阅读说明：本技术 激光辐照合成介孔氮掺杂石墨烯负载二硫化钼的制备方法及在电催化产氢的应用 (Preparation method for synthesizing mesoporous nitrogen-doped graphene-loaded molybdenum disulfide through laser irradiation and application of mesoporous nitrogen-doped graphene-loaded molybdenum dis) 是由 杨静 覃佳艺 杜希文 于 2019-09-03 设计创作，主要内容包括：本发明涉及激光辐照合成介孔氮掺杂石墨烯负载二硫化钼的制备方法及在电催化产氢的应用。针对现有合成工艺并不能在低温低压下合成富含碳吡啶氮金属键的过渡金属氧化物/硫化物复合介孔氮掺杂石墨烯以及不能有效调控此复合体系中碳吡啶氮金属键的含量的问题,发现在177～315mJ范围内激光辐照氧化石墨烯可提升复合催化剂中碳-吡啶氮-钼键含量,且在水热过程中原料激光辐照氧化石墨烯和四硫代钼酸的质量比为1:1～1:8时可优化二硫化钼在介孔石墨烯上的负载量,从而在提高二硫化钼导电性的同时,界面处碳吡啶氮钼键也可以协同提升其本征活性,促进HER的电催化过程。该发明工艺简单,设计巧妙、安全环保、成本低廉。(The invention relates to a preparation method for synthesizing mesoporous nitrogen-doped graphene-loaded molybdenum disulfide through laser irradiation and application of the mesoporous nitrogen-doped graphene-loaded molybdenum disulfide in electrocatalytic hydrogen production. Aiming at the problems that the transition metal oxide/sulfide composite mesoporous nitrogen-doped graphene rich in carbon pyridine nitrogen metal bonds can not be synthesized at low temperature and low pressure by the existing synthesis process and the content of the carbon pyridine nitrogen metal bonds in the composite system can not be effectively regulated, the problem that the content of the carbon pyridine nitrogen-molybdenum bonds in the composite catalyst can be improved by irradiating the graphene oxide with laser within the range of 177-315 mJ is found, and the loading amount of molybdenum disulfide on the mesoporous graphene can be optimized when the mass ratio of the raw material laser irradiation graphene oxide to tetrathiomolybdate is 1: 1-1: 8 in the hydrothermal process, so that the conductivity of the molybdenum disulfide is improved, the carbon pyridine nitrogen molybdenum bonds at the interface can also synergistically improve the intrinsic activity of the carbon pyridine nitrogen molybdenum bonds, and the electrocatalytic process of HER is promoted. The invention has simple process, ingenious design, safety, environmental protection and low cost.)

1. A preparation method of mesoporous nitrogen-doped graphene loaded molybdenum disulfide by laser irradiation synthesis; the method is characterized by comprising the following steps:

(1) putting graphene oxide into absolute ethyl alcohol, carrying out ultrasonic crushing, uniformly dispersing to obtain a suspension of 0.25-0.4 g/L, pouring the suspension into a reactor, and irradiating for 20-30 min by using nanosecond parallel pulse laser under continuous magnetic stirring to obtain the laser-irradiated graphene oxide;

(2) centrifuging the laser-irradiated graphene oxide obtained in the step (1), cleaning the graphene oxide with deionized water, and dispersing the precipitate into the deionized water for freeze-drying;

(3) dispersing the freeze-dried graphene oxide subjected to laser irradiation and the ammonium tetrathiomolybdate obtained in the step (2) in N, N-dimethylformamide according to the mass ratio of 1: 1-1: 8, wherein the mass ratio of the laser-irradiated graphene oxide obtained in the step (2) in the N, N-dimethylformamide is 0.5-1 g/L, then adding urea, the mass ratio of the urea to the laser-irradiated graphene oxide is 20: 1-70: 1, adding hydrazine hydrate after uniform ultrasonic dispersion, enabling the concentration of the ammonium tetrathiomolybdate in the hydrazine hydrate to be 100-200 g/L, and continuing ultrasonic treatment for 10-20 min to obtain a mixed solution;

(4) pouring the mixed solution obtained in the step (3) into a reaction kettle, and reacting at 180-200 ℃ for 12-16 h to obtain a reaction product;

(5) and (4) centrifuging the product obtained in the step (4), cleaning the product with deionized water, and freeze-drying the product with a freeze dryer.

2. The preparation method according to claim 1, wherein the absolute ethanol used for dispersing graphene oxide in the step (1) has a purity of analytical purity or higher.

3. The preparation method according to claim 1, wherein when the nanosecond pulsed laser is irradiated in the step (1), the energy of the laser is 177-315 mJ, the wavelength is 1064nm, the repetition frequency of the laser is 10Hz, and the magnetic stirring speed is controlled to be 300-500 rpm.

4. The preparation method according to claim 1, wherein the liquid volume does not exceed 3/5 of the reactor volume when the laser is irradiated in the step (1), and the whole process is carried out in an ice-water bath.

5. The method according to claim 1, wherein the step (2) and the step (5) are performed by washing with deionized water, and after centrifuging at 15000-20000 rpm for 10-20 minutes, adding deionized water and centrifuging at 15000-20000 rpm for 10-20 minutes, and repeating at least 3 times until the product is odorless.

6. The mesoporous nitrogen-doped graphene-loaded molybdenum disulfide composite material prepared by the method in claim 1 is applied to electrocatalytic hydrogen production.

7. Use according to claim 6, characterised in that it comprises the following steps:

(1) placing mesoporous nitrogen-doped graphene-loaded molybdenum disulfide composite catalyst powder into an aqueous solution containing 4% -8% nafion solution, and performing ultrasonic dispersion after oscillation until uniform catalyst ink is obtained;

(2) dropping the prepared catalyst ink on the hydrophilic carbon fiber to ensure that the loading capacity is 0.3-0.5 mg cm^-2Naturally airing to obtain a working electrode; a three-electrode system is formed by taking a mesoporous nitrogen-doped graphene-loaded molybdenum disulfide composite catalyst as a working electrode, a saturated calomel electrode as a reference electrode and a graphite rod as a counter electrode, and a sulfuric acid aqueous solution is used as an electrolyte.

Technical Field

The invention relates to a method for improving electrocatalytic hydrogen production performance by taking graphene oxide irradiated by laser as a substrate, hydrothermally synthesizing a molybdenum disulfide/mesoporous nitrogen doped graphene compound, and taking carbon-pyridine nitrogen-molybdenum bonds formed by increased conductivity, exposed edge sites and an interface as high-activity sites. In particular to a preparation method for synthesizing mesoporous nitrogen doped graphene loaded molybdenum disulfide by laser irradiation and application thereof in electrocatalytic hydrogen production.

Background

With the increasing consumption of traditional fossil fuels and the resulting environmental degradation, for example: CO 2₂Induced greenhouse effect, SO₂The development and utilization of new clean energy by people are becoming reluctant due to the acid rain pollution and the haze caused by the exceeding of PM 2.5. Among the many clean energy sources, hydrogen energy is one of the most interesting clean energy sources. The application of electrocatalytic water decomposition and a fuel cell is two major ways of generating and utilizing hydrogen, however, in the hydrogen production by electrolyzing water, the key problems are energy consumption saving, cost reduction and yield and efficiency improvement to the maximum extent. The traditional hydrogen evolution electrode material is a platinum catalyst, which has strong corrosion resistance, good conductivity and excellent electrocatalytic performance, but due to high price and cost and poor mechanical strength, researchers at home and abroad successively develop a plurality of non-noble metal catalysts. In order to improve the performance of the non-noble metal catalysts, the modification can be carried out by means of morphological structure design, doping, defect vacancy manufacturing, interface creation and the like. The other half of the reaction OER is usually carried out in an alkaline environment for the purpose of full water splitting, so it is necessary to prepare a catalyst suitable for full pH hydrogen production, and Mo-based materials are advantageous in this respect.

MoS₂Due to the unique structural characteristics and the appropriate gibbs free energy for hydrogen absorption, it is widely used in acidic HER, but its application is greatly limited due to few active sites, mainly concentrated at the edges and poor electrical conductivity. In general we can consider improvements from three aspects: (1) changing the MoS₂The structure and the shape of the catalyst are used for increasing the number of active sites. See: xie J F, Zhang H, Li S, et al adv. Mater.,2013,25, 5807-one 5813. (2) MoS activation by doping of metals and non-metals, creation of sulfur vacancies to create defects₂An inert base surface. See: wang (Wang)H, Ouyang L Y, Zou G F, et al. ACS Catal.,2018,8, 9529-. (3) Mixing MoS₂Growing on the substrate with good conductivity or compounding with the nano material with high conductivity. See: tan Y W, Liu P, Chen L Y, et al adv. Mater.,2014,26, 8023-8028. However, these existing preparation methods tend to be from a single perspective for MoS₂Modification is carried out, namely, at present, no method exists for not damaging MoS₂Under the condition of an internal structure, the inert basal plane can be activated, more active sites are created, and the conductivity is improved, so that the improvement of the intrinsic activity of the material is promoted.

For MoS₂The combination with the carbon material generally improves the electrocatalytic performance from the following four aspects: firstly, the conductivity is increased, secondly, the specific surface area is increased, thirdly, more edge active sites are created, and fourthly, the free energy of H absorption is adjusted. See: li F, Li J, Gao Z, et al.J.Mater.chem.A,2015,3, 21772-21778; li Y G, Wang H L, Xie L M, et al.J.am.chem.Soc.,2011,133, 7296-; ma L B, Hu Y, Zhu G Y, et al chem. mater, 2016,28, 5733-. For MoS₂With nitrogen-doped carbon composites, MoS has been reported₂Loaded on nitrogen-doped carbon nano-box by virtue of excellent conductivity and unique hollow structure of nitrogen-doped carbon nano-box and dispersed ultrathin MoS₂The high specific surface area of the nano-sheets promotes the transfer of electrons and protons, so that the hydrogen production catalytic activity is improved, however, carbon-pyridine nitrogen-molybdenum bonds which are active sites are not formed on the interface to activate MoS₂Thus limiting further enhancement of its catalytic activity. See: yu X Y, Hu H, Wang Y W, et al, Angew, chem, int, Ed.2015,54, 7395-. Until later, Amiinu et al will MoS₂Loaded on ZIF-8 to form Mo-N/C @ MoS₂The structure of (1) is firstly proved by DFT theoretical calculation and comparative experiment that the formation of the interface molybdenum-nitrogen bond structure can lead the electron cloud on N/C to MoS₂Transferring to enhance the adsorption energy of H, thereby improving the HER performance, but the high-temperature annealing method causes the nitrogen species and content to be unadjustable. See: amiinu I S, Pu Z H, Liu X B, et al adv. Funct. Mater.,2017,27, 1702300-1702310. And, in addition, have been reported previouslyThe construction of carbon-pyridine nitrogen-metal bonds is illustrated to be greatly helpful for improving the intrinsic activity of the material, and the method is shown in the following steps: wang X R, Liu J Y, Liu Z W, et al adv. Mater.,2018,30, 1800005-. Therefore, if a means for controllably adjusting the nitrogen contents of different types can be adopted to maximally improve the proportional content of carbon-pyridine nitrogen-molybdenum bonds, the MoS can be activated to the maximum extent₂Thereby creating more reactive sites on the surface and further improving the HER catalytic performance of the system. However, the conditions required for synthesizing the composite system are relatively strict, and the content of different types of carbon-nitrogen-molybdenum bonds cannot be controllably adjusted by direct hydrothermal or high-temperature annealing methods, so that no work is mentioned at present in MoS₂The content of carbon-pyridine nitrogen-molybdenum bonds is increased by controllably adjusting the content of pyridine nitrogen in a nitrogen-doped graphene composite system, so that the HER catalytic performance is optimized. The laser irradiation of graphene oxide can generate a plurality of mesoporous structures under the quenching effect of rapid heating and quenching, the content of the mesoporous structures is increased along with the increase of laser energy, and the total nitrogen doping amount is slightly increased along with the increase of mesoporous density. In the nitrogen doping process, the pyridine N content is increased, the pyrrole N content is reduced, the graphite N content is basically unchanged, and the metal is easier to bond with the pyridine N. Therefore, the laser-irradiated graphene oxide is used as a matrix for hydrothermal nitrogen doping and MoS growth₂More mesoporous structures are created on graphene through laser, so that the content of carbon-pyridine nitrogen-molybdenum bonds in the hydrothermal process is increased, the conductivity is increased, more active sites are exposed, and the formed carbon-pyridine nitrogen-molybdenum bonds synergistically promote the HER electrocatalytic activity of the system. The molybdenum disulfide MoS can be synthesized by the existing synthesis technology₂And molybdenum disulfide composite nitrogen-doped graphene (MoS)₂/NG). Simple MoS₂The acidic hydrogen production performance of the catalyst is 10mA cm^-2The overpotential at (A) is 313.24mV, and the Tafel slope is 124.4mV dec^-1Molybdenum disulfide composite nitrogen-doped graphene MoS₂NG at 10mA cm^-2The overpotential at (A) is 187.14mV, and the Tafel slope is 64.5mV dec^-1. The performance of the mesoporous graphene subjected to laser irradiation is obviously improved and optimized after the mesoporous graphene is loaded with molybdenum disulfideThe performance can reach 10mA cm^-2The overpotential at (A) is 110.58mV, the Tafel slope is 50.1mV dec^-1The performance of the composite material is in the leading level in the current carbon material loaded molybdenum disulfide composite system.

Disclosure of Invention

Aiming at the problems that the existing synthesis process can not synthesize the transition metal oxide/sulfide composite mesoporous nitrogen-doped graphene rich in carbon pyridine nitrogen metal bonds at low temperature and low pressure and the content of the carbon pyridine nitrogen metal bonds in the composite system can not be effectively regulated, the invention discovers that the content of the carbon-pyridine nitrogen-molybdenum bonds in the composite catalyst can be increased by irradiating the graphene oxide with laser within the range of 177-315 mJ, and the loading amount of molybdenum disulfide on the mesoporous graphene can be optimized when the mass ratio of the raw material laser irradiation graphene oxide to tetrathiomolybdic acid is 1: 1-1: 8 in the hydrothermal process, so that the conductivity of the molybdenum disulfide is increased, the intrinsic activity of the carbon pyridine nitrogen molybdenum bonds at the interface can be synergistically increased, and the electrocatalytic process of HER is promoted. The invention has simple process, ingenious design, safety, environmental protection and low cost.

Preparation method for synthesizing mesoporous nitrogen-doped graphene-loaded molybdenum disulfide through laser irradiation and application of mesoporous nitrogen-doped graphene-loaded molybdenum disulfide in electro-catalysis hydrogen production

The invention provides a method for preparing a composite catalyst rich in carbon-pyridine nitrogen-molybdenum bonds by using laser irradiation to oxidize graphene to create more defect edges on the graphene, so that the number of doping sites of pyridine nitrogen is increased, and molybdenum disulfide is hydrothermally loaded on the nitrogen-doped graphene.

The technical scheme of the invention is as follows:

a preparation method for synthesizing mesoporous nitrogen-doped graphene loaded molybdenum disulfide by laser irradiation; the method comprises the following steps:

(1) putting graphene oxide into absolute ethyl alcohol, carrying out ultrasonic crushing, uniformly dispersing to obtain a suspension of 0.25-0.4 g/L, pouring the suspension into a reactor, and irradiating for 20-30 min by using nanosecond parallel pulse laser under continuous magnetic stirring to obtain the laser-irradiated graphene oxide;

(2) centrifuging the laser-irradiated graphene oxide obtained in the step (1), cleaning the graphene oxide with deionized water, and dispersing the precipitate into the deionized water for freeze-drying;

(3) dispersing the freeze-dried graphene oxide subjected to laser irradiation and the ammonium tetrathiomolybdate obtained in the step (2) in N, N-dimethylformamide according to the mass ratio of 1: 1-1: 8, wherein the mass ratio of the laser-irradiated graphene oxide obtained in the step (2) in the N, N-dimethylformamide is 0.5-1 g/L, then adding urea, the mass ratio of the urea to the laser-irradiated graphene oxide is 20: 1-70: 1, adding hydrazine hydrate after uniform ultrasonic dispersion, enabling the concentration of the ammonium tetrathiomolybdate in the hydrazine hydrate to be 100-200 g/L, and continuing ultrasonic treatment for 10-20 min to obtain a mixed solution;

(4) pouring the mixed solution obtained in the step (3) into a reaction kettle, and reacting at 180-200 ℃ for 12-16 h to obtain a reaction product;

(5) and (4) centrifuging the product obtained in the step (4), cleaning the product with deionized water, and freeze-drying the product with a freeze dryer.

Preferred conditions are as follows:

the purity of the absolute ethyl alcohol used for dispersing the graphene oxide in the step (1) is analytically pure or higher.

When the nanosecond pulse laser in the step (1) is irradiated, the energy of the laser is 177-315 mJ, the wavelength is 1064nm, the repetition frequency of the laser is 10Hz, and the magnetic stirring speed is controlled at 300-500 rpm.

When the laser irradiation is carried out in the step (1), the liquid volume does not exceed 3/5 of the volume of the reactor, and the whole process is carried out in an ice-water bath.

And (3) when the step (2) and the step (5) are cleaned by deionized water, after centrifuging for 10-20 minutes at the rotating speed of 15000-20000 rpm, adding the deionized water and centrifuging for 10-20 minutes at the rotating speed of 15000-20000 rpm, and repeating for at least 3 times until the product is odorless.

The mesoporous nitrogen-doped graphene-loaded molybdenum disulfide composite material prepared by the invention is applied to electrocatalytic hydrogen production.

The specific application can comprise the following steps:

(1) placing mesoporous nitrogen-doped graphene-loaded molybdenum disulfide composite catalyst powder into an aqueous solution containing 4% -8% nafion solution, and performing ultrasonic dispersion after oscillation until uniform catalyst ink is obtained;

(2) dropping the prepared catalyst ink on the hydrophilic carbon fiber to ensure that the loading capacity is 0.3-0.5 mg cm^-2Naturally airing to obtain a working electrode; a three-electrode system is formed by taking a mesoporous nitrogen-doped graphene-loaded molybdenum disulfide composite catalyst as a working electrode, a saturated calomel electrode as a reference electrode and a graphite rod as a counter electrode, and a sulfuric acid aqueous solution is used as an electrolyte.

Introducing N into the electrolyte₂And testing Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), EIS impedance spectrum and i-t stability until saturation. All potentials are converted into the potential of the relatively reversible hydrogen electrode by means of a formula, E_RHE＝E_{Saturated calomel}+0.0592 × pH +0.242V + iR correction. Conversion frequency TOF calculation formula: TOF ═ I/2 nF; i denotes the current (A) at a certain overpotential, F denotes the Faraday constant (96485.3C/mol), and n denotes the number of moles (mol) of molybdenum atoms on the prepared electrode.

Finally obtaining the laser-irradiated mesoporous nitrogen-doped graphene molybdenum disulfide-loaded composite catalyst, wherein the hydrogen production catalysis efficiency is realized by the condition that the current in the LSV is not more than 10mA cm within the voltage range of 0-minus 0.45V vs RHE^-2) Pure molybdenum disulfide (10 mA cm in LSV)^-2The overpotential at (A) is 313.24 mV; tafel slope of 124.4mV dec^-1) Molybdenum disulfide composite nitrogen-doped graphene (10 mA cm in LSV) obtained without laser action^-2The overpotential at (A) is 187.14 mV; tafel slope of 64.5mV dec^-1) Performance is improved to 10mA cm in LSV (laser-induced decomposition) of molybdenum disulfide composite mesoporous nitrogen-doped graphene^-2The overpotential of the position is 110.58mV at the lowest and the Tafel slope is 50.1mV dec at the lowest^-1It therefore has a lower reaction barrier and fastest reaction kinetics. And through the test of EIS impedance spectrum, the molybdenum disulfide composite mesoporous nitrogen doped graphene obtained under the action of laser can be found to have a smaller diameter similar to a semicircle than other products, so the electrochemical conductivity of the graphene is improved. In addition, through calculation of TOF (characterization of intrinsic catalytic activity), molybdenum disulfide composite mesoporous nitrogen doped stone obtained by laser action can be foundTOF of graphene can reach 0.21-2.54S^-1Is obviously higher than 0.091S of the molybdenum disulfide composite nitrogen-doped graphene obtained without the action of laser^-1Therefore, the molybdenum disulfide composite mesoporous nitrogen-doped graphene has more excellent intrinsic electrocatalytic hydrogen production activity. The molybdenum disulfide composite mesoporous nitrogen-doped graphene material can well keep the original composite structure characteristics after reaction, and also shows good catalytic stability for 80 hours in long-time tests.

The nanosecond pulse laser wavelength acting on the graphene oxide is 1064nm, and the laser repetition frequency is 10 Hz. In order to ensure that the suspension is uniformly dispersed and the probability of each part being irradiated by laser is equal, the magnetic stirring is required to be carried out continuously in the irradiation process, the whole experiment process is carried out in an exposed environment, protective gas is not required to be introduced in an ice water bath, the product can be directly poured out after the irradiation, and the operation is simple.

The invention has the following advantages: the nanosecond laser is utilized to irradiate the graphene oxide to create more defect edges on the graphene, and the defect edges are used as a substrate for hydrothermal nitrogen doping and MoS growth₂And the molybdenum disulfide/mesoporous nitrogen doped graphene composite material with high intrinsic activity is obtained by laser irradiation and optimization of the amount of raw materials in hydrothermal process to create more carbon-pyridine nitrogen-molybdenum bonds. The method firstly proposes that molybdenum in molybdenum disulfide preferentially forms a bond with pyridine nitrogen compared with other types of nitrogen (pyrrole nitrogen and graphite nitrogen), and the intrinsic activity of an electrocatalyst is positively correlated with the content of carbon-pyridine nitrogen-molybdenum bonds, so that the high-efficiency HER catalytic activity is realized, and a method for controllably regulating carbon-pyridine nitrogen metal bonds is proposed. In addition, the synthesis method adopted by the invention has the advantages of simple process, convenient operation, easy regulation and control, less toxic reaction raw materials and environmental-friendly green synthesis process. XPS tests show that when the laser energy is 177-315 mJ, the total nitrogen content and the pyridine nitrogen content in a sample are high, the pyridine nitrogen content is increased to 2.73-4.14 at% from the original 1.87 at% (molybdenum disulfide composite nitrogen-doped graphene obtained without laser action), and the catalytic hydrogen production performance of the molybdenum disulfide composite mesoporous nitrogen-doped graphene obtained by laser action is improved to 10mA c in LSVm^-2The overpotential of the Tafel is 175.96-110.58 mV and the lowest Tafel slope is 50.1mV dec^-1Compared with the pure nitrogen-doped graphene (the current in the LSV is less than 10mA cm within the voltage range of 0 to-0.45V vs RHE)^-2) Pure molybdenum disulfide (10 mA cm in LSV)^-2The overpotential at (A) is 313.24 mV; tafel slope of 124.4mV dec^-1) Molybdenum disulfide composite nitrogen-doped graphene (10 mA cm in LSV) obtained without laser action^-2The overpotential at (A) is 187.14 mV; tafel slope of 64.5mV dec^-1) There is a significant boost, and thus it has a lower reaction barrier and fastest reaction kinetics. And through the test of EIS impedance spectrum, the molybdenum disulfide composite mesoporous nitrogen doped graphene obtained under the action of laser can be found to have a smaller diameter similar to a semicircle than other products, so that the electrochemical conductivity of the graphene is improved. In addition, through calculation of TOF (characterization of intrinsic catalytic activity), TOF of the molybdenum disulfide composite mesoporous nitrogen-doped graphene obtained by laser action can reach 0.21-2.54S^-1Is obviously higher than 0.091S of the molybdenum disulfide composite nitrogen-doped graphene obtained without the action of laser^-1Therefore, the molybdenum disulfide composite mesoporous nitrogen-doped graphene has more excellent intrinsic electrocatalytic hydrogen production activity. The molybdenum disulfide composite mesoporous nitrogen-doped graphene material can well keep the original composite structure characteristics after reaction, and also shows good catalytic stability for 80 hours in long-time tests.

Drawings

Fig. 1 is a diagram of a process device for preparing mesoporous graphene oxide by nanosecond laser irradiation to expose more defect edges.

The nanosecond pulse laser wavelength acting on the graphene oxide is 1064nm, and the laser repetition frequency is 10 Hz. And (3) irradiating by using 177-315 mJ laser energy to improve the mesoporous density on the graphene oxide, and further obtaining more carbon-pyridine nitrogen-molybdenum bond composite materials in the next hydrothermal reaction. In order to ensure that the suspension is uniformly dispersed and the probability that each part is irradiated by laser is equal, magnetic stirring is required continuously in the irradiation process, the whole experiment process is carried out in an exposed environment, the whole device needs an ice water bath for avoiding that ethanol is heated and inflammable, protective gas is not required to be introduced, and the product can be directly poured out after irradiation, so that the operation is simple.

FIG. 2(a) shows molybdenum disulfide composite nitrogen-doped graphene (MoS)₂/NG) scanning electron micrographs; (b) example 1 molybdenum disulfide composite mesoporous nitrogen doped graphene (MoS)₂/NLG-270); (c) molybdenum disulfide composite nitrogen-doped graphene (MoS)₂/NG) and molybdenum disulfide composite mesoporous nitrogen-doped graphene (MoS) in example 1₂/NLG-270); (d) molybdenum disulfide composite nitrogen-doped graphene (MoS)₂/NG) and molybdenum disulfide composite mesoporous nitrogen-doped graphene (MoS) in example 1₂/NLG-270), inset: molybdenum disulfide composite nitrogen-doped graphene (MoS)₂/NG) and molybdenum disulfide composite mesoporous nitrogen-doped graphene (MoS) in example 1₂/NLG-270).

FIG. 3(a) mechanically mixed molybdenum disulfide and mesoporous nitrogen doped graphene (MoS)₂+ NLG-270), molybdenum disulfide composite nitrogen doped graphene (MoS)₂/NG) and example 1 molybdenum disulfide composite mesoporous nitrogen doped graphene (MoS)₂/NLG-270) from the N1s orbital photoelectron spectroscopy; (b) molybdenum disulfide, mechanically mixed molybdenum disulfide and mesoporous nitrogen doped graphene (MoS)₂+ NLG-270) and example 1 molybdenum disulfide composite mesoporous nitrogen doped graphene (MoS)₂/NLG-270) Mo 3d orbital X-ray photoelectron spectroscopy.

FIG. 4(a) molybdenum disulfide composite nitrogen doped graphene (MoS)₂/NG) and 177-315 mJ of different laser energy to obtain molybdenum disulfide composite mesoporous nitrogen-doped graphene (example 2 MoS)₂NLG-177, example 3MoS₂NLG-220, example 1MoS₂NLG-270, example 4MoS₂NLG-315) at 0.5M H₂SO₄Comparing the electrocatalytic hydrogen production performance in the solution; (b) molybdenum disulfide composite nitrogen-doped graphene (MoS)₂/NG) and 177-315 mJ of different laser energy to obtain molybdenum disulfide composite mesoporous nitrogen-doped graphene (example 2 MoS)₂NLG-177, example 3MoS₂NLG-220, example 1MoS₂NLG-270, example 4MoS₂/NLG-315) as a function of the different types of nitrogen content; (c) molybdenum disulfide composite nitrogen-doped graphene (MoS)₂/NG) and molybdenum disulfide composite mesoporous nitrogen-doped graphene with different loading amounts (example 1 MoS)₂NLG-270, example 5MoS₂-1/NLG-270, example 6MoS₂-4/NLG-270, example 7MoS₂-8/NLG-270) at 0.5M H₂SO₄Comparing the electrocatalytic hydrogen production performance in the solution.

Detailed Description

As shown in the synthesis device diagram of FIG. 1, a laser beam emitted by a laser device is vertically irradiated by a reflector, the position of the reaction container is adjusted to align the laser beam with the liquid level, and the magnetic stirring speed is suitably controlled between 300 revolutions per minute and 500 revolutions per minute. The nanosecond pulse laser wavelength acting on the graphene oxide is 1064nm, and the laser repetition frequency is 10 Hz. The whole experimental process is carried out in an exposed environment, and in order to avoid that the ethanol is heated and inflammable, the whole device needs an ice-water bath without introducing protective gas.

The present invention is further described in detail below by way of specific examples, which will enable one skilled in the art to more fully understand the present invention, but which are not intended to limit the invention in any way.