A photo-thermal and photo-catalytic composite system and a preparation method thereof

Abstract

The application provides a photothermal and photocatalysis composite system and a preparation method thereof, and relates to the technical field of photocatalysis.The photothermal and photocatalysis composite system comprises a floating carrier with a porous structure and a composite photothermal catalyst loaded on the upper half of the floating carrier; in the photothermal and photocatalysis process, the photothermal and photocatalysis composite system provided by the application is in a semi-submerged state, the upper half thereof for a photocatalysis hydrogen production reaction floats above the liquid surface, and the lower half thereof for water vapor transportation is submerged below the liquid surface. Compared with a traditional photothermal system, the application realizes continuous photothermal and photocatalysis by combining the photothermal and photocatalysis in the same system, achieves a higher water evaporation rate and hydrogen production efficiency under the same solar irradiation condition, effectively reduces the continuous leaching of the composite photothermal catalyst by loading the composite photothermal catalyst on the floating carrier with the porous structure, reduces the loss of the composite photothermal catalyst, and improves the retention rate of the composite photothermal catalyst.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalysis, in particular to a photo-thermal and photocatalytic composite system and a preparation method thereof. BACKGROUND

[0002] Energy is an important material basis for human survival and development. At present, the energy used by human beings is mainly non-renewable energy based on fossil fuels. It is estimated that fossil energy based on oil, natural gas and coal will be exhausted before 2050, and harmful gases such as SO2 and CO2 generated during the use of fossil energy have caused a series of environmental problems such as acid rain and greenhouse effect. Energy problems have become a great obstacle to social development. Therefore, in order to realize the sustainable development of society, clean, efficient and renewable new energy development is imminent.

[0003] Hydrogen energy is considered an ideal secondary energy because of its high heat value, clean product and abundant reserves of hydrogen elements on earth. Photocatalytic technology absorbs sunlight through photocatalysts to excite holes and electrons in the catalysts, and the holes are consumed by the sacrificial agent in the reaction system, while the electrons react with water to produce hydrogen. The entire process of producing hydrogen by light is green and pollution-free, which is one of the most ideal ways to obtain hydrogen energy. However, the traditional photocatalytic hydrogen production system has problems such as insufficient solar energy utilization, difficulty in recovering photocatalysts and slow reaction kinetics. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a photo-thermal and photocatalytic composite system and a preparation method thereof. The photo-thermal and photocatalytic composite system has the advantages of high solar energy utilization, high catalyst retention rate and high hydrogen production efficiency.

[0005] The present application provides a photo-thermal and photocatalytic composite system, which comprises a photo-thermal material, a photocatalyst and an additive. The photocatalyst and the additive are loaded on the upper half of the photo-thermal material. The photo-thermal material is a melamine trimer carbon foam carrier with a porous structure. The photocatalyst comprises copper titanium oxide, and the additive comprises ruthenium. In the photo-thermal and photocatalytic process, the photo-thermal and photocatalytic composite system is in a semi-submerged state. The upper half of the photo-thermal material loaded with the photocatalyst and the additive floats above the liquid surface for photocatalytic hydrogen production from water vapor. The lower half of the photo-thermal material is immersed below the liquid surface for absorbing solar energy to generate water vapor and transporting water vapor.

[0006] Under the solar radiation, the photo-thermal and photocatalytic composite system provided by the application generates water vapor quickly through the action of the photo-thermal material carbonized melamine foam carrier and the additive ruthenium, and then the water vapor rapidly diffuses to the active sites with the help of the porous structure of the carbonized melamine foam carrier and continuously performs photocatalytic hydrogen production under the action of the photocatalyst copper titanium oxide and the additive ruthenium; compared with the traditional photo-thermal and photocatalytic system, the photo-thermal and photocatalytic composite material provided by the application realizes the continuous performance of photo-thermal and photocatalysis by combining photo-thermal and photocatalysis in the same material, realizes a higher water evaporation rate and hydrogen production efficiency under the same solar radiation condition, and improves the utilization efficiency of solar energy; and the composite material loads the composite photo-thermal catalyst on the floating carrier with a porous structure, effectively reduces the continuous leaching of the composite photo-thermal catalyst, reduces the loss of the composite photo-thermal catalyst in the catalytic process, improves the retention rate of the composite photo-thermal catalyst, and also improves the continuous operation stability of the composite photo-thermal catalyst.

[0007] In a possible implementation, the additive further includes Mxenes nanosheets, and a material of the Mxenes nanosheets is Ti3C2. The Mxenes nanosheets are used as the additive, and because the Mxenes nanosheets have a large specific surface area, more active sites can be provided, and the efficiency of catalytic hydrogen production can be further improved.

[0008] In a possible implementation, the carbonized melamine foam carrier is prepared from melamine foam through annealing treatment.

[0009] The application further provides a preparation method of the photo-thermal and photocatalytic composite system.

[0010] S1, annealing treatment is performed on melamine foam to obtain a carbonized melamine foam carrier with a porous structure;

[0011] S2, titanium tetrachloride liquid is added dropwise into an aqueous solution containing urea and copper chloride, and stirring, heat preservation, and annealing are performed to obtain copper titanium oxide (CuTiO x );

[0012] S3, the copper titanium oxide in step S2 is ultrasonically dissolved in a mixed solution of deionized water and ethanol, and a ruthenium trichloride solution and a Mxenes nanosheet solution are added during the ultrasonic dissolution process, and then the mixture is uniformly mixed to obtain a precursor solution;

[0013] S4, the upper half of the carbonized melamine foam carrier with the porous structure prepared in step S1 is soaked in the precursor solution, and then the carbonized melamine foam carrier is obtained through drying to obtain the photo-thermal and photocatalytic composite system.

[0014] In a possible implementation, the annealing treatment in step S1 is performed at a temperature of 400-600 ℃.

[0015] In a possible implementation, the annealing treatment in step S1 is performed for 1-3 hours.

[0016] In a possible implementation, the concentration of urea in the aqueous solution in step S2 is 40-60 mg / mL.

[0017] In a possible implementation, the concentration of copper chloride in the aqueous solution in step S2 is 27-110 mg / mL.

[0018] In a possible implementation, the volume ratio of the titanium tetrachloride liquid to the aqueous solution in step S2 is 1:(50-70).

[0019] In a possible implementation, the stirring in step S2 is performed for 30-60 minutes.

[0020] In a possible implementation, the temperature of the heat preservation in step S2 is 80-110 ℃, and the time is 12-24 hours.

[0021] In a possible implementation, the annealing in step S2 is performed at a temperature of 300-500 ℃ at a rate of 2-5 ℃ / min for 1-3 hours.

[0022] In a possible implementation, the volume ratio of the ethanol to the deionized water in the mixed solution in step S3 is 2:1.

[0023] In a possible implementation, the ultrasonic dissolution in step S3 is performed for 10-60 minutes.

[0024] In a possible implementation, the concentration of the ruthenium trichloride solution in step S3 is 5 mg / mL.

[0025] In a possible implementation, the solvent of the ruthenium trichloride solution in step S3 is deionized water.

[0026] In a possible implementation, the concentration of the Mxenes nanosheet solution in step S3 is 1-5 mg / mL, preferably 3 mg / mL.

[0027] In a possible implementation, the preparation method of the Mxenes nanosheet solution in step S3 comprises the following steps: reacting MAX phase Ti3AlC2 in an aqueous solution containing LiF and HCl, centrifuging the reacted solution to obtain a precipitate, configuring the precipitate into an aqueous solution, performing ultrasonic exfoliation under ice bath conditions, and then taking the upper solution to perform centrifugal treatment to obtain a Mxenes nanosheet solution. Generally, the MXene contained in the upper solution is few-layer and single-layer.

[0028] Further, the concentration of LiF in the aqueous solution is 80 mg / mL.

[0029] Further, the concentration of HCl in the aqueous solution is 9 mol / L.

[0030] Further, the temperature of the reaction is 20-40 ℃, and the time is 24-36 h.

[0031] Further, the process of centrifugal washing is as follows: the solution after the reaction is placed in a centrifugal tube, then water is added in the centrifugal tube, after centrifugal washing, the supernatant is poured out, and the above centrifugal washing step is repeated until the pH value of the solution is 6-7, and the precipitate is obtained.

[0032] Further, the temperature of the ice bath is 2-10 ℃, preferably 4 ℃.

[0033] Further, the time of ultrasonic stripping is 10-15 min.

[0034] Further, the speed of centrifugal treatment is 2000-3500 rpm, and the time is 1-3 h.

[0035] In a possible implementation, after the carbonized melamine foam carrier in step S4 is initially soaked in the precursor solution, the first drying is performed, then the second soaking in the precursor solution is performed, and then the second drying is performed, so that the photo-thermal and photocatalytic composite system is obtained.

[0036] Further, the time of the initial soaking is 10-30 min.

[0037] Further, the temperature of the first drying and the second drying is 60-110 ℃.

[0038] Further, the time of the first drying is 1-3 h.

[0039] Further, the time of the second drying is 3-6 h.

[0040] The reagents and raw materials used in the application are commercially available.

[0041] The positive progress effect of the application is that:

[0042] The light-thermal and photocatalytic composite system provided by the application has higher solar energy utilization rate, catalyst retention rate and hydrogen production efficiency than a traditional light-thermal system under the same solar irradiation condition; the light-thermal and photocatalytic composite system can also maintain good reaction activity in river water and seawater, and has excellent environmental adaptability, and is suitable for various scenes such as household water supply, wastewater treatment and seawater desalination; and the composite light-thermal catalyst used does not need noble metals, so that the material cost is significantly reduced, and the floating design of the system reduces the complexity of installation and maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 A physical diagram of the melamine foam without annealing treatment in Example 1.

[0044] Figure 2 A physical diagram of the carbonized melamine foam prepared by annealing treatment in Example 1.

[0045] Figure 3 An SEM diagram of the carbonized melamine foam prepared by annealing treatment in Example 1.

[0046] Figure 4 An SEM diagram of the carbonized melamine foam loaded with copper titanium oxide / Mxenes / Ru prepared in Example 1.

[0047] Figure 5 A TEM diagram and an element distribution diagram of the copper titanium oxide prepared in Example 1.

[0048] Figure 6 A local SEM diagram of the copper titanium oxide / Mxenes / Ru loaded on the carbonized melamine foam in Example 1.

[0049] Figure 7 A TEM diagram of the Mxenes ultrathin nanosheet prepared in Example 1.

[0050] Figure 8 A UV-VIS spectrum diagram of the light-thermal and photocatalytic composite system prepared in Example 1 and Example 2.

[0051] Figure 9 A hydrogen production efficiency data diagram of the light-thermal and photocatalytic composite system prepared in Example 1 and Example 2. DETAILED DESCRIPTION

[0052] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the application, and do not limit the parameter range described in the application, and reasonable changes derived therefrom are still within the protection scope of the claims of the application.

[0053] It is to be understood that the endpoints of the ranges specified in this disclosure are not to be understood as being limited to the exact values recited as the exact dimensions are not to be construed as being resticted:

[0054] Unless otherwise defined, all terms used in disclosing this application, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In some instances, commonly understood terms have been purposefully excluded in order to give meaning to terms used in this disclosure. The terms "a", "an" and "the" used in this disclosure are used generically and not in the limiting sense. The technical methods described or referenced in this disclosure are generally well known to those skilled in the art and are employed by conventional methods. Unless otherwise stated, the use of commercially available kits and reagents, instruments are performed according to the protocols and parameters given by the manufacturer.

[0055] Example 1

[0056] This embodiment provides a photo-thermal and photocatalytic composite system, which is prepared by the following preparation method:

[0057] (1) Preparation of floating carrier; purchased commercial melamine foam is cut into small cubes of 6 cm*3 cm*2 cm, placed in a tube furnace for annealing, the heating rate is set to 5 ℃ / min, the highest temperature is 400 ℃, and after holding for 1 h, it is naturally cooled to obtain carbonized melamine foam;

[0058] (2) Preparation of copper titanium oxide:

[0059] D1, add 50 mL of deionized water to a reaction kettle, and then add 3 g of urea and 1.9-5.4 g of copper chloride under magnetic stirring, stir until the solution color is uniform, and the stirring time is about 10 min;

[0060] D2, slowly add 1.2 mL of titanium tetrachloride liquid to the solution described in step D1, stir vigorously for 30 min, then place it in an oven at 90 ℃ for 12 h, and then centrifuge 2-3 times, and then dry at 60 ℃ to obtain a dry powder;

[0061] D3, place the dry powder described in step D2 in a tube furnace, and anneal under high-purity argon protection, the heating rate of the tube furnace is set to 5 ℃ / min, the highest temperature is 400 ℃, and after holding for 1 h, it is naturally cooled to obtain copper titanium oxide (CuTiO x );

[0062] (3) Preparation of Mxenes ultra-thin nanosheet solution:

[0063] F1, 1.6 g LiF was added to 20 mL of 9M HCl solution, and stirred for 30 min at 40°C to form a mixed solution;

[0064] F2, 1 g of Ti3AlC2 MAX phase was added to the mixed solution described in step F1 in small amounts under stirring, and the addition process was controlled for more than 30 min to obtain a reaction solution;

[0065] F3, the reaction solution described in step F2 was sealed in a reaction tank and stirred at 40°C for 24 h;

[0066] F4, after the reaction was completed, the obtained solution was divided into at least 4 equal parts and loaded into 50 mL centrifuge tubes, then deionized water was added to 45-50 mL for centrifugal washing, the supernatant was discarded, and the above washing step was repeated several times until the solution pH value was 6-7;

[0067] F5, after washing, the obtained precipitate was redispersed in 20-30 mL of deionized water, shaken well to mix evenly, and then ultrasonically stripped for 10-15 min under 4°C ice bath conditions;

[0068] F6, after ultrasonic stripping, centrifugation was performed for 1 h at 2000-3500 rpm, and then the upper solution was taken, which generally contained 1-10 layers of MXene nanosheets, i.e. MXene ultra-thin nanosheets, and the concentration of Mxenes ultra-thin nanosheets in the upper solution was 3 mg / ml;

[0069] (4) Loading of composite photothermal catalyst CTRM (CuTiO x -Ru-Mxenes ultra-thin nanosheet):

[0070] H1, the copper titanium oxide (CuTiO x ) prepared in step (2) was placed in a mixture of 5 mL of deionized water and 10 mL of ethanol and ultrasonicated for 30 min, during which 200 ul of 5 mg / mL ruthenium trichloride solution was added at intervals of 10 min, and then 400 ul of 3 mg / mL Mxenes nanosheet solution was added after 10 min, to form a solution containing a precursor of a composite photothermal catalyst;

[0071] H2, the melamine carbon foam obtained in step (1) is placed in the solution containing the precursor of the composite photothermal catalyst described in step H1, soaked for 10 min, the soaking area of the melamine carbon foam is half of the total height of the melamine carbon foam, then placed in an oven, and after 1 h of heat preservation at 90 ℃, taken out, soaked in the solution containing the precursor of the composite photothermal catalyst again until the solution is almost completely absorbed, and placed in the oven again for 3 h of heat preservation at 90 ℃.

[0072] Example 2

[0073] The present embodiment provides a photothermal and photocatalytic composite system, which is prepared by the following preparation method:

[0074] (1) Preparation of floating carrier; the purchased commercial melamine foam is cut into small cubes of 6 cm*3 cm*2 cm, annealed in a tube furnace, the heating rate is set to 5 ℃ / min, the highest temperature is 400 ℃, and after 1 h of heat preservation, it is naturally cooled to obtain melamine carbon foam;

[0075] (2) Preparation of copper titanium oxide:

[0076] D1, 70 mL of deionized water is added to a reaction kettle, and 3 g of urea and 1.9-5.4 g of copper chloride are added under magnetic stirring, and the solution is stirred until the color is uniform, and the stirring time is about 10 min;

[0077] D2, 1.2 mL of titanium tetrachloride liquid is slowly added to the solution described in step D1, and stirred vigorously for 30 min, then placed in an oven for 12 h of heat preservation at 90 ℃, and then centrifuged 2-3 times, and then dried at 60 ℃ to obtain a dry powder;

[0078] D3, the dry powder described in step D2 is placed in a tube furnace and annealed under high-purity argon protection, the heating rate of the tube furnace is set to 5 ℃ / min, the highest temperature is 400 ℃, and after 1 h of heat preservation, it is naturally cooled to obtain copper titanium oxide (CuTiO x );

[0079] (3) Loading of composite photothermal catalyst CTR (CuTiO x -Ru):

[0080] H1, the copper titanium oxide (CuTiO x ) prepared in step (2) is placed in a mixture of 5 mL of deionized water and 10 mL of ethanol and ultrasonicated for 30 min, and 400 ul of 5 mg / mL ruthenium trichloride solution is added at intervals of 10 min to form a solution containing the precursor of the composite photothermal catalyst;

[0081] H2, the melamine carbon foam obtained in step (1) is placed in the solution containing the precursor of the composite photothermal catalyst described in step H1, soaked for 10 min, the soaking area of the melamine carbon foam is half of the total height of the melamine carbon foam, then placed in an oven, and after 1 h of incubation at 90 ℃, taken out, soaked again in the solution containing the precursor of the composite photothermal catalyst, until the solution is almost completely absorbed, and then placed in the oven again, incubated at 90 ℃ for 3 h.

[0082] Example 3

[0083] The present embodiment provides a photothermal and photocatalytic composite system, which is prepared by the following preparation method:

[0084] (1) Preparation of floating carrier; the purchased commercial melamine foam is cut into small cubes of 6 cm*3 cm*2 cm, and then annealed in a tube furnace, under the protection of high-purity argon gas, the temperature rising rate is set to 5 ℃ / min, the highest temperature is 600 ℃, and after incubation for 1 h, it is naturally cooled to obtain melamine carbon foam;

[0085] (2) Preparation of copper titanium oxide:

[0086] D1, 50 mL of deionized water is added to a reaction kettle, and 3 g of urea and 1.9-5.4 g of copper chloride are added under magnetic stirring, respectively, and stirred until the solution color is uniform, and the stirring time is about 10 min;

[0087] D2, slowly add 1.2 mL of titanium tetrachloride liquid to the solution described in step D1, and stir vigorously for 60 min, then place in an oven and incubate at 80 ℃ for 24 h, then centrifuge 2-3 times, and then dry at 60 ℃ to obtain a dry powder;

[0088] D3, the dry powder described in step D2 is placed in a tube furnace and annealed under the protection of high-purity argon gas, the temperature rising rate of the tube furnace is set to 2 ℃ / min, the highest temperature is 300 ℃, and after incubation for 3 h, it is naturally cooled to obtain copper titanium oxide (CuTiO x );

[0089] (3) Preparation of Mxenes ultra-thin nanosheet solution:

[0090] F1, 1.6 g of LiF is added to 20 mL of 9 mol / L HCl solution, and stirred at 40 ℃ for 30 min to form a mixed solution;

[0091] F2, under stirring, 1 g of Ti3AlC2MAX phase is added to the mixed solution described in step F1 in small amounts, as much as possible each time, and the addition process is controlled for more than 30 min to obtain a reaction solution;

[0092] F3, the reaction solution described in step F2 is closed in a reaction cell, and the reaction is stirred at a temperature of 20 °C for 36 h;

[0093] F4, after the reaction is completed, the obtained solution is divided into at least 4 equal parts and loaded into 50 mL centrifuge tubes, then deionized water is added to 45-50 mL for centrifugal washing, the supernatant is poured out, and the above washing step is repeated multiple times until the solution pH value is 6-7;

[0094] F5, after the washing is completed, the obtained precipitate is redispersed in 20-30 mL deionized water, shaken thoroughly to mix uniformly, and then ultrasonically stripped for 10 min under the condition of 10 °C ice bath;

[0095] F6, after the ultrasonic stripping is completed, centrifugation is performed again for 1 h at a speed of 3500 rmp, and then the upper solution is taken, generally the MXene nanosheet contained in the upper solution has 1-10 layers, that is, MXene ultrathin nanosheet, and the concentration of the Mxenes ultrathin nanosheet in the upper solution is 3 mg / ml;

[0096] (4) loading of the composite photothermal catalyst CTRM (CuTiO x -Ru-Mxenes ultrathin nanosheet):

[0097] H1, the copper titanium oxide (CuTiO x ) prepared in step (2) is placed in a mixture of 5 mL deionized water and 10 mL ethanol and ultrasonically dissolved for 10 min, during which 600 ul of a ruthenium trichloride solution with a concentration of 5 mg / mL is added at intervals of 10 min, and then 200 ul of a Mxenes nanosheet solution with a concentration of 5 mg / mL is added after 10 min, to form a solution containing a precursor of the composite photothermal catalyst;

[0098] H2, the melamine cyanamide carbide foam obtained in step (1) is placed in the solution containing the precursor of the composite photothermal catalyst described in step H1, soaked for 10 min, the soaking area of the melamine cyanamide carbide foam is half of the total height of the melamine cyanamide carbide foam, then placed in an oven, and heated at a temperature of 60 °C for 3 h, taken out again, soaked in the solution containing the precursor of the composite photothermal catalyst again until the solution is almost completely absorbed, and then placed in an oven again, and heated at a temperature of 90 °C for 6 h.

[0099] Example 4

[0100] The embodiment provides a photothermal and photocatalytic composite system, which is prepared by the following preparation method:

[0101] (1) Preparation of floating carrier; purchased commercial melamine foam is cut into small cubes of 6 cm*3 cm*2 cm, placed in a tube furnace for annealing, the heating rate is set to 5 ℃ / min under high-purity argon protection, the highest temperature is 400 ℃, and after holding for 3 h, it is naturally cooled to obtain carbonized melamine foam;

[0102] (2) Preparation of copper titanium oxide:

[0103] D1, 70 mL of deionized water is added to a reaction kettle, and 3 g of urea and 1.9-5.4 g of copper chloride are added under magnetic stirring, respectively, and stirred until the solution color is uniform, and the stirring time is about 10 min;

[0104] D2, 1.2 mL of titanium tetrachloride liquid is slowly added to the solution described in step D1, and stirred vigorously for 60 min, and then placed in an oven at 110 ℃ for 18 h, and then centrifuged 2-3 times, and then dried at 60 ℃ to obtain a dry powder;

[0105] D3, the dry powder described in step D2 is placed in a tube furnace and annealed under high-purity argon protection, the heating rate of the tube furnace is set to 5 ℃ / min, the highest temperature is 500 ℃, and after holding for 1 h, it is naturally cooled to obtain copper titanium oxide (CuTiO x );

[0106] (3) Preparation of Mxenes ultra-thin nanosheet solution:

[0107] F1, 1.6 g of LiF is added to 20 mL of 9M HCl solution, and stirred at 40 ℃ for 30 min to form a mixed solution;

[0108] F2, under stirring, 1 g of Ti3AlC2 MAX phase is added to the mixed solution described in step F1 in multiple small amounts, as small as possible each time, and the addition process is controlled for more than 30 min to obtain a reaction solution;

[0109] F3, the reaction solution described in step F2 is sealed in a reaction cell and stirred at 30 ℃ for 30 h;

[0110] F4, after the reaction is completed, the obtained solution is divided into at least 4 equal parts and loaded into 50 mL centrifuge tubes, then deionized water is added to 45-50 mL for centrifugal cleaning, the supernatant is discarded, and the above cleaning step is repeated multiple times until the solution pH value is 6-7;

[0111] F5, after washing, the obtained precipitate is redispersed in 20-30 mL of deionized water, shaken thoroughly to mix evenly, and then ultrasonically stripped in an ice bath at 2 ℃ for 15 min;

[0112] F6, after ultrasonic exfoliation, centrifugation for 3 h at 2000 rpm, then take the upper solution, the number of layers of MXene nanosheets contained in the upper solution is 1-10 layers, that is, MXene ultrathin nanosheets, the concentration of Mxenes ultrathin nanosheets in the upper solution is 3 mg / ml;

[0113] (4) loading of composite photothermal catalyst CTRM (CuTiO x -Ru-Mxenes ultrathin nanosheets):

[0114] H1, the copper titanium oxide (CuTiO x ) prepared in step (2) is placed in a mixture of 5 mL deionized water and 10 mL ethanol and ultrasonically dissolved for 60 min, during which 800 ul of 5 mg / mL ruthenium trichloride solution is added at intervals of 10 min, and then 100 ul of 1 mg / mL Mxenes nanosheet solution is added after 10 min, forming a solution containing a precursor of a composite photothermal catalyst;

[0115] H2, the melamine carbide foam obtained in step (1) is placed in the solution containing the precursor of the composite photothermal catalyst described in step H1, soaked for 30 min, and the soaking area of the melamine carbide foam is half of the total height of the melamine carbide foam, then placed in an oven, heated at 110 ℃ for 1 h, then taken out, again soaked in the solution containing the precursor of the composite photothermal catalyst until the solution is almost completely absorbed, and then placed in an oven again, heated at 90 ℃ for 3 h.

[0116] Effect test results

[0117] Figure 1 It is a physical map of the melamine foam without annealing treatment in Example 1. As can be seen from the figure, the untreated melamine foam is white.

[0118] Figure 2 It is a physical map of the melamine carbide foam prepared by annealing treatment in Example 1. As can be seen from the figure, after annealing, the melamine foam has been carbonized to form melamine carbide, which is black.

[0119] Figure 3 It is a SEM map of the melamine carbide foam prepared by annealing treatment in Example 1. As can be seen from the figure, the melamine carbide foam has a three-dimensional network structure and very high porosity.

[0120] Figure 4SEM image of the copper titan oxide / Mxenes / Ru loaded melamine carbon foam prepared in Example 1. As can be seen from the figure, due to the loading of copper titan oxide / Mxenes / Ru, part of the grid of the three-dimensional network structure of the melamine carbon foam is covered by copper titan oxide / Mxenes / Ru, which can increase the contact area with water vapor and increase the number of active sites.

[0121] Figure 5 TEM image and element distribution map of the copper titan oxide prepared in Example 1. As can be seen from the figure, the synthesized copper titan oxide contains three elements of copper, titanium and oxygen, and the distribution of copper, titanium and oxygen is uniform.

[0122] Figure 6 Local SEM image of the copper titan oxide / Mxenes / Ru loaded on the melamine carbon foam in Example 1. As can be seen from the figure, the granular copper titan oxide / Mxenes / Ru is distributed very uniformly.

[0123] Figure 7 TEM image of the Mxenes ultra-thin nanosheet prepared in Example 1. As can be seen from the figure, the size of the Mxenes ultra-thin nanosheet is about several hundred nanometers, and the contrast between the Mxenes ultra-thin nanosheet and the background in the figure is very small, indicating that the thickness of the Mxenes ultra-thin nanosheet is very thin.

[0124] Figure 8 UV-VIS spectrum of the photo-thermal and photocatalytic composite system prepared in Example 1 and Example 2. Among them, MS represents melamine foam without annealing treatment, AMS represents carbonized melamine foam after annealing treatment, AMS / Mxenes represents carbonized melamine foam loaded with Mxenes ultra-thin nanosheet, AMS / CT / R represents carbonized melamine foam system loaded with copper titan oxide and ruthenium, and AMS / Mxenes / CT / R represents carbonized melamine foam system loaded with copper titan oxide, Mxenes ultra-thin nanosheet and ruthenium. As can be seen from the data in the figure, the light absorption performance of the carbonized melamine foam after annealing treatment is significantly better than that of the melamine foam without annealing treatment, and for AMS / Mxenes, AMS / Mxenes / CT / R and AMS / Mxenes / CT / R, due to the blocking of copper titan oxide, Mxenes ultra-thin nanosheet and ruthenium, the light absorption performance decreases slightly, but the decrease is small.

[0125] Figure 9A graph of hydrogen production efficiency data of the photo-thermal and photo-catalytic composite system prepared in Example 1 and Example 2 is shown in the figure. The pink mark (Floating-AMS) in the figure represents the hydrogen production efficiency data of the photo-thermal and photo-catalytic composite system loaded on the carbonized melamine foam, and the blue mark (particles) represents the hydrogen production efficiency data of the system using only the particulate catalyst without loading. CuTiO x (Ru20%) represents the system in which copper titanium oxide is used as the photo-catalyst and ruthenium is used as the assistant, CuTiO x (Ru20%Mxenes5%) represents the system in which copper titanium oxide is used as the photo-catalyst and ruthenium and Mxenes ultra-thin nanosheets are used as the assistant. As can be seen from the data in the figure, the hydrogen production efficiency of the system loaded on the carbonized melamine foam is significantly higher than that of the system without loading, and the hydrogen production efficiency of the system using ruthenium and Mxenes ultra-thin nanosheets as the assistant is better than that of the system using only ruthenium as the assistant. According to the data in Figure 8 and Figure 9 , it can be seen that the photo-thermal and photo-catalytic composite system provided by the present application has the advantages of high solar energy utilization rate and high hydrogen production efficiency.

[0126] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacement for part or all of the technical features; and such modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A photo-thermal and photo-catalytic hybrid system, characterized in that, The photocatalytic hydrogen production system comprises a photo-thermal material, a photocatalyst and an assistant, the photocatalyst and the assistant are loaded on the upper half of the photo-thermal material, the photo-thermal material is a melamine carbon foam carrier with a porous structure, the photocatalyst comprises copper titanium oxide, and the assistant comprises ruthenium, in the photo-thermal and photocatalytic process, the photo-thermal and photocatalytic composite system is in a semi-submerged state, the upper half of the photo-thermal material loaded with the photocatalyst and the assistant floats above the liquid surface for photocatalytic hydrogen production of water vapor, and the lower half of the photo-thermal material is immersed below the liquid surface for absorbing solar energy to generate water vapor and transporting the water vapor.

2. The photo-thermal and photo-catalytic hybrid system according to claim 1, wherein, The assistant further comprises Mxenes nanosheets, and a material of the Mxenes nanosheets is Ti3C2: And / or, the melamine carbon foam carrier is prepared by annealing treatment of melamine foam.

3. A method for preparing the photo-thermal and photo-catalytic composite system according to claim 1 or 2, characterized in that, The method comprises the following steps: S1, annealing treatment of melamine foam to obtain a melamine carbon foam carrier with a porous structure; S2, dropwise addition of titanium tetrachloride liquid into an aqueous solution containing urea and copper chloride, stirring, heat preservation and annealing to obtain copper titanium oxide; S3, ultrasonic dissolution of the copper titanium oxide in the solution in step S2 in a mixed solution of deionized water and ethanol, addition of a ruthenium trichloride solution during the ultrasonic dissolution, then addition of a Mxenes nanosheet solution, and mixing to obtain a precursor solution; S4, immersion of the upper half of the melamine carbon foam carrier with a porous structure prepared in step S1 in the precursor solution, and then drying to obtain the photo-thermal and photocatalytic composite system.

4. The preparation method of the photothermal and photocatalytic composite system according to claim 3, characterized in that, The annealing treatment in step S1 is performed at a temperature of 400-600 ℃; And / or, the annealing treatment in step S1 is performed for 1-3 h.

5. The method for preparing the photothermal and photocatalytic composite system according to claim 3, characterized in that, The concentration of the urea in the aqueous solution in step S2 is 40-60 mg / mL; And / or, the concentration of the copper chloride in the aqueous solution in step S2 is 27-110 mg / mL; And / or, the volume ratio of the titanium tetrachloride liquid to the aqueous solution in step S2 is 1:(50-70); And / or, the stirring in step S2 is performed for 30-60 min; And / or, the heat preservation in step S2 is performed at a temperature of 80-110 ℃ for 12-24 h; And / or, the annealing in step S2 is performed at a temperature increasing rate of 2-5 ℃ / min, a temperature of 300-500 ℃ and a time of 1-3 h.

6. The method for preparing the photothermal and photocatalytic composite system according to claim 3, characterized in that, The volume ratio of the ethanol to the deionized water in the mixed solution in step S3 is 2:1; And / or, the ultrasonic dissolution in step S3 is performed for 10-60 min; And / or, the concentration of the ruthenium trichloride solution in step S3 is 5 mg / mL; And / or, the solvent of the ruthenium trichloride solution in step S3 is deionized water; And / or, the concentration of the Mxenes nanosheet solution in step S3 is 1-5 mg / mL; And / or, the preparation method of the Mxenes nanosheet solution in step S3 comprises the following steps: reacting MAX phase Ti3AlC2 in an aqueous solution containing LiF and HCl, centrifuging and washing the reacted solution to obtain a precipitate, configuring the precipitate into an aqueous solution, and performing ultrasonic exfoliation under ice bath conditions, then taking the upper solution for centrifugal treatment to obtain the Mxenes nanosheet solution.

7. The method for preparing the photothermal and photocatalytic composite system according to claim 6, characterized in that, The concentration of LiF in the aqueous solution is 80 mg / mL; And / or, the concentration of HCl in the aqueous solution is 9 mol / L; And / or, the reaction temperature is 20-40 ℃, and the reaction time is 24-36 h; And / or, the centrifugal washing process is to place the reacted solution in a centrifugal tube, then add water in the centrifugal tube, pour away the supernatant after centrifugal washing, repeat the above centrifugal washing steps until the pH value of the solution is 6-7, and obtain the precipitate; And / or, the temperature of the ice bath is 2-10 ℃; And / or, the ultrasonic exfoliation time is 10-15 min; And / or, the centrifugal treatment speed is 2000-3500 rpm, and the centrifugal treatment time is 1-3 h.

8. The method for preparing the photothermal and photocatalytic composite system according to claim 7, characterized in that, The concentration of the Mxenes nanosheet solution in step S3 is 3 mg / mL; And / or, the temperature of the ice bath is 4 ℃.

9. The method for preparing the photothermal and photocatalytic composite system according to claim 3, characterized in that, After the melamine triazine foam carrier in step S4 is initially soaked in the precursor solution, the first drying is performed, then the second soaking in the precursor solution is performed, and the second drying is performed to obtain the light-thermal and photocatalytic composite system.

10. The method for preparing the photothermal and photocatalytic composite system according to claim 9, characterized in that, The initial soaking time is 10-30 min; And / or, the temperature of the first drying and the second drying is 60-110 ℃; And / or, the first drying time is 1-3 h; And / or, the second drying time is 3-6 h.

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