Metal monatomic hydrogen evolution catalyst and preparation method thereof

Abstract

The invention belongs to the technical field of water electrolysis hydrogen production catalysts, and relates to a metal monatomic hydrogen evolution catalyst and a preparation method thereof.The catalyst comprises a large number of metal monatomic and a small number of metal clusters, metal is in an oxidation state in the catalyst, and crystalline PMA exists in the catalyst; c60 and PMA structures coexist in the catalyst; the preparation method comprises the following steps: respectively dissolving an acetylacetone metal complex, phosphomolybdic acid and fullerene in a toluene solution of a 4A type molecular sieve, respectively and sequentially mixing, magnetically stirring, washing and centrifuging to obtain the metal monatomic hydrogen evolution catalyst; the metal monatomic hydrogen evolution catalyst disclosed by the invention has excellent HER performance, a PMA-M-C60 catalyst with high loading capacity and high dispersion of metal monatomic bridging C60 and PMA is realized through a room-temperature synthesis strategy, and the catalysis cost is lower.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by water electrolysis catalysts, and particularly relates to a metal monatomic hydrogen evolution catalyst and a preparation method thereof. BACKGROUND

[0002] With the increasingly serious energy crisis and environmental pollution, it has become an inevitable trend to promote the development and utilization of renewable energy. Hydrogen energy, as a clean, recyclable and zero-pollution energy, is an ideal choice for green energy. Among many hydrogen production processes, water electrolysis technology has attracted much attention. This technology has many significant advantages: it does not rely on fossil fuels and does not produce harmful gases. The purity of the produced hydrogen can reach more than 99.7%, and the technology has high maturity and relatively simple process and equipment. At the same time, it has high tolerance to power fluctuations. Therefore, vigorously promoting the development of water electrolysis hydrogen production technology has important practical significance for the construction of China's green ecological energy system. In the field of water electrolysis hydrogen production, Pt / C catalyst currently occupies an important position. It has shown significant effects in improving the hydrogen evolution reaction rate and reducing the reaction overpotential, helping the water electrolysis hydrogen production reaction to proceed more efficiently.

[0003] However, as a noble metal, Pt is scarce in reserves and expensive in price, which makes the cost of the catalyst high, seriously hindering the large-scale and low-cost application of water electrolysis hydrogen production technology. With the increase of current density, the Pt loading needs to be increased to maintain the catalytic effect, which further increases the cost burden. The cost problem has become a key limiting factor for the further development of Pt / C catalyst in water electrolysis hydrogen production.

[0004] Therefore, there is a need for a low-cost water electrolysis catalyst to solve the above technical problems. SUMMARY

[0005] The application provides the following technical solution: a metal monatomic hydrogen evolution catalyst, which includes a large number of metal monatomic atoms and a small amount of metal clusters. The metal in the catalyst is in an oxidation state, and the metal includes gold, silver, platinum, palladium, rhodium, iridium, ruthenium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, tungsten, rhenium; the combination of "single atom + oxidation state" can produce unique catalytic activity and selectivity different from traditional metal nanoparticles. Crystalline PMA exists in the catalyst; C60 and PMA structures coexist in the catalyst.

[0006] Preferably, the molar ratio of metal atoms to PMA molecules in the catalyst is close to 1:1.

[0007] Preferably, when the metal in the catalyst is platinum, the overpotential of the catalyst at 10 mA cm -2 is less than 9 mV.

[0008] The application further discloses a preparation method of the metal single-atom hydrogen evolution catalyst. Step 1, dehydrating 4A molecular sieve; Step 2, dehydrating the 4A molecular sieve obtained in step 1 in toluene at a ratio of 1g per 90-110 mL for not less than 20 hours; Step 3, dissolving compound A, phosphomolybdic acid and fullerene in toluene obtained in step 2 at a molar ratio of 1:0.9-1.1:0.9-1.1 respectively, and mixing the suspension of acetylacetone metal complex and the suspension of phosphomolybdic acid to obtain suspension B; the compound A comprises acetylacetone metal complex, chloroplatinic acid, chloroauric acid, chloropalladic acid; Step 4, slowly adding the suspension B into the fullerene toluene solution obtained in step 3 drop by drop, continuously introducing nitrogen into the fullerene toluene solution during the adding process, and stirring the obtained mixture C by strong magnetic stirring; the strong stirring is used for inhibiting the aggregation of metal atoms; Step 5, continuously stirring the mixture C by magnetic stirring in a nitrogen atmosphere for not less than 70 hours; Step 6, washing the mixture C after the magnetic stirring in step 5 by toluene, centrifuging at least three times, and vacuum drying the precipitate to obtain the metal single-atom hydrogen evolution catalyst; the residual acetylacetone metal complex, phosphomolybdic acid and fullerene are removed by multiple washing.

[0009] Preferably, in step 1, the dehydrating method comprises the following steps: drying the 4A molecular sieve at 280-320 DEG C for 6-8 hours, and then cooling to room temperature under the protection of nitrogen.

[0010] Preferably, the acetylacetone metal complex comprises acetylacetone gold, acetylacetone silver, acetylacetone platinum, acetylacetone palladium, acetylacetone rhodium, acetylacetone iridium, acetylacetone ruthenium, acetylacetone titanium, acetylacetone vanadium, acetylacetone chromium, acetylacetone manganese, acetylacetone iron, acetylacetone cobalt, acetylacetone nickel, acetylacetone copper, acetylacetone zinc, acetylacetone zirconium, acetylacetone niobium, acetylacetone molybdenum, acetylacetone tungsten, acetylacetone rhenium.

[0011] Preferably, in step 6, the vacuum drying comprises drying at 55-65 DEG C for not less than 20 hours.

[0012] Preferably, in step 3, the molar ratio is 1:1:1.

[0013] The application has the following beneficial effects: 1. The PMA-Pt-C60 catalyst has excellent HER performance, 10 mA cm -2The overpotential is only 9 mV, which is 65% lower than that of the conventional 20 wt% Pt / C catalyst (26 mV), and it is also within 50 mA cm⁻¹. -2 100 mA cm -2 The HER performance of the materials is also superior to that of Pt / C electrode materials, and the cost is lower.

[0014] 2. The preparation method of the metal single-atom hydrogen evolution catalyst of the present invention realizes a PMA-M-C60 catalyst with high loading and high dispersion of metal single atoms bridging C60 and PMA through a room temperature synthesis strategy. Attached Figure Description

[0015] Figure 1 This invention relates to a metal single-atom hydrogen evolution catalyst and its preparation method, specifically PMA-Pt-C. 60 HAADF-STEM spectrum of the catalyst; Figure 2 The PMA-Pt-C of this invention 60 XRD pattern of the catalyst; Figure 3 The PMA-Pt-C of this invention 60 Raman spectrum of the catalyst; Figure 4 The PMA-Pt-C of this invention 60 Pt 4f XPS spectrum of the catalyst; Figure 5 The PMA-Pt-C of this invention 60 LSV curve of the catalyst; Figure 6 The PMA-Pt-C of this invention 60 Tafel slope curve of the catalyst. Detailed Implementation

[0016] The related technologies of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figures 1-6 As shown, this embodiment presents a metal single-atom hydrogen evolution catalyst and its preparation method. This catalyst exhibits uniform single-atom distribution and excellent hydrogen evolution performance in water electrolysis. The preparation method of the metal single-atom hydrogen evolution catalyst includes the following steps: Dry the 4A type molecular sieve at around 300℃ for 6-8 hours, and then cool it to room temperature under nitrogen protection before use.

[0018] 1 g of 4A molecular sieve was added to 100 mL of required toluene for dehydration treatment for 24 hours.

[0019] Acetylacetone metal complex, phosphomolybdic acid and fullerene with a molar ratio of 1:1:1 were dissolved in toluene respectively. The suspension of acetylacetone metal complex and phosphomolybdic acid was mixed uniformly for use.

[0020] The mixed suspension of acetylacetone metal complex and phosphomolybdic acid was slowly added drop by drop into the toluene solution of fullerene with a rubber head dropper. Nitrogen was continuously introduced under the surface of the toluene solution of fullerene, and a magnetic stirrer was used for vigorous stirring.

[0021] The mixed solution prepared in the step was continuously stirred with a magnetic stirrer for 72 hours in a nitrogen atmosphere.

[0022] The mixed solution after sufficient stirring was washed with toluene and centrifuged at least three times. The precipitate was vacuum dried in a vacuum drying oven at 60°C for 24 hours to obtain the metal single-atom hydrogen evolution catalyst.

[0023] The types of acetylacetone metal complex include acetylacetone gold, acetylacetone silver, acetylacetone platinum, acetylacetone palladium, acetylacetone rhodium, acetylacetone iridium, acetylacetone ruthenium, etc. noble metal complex, and acetylacetone titanium, acetylacetone vanadium, acetylacetone chromium, acetylacetone manganese, acetylacetone iron, acetylacetone cobalt, acetylacetone nickel, acetylacetone copper, acetylacetone zinc, acetylacetone zirconium, acetylacetone niobium, acetylacetone molybdenum, acetylacetone tungsten, acetylacetone rhenium, etc. transition metal complex. In addition, acetylacetone metal complex can be replaced by chloroplatinic acid, chloroauric acid, chloropalladic acid.

[0024] Example Example 1 4A molecular sieve was dried at about 300°C for 6-8 hours, and then cooled to room temperature under nitrogen protection for use. 1 g of 4A molecular sieve was added to 100 mL of required toluene for dehydration treatment for 24 hours. Acetylacetone platinum, phosphomolybdic acid and fullerene with a molar ratio of 1:1:1 were dissolved in toluene respectively. The suspension of acetylacetone platinum and phosphomolybdic acid was mixed uniformly for use. The mixed suspension of acetylacetone platinum and phosphomolybdic acid was slowly added drop by drop into the toluene solution of fullerene with a rubber head dropper. Nitrogen was continuously introduced under the surface of the toluene solution of fullerene, and a magnetic stirrer was used for vigorous stirring. The mixed solution prepared was continuously stirred with a magnetic stirrer for 72 hours in a nitrogen atmosphere. The mixed solution after sufficient stirring was washed with toluene and centrifuged at least three times. The precipitate was vacuum dried in a vacuum drying oven at 60°C for 24 hours to obtain PMA-Pt-C60 hydrogen evolution catalyst.

[0025] PMA-Pt-C 60 Morphology, structure and performance detection of hydrogen evolution catalyst: HAADF-STEM characterization: The PMA-Pt-C 60 catalyst obtained in Example 1 was characterized by HAADF-STEM Figure 1 . The specific form of Pt component was further determined by atom resolution HAADF-STEM image, and a large number of Pt single atoms and a small amount of Pt clusters were observed.

[0026] XRD, Raman, XPS characterization: Figure 2 The XRD spectrum of the PMA-Pt-C 60 catalyst obtained in Example 1 is shown, which presents obvious PMA characteristic diffraction peaks, which match well with the standard card, confirming the existence of crystalline PMA in the catalyst. No characteristic peaks of C60 and metal Pt were detected in the spectrum, which may exist in amorphous state or interact with PMA to form a new phase structure. Figure 3 The Raman spectrum of the PMA-Pt-C 60 catalyst obtained in Example 1 is shown, which shows that the characteristic vibration peaks of C60 and PMA appear in the PMA-Pt-C 60 sample, which directly proves the coexistence of C60 and PMA structure in the catalyst. Figure 4 The Pt 4f XPS spectrum of the PMA-Pt-C 60 catalyst obtained in Example 1 is shown, and the spectrum is decomposed into two characteristic peaks corresponding to the +2 and +4 oxidation states of Pt, indicating that Pt does not exist in the form of elemental substance in the catalyst, but in the oxidation state.

[0027] The ICP characterization of the PMA-Pt-C 60 hydrogen evolution catalyst: The ICP test results of the PMA-Pt-C 60 catalyst obtained in Example 1 show that the proportion of Pt and Mo atoms in the PMA-Pt-C 60 catalyst is 1:11, which proves that the molar ratio of Pt atoms to PMA molecules in the catalyst is close to 1:1.

[0028] The electrochemical analysis of the PMA-Pt-C 60 hydrogen evolution catalyst: Polarization current curve (LSV): The PMA-Pt-C60 The polarization current curves of the catalysts and the commercial Pt / C catalyst are shown in Figure 1. Figure 5 In 0.5M H2SO4, the iR compensation is 90%, the Pt loading is 1ug, and the current density is 10 mA cm -2 , the overpotential of the PMA-Pt-C 60 catalyst is only 9mV, which is 26mV lower than that of the Pt / C catalyst, and the overpotential of the PMA-Pt-C -2 catalyst is also lower than that of the commercial Pt / C catalyst at current densities of 50 and 100 mA cm 60 .

[0029] Tafel slope: The Tafel slope of the PMA-Pt-C 60 catalyst obtained in Example 1 is shown in Figure 2. Figure 6 The Tafel slope of the PMA-Pt-C 60 is 18.58 mV dec -1 , which is less than the Tafel slope of the commercial Pt / C catalyst, 25.57 mV dec -1 , which confirms the faster HER reaction kinetics of the PMA-Pt-C

[0030] In summary, the metal monatomic hydrogen evolution catalyst prepared by the present application, especially the PMA-Pt-C60 catalyst, exhibits excellent performance in the water electrolysis hydrogen evolution reaction. The unique "single atom + oxidation state" structure, as well as the coexistence of C60 and PMA, provides excellent catalytic activity and selectivity for the catalyst. Compared with the traditional Pt / C catalyst, the overpotential of the PMA-Pt-C60 catalyst is significantly reduced at 10 mA cm -2 , only 9mV, and at higher current densities, the overpotential of the PMA-Pt-C60 catalyst is also lower than that of the commercial Pt / C catalyst, which fully demonstrates its excellent catalytic performance. In addition, the preparation method realizes the PMA-M-C60 catalyst with high loading, high dispersion of metal monatomic bridging C60 and PMA through room temperature synthesis strategy, which provides a new idea for the preparation of low-cost, high-performance water electrolysis hydrogen catalyst. Therefore, the present application has broad prospects and important value in the practical application of water electrolysis hydrogen production.

[0031] It should be emphasized that: the above is only a preferred embodiment of the present application, and does not limit the present application in any form, any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A metal monatomic hydrogen evolution catalyst, characterized by, The catalyst includes a large amount of metal monatomic and a small amount of metal cluster, the metal in the catalyst is in an oxidation state, and the metal includes gold, silver, platinum, palladium, rhodium, iridium, ruthenium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, tungsten, rhenium; The catalyst includes a large amount of metal monatomic and a small amount of metal cluster, the metal in the catalyst is in an oxidation state, and the metal includes gold, silver, platinum, palladium, rhodium, iridium, ruthenium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, tungsten, rhenium; 2. The metal monatomic hydrogen evolution catalyst of claim 1, wherein, The catalyst includes a large amount of metal monatomic and a small amount of metal cluster, the metal in the catalyst is in an oxidation state, and the metal includes gold, silver, platinum, palladium, rhodium, iridium, ruthenium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, tungsten, rhenium; 3. The metal monatomic hydrogen evolution catalyst of claim 1, wherein, The overpotential of the catalyst 10 mA cm -2 at 9 mV.

4. A method for preparing a metal monatomic hydrogen evolution catalyst, characterized by, The preparation method is used for preparing the metal monatomic hydrogen evolution catalyst according to any one of claims 1 to 3, and the preparation method comprises the following steps: Step 1, the 4A molecular sieve is subjected to dehydration treatment; Step 2, the 4A molecular sieve obtained in step 1 is added in toluene at a proportion of 1g per 90-110ml, and is subjected to dehydration treatment for not less than 20 hours; Step 3, compound A, phosphomolybdic acid and fullerene with a molar ratio of 1:0.9-1.1:0.9-1.1 are respectively dissolved in toluene obtained in step 2, and a suspension of acetylacetone metal complex and a suspension of phosphomolybdic acid are uniformly mixed to obtain a suspension B; the compound A includes acetylacetone metal complex, chloroplatinic acid, chloroauric acid and chloropalladic acid; Step 4, the suspension B is slowly added dropwise into the fullerene toluene solution obtained in step 3, nitrogen is continuously introduced into the fullerene toluene solution during the adding process, and the mixed solution C is prepared through magnetic stirring; Step 5, the mixed solution C is continuously subjected to magnetic stirring in a nitrogen atmosphere for not less than 70 hours; Step 6, the mixed solution C after magnetic stirring in step 5 is washed with toluene, centrifuged for at least three times, and then the precipitate is vacuum dried to obtain the metal monatomic hydrogen evolution catalyst.

5. The method for preparing a metal single-atom hydrogen evolution catalyst according to claim 4, characterized in that, In the step 1, the dehydration treatment mode includes: the 4A molecular sieve is dried at 280-320 DEG C for 6-8 hours, and then cooled to room temperature under nitrogen protection.

6. The method for preparing a metal single-atom hydrogen evolution catalyst according to claim 4, characterized in that, The acetylacetone metal complex includes acetylacetone gold, acetylacetone silver, acetylacetone platinum, acetylacetone palladium, acetylacetone rhodium, acetylacetone iridium, acetylacetone ruthenium, acetylacetone titanium, acetylacetone vanadium, acetylacetone chromium, acetylacetone manganese, acetylacetone iron, acetylacetone cobalt, acetylacetone nickel, acetylacetone copper, acetylacetone zinc, acetylacetone zirconium, acetylacetone niobium, acetylacetone molybdenum, acetylacetone tungsten and acetylacetone rhenium.

7. The method for preparing a metal single-atom hydrogen evolution catalyst according to claim 4, characterized in that, In the step 6, the vacuum drying includes drying at 55-65 DEG C for not less than 20 hours.

8. The method for preparing a metal single-atom hydrogen evolution catalyst according to claim 4, characterized in that, In the step 3, the molar ratio is 1:1:1.

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