A photothermal synergistic photocatalytic hydrogen production composite material and its preparation method and application

Abstract

A photothermal synergistic photocatalytic hydrogen production composite material and its preparation method and application, which relates to a catalytic hydrogen production catalyst and its preparation method and application, and aims to solve the technical problem that the existing hybrid cadmium-rich biochar composite material has poor catalytic effect when used for photocatalytic hydrogen production. The photothermal synergistic photocatalytic hydrogen production composite material of the present invention consists of two parts: biomass carbon and CdS. The surface of the biomass carbon is partially exposed and partially loaded with leaf-shaped CdS. Preparation method: first prepare biomass carbon, then dissolve cadmium nitrate tetrahydrate and thiourea in deionized water, then add biomass carbon, and perform hydrothermal treatment on the mixed solution to obtain a photothermal synergistic photocatalytic hydrogen production composite material. Its photocatalytic hydrogen production performance reaches 1.1-1.3mmol h ‑1 g ‑1 , which can be used in the field of photocatalytic hydrogen production.

Description

Technical Field

[0001] The invention relates to a catalytic hydrogen production catalyst and a preparation method thereof, and belongs to the technical field of catalytic hydrogen production and energy storage. Background Art

[0002] Hydrogen is a green, clean, renewable energy source with high energy density and non-polluting water as its combustion product. It has the potential to replace non-renewable fossil energy in the future. Single photocatalytic hydrogen production materials have low hydrogen production efficiency under illumination conditions and incomplete utilization of sunlight.

[0003] The Chinese patent application number 202010389218.6, entitled "Preparation method and use of a hybrid cadmium-rich biochar composite material", uses cadmium-enriched biomass to be ground into powder, and then uses thiourea to prepare a hybrid biochar modified material. The hybrid biochar composite material prepared by this method, however, is a heteroatom-doped cadmium-rich biochar. Due to the low content of CdS and CdO in the biochar, its catalytic effect is poor when used for photocatalytic hydrogen production. Summary of the invention

[0004] The present invention aims to solve the technical problem that the existing hybrid cadmium-rich biochar composite material has poor catalytic effect when used for photocatalytic hydrogen production, and provides a photothermal synergistic photocatalytic hydrogen production composite material and its preparation method and application. The photothermal synergistic photocatalytic hydrogen production composite material can achieve photothermal synergy in the process of photocatalytic hydrogen production, with high utilization rate of sunlight, and improve hydrogen production efficiency.

[0005] The photothermal synergistic photocatalytic hydrogen production composite material of the present invention consists of two parts: biomass carbon and CdS. The surface of the biomass carbon is partially exposed, and partially loaded with leaf-shaped CdS.

[0006] The preparation method of the above-mentioned photothermal synergistic photocatalytic hydrogen production composite material is carried out according to the following steps:

[0007] 1. Place the biomass raw material in a tubular furnace and calcine it at a temperature of 300-450°C for 2-3 hours to obtain biomass carbon;

[0008] 2. Dissolve cadmium nitrate tetrahydrate and thiourea in deionized water and stir at a speed of 300-800 rpm for 10-60 minutes, then add biomass carbon and stir for 10-120 minutes to obtain a mixed solution; then transfer the mixed solution to a hydrothermal kettle, place the hydrothermal kettle in a furnace at a temperature of 140-180°C for hydrothermal reaction for 12-36 hours; after the reaction is completed, wash and dry to obtain a photothermal synergistic photocatalytic hydrogen production composite material.

[0009] Furthermore, the biomass raw material in step 1 is coffee grounds or straw.

[0010] Furthermore, the molar ratio of cadmium nitrate tetrahydrate to thiourea in step 2 is 1:(0.5-2.5).

[0011] Furthermore, the ratio of the amount of cadmium nitrate tetrahydrate in step 2 to the mass of biomass carbon is 1 mmol: (6-13) mg.

[0012] The application of the above-mentioned photothermal synergistic photocatalytic hydrogen production composite material is to use the photothermal synergistic photocatalytic hydrogen production composite material in photocatalytic hydrogen production.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] The present invention carbonizes biomass at high temperature to obtain biomass carbon material, and uses it as a substrate, and then loads leaf-shaped CdS on the surface of biomass carbon through a simple solvent thermal reaction to obtain a composite material; the composite material is leaf-shaped CdS loaded on the surface of biomass carbon, but not completely wrapped; the leaf-shaped CdS has the performance of photocatalytic hydrogen production under sunlight conditions; the exposed biomass carbon also has photothermal properties under sunlight conditions; the photothermal properties have the ability to synergistically promote the improvement of CdS photocatalytic hydrogen production, that is, the heat generated by the biomass carbon material improves the hydrogen production performance of CdS and reduces the amount of CdS used. Through the effect of photothermal synergy with photocatalytic hydrogen production, the photocatalytic hydrogen production efficiency of the composite material is improved, and its photocatalytic hydrogen production performance reaches 1.1-1.3mmol h -1 g -1 , meeting the needs of sustainable and environmentally friendly green hydrogen production.

[0015] The preparation method of the composite material of the present invention has a simple synthesis method, is easy to operate, and is conducive to large-scale production. It can be used in the field of photocatalytic hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a SEM image of the biomass carbon prepared in step 1 of Example 1;

[0017] Figure 2 This is a SEM image of the photothermal synergistic photocatalytic hydrogen production composite material prepared in step 2 of Example 1;

[0018] Figure 3 The XRD spectrum of the photothermal synergistic photocatalytic hydrogen production composite material prepared in step 2 of Example 1;

[0019] Figure 4 This is a photothermal seawater desalination performance diagram of the biomass carbon prepared in step 1 of Example 1;

[0020] Figure 5 This is a photothermal seawater desalination performance diagram of the photothermal synergistic photocatalytic hydrogen production composite material prepared in step 2 of Example 1;

[0021] Figure 6 This is a performance diagram of photothermal synergistic photocatalytic hydrogen production of the photothermal synergistic photocatalytic hydrogen production composite material prepared in Examples 1 to 4. DETAILED DESCRIPTION

[0022] The beneficial effects of the present invention are verified by the following examples.

[0023] Example 1: The preparation method of the photothermal synergistic photocatalytic hydrogen production composite material of this example is carried out according to the following steps:

[0024] 1. Evenly spread 4 g of waste coffee grounds in a porcelain cup, place the porcelain cup in a tube furnace, and calcine for 2 h at 300 ° C, 350 ° C, 400 ° C, and 450 ° C, respectively, to obtain biomass carbon; recorded as 300 ° C biomass carbon, 350 ° C biomass carbon, 400 ° C biomass carbon, and 450 ° C biomass carbon;

[0025] 2. Dissolve 2.5g of cadmium nitrate tetrahydrate and 1.8g of thiourea in 120mL of deionized water, stir rapidly at 400 rpm for 10 minutes, then add 0.10g of 350℃ biomass carbon and stir for 30 minutes to obtain a mixed solution; then transfer the mixed solution to a hydrothermal kettle, place the hydrothermal kettle in a furnace at 160℃ for hydrothermal reaction for 24 hours; after the reaction is completed, wash with deionized water 3 times, and then dry in a drying oven at 60℃ for 3h to obtain a photothermal synergistic photocatalytic hydrogen production composite material. It is a CdS-loaded biomass carbon composite material.

[0026] The scanning electron microscope photograph of the 350°C biomass carbon prepared in step 1 of this example is as follows: Figure 1 As shown, from Figure 1 It can be seen that the surface of biomass carbon is not smooth, which is conducive to the loading of subsequent materials.

[0027] The scanning electron microscope photomicrograph of the photothermal synergistic photocatalytic hydrogen production composite material prepared in step 2 of this embodiment is shown in FIG. Figure 2 As shown, from Figure 2 It can be seen that the photothermal synergistic photocatalytic hydrogen production composite material prepared in this embodiment consists of two parts: biomass carbon and CdS. The surface of the biomass carbon is partially exposed and partially loaded with leaf-shaped CdS.

[0028] The XRD spectrum of the photothermal synergistic photocatalytic hydrogen production composite material prepared in step 2 of this embodiment is as follows Figure 3 As shown, from Figure 3 It can be seen that the characteristic peak of CdS in the photothermal synergistic photocatalytic hydrogen production composite material corresponds well to the standard card of CdS, indicating that only CdS exists in the photothermal synergistic photocatalytic hydrogen production composite material.

[0029] Example 2: This example is different from Example 1 in that the amount of biomass carbon added in step 2 is 0.05 g, and the other steps and parameters are the same as Example 1.

[0030] Example 3: This example is different from Example 1 in that the amount of biomass carbon added in step 2 is 0.15 g, and the other steps and parameters are the same as Example 1.

[0031] Example 4: This example is different from Example 1 in that the amount of biomass carbon added in step 2 is 0.20 g, and the other steps and parameters are the same as Example 1.

[0032] The 300°C biomass carbon, 350°C biomass carbon, 400°C biomass carbon and 450°C biomass carbon prepared in step 1 of Example 1 and the photothermal synergistic photocatalytic hydrogen production composite material prepared in Examples 1 to 4 were used as catalysts to simultaneously carry out a seawater desalination test. The specific process is: adding the prepared catalyst to NN dimethylamide and mixing evenly to obtain a mixed solution; applying the mixed solution evenly on a foam block, irradiating it under a 300W xenon lamp for 6 hours, and testing the weight of water evaporation;

[0033] The performance of the 300℃ biomass carbon, 350℃ biomass carbon, 400℃ biomass carbon and 450℃ biomass carbon prepared in step 1 of Example 1 for photothermal seawater desalination is shown in the figure below. Figure 4 As shown, from Figure 4 It can be seen that the biomass carbon at 350 °C has the best seawater evaporation performance.

[0034] The performance of the photothermal synergistic photocatalytic hydrogen production composite material prepared in Examples 1 to 4 is shown in the figure below: Figure 5 As shown in Figure 2, when the amount of biomass carbon added was 0.10 g, the photothermal performance of seawater was 17.0375 kg m -2 .

[0035] Compare Figure 4 and Figure 5 It can be concluded that the desalination performance mainly depends on biomass carbon, and the composite material after biomass carbon loaded with CdS has little effect on the desalination performance.

[0036] The photothermal synergistic photocatalytic hydrogen production composite materials prepared in Examples 1 to 4 were used as catalysts for photocatalytic hydrogen production tests. The specific process was as follows: 20 mg of the composite catalyst was added to 45 mL of deionized water and mixed evenly, and 5 mL of lactic acid was added as a sacrificial reagent to perform a photocatalytic hydrogen production test. The performance diagram of the photothermal synergistic photocatalytic hydrogen production obtained was as shown in FIG. Figure 6 As shown, from Figure 6 It can be seen that the photothermal synergistic photocatalytic hydrogen production composite material prepared in Example 1 has the best photocatalytic hydrogen production performance, and its photocatalytic hydrogen production performance is 1.296 mmol h -1 g-1 When the CdS loading is too low, fewer photocatalytic active sites are exposed, which reduces the photocatalytic hydrogen production performance; when the CdS loading is too high, the biocarbon matrix is ​​completely covered, the photothermal synergy is poor, and the photocatalytic hydrogen production performance is reduced.

Claims

1. A method for preparing a photothermal synergistic photocatalytic hydrogen production composite material, characterized in that The method proceeds as follows:

1. Place the biomass raw material in a tubular furnace and calcine it at a temperature of 300-450°C for 2-3 hours to obtain biomass carbon; 2. Dissolve cadmium nitrate tetrahydrate and thiourea in deionized water and stir at a speed of 300-800 rpm for 10-60 minutes, then add biomass carbon and stir for 10-120 minutes to obtain a mixed solution; wherein the mass ratio of cadmium nitrate tetrahydrate to biomass carbon is 1 mmol: (6-13) mg; then transfer the mixed solution to a hydrothermal kettle, place the hydrothermal kettle in a furnace at a temperature of 140-180°C for hydrothermal reaction for 12-36 hours; after the reaction is completed, wash and dry to obtain a photothermal synergistic photocatalytic hydrogen production composite material; the composite material is composed of biomass carbon and CdS, the surface of the biomass carbon is partially exposed, and partially loaded with leaf-shaped CdS.

2. The method for preparing a photothermal synergistic photocatalytic hydrogen production composite material according to claim 1, characterized in that: The biomass raw material described in step 1 is coffee grounds or straw.

3. The method for preparing a photothermal synergistic photocatalytic hydrogen production composite material according to claim 1 or 2, characterized in that: The molar ratio of the cadmium nitrate tetrahydrate to thiourea in step 2 is 1:(0.5-2.5).

4. Application of a photothermal synergistic photocatalytic hydrogen production composite material prepared by the method of claim 1, characterized in that The application is to use photothermal synergistic photocatalytic hydrogen production composite materials in photocatalytic hydrogen production and seawater desalination.

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