A general multi-metal nanocatalyst for liquid fuel cells

Abstract

The present invention discloses a general multi-metal nanocatalyst for liquid fuel cells. For the first time, Pt-based quaternary alloy nanosheets with a thickness of about 4.9 nm and a diameter greater than 700 nm are synthesized. By testing the X-ray diffraction spectrum, its crystal configuration is obtained as face-centered cubic. The hydrazine hydrate oxidation performance of the PtAgBiTe alloy nanosheets is superior to that of commercial platinum supported on carbon, and the mass activities in the oxidation of formic acid / methanol / ethanol / ethylene glycol / glycerol reach 7.29 / 7.97 / 11.92 / 16.9 / 15.35 Amg ‑1 , respectively, all higher than those of commercial platinum supported on carbon under the same conditions, and are 16.95 / 6.04 / 7.18 / 4.57 / 9.19 times that of the commercial standard, respectively. In the stability test, the activity decay of the PtAgBiTe alloy nanosheets is slow, while that of commercial platinum supported on carbon is obvious.

Description

Technical Field

[0001] The present invention relates to a general multi-metal nano-catalyst for liquid fuel cells. Background Art

[0002] Fuel cells are effective power generation devices for solving environmental pollution problems caused by overuse of fossil energy due to their green and efficient characteristics. Low-cost liquids have high volumetric energy density and are easier to store and transport than gaseous fuels. There are no carbon atoms in the liquid molecule hydrazine hydrate, and no carbon dioxide and other greenhouse gases are produced. Formic acid has low permeability, and high-concentration formic acid can be used to obtain high power density. Alcohols are widely available and can be easily extracted from biomass. The oxidation of the above liquid molecules involves multiple-step reactions, with a complex mechanism, and the oxidation of formic acid and alcohols is prone to poisoning. Also affected by the high price and insufficient activity of noble metal catalysts, the development of high-performance general Pt-based catalysts for liquid fuel cells is the current research focus. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a visible light-assisted template method for synthesizing PtAgBiTe quaternary nanosheets. This catalyst synthesis method is green and simple, with a curly sheet-like morphology, a thickness of about 4.9 nm, and a diameter greater than 700 nm. The PtAgBiTe quaternary nanosheets, as the anode of an actual liquid fuel cell, have excellent catalytic performance and stability.

[0004] The technical solution of the present invention is: a general multi-metal nano-catalyst for liquid fuel cells, and the catalyst is an ultra-thin quaternary PtAgBiTe nanosheet.

[0005] The PtAgBiTe nanosheet is an irregular nanosheet, with a thickness of about 4.9 nm and a diameter greater than 700 nm.

[0006] A general multi-metal nano-catalyst for liquid fuel cells comprises the following steps:

[0007] (1) Synthesize Bi2Te3 nanosheets and disperse them in ethanol; (2) Take the solution obtained in step (1) in a petri dish, add 5 - 15 mL of ethylene glycol, and stir at room temperature for 10 min; (3) Add potassium tetrachloroplatinate and silver nitrate to the mixed solution in step (2), stir at room temperature for 15 min, place it in a dark room, and irradiate it with a 40 W table lamp for 1 - 4 hours; (4) Centrifuge and separate the product obtained in step (3) to obtain ultra-thin quaternary PtAgBiTe nanosheets, and store the sample in ethanol.

[0008] The total amount of the platinum salt and silver salt used is 0.01 mmol, and the amount of Bi2Te3 nanosheets is 0.005 mmol. The molar ratio of Pt:Ag:Bi:Te is 9:1:8:10 - 1:9:8:10.

[0009] Application of the described ultrathin quaternary PtAgBiTe nanosheets in an actual liquid fuel cell.

[0010] Beneficial effects of the present invention: By using a visible light-assisted method and taking Bi2Te3 nanosheets as a template, large-sized ultrathin alloy Pt-based quaternary nanosheets are synthesized for the first time, with a thickness of about 4.9 nm and a lateral size greater than 700 nm. X-ray diffraction spectra show that the diffraction peaks of PtAgBiTe match well with the typical peaks of face-centered cubic, and its crystal configuration is face-centered cubic phase. The hydrazine oxidation performance of the PtAgBiTe alloy nanosheets is superior to that of commercial platinum supported on carbon, and the mass activities in the oxidation of formic acid / methanol / ethanol / ethylene glycol / glycerol reach 7.29 / 7.97 / 11.92 / 16.9 / 15.35 Amg -1 respectively, all higher than those of commercial platinum supported on carbon under the same conditions, and are 16.95 / 6.04 / 7.18 / 4.57 / 9.19 times that of the commercial standard respectively. In the stability test, the activity decay of the ultrathin quaternary PtAgBiTe nanosheets is slower, while that of commercial platinum supported on carbon decays significantly. The power density of the ultrathin quaternary PtAgBiTe nanosheets in an actual hydrazine fuel cell is 532.9 mW cm -2 which is 1.35 times that of commercial platinum supported on carbon. The ultrathin quaternary PtAgBiTe nanosheets are a multifunctional catalyst superior to those reported in current literature.

[0011] The ultrathin quaternary PtAgBiTe nanosheets synthesized by this method have a special morphology and a novel structure, with excellent catalytic performance and good stability in actual liquid fuel cells, and have the possibility of replacing the current commercial platinum supported on carbon catalyst. Description of the Drawings

[0012] Figure 1 Figures showing the scanning electron microscope and atomic force microscope observation results of the ultrathin quaternary PtAgBiTe nanosheets;

[0013] Figure 2 Figure showing the X-ray diffraction results of the ultrathin quaternary PtAgBiTe nanosheets;

[0014] Figure 3 Figure showing the comparison of the catalytic performance and stability of the ultrathin quaternary PtAgBiTe nanosheets and commercial platinum supported on carbon in hydrazine oxidation, formic acid oxidation and methanol oxidation;

[0015] Figure 4Power density comparison diagram of ultrathin quaternary PtAgBiTe nanosheets and commercial platinum on carbon in a practical hydrazine fuel cell. Detailed implementation mode

[0016] Example 1:

[0017] (1) Synthesize Bi2Te3 nanosheet seeds and store them in ethanol;

[0018] (2) Take the solution obtained in step (1) in a petri dish, add 10 mL of ethylene glycol, and stir for 10 min;

[0019] (3) Add a total of 0.01 mmol of metals to the mixed solution in step (2), where potassium tetrachloroplatinate is 0.009 mmol and silver nitrate is 0.001 mmol. Stir at room temperature for 15 min and then irradiate with light for 2 hours;

[0020] (4) After cooling the product obtained in step (3), wash it with ethanol, and centrifuge to obtain ultrathin quaternary PtAgBiTe nanosheets. Disperse the sample and store it in ethanol.

[0021] Reverse Example 1

[0022] (1) Ultrasonically dissolve 160 mg of polyvinylpyrrolidone in 4 mL of ethylene glycol;

[0023] (2) Dissolve 0.018 mmol of potassium tetrachloroplatinate and 0.006 mmol of silver nitrate in 1 mL and 0.25 mL of deionized water respectively, and react at 210 °C for 4 h;

[0024] (3) After cooling at room temperature, we add 0.7 mL of concentrated ammonia water and 2 mL of NaBH4 aqueous solution (5.0 mg) for cleaning;

[0025] (4) After 1 hour, add acetone and water and wash twice.

[0026] It can be found by comparing with Reverse Example 1 that the ethanol oxidation mass activity of the PtAg binary nanowires in Reverse Example is 6.1 Amg -1 , which is lower than the activity of the ultrathin quaternary PtAgBiTe nanosheets in this experiment. The performance of oxidizing other liquid molecules was not tested, and the actual fuel cell was not tested either.

[0027] Reverse Example 2

[0028] (1) Take 8 mg of platinum acetylacetonate and 7.7 mg of bismuth acetate as metal precursors, add 250 mg of PVP, 1 mL of glacial acetic acid and 8 mL of N,N-dimethylformamide to a flask, and ultrasonically treat for 5 min to obtain a homogeneous solution;

[0029] (2) Heat from room temperature to 150 °C and hold for 4 hours;

[0030] (3) The obtained product was centrifuged and washed three times with ethanol.

[0031] It can be found by comparing with Comparative Example 2 that the mass activity of the PtBi binary nanoplates in the reverse example in formic acid and glycerol oxidation is 9.06 A mg -1 and 3.45 A mg -1 , and after the 3600 s stability test, only a lower current density is retained, which is less stable than the ultrathin quaternary PtAgBiTe nanosheets in this experiment, and the PtBi nanocrystals in the reverse example did not test the actual liquid fuel cell.

Claims

1. A general multi-metal nano-catalyst for liquid fuel cells, characterized in that: The catalyst described is ultrathin quaternary PtAgBiTe nanosheets; the PtAgBiTe nanosheets are irregular nanosheets with a thickness of 4.9 nm and a diameter greater than 700 nm; wherein the Pt content is 60%-80%, the Ag content is 5%-30%, the Bi content is within 25%, and the Te content is 10%-25%; the preparation method of the PtAgBiTe nanosheets includes the following steps: (1) Synthesize Bi2Te3 nanosheets and store them in ethanol; (2) Take the solution obtained in step (1) in a petri dish, add 5-15 mL of ethylene glycol, and stir at room temperature; (3) Add potassium tetrachloroplatinate and silver nitrate to the mixed solution in step (2), stir at room temperature and then place it in a dark room, and irradiate with table lamp for 1-4 hours; (4) Cool the product obtained in step (3), wash it, and obtain PtAgBiTe nanosheets after centrifugal separation, and disperse the sample and store it in ethanol.

2. The general multi-metal nano-catalyst for a liquid fuel cell according to claim 1, characterized in that: The total amount of potassium tetrachloroplatinate and silver nitrate used is 0.01 mmol, the Bi2Te3 nanosheets are 0.005 mmol, and the molar ratio of Pt:Ag:Bi:Te is 9:1:8:10 - 1:9:8:

10.

3. Application of the ultrathin quaternary PtAgBiTe nanosheets as described in any one of claims 1-2 as an anode catalyst in a practical liquid fuel cell.

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