Background
A fuel cell is a highly efficient, environmentally friendly power generation device that can directly convert chemical energy stored in a fuel and an oxidant into electrical energy. Fuel cell electrocatalysts play the role of a "factory" of electrochemical reactions and are a key material in the core of fuel cells. On the other hand, the current premise of the commercial application of fuel cells is to solve various problems of performance, cost, stability, durability, environmental adaptability, and the like, wherein the most critical is the cost problem. The cost of the battery catalyst is about 1/4-1/3, and the cost cannot be further reduced along with the expansion of the capacity. The main reason is that the electrocatalysts in the prior art use more platinum, and the platinum reserves are limited and expensive, thereby restricting the commercial application of the fuel cell.
Once the substitute material of the platinum-carbon catalyst is successfully developed, the manufacturing cost of the fuel cell can be effectively reduced. It is worth noting that the catalysts used in hydrogen-oxygen fuel cells are divided into cathode catalysts and anode catalysts, where the cathode has a greater demand for platinum loading due to the kinetics of the catalytic reaction (when a platinum-carbon catalyst is used in the anode, the exchange current density is orders of magnitude higher than that of the cathode, and a small amount of platinum is sufficient for the anode). Therefore, it is first required to find a non-platinum cathode catalyst material with low cost and high performance. At present, a variety of non-platinum catalysts have been studied in a large number, and among them, metal oxides, organic metal complexes, heteroatom carbon materials, chalcogenides, and biomimetic materials all exhibit a certain oxygen reduction activity. However, these materials still have the disadvantages of expensive raw materials, unstable performance under acidic electrolyte, and the like.
Melamine resin, also known as melamine formaldehyde resin, contains a large amount of nitrogen elements, and can form a nitrogen-doped porous carbon material after pyrolysis treatment, and iron-nitrogen-carbon (Fe-N-C) non-platinum catalyst is the most potential non-platinum catalyst at present because the catalyst can be used for acid electrolyte. The high-activity Fe-N-C sites can be formed only by doping iron element into melamine resin. However, melamine resin is not sufficiently high in thermal stability and starts to decompose at about 300 ℃ under normal pressure, so that the residual N element at 1000 ℃ is less than 2%, and Fe-N-C oxygen reduction active sites are too few.
Disclosure of Invention
In view of the above, there is a need to overcome at least one of the above-mentioned drawbacks of the prior art, and the present invention provides a method for preparing a fuel cell catalyst by microwave pyrolysis of melamine resin, comprising: (1) crushing melamine resin and sieving the crushed melamine resin with a sieve;
(2) soaking melamine resin powder in 0.5M hydrochloric acid for 24 hr, filtering and drying;
(3) adding 2g of porous activated carbon into 100ml of aqueous solution, and then adding 2-5ml of triton X-100 to form carbon slurry;
(4) 2-5g of the dried melamine resin powder obtained in the step (2) is poured into the carbon slurry and stirred for 5-10 minutes;
(5) adding 10ml of 0.01-0.1M ferrous sulfate aqueous solution, and stirring for 5-10 minutes;
(6) drying at 90 deg.C for 8 hr, and ball milling for 1-2 hr;
(7) heating for 3-30 minutes in a 300-500W microwave oven under the nitrogen atmosphere, wherein the heating period is interrupted for 10-100 times;
(8) soaking in 0.5M sulfuric acid for 8 hr, filtering and drying;
(9) heating to 800-.
According to the background art of the present patent, the current premise of the commercial application of fuel cells needs to solve various problems such as performance, cost, stability, durability, environmental adaptability, etc., wherein the most critical is the cost problem; the method for preparing the fuel cell catalyst by microwave pyrolysis of melamine resin disclosed by the invention has the advantages that the triton X-100 is used for anchoring the surface of the carbon carrier in the preparation process, so that the active reaction area of the catalyst is greatly increased. In addition, the intermittent microwave pyrolysis technology is adopted for the first time to form a large number of nitrogen-doped graphite structures, which is beneficial to forming more Fe-N-C oxygen reduction active sites. The non-platinum catalyst prepared by the method can be used for replacing the existing platinum-carbon catalyst of the cathode of the fuel cell. The oxygen reduction performance of the catalyst under alkaline conditions is larger than that of a platinum-carbon catalyst, and the oxygen reduction performance of the catalyst under acidic conditions is close to that of the platinum-carbon catalyst. Melamine resin is often used as tableware, and a large amount of solid melamine resin is discharged every year, so that the melamine resin is very difficult to recycle at normal temperature and pressure. The raw materials required by the invention can be obtained by simple crushing treatment. Due to the wide source of raw materials, the production cost is only equivalent to that of the platinum-carbon catalyst 1/200. The preparation can be completed through one-step pyrolysis treatment, the process is simple, and the method is suitable for large-scale production. .
In addition, the method for preparing the fuel cell catalyst by microwave pyrolysis of melamine resin disclosed by the invention also has the following additional technical characteristics:
further, in step 1, the mesh size is 100-300 mesh.
Further, the mesh sieve adopts 100, 150, 200, 250 and 300 meshes.
Too small a mesh screen makes the particles too small and the effect is rather reduced, too large particles and the effect is difficult to achieve.
Further, in step 3, the porous activated carbon was washed with 0.5M hydrochloric acid and dried.
Further, in step 3, a carbon slurry is formed by ultrasonic dispersion.
Further, the melamine resin in the step (1) is one or more of self-synthesized melamine resin, commercial finished melamine resin particles, or plastic products containing a large amount of melamine resin.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Detailed Description
The invention has the following conception that the invention provides a method for preparing a fuel cell catalyst by microwave pyrolysis of melamine resin, wherein triton X-100 is used for anchoring the surface of a carbon carrier in the preparation process, so that the active reaction area of the catalyst is greatly increased. In addition, the intermittent microwave pyrolysis technology is adopted for the first time to form a large number of nitrogen-doped graphite structures, which is beneficial to forming more Fe-N-C oxygen reduction active sites. The non-platinum catalyst prepared by the method can be used for replacing the existing platinum-carbon catalyst of the cathode of the fuel cell. The oxygen reduction performance of the catalyst under alkaline conditions is larger than that of a platinum-carbon catalyst, and the oxygen reduction performance of the catalyst under acidic conditions is close to that of the platinum-carbon catalyst. Melamine resin is often used as tableware, and a large amount of solid melamine resin is discharged every year, so that the melamine resin is very difficult to recycle at normal temperature and pressure. The raw materials required by the invention can be obtained by simple crushing treatment. Due to the wide source of raw materials, the production cost is only equivalent to that of the platinum-carbon catalyst 1/200. The preparation can be completed through one-step pyrolysis treatment, the process is simple, and the method is suitable for large-scale production.
According to an embodiment of the invention, the preparation method comprises: (1) crushing melamine resin and sieving the crushed melamine resin with a sieve;
(2) soaking melamine resin powder in 0.5M hydrochloric acid for 24 hr, filtering and drying;
(3) adding 2g of porous activated carbon into 100ml of aqueous solution, and then adding 2-5ml of triton X-100 to form carbon slurry;
(4) 2-5g of the dried melamine resin powder obtained in the step (2) is poured into the carbon slurry and stirred for 5-10 minutes;
(5) adding 10ml of 0.01-0.1M ferrous sulfate aqueous solution, and stirring for 5-10 minutes;
(6) drying at 90 deg.C for 8 hr, and ball milling for 1-2 hr;
(7) heating for 3-30 minutes in a 300-500W microwave oven under the nitrogen atmosphere, wherein the heating period is interrupted for 10-100 times;
(8) soaking in 0.5M sulfuric acid for 8 hr, filtering and drying;
(9) heating to 800-.
In addition, the method for preparing the fuel cell catalyst by microwave pyrolysis of melamine resin disclosed by the invention also has the following additional technical characteristics:
according to one embodiment of the invention, in step 1, the mesh size is 100-300 mesh.
Further, the mesh sieve adopts 100, 150, 200, 250 and 300 meshes.
According to one embodiment of the invention, in step 3, the porous activated carbon is washed with 0.5M hydrochloric acid and dried.
According to one embodiment of the invention, in step 3, a carbon slurry is formed using ultrasonic dispersion.
According to an embodiment of the invention, the melamine resin in step (1) is one or more of self-synthesized melamine resin, or commercially finished melamine resin particles, or plastic products containing a large amount of melamine resin.
According to one embodiment of the invention, the steps are as follows:
(1) crushing melamine resin, and sieving with a 200-mesh sieve;
(2) soaking melamine resin powder in 0.5M hydrochloric acid for 24 hr, filtering and drying;
(3) adding 2g of porous activated carbon (which has been washed and dried with 0.5M hydrochloric acid) into 100ml of aqueous solution, adding 2ml of Triton X-100, and performing ultrasonic dispersion to form carbon slurry;
(4) 2g of the dried melamine resin powder obtained in the step (2) is poured into the carbon slurry and stirred for 10 minutes;
(5) adding 10ml of 0.01M ferrous sulfate aqueous solution, and stirring for 5-10 minutes;
(6) drying at 90 deg.C for 8 hr, and ball milling for 2 hr;
(7) heating in a 300W microwave oven for 3 minutes in a nitrogen atmosphere, wherein the heating period is intermittent for 10 times;
(8) soaking in 0.5M sulfuric acid for 8 hr, filtering and drying;
(9) heating to 1050 ℃ in a tubular furnace under the nitrogen atmosphere, preserving heat for 1 hour, and cooling along with the furnace.
According to one embodiment of the invention, the steps are as follows:
(1) crushing melamine resin, and sieving with a 200-mesh sieve;
(2) soaking melamine resin powder in 0.5M hydrochloric acid for 24 hr, filtering and drying;
(3) adding 2g of porous activated carbon (which has been washed and dried with 0.5M hydrochloric acid) into 100ml of aqueous solution, adding 2ml of Triton X-100, and performing ultrasonic dispersion to form carbon slurry;
(4) 5g of the dried melamine resin powder obtained in the step (2) is poured into the carbon slurry and stirred for 10 minutes;
(5) adding 10ml of 0.01M ferrous sulfate aqueous solution, and stirring for 10 minutes;
(6) drying at 90 deg.C for 8 hr, and ball milling for 2 hr;
(7) heating with 300W microwave oven under nitrogen atmosphere for 30 min, wherein the heating period is intermittent 100 times;
(8) soaking in 0.5M sulfuric acid for 8 hr, filtering and drying;
(9) heating to 1000 ℃ in a tubular furnace under the nitrogen atmosphere, preserving heat for 1 hour, and cooling along with the furnace.
Any reference to "one embodiment," "an embodiment," "example embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention; the schematic representations in various places in the specification do not necessarily refer to the same embodiment; further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
While specific embodiments of the invention have been described in detail with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention; in particular, reasonable variations and modifications are possible in the component parts and/or arrangements of the sub-combinations within the scope of the foregoing disclosure and the appended claims without departing from the spirit of the invention; except variations and modifications in the component parts and/or arrangements, the scope of which is defined by the appended claims and equivalents thereof.