A bismuth oxychloride layered film, and a preparation method and application thereof

Abstract

This invention discloses a bismuth oxychloride layered membrane, its preparation method, and its application. The preparation method includes the following steps: Step 1: preparing bismuth oxychloride nanosheets via liquid-phase reaction. Concentrated hydrochloric acid is added to deionized water and heated to a stable temperature. A surfactant is added, and the mixture is mechanically stirred until homogeneous. A bismuth nitrate solution is added using a peristaltic pump, and the addition rate of sodium hydroxide solution is adjusted to stabilize the pH of the reaction system. When the size of the bismuth oxychloride nanosheets reaches a predetermined value, sodium hydroxide solution is rapidly added to adjust the pH of the reaction system. Heating and stirring are stopped to obtain bismuth oxychloride nanosheets. Step 2: preparing a two-dimensional layered membrane via vacuum filtration and self-assembly. One-dimensional materials and bismuth oxychloride nanosheets are added to distilled water to obtain a dispersed precursor. The dispersed precursor is vacuum filtered and naturally dried to obtain the bismuth oxychloride layered membrane. This bismuth oxychloride layered membrane exhibits excellent solar interface water evaporation and photocatalytic hydrogen evolution performance, enabling high comprehensive solar energy utilization efficiency.

Description

Technical Field

[0001] This invention relates to the fields of solar interface water evaporation and photocatalytic hydrogen evolution technology, specifically to a bismuth oxychloride layered film, its preparation method, and its application. Background Technology

[0002] Energy, as a fundamental human need, plays a vital role in socio-economic development. With the continued use and increasing demand for non-renewable resources such as fossil fuels, their harmful impacts on climate and the environment force us to re-examine the feasibility of non-renewable resources as primary energy sources. Solar energy is undoubtedly the most widely used renewable energy source. It is well known that solar radiation consists of light of different wavelengths, including ultraviolet (290-400 nm, 3%), visible light (400-760 nm, 45%), and infrared light (760-2500 nm, 52%). Photocatalysis is a promising pathway to convert solar energy into green chemical energy, providing an important zero-emission technology for the development of sustainable and renewable energy. To date, various semiconductors, including TiO2, CdS, BiVO4, and NiCo2S4, have been used for photocatalytic hydrogen evolution. However, most photocatalysts are limited by their wide bandgap and low quantum efficiency, allowing them to be used only under high-energy ultraviolet light, and most of the low-energy visible-near-infrared light is absorbed and converted into heat energy. Traditional photocatalytic processes do not make sufficient use of solar energy; for example, photocatalytic water splitting can only achieve a conversion efficiency of about 1%.

[0003] Freshwater scarcity has become a pressing global threat, with traditional methods for obtaining freshwater including reverse osmosis and membrane distillation. Solar interfacial water evaporation, as a feasible and environmentally friendly solar energy utilization technology for freshwater acquisition, has been extensively studied in recent years. Currently, many researchers continue to develop different photothermal materials for solar evaporators, including carbonaceous materials, surface plasmon metals, and semiconductor-based materials. Semiconductor-based materials with appropriate band gaps acquire electron / hole pairs through photoexcitation. On one hand, photogenerated electrons return from a high-energy state (conduction band) to a low-energy state (valence band), releasing energy through radiative photons or non-radiative heat generation. On the other hand, the photogenerated electron / hole pairs, which do not require recombination, can be extended to wastewater treatment, such as the degradation of organic pollutants (e.g., dyes, pesticides, and pharmaceuticals) and the removal of heavy metals.

[0004] In recent years, some have proposed combining solar interfacial water evaporation with photovoltaic or photoelectric energy to achieve comprehensive utilization of solar energy. Among these approaches, using solar energy to address the combined shortage of energy and water resources is gaining increasing attention due to its sustainability, renewability, and cleanliness. From a practical perspective, combining solar interfacial water evaporation with photocatalysis is a promising strategy for comprehensive solar energy utilization. Summary of the Invention

[0005] To address the aforementioned problems, the first objective of this invention is to provide a method for preparing bismuth oxychloride layered membranes. This method constructs layered membranes using one-dimensional cellulose nanofibers (CNF), carbon nanotubes (CNT), and CNF@CNT assemblies, along with two-dimensional bismuth oxychloride nanosheets. The interlayer nanochannels provide reactive sites and achieve excellent water transport performance.

[0006] A second objective of the present invention is to provide a bismuth oxychloride layered membrane as described above, which has excellent solution stability, mechanical strength and cycling performance.

[0007] A third objective of this invention is to provide applications of the aforementioned bismuth oxychloride layered membrane, including applications in the fields of solar interface water evaporation and photocatalytic hydrogen evolution.

[0008] The first technical solution adopted in this invention is: a method for preparing a bismuth oxychloride layered film, comprising the following steps:

[0009] Step 1: Preparation of bismuth oxychloride nanosheets by liquid-phase reaction, including the following specific sub-steps:

[0010] 1) Add concentrated hydrochloric acid to deionized water and heat to a stable temperature;

[0011] 2) Add the surfactant and mechanically stir to make the system homogeneous;

[0012] 3) Use a peristaltic pump to add bismuth nitrate solution and adjust the addition rate of sodium hydroxide solution to stabilize the pH of the reaction system;

[0013] 4) When the size of the bismuth oxychloride nanosheets reaches the predetermined value, sodium hydroxide solution is quickly added to adjust the pH value of the reaction system;

[0014] 5) Stop heating and stirring to obtain solid bismuth oxychloride nanosheets;

[0015] Step 2: Prepare a two-dimensional layered membrane by vacuum filtration self-assembly, including the following specific sub-steps:

[0016] 6) The one-dimensional material and bismuth oxychloride nanosheets were added to distilled water in a predetermined ratio, and the mixture was stirred and sonicated to obtain a uniformly dispersed precursor.

[0017] 7) The uniformly dispersed precursor was vacuum filtered and naturally dried to obtain a bismuth oxychloride layered membrane.

[0018] Preferably, in step one, the volume of deionized water is 1-1.5 L, the volume of concentrated hydrochloric acid is 15-22 mL, the heating temperature is 65-80 ℃, the surfactant is hexadecyltrimethylammonium chloride, the stirring rate is 700 rpm, the mass ratio of bismuth nitrate:concentrated hydrochloric acid:water in the bismuth nitrate solution is (0.9-1.5):(0.85-1.4):(0.7-0.95), the mass fraction of the sodium hydroxide solution is 5-25%, and the size of the bismuth oxychloride nanosheets is 0.25-15 μm.

[0019] Preferably, the specific conditions for stirring and sonicating in step two are: mechanical stirring for 10-20 minutes, sonicating for 30-60 minutes, and stirring and sonicating 4-8 times in sequence.

[0020] Preferably, the one-dimensional material includes cellulose nanofibers (CNF), carbon nanotubes (CNT), and CNF@CNT assemblies.

[0021] Preferably, the carbon nanotubes (CNTs) include single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs).

[0022] Preferably, the mass ratio of the cellulose nanofibers (CNF), carbon nanotubes (CNT), and CNF@CNT assemblies to bismuth oxychloride nanosheets is 0.01~0.2:1.

[0023] The second technical solution adopted in this invention is: a bismuth oxychloride layered film obtained by the preparation method in the first technical solution.

[0024] The third technical solution adopted in this invention is: the application of the bismuth oxychloride layered film in the second technical solution in solar interface water evaporation and photocatalytic hydrogen evolution.

[0025] The advantages of this invention compared with the prior art are: 1) This invention constructs a porous layered membrane using one-dimensional and two-dimensional materials. Its rich nanochannels provide reactive sites and rapid water transport channels for photocatalytic hydrogen evolution, and exhibit good structural stability in solution.

[0026] 2) In the layered membrane disclosed in this invention, CNTs serve as transport channels for photogenerated carriers, improving the separation of electrons and holes, reducing the interfacial charge transfer impedance and the recombination rate of photogenerated carriers, and acting as reactive sites for hydrogen evolution, thus broadening the light absorption capacity in the visible and infrared regions and resulting in higher local thermal conversion; CNFs regulate the hydrogen bond network of confined water molecules and reduce the enthalpy of water vaporization, thereby improving the photocatalytic hydrogen evolution of the two-dimensional layered membrane and the evaporation of water at the solar interface.

[0027] 3) The layered membrane disclosed in this invention has both solar interface water evaporation and photocatalytic hydrogen evolution properties, which can improve the comprehensive utilization efficiency of solar energy.

[0028] 4) The preparation process involved in this invention avoids complicated steps, is easy to operate, can be carried out at room temperature, is clean and environmentally friendly, fast and efficient, and is conducive to integration and scaling up. Attached Figure Description

[0029] Figure 1 This is a scanning electron microscope image of the bismuth oxychloride nanosheets prepared in Example 1;

[0030] Figure 2 A digital photograph of the bismuth oxychloride nanosheets prepared in Example 1;

[0031] Figure 3 An optical microscope image of the bismuth oxychloride nanosheets prepared in Example 2;

[0032] Figure 4 A digital photograph of the bismuth oxychloride nanosheets prepared in Example 2;

[0033] Figure 5 An optical microscope image of the bismuth oxychloride nanosheets prepared in Example 3;

[0034] Figure 6 Digital photographs of the dispersed precursors and bismuth oxychloride lamellar films in Examples 4-6;

[0035] Figure 7 This is a scanning electron microscope cross-sectional view of the bismuth oxychloride layered film in Example 4;

[0036] Figure 8 This is a digital photograph of the bismuth oxychloride layered film in Example 7;

[0037] Figure 9 Digital photographs of the bismuth oxychloride layered films obtained in Examples 2 and 3 of Example 8;

[0038] Figure 10 A comparative graph showing the temperature distribution changes on the surface of the layered films prepared in Examples 4-6 of Application Example 1;

[0039] Figure 11 This is a schematic diagram comparing the water loss mass change curves and water evaporation rates of the bismuth oxychloride layered films prepared in Examples 4-6 of Application Example 2 under light intensity.

[0040] Figure 12 This is a schematic diagram comparing the hydrogen production capacity and hydrogen production rate of the bismuth oxychloride layered membranes prepared in Examples 4-6 of Application Example 2; Detailed Implementation

[0041] The present invention will be further illustrated below with specific embodiments. It should be noted that those skilled in the art can make several modifications and improvements without departing from the principle of the present invention, and these should also be considered to fall within the protection scope of the present invention.

[0042] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0043] This invention discloses a method for preparing a reduced graphene oxide layered film, comprising the following steps:

[0044] Step 1: Preparation of bismuth oxychloride nanosheets. Add 15-22 mL of concentrated hydrochloric acid to 1-1.5 L of deionized water and heat to a stable temperature of 65-80 ℃. Add the surfactant hexadecyltrimethylammonium chloride and stir mechanically until homogeneous. Add bismuth nitrate solution using a peristaltic pump (mass ratio of bismuth nitrate: concentrated hydrochloric acid: water is (0.9-1.5):(0.85-1.4):(0.7-0.95)). Stabilize the pH of the reaction system by adjusting the addition rate of 5-25% sodium hydroxide solution. When the size of the bismuth oxychloride nanosheets reaches 0.25-15 μm, quickly add sodium hydroxide solution to adjust the pH of the reaction system. Stop heating and stirring. After the solid material precipitates, remove the upper liquid. The lower solid material is the obtained bismuth oxychloride nanosheets.

[0045] 1) Add concentrated hydrochloric acid to 1-1.5 L of deionized water and heat to a stable temperature of 65-80 ℃;

[0046] 2) Add the surfactant hexadecyltrimethylammonium chloride and mechanically stir to make the system homogeneous;

[0047] 3) Use a peristaltic pump to add bismuth nitrate solution (the mass ratio of bismuth nitrate: concentrated hydrochloric acid: water is (0.9-1.5):(0.85-1.4):(0.7-0.95)), and stabilize the pH of the reaction system by adjusting the addition rate of sodium hydroxide solution with a mass fraction of 5-25%;

[0048] 4) When the size of the bismuth oxychloride nanosheets reaches 0.25-15 μm, quickly add sodium hydroxide solution to adjust the pH of the reaction system;

[0049] 5) Stop heating and stirring. After the solid material settles, remove the upper liquid. The lower solid material is the obtained bismuth oxychloride nanosheets.

[0050] Step 2: Prepare a two-dimensional layered membrane by vacuum filtration and self-assembly.

[0051] 6) One-dimensional materials, cellulose nanofibers (CNF), carbon nanotubes (CNT), and CNF@CNT assemblies, are added to distilled water at a mass ratio of 0.01~0.2:1. The carbon nanotubes (CNT) include single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT). The mixture is mechanically stirred for 10-20 minutes and sonicated for 30-60 minutes. The stirring and sonication are repeated 4-8 times to obtain a uniformly dispersed precursor.

[0052] 7) The uniformly dispersed precursor was vacuum filtered and naturally dried to obtain a bismuth oxychloride layered membrane.

[0053] Example 1

[0054] To prepare bismuth oxychloride nanosheets, 15 mL of concentrated hydrochloric acid was added to 1.5 L of deionized water and heated to a stable temperature of 65 °C. The surfactant hexadecyltrimethylammonium chloride was added and mechanically stirred until homogeneous. A bismuth nitrate solution (bismuth nitrate:concentrated hydrochloric acid:water mass ratio of 0.9:1.4:0.95) was added using a peristaltic pump, and the pH of the reaction system was stabilized by adjusting the addition rate of a 25% sodium hydroxide solution. When the size of the bismuth oxychloride nanosheets reached 0.25 μm, sodium hydroxide solution was rapidly added to adjust the pH of the reaction system. Heating and stirring were stopped, and after the solid material precipitated, the upper liquid was removed; the lower solid material was the obtained bismuth oxychloride nanosheets.

[0055] The scanning electron microscope image of the bismuth oxychloride nanosheets prepared in Example 1 is shown below. Figure 1 See digital photos Figure 2 .

[0056] Example 2

[0057] To prepare bismuth oxychloride nanosheets, 22 mL of concentrated hydrochloric acid was added to 1 L of deionized water and heated to a stable temperature of 80 °C. The surfactant hexadecyltrimethylammonium chloride was added and mechanically stirred until homogeneous. A bismuth nitrate solution (bismuth nitrate:concentrated hydrochloric acid:water mass ratio of 1.5:0.85:0.7) was added using a peristaltic pump, and the pH of the reaction system was stabilized by adjusting the addition rate of a 20% sodium hydroxide solution. When the size of the bismuth oxychloride nanosheets reached 15 μm, sodium hydroxide solution was rapidly added to adjust the pH of the reaction system. Heating and stirring were stopped, and after the solid material precipitated, the upper liquid was removed; the lower solid material was the obtained bismuth oxychloride nanosheets.

[0058] Optical microscope images of the bismuth oxychloride nanosheets prepared in Example 2 are shown below. Figure 3 See digital photos Figure 4 .

[0059] Example 3

[0060] To prepare bismuth oxychloride nanosheets, 15 mL of concentrated hydrochloric acid was added to 1 L of deionized water and heated to a stable temperature of 70 °C. The surfactant hexadecyltrimethylammonium chloride was added and mechanically stirred until homogeneous. A bismuth nitrate solution (bismuth nitrate:concentrated hydrochloric acid:water mass ratio of 1.5:0.85:0.7) was added using a peristaltic pump, and the pH of the reaction system was stabilized by adjusting the addition rate of a 5% sodium hydroxide solution. When the size of the bismuth oxychloride nanosheets reached 8 μm, sodium hydroxide solution was rapidly added to adjust the pH of the reaction system. Heating and stirring were stopped, and after the solid material precipitated, the upper liquid was removed; the lower solid material was the obtained bismuth oxychloride nanosheets.

[0061] An optical microscope image of the bismuth oxychloride nanosheets prepared in Example 3 is shown below. Figure 5 .

[0062] Example 4

[0063] One-dimensional cellulose nanofibers (CNF) and bismuth oxychloride nanosheets obtained in Example 1 were added to distilled water at a mass ratio of 0.01:1. The mixture was mechanically stirred for 10 minutes and sonicated for 30 minutes. The stirring and sonication were repeated 4 times to obtain a uniformly dispersed precursor. The uniformly dispersed precursor was vacuum filtered and naturally dried to obtain a bismuth oxychloride layered membrane.

[0064] Digital photographs of the dispersed precursor and bismuth oxychloride layered film in Example 4 are shown below. Figure 6 (a) A cross-sectional image of the bismuth oxychloride layered film obtained by scanning electron microscopy is shown in 7.

[0065] Example 5

[0066] One-dimensional carbon nanotubes (CNTs) and bismuth oxychloride nanosheets obtained in Example 1 were added to distilled water at a mass ratio of 0.05:1. The mixture was mechanically stirred for 15 minutes and sonicated for 45 minutes. The stirring and sonication were repeated 8 times to obtain a uniformly dispersed precursor. The uniformly dispersed precursor was vacuum filtered and naturally dried to obtain a bismuth oxychloride layered film.

[0067] Digital photographs of the dispersed precursor and bismuth oxychloride layered film in Example 5 are shown below. Figure 6 (b)

[0068] Example 6

[0069] One-dimensional single-walled carbon nanotubes (SWCNTs) and CNF@CNT assemblies of cellulose nanofibers (CNFs) obtained in Example 1 were added to distilled water at a mass ratio of 0.2:1. The mixture was mechanically stirred for 20 minutes and sonicated for 60 minutes. The stirring and sonication were repeated 8 times to obtain a uniformly dispersed precursor. The uniformly dispersed precursor was then vacuum filtered and naturally dried to obtain a bismuth oxychloride layered membrane.

[0070] Digital photographs of the dispersed precursor and bismuth oxychloride layered film in Example 6 are shown below. Figure 6 (c)

[0071] Example 7

[0072] One-dimensional multi-walled carbon nanotubes (MWCNTs) and CNF@CNT assemblies of cellulose nanofibers (CNFs) obtained in Example 1 were added to distilled water at a mass ratio of 0.2:1. The mixture was mechanically stirred for 20 minutes and sonicated for 60 minutes, and the stirring and sonication were repeated 8 times to obtain a uniformly dispersed precursor. The uniformly dispersed precursor was then vacuum filtered and naturally dried to obtain a bismuth oxychloride layered membrane.

[0073] A digital photograph of the bismuth oxychloride layered film of Example 7 is shown below. Figure 8 .

[0074] Example 8

[0075] One-dimensional cellulose nanofibers (CNF) and bismuth oxychloride nanosheets obtained in Examples 2 and 3 were added to distilled water at a mass ratio of 0.01:1. The mixture was mechanically stirred for 10 minutes and sonicated for 30 minutes. The stirring and sonication were repeated 4 times to obtain a uniformly dispersed precursor. The uniformly dispersed precursor was vacuum filtered and naturally dried to obtain a bismuth oxychloride layered membrane.

[0076] Example 8 is a digital photograph of the bismuth oxychloride layered film obtained in Examples 2 and 3. Figure 9 (a) and 9(b).

[0077] Application Example 1

[0078] The surface temperature of the bismuth oxychloride layered films prepared in Examples 4-6 was tested. Under one times the solar intensity (1 kW·m⁻²), the distribution of surface temperature of the layered films changed with increasing illumination time as follows: Figure 10 As shown, the temperature of the bismuth oxychloride layered film tends to stabilize after 150 s.

[0079] Application Example 2

[0080] The bismuth oxychloride layered membranes prepared in Examples 4-6 were used as photothermal evaporators for photothermal evaporation tests. The diameter of the layered membrane was 3.8 cm, and the light intensity was 1 kW·m⁻². The water loss mass change curves and water evaporation rates of the bismuth oxychloride layered membranes under different light intensities are shown below. Figure 11 As shown, it exhibits excellent photothermal evaporation performance and demonstrates great potential in the field of interfacial water evaporation.

[0081] Application Example 3

[0082] The bismuth oxychloride layered membranes prepared in Examples 4-6 were used as catalysts for photocatalytic hydrogen evolution, with a 300 W xenon lamp as the light source. The prepared layered membranes were fixed on a self-made support and placed in a photocatalytic reactor, with 100 mL of aqueous solution (containing 10 mL of triethanolamine (TEOA) as a sacrificial agent) added. Before light irradiation, the closed hydrogen production system was evacuated to remove residual gases from the reaction system. The amount of hydrogen produced was measured and calculated online using a gas chromatograph, with nitrogen as the carrier gas. The hydrogen production rate and yield are as follows: Figure 12 As shown.

[0083] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. The application of a bismuth oxychloride layered film in the performance of water evaporation and photocatalytic hydrogen evolution at the solar interface, characterized in that, The method for preparing the bismuth oxychloride layered film includes the following steps: Step 1: Preparation of bismuth oxychloride nanosheets by liquid-phase reaction, including the following specific sub-steps: 1) Add 15-22 mL of concentrated hydrochloric acid to 1-1.5 L of deionized water and heat to a stable temperature of 65-80 ℃; 2) Add the surfactant hexadecyltrimethylammonium chloride and mechanically stir at a speed of 700 rpm to make the system homogeneous; 3) Add bismuth nitrate solution using a peristaltic pump. The mass ratio of bismuth nitrate to concentrated hydrochloric acid to water in the bismuth nitrate solution is (0.9-1.5):(0.85-1.4):(0.7-0.95). Adjust the addition rate of sodium hydroxide solution to stabilize the pH of the reaction system. The mass fraction of the sodium hydroxide solution is 5-25%. 4) When the size of the bismuth oxychloride nanosheets reaches 0.25-15 μm, quickly add sodium hydroxide solution to adjust the pH value of the reaction system; 5) Stop heating and stirring to obtain solid bismuth oxychloride nanosheets; Step 2: Prepare a two-dimensional layered membrane by vacuum filtration self-assembly, including the following specific sub-steps: 6) The one-dimensional material and bismuth oxychloride nanosheets are added to distilled water in a predetermined ratio, and the mixture is stirred and sonicated to obtain a uniformly dispersed precursor; the one-dimensional material includes one of cellulose nanofibers (CNF), carbon nanotubes (CNT), and CNF@CNT assemblies; the mass ratio of one of the cellulose nanofibers (CNF), carbon nanotubes (CNT), and CNF@CNT assemblies to bismuth oxychloride nanosheets is 0.01~0.2:1; 7) The uniformly dispersed precursor was vacuum filtered and naturally dried to obtain a bismuth oxychloride layered membrane.

2. The application of the bismuth oxychloride layered film according to claim 1 in the performance of solar interface water evaporation and photocatalytic hydrogen evolution, characterized in that, The specific conditions for stirring and sonication in step two of the method for preparing the bismuth oxychloride layered film are as follows: mechanical stirring for 10-20 minutes, sonication for 30-60 minutes, and stirring and sonication are performed 4-8 times in sequence.

3. The application of the bismuth oxychloride layered film according to claim 1 in the performance of water evaporation and photocatalytic hydrogen evolution at the solar interface, characterized in that, In the method for preparing the bismuth oxychloride layered film, the carbon nanotubes (CNTs) include one of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs).

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