Three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material and preparation method thereof
阅读说明：本技术 一种三维碳材料/二硒化钼电催化析氢材料及其制备方法 (Three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material and preparation method thereof ) 是由 郭大刚 罗浩 张珂馨 高燕 于 2021-09-29 设计创作，主要内容包括：本发明公开了一种三维碳材料/二硒化钼电催化析氢材料及其制备方法,制备方法包括如下过程：将石墨烯卷-碳纳米管三维碳材料加入溶液A中,之后进行水热反应,将水热反应的产物进行清洗、烘干；石墨烯卷-碳纳米管三维碳材料的制备过程包括：向氧化石墨烯水分散液中加入六水合硝酸镍,经搅拌溶解、淬冷,冷冻干燥后得到包裹硝酸镍的氧化石墨烯卷；在包裹硝酸镍的氧化石墨烯卷上进行碳纳米管的CVD生长,得到石墨烯卷-碳纳米管三维碳材料；溶液A的制备过程包括：将二水合钼酸钠和六水合硝酸钴加入含硒水合肼溶液,之后加入溶剂,搅拌均匀。本发明的三维碳材料/二硒化钼电催化析氢材料适用于在强酸或强碱电解液中进行高效析氢反应且性能稳定。(The invention discloses a three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material and a preparation method thereof, wherein the preparation method comprises the following steps: adding a graphene roll-carbon nanotube three-dimensional carbon material into the solution A, then carrying out hydrothermal reaction, and cleaning and drying a product of the hydrothermal reaction; the preparation process of the graphene roll-carbon nanotube three-dimensional carbon material comprises the following steps: adding nickel nitrate hexahydrate into the graphene oxide aqueous dispersion, stirring, dissolving, quenching, and freeze-drying to obtain a nickel nitrate-coated graphene oxide roll; carrying out CVD growth of a carbon nano tube on a graphene oxide roll wrapped with nickel nitrate to obtain a graphene roll-carbon nano tube three-dimensional carbon material; the preparation process of the solution A comprises the following steps: adding sodium molybdate dihydrate and cobalt nitrate hexahydrate into a selenium-containing hydrazine hydrate solution, then adding a solvent, and uniformly stirring. The three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material is suitable for carrying out high-efficiency hydrogen evolution reaction in strong acid or strong base electrolyte and has stable performance.)
1. A preparation method of a three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material is characterized by comprising the following steps:
adding a graphene roll-carbon nanotube three-dimensional carbon material into the solution A, then carrying out hydrothermal reaction, and cleaning and drying a product of the hydrothermal reaction to obtain the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material;
the preparation process of the graphene roll-carbon nanotube three-dimensional carbon material comprises the following steps:
adding nickel nitrate hexahydrate into the graphene oxide aqueous dispersion, stirring, dissolving, quenching, and freeze-drying to obtain a nickel nitrate-coated graphene oxide roll;
carrying out CVD growth of a carbon nano tube on a graphene oxide roll wrapped with nickel nitrate to obtain a graphene roll-carbon nano tube three-dimensional carbon material;
wherein the preparation process of the solution A comprises the following steps: adding sodium molybdate dihydrate and cobalt nitrate hexahydrate into a selenium-containing hydrazine hydrate solution, then adding a solvent, and uniformly stirring to obtain a solution A.
2. The preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 1, wherein in the process of preparing the graphene roll-carbon nanotube three-dimensional carbon material, the mass concentration of graphene oxide in the graphene oxide aqueous dispersion is 0.5-5 mg/mL;
the mass ratio of the cobalt nitrate hexahydrate to the graphene oxide is (1-10) to (10-1).
3. The preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 1, wherein in the process of preparing the graphene roll-carbon nanotube three-dimensional carbon material, nickel nitrate hexahydrate is added into graphene oxide aqueous dispersion, and then the mixture is magnetically stirred for 20-30 min to dissolve and is subjected to ultrasound for 30-60 min;
the temperature during freeze drying is-30 to-10 ℃, the vacuum degree is 10 to 50Pa, and the freeze drying time is 36 to 48 hours.
4. The method for preparing the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 1, wherein during the CVD growth of the carbon nanotubes on the graphene oxide roll coated with nickel nitrate:
firstly, carrying out heat treatment on the graphene oxide roll wrapped with the nickel nitrate, and then switching a carbon source gas to carry out CVD growth of the carbon nano tube.
5. The preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 4, wherein when the graphene oxide roll coated with the nickel nitrate is subjected to heat treatment, the graphene oxide roll coated with the nickel nitrate is heated to 700-800 ℃ at a rate of 3-10 ℃/min under Ar atmosphere, and then the temperature is kept for 20-40 min, so that the heat treatment is completed;
when the CVD growth of the carbon nano tube is carried out, the adopted carbon source gas is 5% -10% of ethylene-argon mixed gas, the gas flow rate is 100-200 sccm, and the growth time is 30-60 min.
6. The preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 1, wherein the selenium concentration in the selenium-containing hydrazine hydrate solution is 1-5 mg/mL; the molar ratio of molybdenum in sodium molybdate dihydrate to selenium in the selenium-containing hydrazine hydrate solution is 1 (2-4), and the molar ratio of molybdenum in sodium molybdate dihydrate to Co in cobalt nitrate hexahydrate is (20-100): 1.
7. The method for preparing the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 6, wherein the solvent is DMF solvent, and the volume of the DMF solvent is the same as the total volume of the sodium molybdate dihydrate, the cobalt nitrate hexahydrate and the selenium-containing hydrazine hydrate solution;
adding sodium molybdate dihydrate and cobalt nitrate hexahydrate into a selenium-containing hydrazine hydrate solution, then adding a DMF (dimethyl formamide) solvent, and carrying out ultrasonic treatment for 20-30 min to obtain a solution A.
8. The preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 1, wherein the graphene roll-carbon nanotube three-dimensional carbon material is added into the solution A according to a mass ratio of the graphene roll-carbon nanotube three-dimensional carbon material to sodium molybdate dihydrate of 1 (1-10).
9. The preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material as claimed in claim 1, wherein the hydrothermal reaction is carried out for 10-15 hours at 180-200 ℃, then products of the hydrothermal reaction are sequentially washed by deionized water and water ethanol, and are dried at 40-80 ℃ after being washed clean, so as to obtain the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material.
10. A three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material prepared by the preparation method of any one of claims 1 to 9.
Technical Field
The invention belongs to the technical field of electrocatalytic hydrogen evolution, and particularly relates to a three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material and a preparation method thereof.
Background
In order to achieve the goal of carbon neutralization, the basic directions of energy transformation in the future are mainly hydrogen energy, carbon capture, biomass and the like. The hydrogen energy source is mainly produced by coal gasification, petroleum cracking, low-temperature distillation and other preparation methods. At present, the hydrogen production by electrolyzing water is used as a clean and efficient mode, and the problem that the demand is contrary to the reality can be perfectly solved. In the electrolytic process, the electrode catalyst has considerable effects, such as reducing additional energy consumption, accelerating the hydrogen evolution rate, and the like. The noble metal catalyst has a unique electronic structure so that the noble metal catalyst shows high-efficiency hydrogen evolution performance. However, the high price and rarity are very daunting for the industry. Therefore, it is urgent to search for a catalyst which is efficient, inexpensive and abundant in reserves.
Theoretical calculations indicate that transition metal chalcogenides (MoS)2,MoSe2,CoSe2Etc.) has an electronic structure similar to that of Pt-based metal, meaning that it also has excellent hydrogen evolution properties in theory. However, MoSe2The tendency to agglomerate leads to a large reduction in catalytic sites at the edges and defect sites and its inherently poor conductivity is detrimental to the transport of electrons within the electrode/catalyst and catalyst. These limit MoSe2The electrocatalytic effect thereof cannot be sufficiently exerted. At present, to improve MoSe2The catalytic performance of (2) is mainly determined by the following three strategies. First, preparation of highly dispersed MoSe2Nano-sheet or nano-flower and the like, and a great amount of edges and defect active sites are generated by introducing defects into the crystal structure of the nano-sheet or nano-flower and the like; secondly, the electronic structure is regulated and controlled by doping heteroatom, phase transformation between 2H/1T phases is carried out, the conductivity of the electronic structure is increased, and the electronic transmission speed is improved; thirdly, compounding with three-dimensional carbon material, which can be MoSe2The growth of the catalyst provides a large amount of specific surface area, and the conductivity of the catalyst is greatly improved, so that the catalytic performance of the electrolyzed water is effectively improved. There is a great deal of research being devoted to the promotion of MoSe today2The improvement of the performance is realized,the composite materials synthesized still have a large gap compared to noble metal-based catalysts. Thus, MoSe2The electrocatalytic hydrogen evolution performance of the composite material still needs to be improved. In addition, current research is mainly based on acidic electrolytes, while in alkaline electrolytes, dissociation of water on the catalyst is slow, higher overpotential is required and catalytic efficiency is not high. Therefore, the development of the non-noble metal catalyst which is simultaneously suitable for strong acid and strong alkali conditions and has high electrocatalytic hydrogen evolution activity and stable performance has important significance.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material and a preparation method thereof.
The technical scheme adopted by the invention is as follows:
a preparation method of a three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material comprises the following steps:
adding a graphene roll-carbon nanotube three-dimensional carbon material into the solution A, then carrying out hydrothermal reaction, and cleaning and drying a product of the hydrothermal reaction to obtain the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material;
the preparation process of the graphene roll-carbon nanotube three-dimensional carbon material comprises the following steps:
adding nickel nitrate hexahydrate into the graphene oxide aqueous dispersion, stirring, dissolving, quenching, and freeze-drying to obtain a nickel nitrate-coated graphene oxide roll;
carrying out CVD growth of a carbon nano tube on a graphene oxide roll wrapped with nickel nitrate to obtain a graphene roll-carbon nano tube three-dimensional carbon material;
wherein the preparation process of the solution A comprises the following steps: adding sodium molybdate dihydrate and cobalt nitrate hexahydrate into a selenium-containing hydrazine hydrate solution, then adding a solvent, and uniformly stirring to obtain a solution A.
Preferably, in the process of preparing the graphene roll-carbon nanotube three-dimensional carbon material, the mass concentration of graphene oxide in the graphene oxide aqueous dispersion is 0.5-5 mg/mL;
the mass ratio of the cobalt nitrate hexahydrate to the graphene oxide is (1-10) to (10-1).
Preferably, in the process of preparing the graphene roll-carbon nanotube three-dimensional carbon material, nickel nitrate hexahydrate is added into graphene oxide aqueous dispersion, and the graphene oxide aqueous dispersion is magnetically stirred for 20-30 min to dissolve and then is subjected to ultrasonic treatment for 30-60 min;
the temperature during freeze drying is-30 to-10 ℃, the vacuum degree is 10 to 50Pa, and the freeze drying time is 36 to 48 hours.
Preferably, when the CVD growth of carbon nanotubes is performed on a graphene oxide roll wrapped with nickel nitrate:
firstly, carrying out heat treatment on the graphene oxide roll wrapped with the nickel nitrate, and then switching a carbon source gas to carry out CVD growth of the carbon nano tube.
Preferably, when the graphene oxide roll coated with the nickel nitrate is subjected to heat treatment, the graphene oxide roll coated with the nickel nitrate is heated to 700-800 ℃ at a speed of 3-10 ℃/min under Ar atmosphere, and then the temperature is kept for 20-40 min, so that the heat treatment is completed;
when the CVD growth of the carbon nano tube is carried out, the adopted carbon source gas is 5% -10% of ethylene-argon mixed gas, the gas flow rate is 100-200 sccm, and the growth time is 30-60 min.
Preferably, the selenium concentration in the selenium-containing hydrazine hydrate solution is 1-5 mg/mL; the molar ratio of molybdenum in sodium molybdate dihydrate to selenium in the selenium-containing hydrazine hydrate solution is 1 (2-4), and the molar ratio of molybdenum in sodium molybdate dihydrate to Co in cobalt nitrate hexahydrate is (20-100): 1.
Preferably, the solvent is DMF (namely N, N-dimethylformamide) solvent, and the volumes of sodium molybdate dihydrate, cobalt nitrate hexahydrate and the total volume of the selenium-containing hydrazine hydrate solution are the same;
adding sodium molybdate dihydrate and cobalt nitrate hexahydrate into a selenium-containing hydrazine hydrate solution, then adding a DMF (dimethyl formamide) solvent, and carrying out ultrasonic treatment for 20-30 min to obtain a solution A.
Preferably, when the graphene roll-carbon nanotube three-dimensional carbon material is added into the solution A, the graphene roll-carbon nanotube three-dimensional carbon material and sodium molybdate dihydrate are added according to the mass ratio of 1 (5-10).
Preferably, the hydrothermal reaction is carried out at 180-200 ℃ for 10-15 h, then the product of the hydrothermal reaction is sequentially washed by deionized water and ethanol, and dried at 40-80 ℃ after being washed, so as to obtain the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material.
The invention also provides a three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material which is prepared by the preparation method.
The invention has the following beneficial effects:
according to the preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material, graphene oxide rolls coated with nickel nitrate are prepared by using graphene oxide aqueous dispersion and nickel nitrate hexahydrate, and CVD growth of carbon nanotubes is carried out on the graphene oxide rolls coated with nickel nitrate, so that the carbon nanotubes grow on the inner layer, the outer layer and the interlayer of the graphene oxide rolls, the interlayer space of the graphene oxide rolls is expanded, and a larger specific surface area and a rich hierarchical pore structure are provided, as shown in figure 1. Thus, the loading of more active catalyst is facilitated. The confinement effect of the rich multi-level pore channel structure can accelerate the transfer speed of substances and charges, and lays a foundation for excellent hydrogen evolution performance. When a solution A prepared from sodium molybdate dihydrate, cobalt nitrate hexahydrate, selenium-containing hydrazine hydrate solution and solvent is subjected to hydrothermal reaction with a graphene roll-carbon nanotube three-dimensional carbon material, a graphene roll-carbon nanotube framework is used as MoSe2Growth of template to MoSe2The dispersion is more uniform, the agglomeration is prevented, and the interaction is compact, so that the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material can stably, durably and efficiently generate catalytic action in a strong acid or strong alkaline medium. In conclusion, the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material is suitable for carrying out high-efficiency hydrogen evolution reaction in strong acid or strong base electrolyte and has stable performance.
Drawings
Fig. 1 is an SEM image of the graphene roll-carbon nanotube three-dimensional carbon material (GNS @ CNT) prepared in comparative example 3.
FIG. 2 is a graphene roll-carbon nanotube composite (Co-MoSe) loaded with cobalt-doped 1T/2H mixed phase molybdenum diselenide prepared in example 12-GNS @ CNT).
FIG. 3 is a LSV polarization curve for example 1 versus comparative examples 1,2,3,4 and Pt/C under acidic conditions.
FIG. 4 is the LSV polarization curves for example 1 versus comparative examples 1,2,3,4 and Pt/C under basic conditions.
Detailed Description
The invention is further described below with reference to the figures and examples.
The invention aims to prepare a catalyst which is suitable for carrying out high-efficiency hydrogen evolution reaction in strong acid or strong base electrolyte and has stable performance. In the invention, the load of the cobalt-doped 1T/2H mixed phase molybdenum diselenide is carried out by taking the graphene roll-carbon nanotube three-dimensional carbon material as a framework, so that the problem of MoSe is solved2The catalytic hydrogen evolution activity is poor in practical use, and the catalytic hydrogen production can be efficiently carried out under the strong acid or strong alkaline condition.
Specifically, the preparation method of the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material comprises the following steps:
preparation of graphene roll-carbon nanotube three-dimensional carbon material
(1) Dispersing graphene oxide in deionized water, magnetically stirring for 20-30 min, and then performing ultrasonic treatment for 30-60 min to obtain graphene oxide aqueous dispersion with the mass concentration of 0.5-5 mg/mL;
(2) adding nickel nitrate hexahydrate into the graphene oxide aqueous dispersion prepared in the step (1), magnetically stirring for 20-30 min to dissolve, then performing ultrasonic treatment for 30-60 min, then quenching, and freeze-drying to obtain a graphene oxide roll coated with the nickel nitrate, wherein the mass ratio of the nickel nitrate hexahydrate to the graphene oxide is 1: 10-10: 1; quenching is carried out in liquid nitrogen; the freeze drying temperature is-30 to-10 ℃, the vacuum degree is 10 to 50Pa, and the freeze drying time is 36 to 48 hours.
(3) Transferring the oxidized graphene roll coated with the nickel nitrate into an aluminum oxide square boat, and then pushing the oxidized graphene roll into a tube furnace for heat treatment, wherein the heat treatment is carried out in Ar atmosphere at 700-800 ℃, the heating rate is 3-10 ℃/min, and the heat preservation time is 20-40 min; after the heat preservation is finished, switching to ethylene gas as a carbon source to perform CVD growth of the carbon nano tube, and obtaining the graphene roll-carbon nano tube three-dimensional carbon material, wherein the CVD growth conditions are as follows: the temperature is 700-800 ℃, the growth time is 30-60 min, the carbon source gas is 5-10% of ethylene-argon mixed gas, and the gas flow rate is 100-200 sccm.
Solvothermal synthesis of cobalt-doped 1T/2H mixed phase molybdenum diselenide loaded graphene roll-carbon nanotube hybrid material
(4) Adding selenium powder into hydrazine hydrate, heating to 80 ℃, and magnetically stirring for 1-3 h to obtain a selenium-containing hydrazine hydrate solution with the selenium content concentration of 1-5 mg/mL;
(5) adding a certain amount of sodium molybdate dihydrate and cobalt nitrate hexahydrate into the solution obtained in the step (4), then adding an isometric DMF solvent, and carrying out ultrasonic treatment for 20-30 min to obtain a uniform solution, wherein the ratio of Mo in the sodium molybdate dihydrate and the selenium powder: the molar ratio of Se is 1: 2-1: 4, the molar ratio of sodium molybdate dihydrate to Mo in cobalt nitrate hexahydrate is as follows: the molar ratio of Co is 100: 1-20: 1.
(6) Transferring the solution obtained in the step (5) into a polytetrafluoroethylene hydrothermal reaction kettle, adding a certain amount of the graphene roll-carbon nano tube three-dimensional carbon material prepared in the step (3), reacting for 10-15H at 180-200 ℃, washing a hydrothermal product with deionized water for 3 times, washing with absolute ethyl alcohol for 3 times, and drying in an oven at 40-80 ℃ to obtain the cobalt-doped 1T/2H mixed phase molybdenum diselenide-loaded graphene roll-carbon nano tube composite material, wherein the mass ratio of the graphene roll-carbon nano tube carbon material to sodium molybdate dihydrate is 1: 5-1: 10.
The preparation method of the cobalt-doped 1T/2H mixed-phase molybdenum diselenide-loaded graphene roll-carbon nanotube composite material provided by the invention is further described in detail with reference to specific examples.
Example 1
Example Co-MoSe2-GNS @ CNT preparation process comprising the following steps:
(1) dispersing graphene oxide in deionized water, magnetically stirring for 30min, and then performing ultrasonic treatment for 60min to obtain 2mg/mL graphene oxide aqueous dispersion;
(2) adding 40mg of nickel nitrate hexahydrate into 25mL of graphene oxide aqueous dispersion with the concentration of 2mg/mL prepared in the step (1), magnetically stirring for 30min to dissolve, and performing ultrasonic treatment for 60min to form uniform dispersion;
(3) placing the mixed solution obtained in the step (2) in a mould, and quickly freezing for 15min in liquid nitrogen;
(4) placing the frozen sample obtained in the step (3) in a freeze dryer for freeze drying at the temperature of minus 20 ℃, the vacuum degree of 30Pa and the freeze drying time of 48h to obtain a nickel nitrate-coated graphene oxide roll;
(5) and placing the graphene oxide roll wrapped with the nickel nitrate into an aluminum oxide square boat, pushing the aluminum oxide square boat into a tube furnace, performing heat treatment in an argon atmosphere at the temperature of 750 ℃, the heating rate of 5 ℃/min and the heat preservation time of 30min, then switching to 5% ethylene-argon mixed gas as a carbon source, the gas flow rate of 200sccm, the reaction temperature of 750 ℃ and the reaction time of 30min, and performing CVD growth of the carbon nanotube to obtain the graphene roll-carbon nanotube three-dimensional carbon material. As shown in fig. 1, in the obtained graphene roll-carbon nanotube three-dimensional carbon material prepared in this embodiment, the carbon nanotubes grow in the inner and outer layers and the interlayer of the graphene oxide roll, and the interlayer space of the graphene oxide roll is expanded, so as to provide a larger specific surface area and a rich hierarchical pore structure.
(6) 60mg of selenium powder is weighed and added into 20mL of hydrazine hydrate, the mixture is heated to 80 ℃ and stirred magnetically for 2h to obtain a selenium hydrazine hydrate solution, and then 80mg of sodium molybdate dihydrate, 2mg of cobalt nitrate hexahydrate and 20mLDMF are added into the mixture, and the mixture is subjected to ultrasonic treatment for 30min to obtain a uniform solution. And finally, adding 10mg of graphene roll-carbon nanotube three-dimensional carbon material into the system, transferring the graphene roll-carbon nanotube three-dimensional carbon material into a polytetrafluoroethylene hydrothermal reaction kettle, reacting for 12 hours at 180 ℃, cleaning a hydrothermal product with deionized water for 3 times, cleaning with absolute ethyl alcohol for 3 times, and drying in a 60 ℃ drying oven to obtain the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material. As shown in fig. 2, in the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material prepared by the embodiment, molybdenum diselenide uniformly grows on the three-dimensional carbon material in a nano-flake form and is tightly combined, so that the defect that the molybdenum diselenide is easy to agglomerate is overcome, the exposure of an active site of the molybdenum diselenide is facilitated in the electrocatalysis process, and the catalytic performance and the structural stability are greatly improved. In addition, molybdenum diselenide grows at the tip of the carbon nano tube to obtain a special three-layer sandwich structure. Due to the influence of the electron shuttling effect, the nano metal nickel particles in the carbon nano tube pass through the carbon nano tube layer to supply electrons to the molybdenum diselenide, so that the electronic structure of the molybdenum diselenide is optimized, the delta G value of H adsorbed on the crystal of the H is close to 0eV, and the conductivity of the H is increased. Therefore, the overpotential of hydrogen evolution is greatly reduced, and the performance of electrocatalytic hydrogen evolution is greatly improved.
Example 2
The preparation process of this example includes the following steps:
(1) dispersing graphene oxide in deionized water, magnetically stirring for 30min, and then performing ultrasonic treatment for 60min to obtain 5mg/mL graphene oxide aqueous dispersion;
(2) adding 12.5mg of nickel nitrate hexahydrate into 25mL of 5mg/mL graphene oxide aqueous dispersion prepared in the step (1), magnetically stirring for 25min to dissolve, and then performing ultrasonic treatment for 40min to form uniform dispersion;
(3) placing the mixed solution obtained in the step (2) in a mould, and quickly freezing for 15min in liquid nitrogen;
(4) placing the frozen sample obtained in the step (3) in a freeze dryer for freeze drying at the temperature of-10 ℃, the vacuum degree of 10Pa and the freeze drying time of 36h to obtain a nickel nitrate-coated graphene oxide roll;
(5) and placing the graphene oxide roll wrapped with the nickel nitrate into an aluminum oxide square boat, pushing the aluminum oxide square boat into a tube furnace, performing heat treatment in an argon atmosphere at the temperature of 700 ℃, the heating rate of 3 ℃/min, and the heat preservation time of 20min, then switching to 8% ethylene-argon mixed gas as a carbon source, the gas flow rate of 100sccm, the reaction temperature of 700 ℃, and the reaction time of 60min, and performing CVD growth of the carbon nanotube to obtain the graphene roll-carbon nanotube three-dimensional carbon material.
(6) Weighing 33mg of selenium powder, adding the selenium powder into 33mL of hydrazine hydrate, heating to 80 ℃, magnetically stirring for 2h to obtain a selenium hydrazine hydrate solution, then adding 50mg of sodium molybdate dihydrate, 0.6mg of cobalt nitrate hexahydrate and 33mLDMF, and carrying out ultrasonic treatment for 30min to obtain a uniform solution. And finally, adding 10mg of graphene roll-carbon nanotube three-dimensional carbon material into the system, transferring the graphene roll-carbon nanotube three-dimensional carbon material into a polytetrafluoroethylene hydrothermal reaction kettle, reacting for 10 hours at 190 ℃, washing a hydrothermal product with deionized water for 3 times, washing with absolute ethyl alcohol for 3 times, and drying in a drying oven at 40 ℃ to obtain the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material.
Example 3
The preparation process of this example includes the following steps:
(1) dispersing graphene oxide in deionized water, magnetically stirring for 30min, and then performing ultrasonic treatment for 60min to obtain 0.5mg/mL graphene oxide aqueous dispersion;
(2) adding 125mg of nickel nitrate hexahydrate into 25mL of 0.5mg/mL graphene oxide aqueous dispersion prepared in the step (1), magnetically stirring for 25min to dissolve, and then performing ultrasonic treatment for 40min to form uniform dispersion;
(3) placing the mixed solution obtained in the step (2) in a mould, and quickly freezing for 15min in liquid nitrogen;
(4) putting the frozen sample obtained in the step (3) into a freeze dryer for freeze drying at-30 ℃, under the vacuum degree of 50Pa, for 44h to obtain a nickel nitrate-coated graphene oxide roll;
(5) and placing the graphene oxide roll coated with the nickel nitrate into an aluminum oxide square boat, pushing the aluminum oxide square boat into a tube furnace, performing heat treatment under the argon atmosphere, then switching to 5% ethylene-argon mixed gas as a carbon source with the gas flow rate of 150sccm, the reaction temperature of 800 ℃ and the reaction time of 60min, and performing CVD growth of the carbon nanotube to obtain the graphene roll-carbon nanotube three-dimensional carbon material, wherein the temperature is 800 ℃, the heating rate is 10 ℃/min and the heat preservation time is 40 min.
(6) Weighing 130mg of selenium powder, adding the selenium powder into 26mL of hydrazine hydrate, heating to 80 ℃, magnetically stirring for 2h to obtain a selenium hydrazine hydrate solution, then adding 100mg of sodium molybdate dihydrate, 6mg of cobalt nitrate hexahydrate and 26mLDMF, and carrying out ultrasonic treatment for 30min to obtain a uniform solution. And finally, adding 10mg of graphene roll-carbon nanotube three-dimensional carbon material into the system, transferring the graphene roll-carbon nanotube three-dimensional carbon material into a polytetrafluoroethylene hydrothermal reaction kettle, reacting for 15 hours at 200 ℃, washing a hydrothermal product with deionized water for 3 times, washing with absolute ethyl alcohol for 3 times, and drying in an oven at 80 ℃ to obtain the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material.
Comparative example 1
The comparative example is used for preparing a graphene roll-carbon nanotube composite material MoSe loaded with 1T/2H mixed phase molybdenum diselenide2-GNS @ CNT comprising the steps of:
(1) dispersing graphene oxide in deionized water, magnetically stirring for 30min, and then performing ultrasonic treatment for 60min to obtain 2mg/mL graphene oxide aqueous dispersion;
(2) adding 40mg of nickel nitrate hexahydrate into 25mL of 5mg/mL graphene oxide aqueous dispersion prepared in the step (1), magnetically stirring for 30min to dissolve, and then performing ultrasonic treatment for 60min to form uniform dispersion;
(3) placing the mixed solution obtained in the step (2) in a mould, and quickly freezing for 15min in liquid nitrogen;
(4) placing the frozen sample obtained in the step (3) in a freeze dryer for freeze drying at the temperature of minus 20 ℃, the vacuum degree of 30Pa and the freeze drying time of 48h to obtain a nickel nitrate-coated graphene oxide roll;
(5) and placing the graphene oxide roll wrapped with the nickel nitrate into an aluminum oxide square boat, pushing the aluminum oxide square boat into a tube furnace, performing heat treatment in an argon atmosphere at the temperature of 750 ℃, the heating rate of 5 ℃/min and the heat preservation time of 30min, then switching to 5% ethylene-argon mixed gas as a carbon source, the gas flow rate of 200sccm, the reaction temperature of 750 ℃ and the reaction time of 30min, and performing CVD growth of the carbon nanotube to obtain the graphene roll-carbon nanotube three-dimensional carbon material.
(6) 60mg of selenium powder is weighed and added into 20mL of hydrazine hydrate, the mixture is heated to 80 ℃ and stirred magnetically for 2h to obtain a selenium hydrazine hydrate solution, and then 80mg of sodium molybdate dihydrate and 20mLDMF are added into the solution, and the solution is subjected to ultrasonic treatment for 30min to obtain a uniform solution. And finally, adding 10mg of graphene roll-carbon nanotube three-dimensional carbon material into the system, transferring the graphene roll-carbon nanotube three-dimensional carbon material into a polytetrafluoroethylene hydrothermal reaction kettle, reacting for 12 hours at 180 ℃, washing a hydrothermal product with deionized water for 3 times, washing with absolute ethyl alcohol for 3 times, and drying in a 60 ℃ drying oven to obtain the 1T/2H mixed phase molybdenum diselenide loaded graphene roll-carbon nanotube composite material.
Comparative example 2
The comparative example is used for preparing a graphene roll composite material MoSe loaded with 1T/2H mixed phase molybdenum diselenide2-GNS, comprising the steps of:
(1) dispersing graphene oxide in deionized water, magnetically stirring for 30min, and then performing ultrasonic treatment for 60min to obtain 2mg/mL graphene oxide aqueous dispersion;
(2) adding 40mg of nickel nitrate hexahydrate into 25mL of graphene oxide aqueous dispersion with the concentration of 2mg/mL prepared in the step (1), magnetically stirring for 30min to dissolve, and performing ultrasonic treatment for 60min to form uniform dispersion;
(3) placing the mixed solution obtained in the step (2) in a mould, and quickly freezing for 15min in liquid nitrogen;
(4) placing the frozen sample obtained in the step (3) in a freeze dryer for freeze drying at the temperature of minus 20 ℃, the vacuum degree of 30Pa and the freeze drying time of 48h to obtain a nickel nitrate-coated graphene oxide roll;
(5) 60mg of selenium powder is weighed and added into 20mL of hydrazine hydrate, the mixture is heated to 80 ℃ and stirred magnetically for 2h to obtain a selenium hydrazine hydrate solution, and then 80mg of sodium molybdate dihydrate and 20mLDMF are added into the solution, and the solution is subjected to ultrasonic treatment for 30min to obtain a uniform solution. Finally, adding 10mg of graphene roll into the system, transferring the graphene roll into a polytetrafluoroethylene hydrothermal reaction kettle, reacting for 12 hours at 180 ℃, cleaning a hydrothermal product with deionized water for 3 times, cleaning with absolute ethyl alcohol for 3 times, and drying in a 60 ℃ oven to obtain the 1T/2H mixed phase molybdenum diselenide loaded graphene roll composite material MoSe2-GNS。
Comparative example 3
The comparative example prepares a graphene roll-carbon nanotube three-dimensional carbon material GNS @ CNT, and comprises the following processes:
(1) dispersing graphene oxide in deionized water, magnetically stirring for 30min, and then performing ultrasonic treatment for 60min to obtain 2mg/mL graphene oxide aqueous dispersion;
(2) adding 40mg of nickel nitrate hexahydrate into 25mL of graphene oxide aqueous dispersion with the concentration of 2mg/mL prepared in the step (1), magnetically stirring for 30min to dissolve, and performing ultrasonic treatment for 60min to form uniform dispersion;
(3) placing the mixed solution obtained in the step (2) in a mould, and quickly freezing for 15min in liquid nitrogen;
(4) placing the frozen sample obtained in the step (3) in a freeze dryer for freeze drying at the temperature of minus 20 ℃, the vacuum degree of 30Pa and the freeze drying time of 48h to obtain a nickel nitrate-coated graphene oxide roll;
(5) and placing the graphene oxide roll wrapped with the nickel nitrate into an aluminum oxide square boat, pushing the aluminum oxide square boat into a tube furnace, performing heat treatment in an argon atmosphere at the temperature of 750 ℃, the heating rate of 5 ℃/min and the heat preservation time of 30min, then switching to 5% ethylene-argon mixed gas as a carbon source, the gas flow rate of 200sccm, the reaction temperature of 750 ℃ and the reaction time of 30min, and performing CVD growth of the carbon nanotube to obtain the graphene roll-carbon nanotube three-dimensional carbon material.
Comparative example 4
Preparation of 1T/2H Mixed phase molybdenum diselenide MoSe according to the comparative example2The method comprises the following steps:
60mg of selenium powder is weighed and added into 20mL of hydrazine hydrate, the mixture is heated to 80 ℃ and stirred magnetically for 2h to obtain a selenium hydrazine hydrate solution, and then 80mg of sodium molybdate dihydrate and 20mLDMF are added into the solution, and the solution is subjected to ultrasonic treatment for 30min to obtain a uniform solution. Transferring the mixture into a polytetrafluoroethylene hydrothermal reaction kettle, reacting for 12 hours at 180 ℃, cleaning a hydrothermal product with deionized water for 3 times, cleaning with absolute ethyl alcohol for 3 times, and drying in a 60 ℃ drying oven.
The samples prepared in the above examples and comparative examples were dispersed in a mixed solvent of water and ethanol, and 5% Nafion solution was added thereto, followed by ultrasonic dispersion to form an ink-like solution. The ink is uniformly dripped on the surface of a glassy carbon electrode, and is used as a working electrode after being dried, an Ag/AgCl electrode is used as a reference electrode, a carbon rod is used as a counter electrode, and a three-electrode system using 0.5M sulfuric acid solution or 1M potassium hydroxide solution as electrolyte is used for carrying out an electrochemical hydrogen evolution performance test, wherein the test standard is GB 32311 plus 2015, and the measurement result is shown in Table 1.
TABLE 1
As shown in FIG. 3, the current density was 10mA cm under acidic conditions-2Meanwhile, the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material has a lower overpotential of only 112mV, which shows that under an acidic condition, the unique three-dimensional carbon material of the invention, in cooperation with the doping and phase control of the molybdenum diselenide, greatly improves the catalytic hydrogen evolution performance.
As shown in FIG. 4, the current density under the alkaline condition was 10mA cm-2Meanwhile, the three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material also has a lower overpotential of only 113mV, which shows that the electrocatalytic hydrogen evolution material also has good catalytic hydrogen evolution performance under an alkaline condition.
As can be seen from table 1, compared with graphene, the graphene-carbon nanotube three-dimensional carbon material serving as a framework of molybdenum diselenide has a lower hydrogen evolution overpotential and lower required consumed electric energy no matter under strong acid or strong alkali conditions, and is more favorable for improving the hydrogen evolution performance of the active substance molybdenum diselenide. In addition, the hydrogen evolution overpotential is synergistically reduced by doping and phase control of the loaded molybdenum diselenide, so that the hydrogen evolution performance is optimized. The three-dimensional carbon material/molybdenum diselenide electrocatalytic hydrogen evolution material can be suitable for carrying out high-efficiency electrocatalytic hydrogen evolution reaction in strong acid or strong base electrolyte and has stable performance.
In summary, the technical scheme of the invention has the following characteristics:
(1) the unique graphene roll-carbon nanotube prepared by the invention is used as MoSe2The carbon support material greatly improves the catalytic hydrogen evolution performance. The three-dimensional graphene roll-carbon nanotube framework fully plays the role from three aspects. First, the Ni nanoparticles with unique structure in the three-dimensional carbon skeleton are wrapped by the tips of the carbon nanotubes. When MoSe is loaded on the framework2When the electron shuttling effect is influenced, the electrons in the Ni nano-particles can be transferred to MoSe through the carbon nano-tubes2On the nano-scale, thereby influencing its electronic structure, transferred from the semiconductor properties in the vicinity of the fermi surfaceChanging to metallic properties, the Δ G value for optimal H adsorption on its crystal is close to 0eV and increases its conductivity. Therefore, the hydrogen evolution overpotential is greatly reduced, and the MoSe is optimized2Hydrogen evolution activity of (1). In the unique structure, the carbon nano tubes grow on the inner layer, the outer layer and the interlayer of the graphene roll, and the interlayer space of the graphene roll is expanded, so that a larger specific surface area and a rich hierarchical pore structure are provided. Thus, the loading of more active catalyst is facilitated. The confinement effect of the rich multi-level pore channel structure can accelerate the transfer speed of substances and charges, and lays a foundation for excellent hydrogen evolution performance. Thirdly, the graphene roll-carbon nanotube skeleton is used as MoSe2The template is grown, so that the dispersion is more uniform, the agglomeration is prevented, the interaction is tight, and the catalyst can stably, durably and efficiently generate a catalytic action in a strong acid or strong alkaline medium.
(2) The invention synthesizes Co-doped 1T/2H mixed phase MoSe loaded by a solvothermal method2The graphene roll-carbon nanotube composite material. One, doping Co atoms in MoSe2In the nano-sheet, the electronic structure can be regulated, the catalytic activity of Se and Mo sites around Co can be activated, and the conductivity of the nano-sheet can be enhanced. Secondly, excessive Se is added in the solvothermal synthesis process, so that the excessive Se can be inserted into MoSe2In the nanosheet layer, 2H phase MoSe is caused2MoSe in which partial phase transition occurs to obtain 1T/2H mixed phase2. MoSe with phase transition2The conductivity is greatly improved. The invention utilizes the synergistic effect of atom doping and phase transition to reduce the charge transfer resistance and the internal resistance of the electrode and accelerate the MoSe2The electron transfer rate of (2) and the electrocatalytic hydrogen evolution activity of (3) are improved.
(3) The invention utilizes and improves MoSe2The high-efficiency non-noble metal hydrogen evolution catalyst is designed under the synergistic effect of three strategies on the catalytic performance. The composite material prepared by the invention has a unique multilevel structure, and can exert the catalytic hydrogen evolution performance with high efficiency and stable performance under the acidic or alkaline condition. The preparation method is simple, low in cost, wide in application range, excellent in electrocatalytic hydrogen evolution performance and wide in application prospect.