A PtCu alloy / G - Bacteria-modified rGO composite catalytic materials, their preparation and application in fuel cells

Abstract

The present invention belongs to the field of fuel cell materials, and specifically relates to a PtCu alloy / G ‑ Bacteria modified rGO composite catalytic materials, including G ‑ Bacteria modified rGO substrate and PtCu alloy particles composited on the substrate; the G ‑ Bacteria modified rGO substrate into G ‑ The present invention also provides the preparation of the material and its application in ORR materials. In the present invention, the material has excellent PtCu alloy loading capacity and loading stability, and is based on PtCu alloy and G ‑ The combined synergy of bacteria-modified rGO can synergistically improve the ORR performance of the material and improve the electrochemical performance of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell materials, and in particular to the field of fuel cell electrode catalytic materials. Background Art

[0002] In recent years, proton exchange membrane fuel cells (PEMFCs), a green, clean, and hydrogen-based energy conversion device, have garnered significant research attention. Their primary applications include transportation and mobile electronic devices, with some hydrogen fuel cell vehicles already commercialized. However, three key unresolved issues with PEMFC catalysts have limited their global industrialization: ① Commercial Pt / C catalysts utilize pure Pt, a precious metal, which is expensive and leads to high overall battery costs, limiting their global industrialization. ② Under actual fuel cell operating conditions, Pt / C catalysts exhibit poor stability, resulting in a short overall battery life due to the corrosion of the support and the instability of Pt nanoparticles. ③ The low activity of the cathode catalyst currently used in fuel cells leads to a slow oxygen reduction process at the cathode, resulting in low power generation. Therefore, improving the activity and stability of fuel cell catalysts and reducing Pt usage to lower catalyst costs are urgent priorities.

[0003] Currently, commercial fuel cell catalysts consist of 40% platinum nanoparticles directly supported on carbon black. However, the scarcity and high cost of platinum resources have directly hindered the expansion of fuel cell technology and hindered its global commercialization. Cu, a non-precious metal, is widely available and inexpensive. When alloyed with Pt, Cu can modulate the crystal and electronic structure of Pt through ligand effects, improving the performance of Pt catalysts. Furthermore, replacing some Pt ​​atoms with Cu can reduce catalyst costs. Furthermore, carbon black, as a support with a defect-rich surface, is susceptible to corrosion under harsh service environments. Graphene's inherent corrosion resistance can address this support instability. However, rGO (reduced graphene oxide) has fewer surface active groups and poor metal capture, making it difficult to achieve effective catalytic performance. To address this industry-wide issue, existing technologies primarily use graphene oxide (GO), which has a rich oxygen-containing surface, as a starting material, pre-compounding it with a metal and then reducing it to form rGO-based metal composites. However, this method easily disrupts the graphene network structure and is not conducive to uniform dispersion and efficient metal loading, resulting in unsatisfactory performance. Summary of the Invention

[0004] In view of the problem that the metal loading amount and material performance of existing graphene-based metal composite materials are not ideal, the first purpose of the present invention is to provide a PtCu alloy / G - The bacterial-modified rGO composite catalytic material aims to provide a new material with excellent ORR catalytic performance.

[0005] The second object of the present invention is to provide the PtCu alloy / G - The present invention provides a method for preparing a bacterial-modified rGO composite catalytic material, which aims to provide a new material having high metal loading, excellent loading performance and excellent ORR catalytic performance prepared based on rGO as a support.

[0006] The third object of the present invention is to provide the PtCu alloy / G - Application of bacteria-modified rGO composite catalytic materials in fuel cells.

[0007] The fourth object of the present invention is to provide a method comprising the PtCu alloy / G - Fuel cell electrodes based on bacteria-modified rGO composite catalytic materials.

[0008] A PtCu alloy / G - Bacteria modified rGO composite catalytic materials, including G - Bacteria-modified rGO substrate and PtCu alloy particles composited on the substrate;

[0009] The G - Bacteria modified rGO substrate into G - Bacterial crushed material-rGO carbonization.

[0010] The present invention provides a new material, which is based on G - The present invention found that the RGO modified by bacteria is a substrate, and the PtCu alloy particles are compounded on the substrate. - The combined synergistic effect of bacteria-modified rGO and PtCu alloy particles can significantly improve the catalytic performance of the material, reduce the catalyst cost, significantly improve the catalytic activity and stability of ORR, and improve the electrochemical performance of fuel cells.

[0011] In the present invention, the G - The combination of bacteria-modified rGO composites and PtCu alloy particles is the key to synergistically improving their catalytic activity and improving their fuel cell catalytic performance.

[0012] Preferably, the G - The bacteria is at least one of Escherichia coli, Shewanella, Shigella dysenteriae, Salmonella typhi, and Proteus.

[0013] Preferably, the G - The bacteria-modified rGO substrate is in the form of flakes or blocks;

[0014] Preferably, G -In the bacteria-modified rGO substrate, the content of rGO is 30-90 wt.%. The present invention has found that controlling the content of rGO in the substrate to an optimal ratio helps to further synergistically improve the catalytic performance of the material and can exhibit better electrochemical performance of the fuel cell.

[0015] In the present invention, the PtCu alloy particles are uniformly dispersed in the G - bacteria-modified rGO substrate.

[0016] Preferably, the molar ratio of Pt to Cu in the PtCu alloy particles is 1:3 to 3:1. In the present invention, the PtCu ratio helps to further synergistically improve the catalytic and electrochemical properties of the composite material.

[0017] Preferably, the PtCu alloy particles are nanoparticles, preferably with a particle size of 3 to 20 nm;

[0018] Preferably, in the PtCu alloy / G-bacteria modified rGO composite catalytic material, the content of PtCu alloy particles is greater than or equal to 40wt%, preferably 40-60wt.%, and more preferably 50-60wt.%. The method of the present invention, based on the G - Bacteria-modified rGO substrate can significantly improve the metal loading capacity. In addition, it also helps to control the metal grain size and dispersion uniformity, which helps to synergistically improve the catalytic performance of the composite material and improve the electrochemical performance of the fuel cell.

[0019] The present invention also attempts to provide a method for preparing PtCu alloy / G based on rGO as a direct loading substrate. - The present invention discloses a method for preparing a novel material of rGO composite catalytic material modified by bacteria. However, it was found in the early stage of the research that the preparation of the novel material of the present invention based on the direct loading of rGO faces the following preparation difficulties: (a) how to solve the problem that the PtCu is difficult to capture and composite due to the small number of active groups on the surface of rGO and the difference in bonding behavior between different metals; (b) how to control the grain size, composite stability and dispersion uniformity of PtCu; (c) how to improve the catalytic performance and electrochemical performance of the prepared material. In view of the problems of low PtCu loading, difficult grain control, poor loading uniformity and stability, and unsatisfactory catalytic performance caused by directly using rGO as the starting substrate, the present invention provides the following solutions:

[0020] A PtCu alloy / G - The preparation method of the bacteria-modified rGO composite catalytic material comprises the following steps:

[0021] Step (1):

[0022] G -The bacteria were cultured in a liquid medium containing rGO to make G - The bacteria grew on rGO to produce G - bacteria-rGO composites;

[0023] Step (2):

[0024] G - The bacteria-rGO composite material is mixed with a Pt source and a Cu source in liquid phase to obtain a mixed solution, and then the mixed solution is desolvated to obtain a composite precursor material;

[0025] Before, during or after mixing, - G in bacteria-rGO composites - Bacteria are crushed;

[0026] Step (3):

[0027] The precursor material is carbonized and reduced; or the composite precursor material is carbonized under a reducing atmosphere to obtain the PtCu alloy / G - Bacteria modified rGO composite catalytic materials.

[0028] The present invention provides a method for preparing a metal composite material using rGO as a starting carrier, and in order to solve the many preparation problems faced by the preparation method, the present invention innovatively adopts G - The rGO is modified by pre-filming and cell crushing by bacteria, and further combined with the Pt source-Cu source and the subsequent step (3) carbonization-reduction (or reduction carbonization) process, so that the process synergy can be achieved and G - The bacterial intracellular substances modify rGO, thereby improving the capture ability of Pt-Cu and the Pt-Cu loading effect. In addition, it can effectively control the Pt-Cu grain size, improve its dispersion uniformity and binding stability, and thus improve its catalytic performance and its electrochemical performance in fuel cells.

[0029] In the present invention, the rGO can be commercially available or prepared using existing methods. For example, the rGO can be obtained by reducing GO. The GO can be prepared using existing methods, for example, by a modified Hummers method.

[0030] For example, the preparation process for rGO involves adding 1-3g of flake graphite to a mixture of concentrated sulfuric acid and phosphoric acid (9:1 by volume). After uniform dispersion, 4-15g of potassium permanganate is slowly added and stirred for 10-20 hours. Subsequently, 1-5ml of 30% hydrogen peroxide is added in an ice-water bath. The mixture is sonicated, centrifuged, washed with water until neutral, and dried to obtain graphene oxide (GO). This is then reduced to graphene (rGO) using sodium borohydride. The concentrated sulfuric acid, phosphoric acid, sodium borohydride, and hydrogen peroxide involved are all common commercially available reagents.

[0031] In the present invention, the G - Control of bacterial types, and G - The pre-coating of rGO by bacteria and the subsequent crushing treatment are the key to synergistically improving the Pt-Cu loading capacity, improving the PtCu dispersion uniformity and controlling the grain size.

[0032] In the present invention, the G - The bacteria may be Gram-negative bacteria known in the industry; for example, at least one of Escherichia coli, Shewanella, Shigella dysenteriae, Salmonella typhi, and Proteus.

[0033] In the present invention, G - The bacteria were cultured in rGO culture medium, which helped to improve the adaptability of PtCu, unexpectedly improved the capture performance and composite stability of PtCu, and helped to synergistically improve the catalytic performance of the material.

[0034] In the present invention, the culture medium can be a conventional culture medium in the industry that can be applied to G - The culture medium for the growth of bacteria is pre-added with G - The rGO carrier with bacterial biofilm. The culture medium is, for example, Luria-Bertani culture medium.

[0035] In the present invention, in step (1), the culture method is shaking culture;

[0036] Preferably, the culture time is 10-20 hours, preferably 14 to 16 hours.

[0037] Preferably, G - Based on the dry weight of the bacteria-rGO composite material, the weight proportion of rGO is 30 to 60 wt.%.

[0038] In the present invention, after culturing, G - The bacteria-rGO composite material was then mixed with Pt source and Cu source, and the G in the system was innovatively regulated before, during and after mixing. -The bacteria are crushed, which can unexpectedly improve the PtCu bonding loading capacity, help induce the uniform dispersion and stable composite of PtCu, and help control its grain size, thus synergistically improving the catalytic and electrochemical properties of the composite material.

[0039] In the present invention, G can be treated based on existing methods. - The bacteria are crushed. For example, the crushing means is to use a cell crusher to crush;

[0040] Preferably, the power of the cell disruptor is set to 800-950W;

[0041] Preferably, the cell disruption process is carried out in a temperature bath less than or equal to 4°C;

[0042] Preferably, the crushing time is 5 to 10 minutes;

[0043] Preferably, the Pt source is a water-soluble platinum compound, preferably at least one of a chloroplatinic acid solution and a water-soluble salt of chloroplatinic acid;

[0044] Preferably, the Cu source is a water-soluble copper salt, preferably at least one of copper nitrate, copper chloride and copper acetate;

[0045] Preferably, during the mixing stage, the pH of the mixed solution is controlled at 1 to 6;

[0046] Preferably, step (2) is mixed using a shaking table;

[0047] Preferably, the mixing time in step (2) is 20-24 hours;

[0048] Preferably, the solvent is removed by freeze drying or evaporation.

[0049] In the present invention, the obtained precursor material is subjected to a carbonization-reduction treatment, or a carbonization treatment is performed under a reducing atmosphere to prepare the material.

[0050] Preferably, in step (3), the precursor material is carbonized in advance and then reduced in a reducing atmosphere;

[0051] Preferably, the atmosphere during the carbonization stage is a protective atmosphere. In the present invention, the protective atmosphere is at least one of inert gases such as nitrogen and argon.

[0052] Preferably, the carbonization temperature is 600°C to 900°C;

[0053] Preferably, the heating rate in the carbonization stage is 0.2°C / min to 3°C / min;

[0054] Preferably, the holding time of the carbonization stage is 1.5 to 2.5 hours;

[0055] Preferably, the reducing atmosphere is an atmosphere containing hydrogen, preferably a mixture of hydrogen and protective atmosphere;

[0056] Preferably, the temperature in the reduction stage is 150°C to 250°C;

[0057] Preferably, the holding time in the reduction stage is 2 to 4 hours.

[0058] When reduction and carbonization are performed in one step, that is, carbonization is performed under a reducing atmosphere, the carbonization temperature is preferably 600° C. to 900° C., and the carbonization time is preferably 1 to 5 hours.

[0059] A preferred PtCu alloy / G of the present invention - A method for preparing a bacteria-modified rGO composite catalytic material, the method comprising the following steps:

[0060] 1) Take G - The bacterial strain was cultured in a culture dish containing an appropriate amount of reduced graphene oxide (rGO) to obtain G - bacteria-rGO complex; the culture time is 14 to 16 hours;

[0061] 2) G - The bacteria-rGO complex was stirred in a cell crusher to break the cells, and then the platinum source and copper source were mixed with the broken G - The bacteria-rGO complex is stirred to fully adsorb platinum and copper, yielding a precursor material. Disruption is performed in a cell disruptor at high speed, set to 800-950W, for 5-10 minutes (in an ice bath). The adsorption phase is performed on a shaker for 20-24 hours, maintaining a pH of 1-6. The platinum source is either chloroplatinic acid solution or a chloroplatinate salt. The copper source is either copper nitrate, copper chloride, or copper acetate.

[0062] 3) The precursor material is subjected to carbonization and reduction treatment to obtain the product. The carbonization process is as follows: in an argon protective atmosphere, the temperature is raised to 600°C to 900°C at a heating rate of 0.2°C / min to 3°C / min, and the temperature is kept for 1.5 to 2.5 hours. The carbonization process is to convert the biochar into a carbon material with high conductivity and to obtain PtCu alloy / G - The rGO composite catalytic material modified by bacteria is subjected to a reduction treatment process comprising: maintaining the temperature at 150°C to 250°C for 2 to 4 hours in a hydrogen reducing atmosphere. The reduction process primarily reduces the material to form a platinum-copper alloy.

[0063] The technical solution of the present invention adopts G -The composite carrier was synthesized by reducing rGO with bacteria modification. However, due to the small number of surface defects on rGO, it was not possible to achieve a high content of Pt-based alloy nanoparticles. - The bacteria have abundant oxygen-containing functional groups inside, which can unexpectedly adapt to metals such as platinum and copper, and can unexpectedly facilitate the capture of platinum and copper, thereby greatly increasing the loading capacity of Pt-based alloy catalysts on rGO. - The functional groups on the surface of bacteria are less than those inside the cells, so G - The release of functional groups inside the bacteria further increases the metal loading, and ultimately achieves the modified rGO loaded with high Pt-based alloy catalysts. On the other hand, the use of Cu and Pt alloying can greatly reduce the amount of precious metal Pt compared to pure Pt, and the introduction of Cu will cause the Pt lattice to distort, adjust the Pt electronic structure, and further improve the performance of Pt-based catalysts. In addition, G - The bacteria and culture medium contain more nitrogen, and the carbonized crushed G - The bacteria-rGO composite material has a nitrogen doping effect. Using it to load nano-platinum-copper particles can not only improve the loading stability of platinum-copper, but also synergistically improve the catalytic activity of platinum-copper.

[0064] Further preferred PtCu alloy / G - The preparation method of the bacteria-modified rGO composite catalytic material includes the following specific process steps:

[0065] 1. Preparation of G-bacteria modified rGO composite materials:

[0066] Weigh yeast extract, NaCl, tryptone and rGO to prepare Luria-Bertani medium (LB medium) containing rGO and sterilize it; streak the preserved strain and select single G - The bacterial colony was inoculated into LB medium and cultured under shaking for 14 to 16 hours to allow G - The bacteria were fully grown, and the products were collected by centrifugation and washed 2 to 3 times with phosphate buffer and sterile water respectively. - The bacteria-rGO mixture was redissolved (ultrasound 0.5h) in an appropriate amount of deionized water and G - The bacteria-rGO mixture was stirred in a cell crusher with a power of 800-950W for 5-10 minutes to obtain crushed G - bacteria-rGO composite materials.

[0067] 2. Broken G - Bacteria-rGO composite material adsorbs platinum and copper bimetallics:

[0068] According to the molar ratio of Pt:Cu=1:3~3:1, the precursors chloroplatinic acid and copper nitrate were weighed and dissolved in aqueous solution. After ultrasonication for 30 minutes, the mixture was slowly dripped into the crushed G using a syringe needle. - The solution was added to the rGO composite material (pH = 4), and magnetic stirring was used throughout the process. After the solution was added, it was stirred for an additional 20 to 24 hours to ensure the dispersion of the subsequent metals. After stirring, it was shaken at 30 ° C and 170 rpm for 60 minutes to ensure that the G - The bacteria-rGO has a high adsorption capacity for platinum and copper; finally, the sample was collected by centrifugation at 12000 rpm for 7 minutes, vacuum freeze-dried, and weighed and ground.

[0069] 3. Heat treatment:

[0070] The material obtained in step 2 was placed in a tube furnace, and heated to 600°C to 900°C at a heating rate of 0.2°C / min to 3°C / min under an argon protective atmosphere, and kept warm for 1.5 to 2.5 hours to make G - The bacteria-rGO composite was completely carbonized.

[0071] 4. H2 reduction:

[0072] The sample obtained in step 3 is kept at 150℃~250℃ for 2~4h in hydrogen reducing atmosphere to fully reduce the platinum copper alloy. - Bacteria modified rGO loaded with high platinum copper (Pt x Cu y / G - Bacteria-modified rGO) catalytic materials.

[0073] The present invention also includes the PtCu alloy / G prepared by the preparation method - Bacteria-modified rGO composite catalytic material. In the present invention, the preparation method can give the material special structural properties and can significantly improve its ORR catalytic performance and improve the electrochemical performance of fuel cells.

[0074] The present invention also provides a PtCu alloy / G - Application of bacteria-modified rGO composite catalytic materials as ORR catalysts;

[0075] Preferably, it is used as an ORR catalyst for preparing a fuel cell;

[0076] Preferably, the fuel cell is a proton exchange membrane fuel cell.

[0077] In the present invention, the PtCu alloy / G -Fuel cells and their components required for the preparation of bacteria-modified rGO composite catalytic materials.

[0078] The present invention also provides a fuel cell electrode, comprising the PtCu alloy / G - Bacteria modified rGO composite catalytic materials.

[0079] In the present invention, the electrode is added with the PtCu alloy / G - Except for the bacteria-modified rGO composite catalytic material, other materials and electrode structures can be well known.

[0080] The present invention also provides a fuel cell comprising the PtCu alloy / G - Electrode of bacteria-modified rGO composite catalytic material.

[0081] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0082] 1) The present invention provides a new PtCu alloy / G - Bacteria modified rGO composite catalytic material based on PtCu alloy and G - The combination of bacterial-modified rGO can synergistically improve its catalytic and electrochemical properties.

[0083] 2) The present invention also provides a method for preparing PtCu alloy / G based on direct loading of rGO - The preparation idea of ​​bacteria-modified rGO composite catalytic material. In order to solve the problems faced by the preparation of this material with this idea, such as low PtCu loading, difficult to control the grains, poor loading uniformity and stability, and unsatisfactory catalytic performance, G - The rGO is pre-filmed and crushed by bacteria, and further combined with the Pt source-Cu source and the subsequent step (3) carbonization-reduction (or reduction carbonization) process, so that the process synergy can be achieved and G - The bacterial intracellular substances modify rGO, thereby improving the bonding ability of Pt-Cu and the Pt-Cu loading effect. In addition, it can effectively control the Pt-Cu grain size, improve its dispersion uniformity and composite stability, and thus improve its catalytic performance and its electrochemical performance in fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0084]

Figure 1

[0085]

Figure 2

[0086]

Figure 3

[0087]

Figure 4

[0088]

Figure 5

[0089] 【 Figure 6 This figure compares the LSV of a commercial 40% Pt / C fuel cell catalyst before and after 30,000 cycles of ADT in an acidic system. After 30,000 cycles of stability testing, the half-wave potential of the 40% Pt / C catalyst dropped by 98 mV. DETAILED DESCRIPTION

[0090] The following specific examples are intended to further illustrate the present invention in detail, rather than to further limit the scope of protection of the claims of the present invention.

[0091] Unless otherwise specified, the reagents involved in the following examples are commercial reagents purchased directly from the market.

[0092] The reduced graphene oxide (rGO) involved in the following examples and comparative examples was prepared by the following method: 1.8 g of flake graphite was added to a mixture of concentrated sulfuric acid and phosphoric acid (volume ratio of 9:1), and after uniform dispersion, 9.5 g of potassium permanganate was slowly added and stirred for 20 hours; then 3 ml of 30% concentration hydrogen peroxide was added in an ice water bath; after sonication, centrifugation, washing with water to neutrality, and drying, graphene oxide (GO) was obtained, and then reduced with sodium borohydride for 5 hours to obtain reduced graphene oxide (rGO).

[0093] Example 1

[0094] Step (1), preparation of E. coli modified rGO composite material:

[0095] 5 g yeast extract, 5 g NaCl, 10 g tryptone and 80 mg rGO were weighed to prepare Luria-Bertani medium containing rGO and sterilized; the preserved Escherichia coli (E. coli; G-bacteria) was streaked, and a single colony was selected and inoculated into 50 mL of the above-mentioned LB medium for culture; the E. coli was fully grown by shaking at 170 rpm at 30°C for 15 h (culture time), and finally the product was collected by centrifugation at 12000 rpm for 7 min and washed three times with phosphate buffer and sterile water respectively (the rGO content in the rGO composite material after E. coli biofilm growth was 50 wt.% on a dry weight basis). The washed E. coli-rGO mixture was redissolved (ultrasound for 0.5 h) in an appropriate amount of deionized water, and the E. coli-rGO mixture was stirred in a cell crusher with a power of 950 W for 10 min under ice bath conditions to obtain a crushed E. coli-rGO composite material.

[0096] Step (2), crushing the E. coli-rGO composite material to adsorb platinum and copper bimetallics:

[0097] According to the molar ratio of Pt:Cu=1:3, the precursors chloroplatinic acid and copper nitrate were weighed and dissolved in aqueous solution respectively. After ultrasonication for 30 minutes, the above mixture was slowly added to the crushed E. coli-rGO composite material (the solution pH was adjusted to 4) using a syringe needle, and magnetic stirring was used throughout the process. After the solution was added, it was stirred for an additional 24 hours to ensure the subsequent dispersion of the metal; after stirring, it was then shaken at 170 rpm at 30°C for 60 minutes to ensure the high adsorption capacity of platinum and copper by the crushed E. coli-rGO; finally, the sample was collected by centrifugation at 12000 rpm for 7 minutes, vacuum freeze-dried, and weighed and ground.

[0098] Step (3), heat treatment:

[0099] The material obtained in step (2) was placed in a tube furnace, and under an argon protective atmosphere, the temperature was increased to 800°C at a heating rate of 2°C / min and kept at this temperature for 2 hours to completely carbonize the crushed E. coli-rGO composite.

[0100] Step (4), H2 reduction:

[0101] The sample obtained in step (3) was kept at 200°C for 3 hours under a hydrogen reducing atmosphere to fully reduce the platinum-copper alloy. Finally, an E. coli-modified rGO loaded with high platinum-copper loading (PtCu3 / rGO-E. coli) catalytic material was obtained.

[0102] Electrochemical detection

[0103] 4 mg of the prepared PtCu3 / rGO-E. coli catalyst was dispersed in a mixture of 500 μL of ethanol, 400 μL of distilled water, and 100 μL of a 5 wt% Nafion solution. After ultrasonication for half an hour, 15 μL of the mixed solution was dropped onto a rotating disk electrode. After natural drying, the electrochemical performance of the PtCu3 / rGO-E. coli catalyst was tested using an electrochemical workstation. A saturated calomel electrode was used as the reference electrode, a graphite rod as the counter electrode, and 0.1 M HClO4 as the electrolyte. The catalytic activity in an acidic environment was tested at a scan rate of 0.01 V / s. Stability was tested at a scan rate of 0.05 V / s for 30,000 cycles. For comparison, commercial 40% Pt / C was also tested using the same method.

[0104] Example 2

[0105] Compared with Example 1, the only difference is that the molar ratio of Pt to Cu in step (2) is changed to Pt:Cu=3:1.

[0106] Example 3

[0107] Compared with Example 1, the only difference is that the molar ratio of Pt to Cu in step (2) is changed to Pt:Cu=1:1.

[0108] Example 4

[0109] Compared with Example 1, the only difference is that Escherichia coli is replaced by other G - Bacteria, other operations and parameters are the same as in Example 1; the experimental groups are:

[0110] Group A: G - The bacteria is Shewanella;

[0111] Group B: G - The bacteria is Proteus;

[0112] Group C: G - The bacteria is Salmonella typhi.

[0113] Example 5

[0114] Compared with Example 1, the only difference is that G is changed - The culture time of the bacteria, other operations and parameters were the same as in Example 1; the experimental groups were:

[0115] Group A: The culture time was changed from 15 h to 14 h. After E. coli biofilm growth, the content of rGO in the rGO composite material was 60 wt.% based on dry weight.

[0116] Group B: The culture time was changed from 15 h to 16 h. After E. coli biofilm growth, the rGO content in the rGO composite material was 40 wt.% on a dry weight basis.

[0117] Example 6

[0118] Compared with Example 1, the only difference is that G - After the bacteria-rGO was crushed, the adsorption of PtCu was changed to G - The bacteria-rGO adsorbed PtCu and then the cells were broken. Other operations and parameters were the same as in Example 1.

[0119] Example 7

[0120] Compared with Example 1, the only difference is that steps (3) and (4) are combined into step (3), and the following is changed: the material obtained in step (2) is placed in a tube furnace, and heated to 600-900°C at a rate of 2°C / min under a 5% hydrogen-95% argon atmosphere, and kept at this temperature for 2 hours to completely carbonize the crushed E. coli-rGO composite and reduce the PtCu alloy. Other operations and parameters are the same as in Example 1; the experimental groups are:

[0121] Group A: heated to 600℃ for carbonization for 2h;

[0122] Group B: heating to 700℃ for carbonization for 2h;

[0123] Group C: heated to 800℃ for carbonization for 2h;

[0124] Group D: Heating to 900℃ and carbonization for 2h.

[0125] Comparative Example 1

[0126] Compared with Example 1, the only difference is that Staphylococcus aureus is used to replace the Escherichia coli, and other operations and parameters are the same as Example 1.

[0127] Comparative Example 2

[0128] Compared with Example 1, the only difference is that E. coli is not cultured in advance in LB medium containing rGO to form biofilms. Instead, E. coli is first grown in LB medium, and then the culture solution and rGO are mixed and centrifuged to obtain the E. coli-rGO composite material.

[0129] Comparative Example 3

[0130] Compared with Example 1, the only difference is that in step (2), no crushing process is performed.

[0131] Comparative Example 4

[0132] Compared with Example 1, the only difference is that in step (2), an equimolar amount of Co is used to replace Cu, that is, Pt:Co=1:3. Other operations and parameters are the same as in Example 1.

[0133] Comparative Example 5

[0134] Compared with Example 1, the only difference is that the E. coli modification treatment in step (1) is omitted, that is, in step (2), rGO is directly used to adsorb PtCu. Other operations and parameters are the same as in Example 1.

[0135] Comparative Example 6

[0136] Compared with Example 1, the only difference is that step (4) is omitted.

[0137] Comparative Example 7

[0138] Compared with Example 1, the only difference is that rGO is not added in step (1), and other operations and parameters are the same as Example 1.

[0139] Comparative Example 8

[0140] Compared with Example 1, the only difference is that rGO in step (1) is replaced by GO, and the other operations and parameters are the same as Example 1.

[0141] Comparative Example 9

[0142] Compared with Example 7, the only difference is that the temperature of the one-step carbonization reduction is set to 500° C., and other operations and parameters are the same as Example 7.

[0143] Comparative Example 10

[0144] Compared with Example 7, the only difference is that the temperature of the one-step carbonization reduction is set to 1000° C., and other operations and parameters are the same as Example 7.

[0145] The electrochemical test results of the catalysts prepared in each example and comparative example and commercial 40% Pt / C and the subsequent calculation results are listed in Table 1.

[0146]

[0147]

[0148] Table 1 Metal loading and electrochemical performance of each catalyst

[0149] Examples 1, 2, and 3 investigated the catalysts prepared using different PtCu molar ratios and their performance tests. The PtCu3 / rGO-E.coli catalyst obtained in Example 1 had the highest mass specific activity (reaching 0.924 A / mg at 0.9 V). Pt, that is, each mg of Pt can generate 0.924 A of current), which is 12.32 times that of commercial 40% Pt / C. It can be seen that although the Pt content in PtCu3 / rGO-E.coli is only 13.2% (52.9%*1 / 4), its activity is much higher than that of commercial 40% Pt / C with a Pt content of up to 39.5%. This result shows that the PtCu3 / rGO-E.coli catalyst prepared by the present invention reduces the amount of Pt used while improving the catalytic activity of the Pt-based catalyst. In addition, from the decay rate of the mass specific activity after 30,000 cycles, it can be seen that the mass specific activity decay of PtCu3 / rGO-E.coli is 12.2%, while the commercial 40% Pt / C decays by 49.8%. The high stability of PtCu3 / rGO-E.coli is due to the fact that the carrier used is a graphene composite, which has extremely high stability itself, and the interaction between the composite carrier and PtCu3 alloy nanoparticles is extremely strong. In addition, the nitrogen doping effect makes PtCu3 / rGO-E.coli extremely stable.

[0150] The stability of the catalysts obtained in Example 1, Example 2 and Example 3 is not much different, and the stability of the catalysts is basically the same, but all are much higher than commercial 40% Pt / C.

[0151] Example 1, Example 4-A, Example 4-B and Example 4-C investigated different G - The PtCu3 alloy catalyst synthesized by crushing bacteria and rGO was loaded. The results showed that the PtCu3 loading amount and the performance of the catalyst obtained in each embodiment were not much different, indicating that the use of different G - Bacteria-modified rGO will not have a significant effect on the performance of the final synthesized PtCu3 alloy catalyst.

[0152] Example 1, Example 5-A and Example 5-B investigated the G - The PtCu3 alloy catalyst synthesized by the crushed composite of bacteria and rGO was loaded. The results showed that the PtCu3 loading amount and the performance of the catalysts finally obtained in each embodiment were not much different, and all of them could obtain excellent ORR catalytic performance and fuel cell cycle stability.

[0153] Example 1 and Example 6 investigated the effect of crushing order on the final synthesized PtCu3 alloy catalyst. The results showed that the PtCu3 loading and performance of the catalysts finally obtained in each example were not much different, and all of them could achieve excellent ORR catalytic performance and fuel cell cycle stability.

[0154] Example 1, Example 7-A, Example 7-B, 7-C and Example 7-D investigated the effects of carbonization followed by reduction, one-step carbonization reduction and the temperature of one-step carbonization reduction on the synthesized PtCu3 alloy catalyst. The results showed that the PtCu3 loading amount and the performance of the catalysts finally obtained in each example were not much different, and all of them could achieve excellent ORR catalytic performance and fuel cell cycle stability.

[0155] The above results show that the PtCu alloy / G - The bacteria-modified rGO composite catalytic material has excellent catalytic activity and stability, and the Pt dosage is low, and can be used on a large scale in proton exchange membrane fuel cells.

[0156] The above describes the specific embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A PtCu alloy / G - The preparation method of bacteria-modified rGO composite catalytic material is characterized by: include: Step (1): G - The bacteria were cultured in a liquid medium containing rGO to make G - The bacteria grew on rGO to produce G - bacteria-rGO composite material; the G - The bacteria is at least one of Escherichia coli, Shewanella, Shigella dysenteriae, Salmonella typhi, and Proteus; Step (2): G - The bacteria-rGO composite material is mixed with a Pt source and a Cu source in liquid phase to obtain a mixed solution, and then the mixed solution is desolvated to obtain a composite precursor material; Before, during or after mixing, - G in bacteria-rGO composites - Bacteria are crushed; Step (3): The composite precursor material is carbonized and reduced; or the composite precursor material is carbonized in a reducing atmosphere to obtain the PtCu alloy / G - Bacteria modified rGO composite catalytic materials; The carbonization temperature is 600°C to 900°C; The temperature in the reduction stage is 150°C~250°C; The PtCu alloy / G - Bacteria modified rGO composite catalytic materials include G - Bacteria-modified rGO substrate and PtCu alloy particles composited on the substrate; The G - Bacteria modified rGO substrate into G - Bacterial crushed material-rGO carbonization.

2. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The G - The bacteria-modified rGO substrate is in the form of flakes or blocks.

3. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: G - In the bacteria-modified rGO substrate, the content of rGO is 30~90wt.%.

4. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In the PtCu alloy particles, the molar ratio of Pt to Cu is 1:3 to 3:

1.

5. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The PtCu alloy particles are nanoparticles with a particle size of 3 to 20 nm.

6. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In the PtCu alloy / G-bacteria modified rGO composite catalytic material, the content of PtCu alloy particles is greater than or equal to 40wt%.

7. The PtCu alloy / G according to claim 6 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In the PtCu alloy / G-bacteria modified rGO composite catalytic material, the content of PtCu alloy particles is 40-60wt.%.

8. The PtCu alloy / G according to claim 7 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In the PtCu alloy / G-bacteria modified rGO composite catalytic material, the content of PtCu alloy particles is 50-60wt.%.

9. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The rGO is obtained by reducing GO; The GO is prepared by a modified Hummers method.

10. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In step (1), the culture method is shaking culture.

11. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The culture medium used in the culturing stage was G - Liquid culture medium suitable for bacterial growth.

12. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The culture time is 10-20 h.

13. The PtCu alloy / G according to claim 12 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The culture time is 14 to 16 hours.

14. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: G - Based on the dry weight of bacteria-rGO composite materials, the weight proportion of rGO is 30~60wt.%.

15. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In step (2), G - The bacteria-rGO composite material is dispersed in an aqueous solution and crushed, and then a Pt source and a Cu source are added to perform liquid phase mixing to obtain the mixed solution.

16. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The crushing means is crushing with a cell crusher.

17. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The power of the cell disruptor was set to 800-950 W.

18. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The cell disruption process was performed in a temperature bath less than or equal to 4°C.

19. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The crushing time is 5~10min.

20. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The Pt source is a water-soluble platinum compound.

21. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The Pt source is at least one of a chloroplatinic acid solution and a water-soluble salt of chloroplatinic acid.

22. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The Cu source is a water-soluble copper salt.

23. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: The Cu source is at least one of copper nitrate, copper chloride and copper acetate.

24. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: During the mixing stage, the pH of the mixed solution is controlled at 1~6.

25. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In the mixing stage, a shaking table is used for mixing; The mixing time is 20-24 h; The solvent is removed by freeze drying or evaporation.

26. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In step (3), the precursor material is carbonized in advance and then reduced in a reducing atmosphere.

27. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In step (3), the atmosphere during the carbonization stage is a protective atmosphere; The heating rate in the carbonization stage is 0.2 ℃ / min ~3 ℃ / min; The holding time of the carbonization stage is 1.5~2.5 h.

28. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In step (3), the reducing atmosphere is an atmosphere containing hydrogen; The holding time of the reduction stage is 2~4 h.

29. The PtCu alloy / G according to claim 1 - The preparation method of the bacteria-modified rGO composite catalytic material is characterized by: In step (3), the carbonization stage is carried out under a reducing atmosphere, wherein the carbonization temperature is 600°C to 900°C and the time is 1 to 5 hours.

30. A PtCu alloy / G prepared by the preparation method according to any one of claims 1 to 29 - Bacteria modified rGO composite catalytic materials.

31. A PtCu alloy / G prepared by the preparation method according to any one of claims 1 to 29 - The application of bacteria-modified rGO composite catalytic material is characterized by: It is used as an ORR catalyst.

32. The use according to claim 31, characterized in that: It is used as an ORR catalyst to prepare fuel cells.

33. The use according to claim 32, characterized in that: The fuel cell is a proton exchange membrane fuel cell.

34. A fuel cell electrode, characterized in that PtCu alloy / G prepared by the preparation method according to any one of claims 1 to 29 - Bacteria modified rGO composite catalytic materials.

35. A fuel cell, characterized in that: Comprising the electrode according to claim 34.

Images