阅读说明：本技术 N、s缺陷共掺杂氧还原电催化剂 (N, S defect co-doped oxygen reduction electrocatalyst ) 是由 刘福臣 郭琪 于 2021-01-11 设计创作，主要内容包括：本发明公开了一种新型提出了一种利用逐步掺杂以及脱除过程来制备碳基催化剂的新型方法,可以分步地引入或脱除不同活性中心,从而对材料中的活性位种类和数量进行控制,逐步地提升材料催化性能。与其他合成方法相比,该方法简单,容易控制。N、S缺陷共掺杂缺陷碳材料具有高效的ORR催化性能,其半波电位为0.77V,研究表明缺陷与杂原子的掺杂共同促进了材料的氧还原反应性能。(The invention discloses a novel method for preparing a carbon-based catalyst by utilizing a gradual doping and removing process, which can introduce or remove different active centers step by step, thereby controlling the types and the number of active sites in a material and gradually improving the catalytic performance of the material. Compared with other synthesis methods, the method is simple and easy to control. N, S defect co-doped defect carbon material has high-efficiency ORR catalytic performance, the half-wave potential of the carbon material is 0.77V, and researches show that the oxygen reduction reaction performance of the material is promoted by doping of defects and heteroatoms.)

1. A preparation method of an electrocatalytic oxygen reduction catalyst. The method is characterized in that: the type and the quantity of active sites in the material are controlled by introducing different active centers in a stepwise manner, so that the N, S defect co-doped carbon-based oxygen reduction electrocatalyst is prepared, and the oxygen reduction property is tested.

2. The electrocatalytic oxygen reduction catalyst preparation method according to claim 1, characterized by: the high-temperature carbonization mode is temperature programming, and the heating and cooling speed is 10 ℃/min.

3. The electrocatalytic oxygen reduction catalyst preparation method according to claim 1, characterized by: when the active sites are introduced step by step, the sublimed sulphur is placed upstream of the tube furnace and the material is placed downstream. The temperature was 400 ℃.

4. The electrocatalytic oxygen reduction catalyst preparation method according to claim 1, characterized by: the carbonized carbon material was washed with 10% HF, 10% HCl, absolute ethanol, and acetone, respectively.

5. The electrocatalytic oxygen reduction catalyst preparation method according to claim 1, characterized by: in the electrochemical test, the electrode preparation ratio is a mixed solution of carbon material 6mg, 500. mu.l of distilled water and 500. mu.l of anhydrous ethanol and 50. mu.l of 5% Nafion, ultrasonic treatment is carried out for more than 2 hours, and 15. mu.l of the mixed solution is coated on the electrode (d is 5.5mm) to carry out the electrochemical oxygen reduction performance test.

6. The electrocatalytic oxygen reduction catalyst preparation method according to claim 1, characterized by: in electrochemical tests, electrolytesIs 0.1M HClO₄And (3) solution.

7. The method for preparing an electrocatalytic oxygen reduction catalyst according to claim 1, wherein: the N, S defect co-doped carbon material oxygen reduction catalyst synthesized by the method has a half-wave potential of 0.77V, so that the catalyst has excellent electrocatalytic oxygen reduction performance.

The technical field is as follows:

the invention belongs to the field of micromolecule electrocatalysis, and relates to an electrochemical oxygen reduction catalyst. The catalyst has high catalytic performance and excellent stability in an acid medium. Specifically, different active centers are introduced in a stepwise manner, so that the type and the quantity of active sites in the material are controlled, and the N, S defect co-doped carbon-based oxygen reduction electrocatalyst is prepared.

Background of the invention:

fuel cells are considered to be one of the cleanest solutions used in future portable electronic products and transportation systems. But due to the slow kinetics of the ORR reaction, the overall performance of the fuel cell is greatly limited. In order to promote the practical application of fuel cells, it is of decisive importance to develop an ORR electrocatalyst with economic efficiency to lower the reaction energy barrier and to improve the energy efficiency. Defect-rich metal-free carbon nanomaterials are used as cathodic Oxygen Reduction Reaction (ORR) catalysts due to their low cost, high conductivity and strong stability. Previous reports have conducted extensive research on heteroatom-doped metal-defect-free carbon materials. However, most of the metal-free carbon catalysts so far introduce all heteroatoms and defect sites by a one-step method, so that it is difficult to control the kinds and the number of active sites in the material, which greatly limits the reasonable design of the high-activity catalyst and prevents the further improvement of the catalytic performance of the material.

To this end, a novel method for preparing a carbon-based catalyst by using a stepwise doping and removal process is proposed, so as to introduce or remove different active centers step by step, thereby controlling the types and the number of active sites in the material and preparing a novel N, S defect co-doped electrocatalyst with high catalytic performance.

The invention content is as follows:

the invention provides a novel method for preparing N, S defect co-doped oxygen reduction catalyst by introducing active sites step by step, which adopts the following technical scheme:

(1) firstly, 3mg of ZnO QDs are ultrasonically dispersed in 100ml of DMF, and the mixture is magnetically stirred for 24 hours and then centrifuged by a centrifuge for 2min to obtain white precipitate. The resulting white precipitate was dried under vacuum at 40 ℃ for 3h to give a white powder.

(2) 200mg of the white powder dried in step (1) was weighed and placed in a tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Heating to 1000 deg.C at a heating rate of 10 deg.C/min, keeping the temperature for 2h, cooling to 300 deg.C at 10 deg.C per minute, and naturally cooling to room temperature to obtain black powder.

(3) And (3) putting the black powder obtained in the step (2) into the downstream of a tube furnace, and putting 100mg of sublimed sulfur into the upstream of the tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Heating to 400 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 2h, cooling to 300 ℃ at 10 ℃ per minute, and naturally cooling to room temperature.

(4) And (4) washing the material obtained in the step (3) for 2 hours respectively according to the sequence of 10% HF, 10% HCl, distilled water, absolute ethyl alcohol and acetone. Then the mixture is put into a vacuum drying oven to be dried at 60 ℃.

(5) After 6mg of the material obtained in step (4) was sufficiently ground, 500. mu.l of distilled water and 500. mu.l of absolute ethanol and 50. mu.l of a 5% Nafion solution were mixed, and subjected to ultrasonic treatment for 2 hours or more, and 15. mu.l of the mixture was applied to an electrode (d 5.5mm) to conduct an electrochemical oxygen reduction performance test.

Further, the temperature of the tube furnace in the step (2) can be 1000 ℃, 900 ℃ and 1100 ℃.

The invention has the following advantages:

(1) the method is simple and easy to control and operate.

(2) N, S defect co-doped electrocatalyst is synthesized by a two-step method, so that different active sites can be introduced step by step to control the material.

Description of the drawings:

fig. 1 is an XRD pattern of an N, S-defect carbon material oxygen-reduction electrocatalyst provided by an embodiment of the present invention.

Fig. 2 is a graph of the oxygen reduction performance of an N, S defective carbon material electrocatalyst provided in an example of the present invention.

The specific implementation mode is as follows:

the present invention is further illustrated by the following examples, which are not to be construed as limiting the invention to the particular embodiments set forth herein.

Example 1:

(1) firstly, 3mg of ZnO QDs are ultrasonically dispersed in 100ml of DMF, and the mixture is magnetically stirred for 24 hours and then centrifuged by a centrifuge for 2min to obtain white precipitate. The resulting white precipitate was dried under vacuum at 40 ℃ for 3h to give a white powder.

(2) 200mg of the white powder dried in step (1) was weighed and placed in a tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Temperature is programmed to rise at a temperature rise rate of 10 ℃/min

Keeping the temperature at 1000 ℃ for 2h, reducing the temperature to 300 ℃ per minute at 10 ℃, and then naturally reducing the temperature to room temperature to obtain black powder.

(3) And (3) putting the black powder obtained in the step (2) into the downstream of a tube furnace, and putting 100mg of sublimed sulfur into the upstream of the tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Heating to 400 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 2h, cooling to 300 ℃ at 10 ℃ per minute, and naturally cooling to room temperature.

(4) And (4) washing the material obtained in the step (3) for 2 hours respectively according to the sequence of 10% HF, 10% HCl, distilled water, absolute ethyl alcohol and acetone. Then the mixture is put into a vacuum drying oven to be dried at 60 ℃.

(5) Taking 6mg of the material obtained in the step (4), fully grinding, and mixing with 500. mu.l of distilled water and 500 mul of absolute ethyl alcohol and 50 mul of 5% Nafion solution are mixed, ultrasonic treatment is carried out for more than 2 hours, and 15 mul of the mixture is coated on an electrode (d is 5.5mm) to carry out electrochemical oxygen reduction performance test. The test system adopts a three-electrode system, the prepared ring disc electrode is used as a working electrode, Ag/AgCl (stored in saturated 3M KCl) is used as a reference electrode, a carbon rod is used as a counter electrode, and 0.1M HClO is selected as electrolyte₄The voltage range is-0.2V-1.1V (RHE), the sweep rate is 0.01V/s, the test is carried out in the atmosphere of oxygen, the electrode rotation speed is 1600rpm, the test system needs to be ventilated for 30 minutes before the test, the electrolyte gas saturation is ensured, and the gas flow rate is controlled by a flowmeter.

Example 2:

(1) firstly, 3mg of ZnO QDs are ultrasonically dispersed in 100ml of DMF, and the mixture is magnetically stirred for 24 hours and then centrifuged by a centrifuge for 2min to obtain white precipitate. The resulting white precipitate was dried under vacuum at 40 ℃ for 3h to give a white powder.

(2) 200mg of the white powder dried in step (1) was weighed and placed in a tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Heating to 900 deg.C at a heating rate of 10 deg.C/min, holding for 2h, cooling to 300 deg.C per minute at 10 deg.C, and naturally cooling to room temperature to obtain black powder.

(3) And (3) putting the black powder obtained in the step (2) into the downstream of a tube furnace, and putting 100mg of sublimed sulfur into the upstream of the tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Heating to 400 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 2h, cooling to 300 ℃ at 10 ℃ per minute, and naturally cooling to room temperature.

(4) And (4) washing the material obtained in the step (3) for 2 hours respectively according to the sequence of 10% HF, 10% HCl, distilled water, absolute ethyl alcohol and acetone. Then the mixture is put into a vacuum drying oven to be dried at 60 ℃.

(5) After 6mg of the material obtained in step (4) was sufficiently ground, 500. mu.l of distilled water and 500. mu.l of absolute ethanol and 50. mu.l of a 5% Nafion solution were mixed, and subjected to ultrasonic treatment for 2 hours or more, and 15. mu.l of the mixture was applied to an electrode (d 5.5mm) to conduct an electrochemical oxygen reduction performance test. The test system adopts a three-electrode system, the prepared ring disc electrode is a working electrode, and Ag/AgCl (preserved in saturated 3M KCl) is used as a working electrodeA reference electrode, a carbon rod counter electrode and an electrolyte are selected from 0.1M HClO₄The voltage range is-0.2V-1.1V (RHE), the sweep rate is 0.01V/s, the test is carried out in the atmosphere of oxygen, the electrode rotation speed is 1600rpm, the test system needs to be ventilated for 30 minutes before the test, the electrolyte gas saturation is ensured, and the gas flow rate is controlled by a flowmeter.

Example 3:

(1) firstly, 3mg of ZnO QDs are ultrasonically dispersed in 100ml of DMF, and the mixture is magnetically stirred for 24 hours and then centrifuged by a centrifuge for 2min to obtain white precipitate. The resulting white precipitate was dried under vacuum at 40 ℃ for 3h to give a white powder.

(2) 200mg of the white powder dried in step (1) was weighed and placed in a tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Heating to 1100 deg.C at a heating rate of 10 deg.C/min, holding for 2h, cooling to 300 deg.C per minute at 10 deg.C, and naturally cooling to room temperature to obtain black powder.

(3) And (3) putting the black powder obtained in the step (2) into the downstream of a tube furnace, and putting 100mg of sublimed sulfur into the upstream of the tube furnace. Nitrogen was introduced into the tube furnace for 30 minutes to ensure saturation with nitrogen. Heating to 400 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 2h, cooling to 300 ℃ at 10 ℃ per minute, and naturally cooling to room temperature.

(4) And (4) washing the material obtained in the step (3) for 2 hours respectively according to the sequence of 10% HF, 10% HCl, distilled water, absolute ethyl alcohol and acetone. Then the mixture is put into a vacuum drying oven to be dried at 60 ℃.

(5) After 6mg of the material obtained in step (4) was sufficiently ground, 500. mu.l of distilled water and 500. mu.l of absolute ethanol and 50. mu.l of a 5% Nafion solution were mixed, and subjected to ultrasonic treatment for 2 hours or more, and 15. mu.l of the mixture was applied to an electrode (d 5.5mm) to conduct an electrochemical oxygen reduction performance test. The test system adopts a three-electrode system, the prepared ring disc electrode is used as a working electrode, Ag/AgCl (stored in saturated 3M KCl) is used as a reference electrode, a carbon rod is used as a counter electrode, and 0.1M HClO is selected as electrolyte₄The voltage range is-0.2V-1.1V (RHE), the sweep rate is 0.01V/s, the test is carried out in the atmosphere of oxygen, the electrode rotation speed is 1600rpm, the test system needs to be ventilated for 30 minutes before the test, and the gas saturation of the electrolyte is ensuredThe gas flow rate is controlled by a flow meter.

The above examples show that: the electrochemical oxygen reduction catalyst material synthesized by the method provided by the invention has a half-wave potential of 0.77V, and can be compared favorably with a commercial Pt/C catalyst, so that the electrochemical oxygen reduction catalyst material has excellent electro-catalytic hydrogen evolution performance.