hours to obtain palladium nanodendrites.

2. The method for preparing palladium hydride according to claim 1, It is characterized in that The ratio of the metal palladium to the alcohol compound is (0.01-100) mg: (1-100) mL.

3. The method for preparing palladium hydride according to claim 1, It is characterized in that The reaction temperature is 160-200° C., and the reaction time is 6-12 hours.

4. The method for preparing palladium hydride according to claim 1, It is characterized in that The drying temperature is 20-25°C.

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