Preparation method and application of photocatalytic ferroelectric heterojunction with photothermal-pyroelectric effect

Abstract

The invention discloses a preparation method of a photocatalytic ferroelectric heterojunction with a photothermal-pyroelectric effect, which comprises the following steps: step 1, preparing carboxylated BaTiO3 nanoparticles (BaTiO3NPs), adding a carboxylic acid modified ferroelectric material and a metal salt solution into a mixed solution of H2O and ethanol, and stirring to obtain a mixed solution; wherein the ferroelectric material is BaTiO3NPs, and the metal salt is In (NO3) 3.4 H2O; 2, adding a mixed solution of ammonia water and an ethanol solution into the mixed solution, reacting in an oil bath at 80 DEG C for 30 minutes, carrying out centrifugal washing and drying to obtain BaTiO3 / In (OH) 3, and carrying out high-temperature calcination in a muffle furnace to obtain a BaTiO3 / In2O3 heterojunction; and step 3, grinding the obtained BaTiO3 / In2O3 and NaBH4 according to a ratio, uniformly mixing the obtained BaTiO3 / In2O3 and NaBH4, and roasting the obtained mixture in a tubular furnace in an argon atmosphere to obtain the black BaTiO3 / B-In2O3 heterojunction. A semiconductor material with photo-thermal conversion performance is combined with a pyroelectric material, so that the prepared heterojunction has relatively high photocatalytic reduction activity, and the catalytic efficiency is improved.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a photocatalytic ferroelectric heterojunction with photothermal-pyroelectric effect, and belongs to the field of photocatalytic materials. Background Art

[0002] Excessive emission of CO2 has led to an increasingly severe greenhouse effect in the world. Photocatalytic technology, especially photocatalytic reduction of CO2, as an important strategy for the development and utilization of solar energy, has great potential in alleviating global environmental pollution and energy crisis. Using sustainable solar energy to convert CO2 into high-value-added chemicals is an effective green way to solve environmental pollution and energy crisis at the same time. Traditional photocatalysts can only absorb ultraviolet light with a wavelength less than 380nm due to their wide band gap, and the utilization rate of solar light can only reach 3-5%. Infrared light, which accounts for more than 50% of solar energy, is often ignored. At present, traditional photocatalysts still have problems such as narrow light absorption range, fast electron-hole recombination rate, and low light conversion efficiency. Seeking efficient photocatalytic reduction of CO2 catalysts remains an important goal in the field of photocatalytic technology. Increasing the absorption of sunlight by catalysts and improving the separation efficiency of electrons and holes are two main ways to improve photocatalytic efficiency. In recent years, the method of accelerating electron-hole separation by constructing an external field has attracted widespread attention due to its high efficiency. When the temperature changes, the pyroelectric material releases the bound charges on the surface generated by spontaneous polarization and participates in the catalytic reaction. At the same time, the pyroelectric electric field formed can also promote the efficiency of carrier separation. Combining the photothermal conversion material with the pyroelectric material, using the heat generated by near-infrared light as the driving force for the temperature fluctuation of the pyroelectric material, the pyroelectric effect releases the charge and generates the pyroelectric potential, which participates in the photocatalytic reaction and improves the photocatalytic efficiency of the material.

[0003] Among pyroelectric materials, BaTiO3 has become a widely used pyroelectric material due to its large pyroelectric coefficient and suitable Curie temperature (130°C). In2O3-x, as a non-stoichiometric black indium oxide (B-In2O3), can absorb light in the entire range of sunlight and has a high photothermal conversion effect. B-In2O3 can achieve photothermal reverse water-gas shift reaction (RWGS) with 100% selectivity under ambient conditions. In the present invention, In2O3 is in situ grown on the surface of barium titanate, and BaTiO3 / B-In2O3 heterojunction is prepared by high-temperature reduction. Under sunlight irradiation, the heat generated by B-In2O3 provides a driving force for temperature change for the pyroelectric effect of BaTiO3. BaTiO3 releases charge and generates pyroelectric potential to further act on B-In2O3, affecting its photocatalytic reaction. This study combines photothermal effect, pyroelectric effect and photocatalysis to study the photocatalytic reduction performance of BaTiO3 / B-In2O3 heterojunction and reveal its reaction mechanism. This paper provides a theoretical basis for the design of efficient photocatalysts based on pyroelectric materials. Therefore, exploring the built-in electric field of pyroelectrics to accelerate the separation and transfer of photogenerated carriers and further improve the photocatalytic activity of BaTiO3 / B-In2O3 heterojunctions is the next challenge that scientific researchers need to face. Summary of the invention

[0004] The present invention designs and develops a method for preparing a photocatalytic ferroelectric heterojunction with a photothermal-pyroelectric effect, which combines a semiconductor material with a photothermal conversion performance with a pyroelectric material. The prepared heterojunction has high photocatalytic reduction activity and improves the catalytic efficiency.

[0005] The present invention also provides an application of a photocatalytic ferroelectric heterojunction with a photothermal-pyroelectric effect, and the prepared BaTiO3 / B-In2O3 heterojunction agent is used for a photocatalytic carbon dioxide reduction reaction.

[0006] The technical solution provided by the present invention is:

[0007] A method for preparing a photocatalytic ferroelectric heterojunction with a photothermal-pyroelectric effect, comprising:

[0008] Step 1: prepare carboxylated BaTiO3 NPs, add the carboxylated BaTiO3 NPs and a metal salt solution into a mixed solution of H2O and ethanol, and stir to obtain a mixed solution;

[0009] Among them, the metal salt is In(NO3)3·4H2O;

[0010] Step 2: adding ammonia water and ethanol solution to the mixed solution to form a homogeneous solution, reacting in an oil bath at 80° C. for 30 min, centrifugally washing and drying to obtain BaTiO3 / In(OH)3, and then calcining at high temperature in a muffle furnace to obtain a BaTiO3 / In2O3 heterojunction;

[0011] Step 3: Grind the obtained BaTiO3 / In2O3 and NaBH4 in proportion and mix them evenly, and then calcine and wash them in an argon atmosphere in a tube furnace to obtain a BaTiO3 / B-In2O3 heterojunction.

[0012] Preferably, the preparation process of the carboxylated BaTiO3 NPs comprises:

[0013] 0.50 mL, 6.4 mmol, of 3-aminopropyltriethoxysilane was added dropwise to a DMF solution containing succinic anhydride and stirred at room temperature for 3 h to generate N-3-(triethoxysilyl)propyl-4-carboxybutyramide; BaTiO3NPs were added to the solvent and dispersed in a mixed solvent, stirred at room temperature for 8 h, and then washed with distilled water and ethanol at 5000 rpm for 3 times, and dried at 60°C under vacuum for 10 h to obtain carboxylated BaTiO3NPs;

[0014] Among them, succinic anhydride is 0.30 g, 3 mmol, DMF is 20 mL, and the mixed solvent is deionized water and DMF solution with a volume ratio of 1:5.

[0015] Preferably, in step 1, the volume ratio of the mixed solution of H2O and ethanol is 1:3.

[0016] Preferably, in the step 2, the calcination temperature in the muffle furnace is 450° C. and the calcination time is 3 hours.

[0017] Preferably, the step three comprises:

[0018] BTO / In2O3 and NaBH4 with a mass ratio of 1:2 were ground and mixed evenly, calcined in an argon atmosphere at 400°C in a tube furnace for 3 hours, added with water and stirred for 12 hours, then washed twice with H2O and ethanol and centrifuged until the residual NaBH4 was completely removed, and dried at 60°C to obtain black BTO / B-In2O3.

[0019] An application of a photocatalytic ferroelectric heterojunction with a photothermal-pyroelectric effect, wherein a BaTiO3 / B-In2O3 heterojunction is prepared using the method for preparing a photocatalytic ferroelectric heterojunction with a photothermal-pyroelectric effect, and the BaTiO3 / B-In2O3 heterojunction is used for a photocatalytic carbon dioxide reduction reaction.

[0020] The beneficial effects of the present invention are as follows: in the process of preparing the BTO / B-In2O3 heterojunction, carboxyl-modified BaTiO3 nanoparticles are added to a solution containing In(NO3)3·4H2O, and the positively charged In 3+ It will be adsorbed on the surface of carboxylated BaTiO3 nanoparticles through electrostatic attraction. Then ammonia water is added, and In(OH)3 nanoparticles will grow in situ on the surface of BaTiO3 nanoparticles under solvent thermal conditions. The unanchored In(OH)3 nanoparticles are removed by centrifugal washing, and then calcined at high temperature to obtain BTO / In2O3 heterojunction. BTO / In2O3 and NaBH4 with a mass ratio of 1:2 are ground and mixed evenly, and calcined in argon gas at 400℃ tube furnace for 3h to obtain BTO / B-In2O3 heterojunction, which has great application potential in the field of photocatalysis.

[0021] In the present invention, after a full spectrum reaction for 4 hours, BTO, In2O3, B-In2O3, BTO / In2O3, BTO / B-In2O3 and BTO / B-In2O3 photocatalytically reduce CO2 to CO under temperature fluctuation, and the CO yields of BTO, In2O3, B-In2O3, BTO / In2O3 and BTO / B-In2O3 are 24.14, 27.14, 42.53, 85.46 and 146.56 μmol·g, respectively. -1 ·h -1 The CO yield of BTO / B-In2O3 was 6.07, 5.4, 3.45 and 1.71 times that of BTO, In2O3, B-In2O3 and BTO / In2O3 under the same conditions, respectively. The light source was turned on and off every 10 minutes (about 8 cycles) to test the photocatalytic reduction of CO2 on BTO / B-In2O3. It was found that the CO yield of the BTO / B-In2O3 heterojunction was further improved to 215.43 μmol·g -1 ·h -1 , which is 1.47 times that of BTO / B-In2O3 without temperature change, indicating that the pyroelectric effect of BTO can improve the photocatalytic CO2 reduction efficiency of heterojunction materials.

[0022] In the field of material application, this method comprehensively considers that under full-spectrum light irradiation, B-In2O3 in the BTO / B-In2O3 heterojunction can act as a photothermal converter, providing a driving force for the temperature change (ΔT) of the pyroelectric effect of BaTiO3. ΔT causes BaTiO3 to polarize and release surface charges under sunlight irradiation, thereby affecting the carrier separation rate and electron transfer rate in B-In2O3 nanoparticles, resulting in a higher photocatalytic reduction of CO2 efficiency. The photothermal-pyroelectric-photocatalyst BTO / B-In2O3 heterojunction constructed by introducing photothermal and pyroelectric effects has a high photocatalytic reduction of CO2 activity. Among pyroelectric materials, BaTiO3 has a large pyroelectric coefficient and a suitable Curie temperature (130℃), and is a traditional pyroelectric material. Combining semiconductor materials with photothermal conversion properties with pyroelectric materials and using light as the driving force of the pyroelectric effect will provide new insights into new and efficient photothermal-pyroelectric-photocatalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a transmission electron microscope photograph of the BTO / B-In2O3 heterojunction obtained in the present invention.

[0024] FIG. 1( a ) is a transmission electron micrograph of the BTO NPs described in the present invention.

[0025] FIG1( b ) is a transmission electron microscope image of the BTO / In2O3 heterojunction described in the present invention.

[0026] FIG1( c ) is a transmission electron microscope image of the BTO / B-In2O3 heterojunction described in the present invention.

[0027] FIG1( d ) is a transmission electron microscope image of the BTO / B-In 2 O 3 heterojunction described in the present invention.

[0028] FIG. 1( e ) is an EDS element mapping image of the Ba element in the BTO / B-In 2 O 3 heterojunction described in the present invention.

[0029] FIG1( f ) is an EDS element mapping image of the Ti element in the BTO / B-In2O3 heterojunction described in the present invention.

[0030] FIG1( g ) is an EDS element mapping image of the O element in the BTO / B-In2O3 heterojunction of the present invention.

[0031] FIG1(h) is an EDS element mapping image of the In element in the BTO / B-In2O3 heterojunction described in the present invention.

[0032] Figure 2 This is the X-ray diffraction pattern of the BTO / B-In2O3 heterojunction obtained in the present invention.

[0033] Figure 3(a) is a temperature variation diagram of the blank sample, BTO, In2O3, BTO / In2O3, B-In2O3 and BTO / B-In2O3 described in the present invention under full spectrum irradiation.

[0034] FIG3( b ) is a three-dimensional temperature change bar graph according to the present invention.

[0035] Figure 4(a) is a graph of CO production of BTO, In2O3, B-In2O3, BTO / In2O3 and BTO / B-In2O3 according to the present invention and BTO / B-In2O3 under temperature fluctuation.

[0036] 4(b) is a diagram of the CO yield of BTO, In2O3, B-In2O3, BTO / In2O3 and BTO / B-In2O3 described in the present invention and BTO / B-In2O3 under temperature fluctuation. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0038] As shown in FIGS. 1-4 , the present invention provides a method for preparing a photocatalytic ferroelectric heterojunction having a photothermal-pyroelectric effect, comprising:

[0039] Step 1: prepare carboxylated BaTiO3 NPs, add the carboxylated BaTiO3 NPs and a metal salt solution into a mixed solution of H2O and ethanol, and stir to obtain a mixed solution; wherein the metal salt is In(NO3)3·4H2O;

[0040] Step 2: adding ammonia water and ethanol solution to the mixed solution to form a homogeneous solution, reacting in an oil bath at 80° C. for 30 min, centrifugally washing and drying to obtain BaTiO3 / In(OH)3, and then calcining at high temperature in a muffle furnace to obtain a BaTiO3 / In2O3 heterojunction;

[0041] Step 3: Grind the obtained BaTiO3 / In2O3 and NaBH4 in proportion and mix them evenly, and then calcine and wash them in an argon atmosphere in a tube furnace to obtain a BaTiO3 / B-In2O3 heterojunction.

[0042] Specifically include:

[0043] Preparation of carboxylated BaTiO3 NPs:

[0044] 0.50 mL, 6.4 mmol, of 3-aminopropyltriethoxysilane was added dropwise to a DMF solution containing succinic anhydride and stirred at room temperature for 3 h to generate N-3-(triethoxysilyl)propyl-4-carboxybutyramide; BaTiO3NPs were added to the solvent and dispersed in a mixed solvent, stirred at room temperature for 8 h, and then washed with distilled water and ethanol at 5000 rpm for 3 times, and dried at 60°C under vacuum for 10 h to obtain carboxylated BaTiO3NPs;

[0045] Among them, succinic anhydride is 0.30 g, 3 mmol, DMF is 20 mL, and the mixed solvent is deionized water and DMF solution with a volume ratio of 1:5.

[0046] The carboxylic acid-modified BaTiO3 NPs ferroelectric material and the metal salt solution are placed in a mixed solution of NH3·H2O and ethanol, and stirred to obtain a mixed solution;

[0047] The ferroelectric material is BaTiO3 nanoparticles, the metal salt is In(NO3)3·4H2O, and the volume ratio of the H2O and ethanol mixed solution is (V:V=1:3). When carboxyl-modified BaTiO3 NPs are added to the above solution, the positively charged In 3+ They will be adsorbed on the surface of carboxylated BaTiO3 NPs through electrostatic attraction.

[0048] Ammonia water and ethanol solution were added to the mixed solution to form a homogeneous solution, and the solution was reacted in an oil bath at 80°C for 30 minutes. BaTiO3 / In(OH)3 was obtained after centrifugal washing and drying. Under solvent thermal conditions, In(OH)3 nanoparticles were in situ grown on the surface of BaTiO3 nanoparticles. Unanchored In(OH)3 nanoparticles were removed by centrifugal washing. The solution was then calcined in a muffle furnace at 450°C for 3 hours to obtain a BaTiO3 / In2O3 heterojunction.

[0049] The centrifugal washing was performed 3 to 5 times, the centrifuge speed was 5000 r / min, and the drying conditions were vacuum drying oven at 60°C-80°C.

[0050] BTO / In2O3 and NaBH4 with a mass ratio of 1:2 were ground and mixed evenly, calcined in an argon atmosphere at 400°C in a tube furnace for 3 hours, added with water and stirred for 12 hours, then washed twice with H2O and ethanol and centrifuged until the residual NaBH4 was completely removed, and dried at 60°C to obtain black BTO / B-In2O3.

[0051] The BaTiO3 / B-In2O3 heterojunction prepared by the present invention can be used as a catalyst for photocatalytic carbon dioxide reduction reaction.

[0052] BTO is the abbreviation of BaTiO3.

[0053] Example

[0054] 2 g of In(NO3)3·4H2O was added to solution A to form a homogeneous solution. Then, carboxylated BTO NPs were added to the homogeneous solution and stirred for 12 h. Solution B was slowly added dropwise. After the addition was completed, the solution was stirred in an oil bath at 80°C for 30 min. BaTiO3 / In(OH)3 was obtained after centrifugation, washing and vacuum drying at 60°C. It was then calcined at high temperature in a muffle furnace to obtain a BaTiO3 / In2O3 heterojunction.

[0055] BTO / In2O3 and NaBH4 with a mass ratio of 1:2 were ground and mixed evenly, calcined in an argon atmosphere at 400°C in a tube furnace for 3 hours, added with water and stirred for 12 hours until the residual NaBH4 was completely removed, and then washed twice with H2O and ethanol, centrifuged, and dried at 60°C to obtain black BTO / B-In2O3.

[0056] Wherein, solution A is a mixture of C2H5OH and H2O in a volume ratio of 3:1, and solvent B is a mixture of 18 mL NH3·H2O and 54 mL ethanol.

[0057] As shown in Figure 1(a) and Figure 1(c), by observing the morphology and structure of the samples by TEM, it can be observed that BTO NPs are irregular spherical particles with smooth surfaces and an average diameter of about 200nm. From the TEM image of the BTO / B-In2O3 heterojunction, it can be clearly seen that many irregular B-In2O3 nanoparticles surround the spherical BTO NPs, indicating that B-In2O3 NPs were successfully prepared in situ on the surface of BTONPs. The HRTEM image of BTO / B-In2O3, Figure 1(b), clearly shows a lattice with a spacing of 0.398nm, corresponding to the (100) crystal plane of the tetragonal BTO NPs, while the lattices with spacings of 0.247nm and 0.292nm correspond to the (002) and (222) crystal planes of In and In2O3, respectively, indicating that after NaBH4 reduction, BTO / In2O3 not only generates B-In2O3, but also generates In element. The EDS element mapping images in Figure 1 (d) to (h) show that Ba, Ti, O, and In elements are uniformly distributed on the surface of BTO / B-In2O3. Compared with Ba and Ti, the positions of O and In elements indicate that B-In2O3 is anchored on the surface of BTO NPs.

[0058] like Figure 2As shown in the figure, the crystal structures of BTO, In2O3, B-In2O3, BTO / In2O3 and BTO / B-In2O3 were characterized by XRD. The original BTO showed the typical tetragonal diffraction peaks of BTO. The peaks of In2O3 at 21.5°, 30.6°, 35.2°, 37.7°, 41.8°, 45.7°, 51.0° and 60.6° correspond to the (211), (222), (400), (411), (332), (431), (440) and (622) crystal planes of In2O3, respectively (JCPDS#71-2194). Different from In2O3, B-In2O3 showed characteristic peaks of 30.5°(222), 33.1°(321), 35.5°(400), 51.0°(440), 60.7°(622), among which the diffraction peaks of 32.9°(101), 36.3°(002), 39.2°(110), 54.5°(112), 56.6°(200), 63.2°(103) and 67.0°(211), 69.1°(202) all belonged to In. This result was consistent with the TEM analysis results, indicating that part of In2O3 was reduced to B-In2O3 and part of In2O3 was reduced to In element. In the BTO / In2O3 heterojunction, the characteristic XRD diffraction peaks of In2O3 and BTO can be observed, indicating that In2O3 NPs were successfully grown on the surface of carboxylated BTO NPs. After reduction by NaBH4, the characteristic diffraction peaks of BTO NPs and B-In2O3 indicated that In2O3 on the surface of BTO NPs was successfully reduced to B-In2O3.

[0059] like Figure 3(a) , 3(b)As shown in the figure, the temperature of the blank sample, BTO, In2O3, B-In2O3, BTO / B-In2O3 and BTO / In2O3 changes with time under full spectrum irradiation. The temperature of the catalyst surface was detected in real time by an infrared thermometer. After 60s of full spectrum light irradiation, the temperature changes of the blank sample, BTO, In2O3, BTO / In2O3, B-In2O3 and BTO / B-In2O3 were 46℃, 70.8℃, 112.7℃, 116.7℃, 248.7℃ and 238.2℃ respectively. Both B-In2O3 and BTO / B-In2O3 heterojunctions have excellent photothermal conversion performance, which is due to the large number of oxygen defects introduced on the surface of B-In2O3, which can make the material absorb light in the entire full spectrum range, thereby improving the photothermal conversion efficiency. B-In2O3 has better light absorption performance than BTO / B-In2O3, so it has higher photothermal conversion efficiency. Using full-spectrum light source irradiation photothermal-pyroelectric-photocatalytic reduction of CO2, the catalytic activity of BTO, In2O3, B-In2O3, BTO / In2O3, BTO / B-In2O3 and BTO / B-In2O3 in photocatalytic reduction of CO2 under temperature fluctuations was investigated.

[0060] As shown in Figure 4(a), the yield graph of the photocatalytic reduction of CO2 to CO by BTO, In2O3, B-In2O3, BTO / In2O3, BTO / B-In2O3 and BTO / B-In2O3 under temperature fluctuation after 4 h of reaction is shown in Figure 4(b), which is the CO yield graph of the corresponding catalysts. The CO yields of BTO, In2O3, B-In2O3, BTO / In2O3 and BTO / B-In2O3 are 24.14, 27.14, 42.53, 85.46 and 146.56 μmol·g, respectively. -1 ·h -1 The CO yield of BTO / B-In2O3 was 6.07, 5.4, 3.45 and 1.71 times that of BTO, In2O3, B-In2O3 and BTO / In2O3 under the same conditions, respectively. The light source was turned on and off every 10 minutes (about 8 cycles) to test the photocatalytic reduction of CO2 on BTO / B-In2O3. It was found that the CO yield of the BTO / B-In2O3 heterojunction was further improved to 215.43 μmol·g -1 ·h -1 , which is 1.47 times that of BTO / B-In2O3 without temperature change, indicating that the pyroelectric effect of BTO can improve the photocatalytic CO2 reduction efficiency of heterojunction materials.

[0061] The preparation method of BTO / B-In2O3 provided by the present invention is simple, safe, and low in energy consumption. There is no toxic solvent in the preparation process, which is green and environmentally friendly. It shows efficient photocatalytic CO2 reduction efficiency, and the cost and photocatalytic CO2 reduction efficiency have important industrial application value.

[0062] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for preparing a photocatalytic ferroelectric heterojunction with photothermal-pyroelectric effect, characterized in that: include: Step 1: prepare carboxylated BaTiO3 NPs, add the carboxylated BaTiO3 NPs and a metal salt solution into a mixed solution of H2O and ethanol, and stir to obtain a mixed solution; Among them, the metal salt is In(NO3)3·4H2O; Step 2: adding ammonia water and ethanol solution to the mixed solution to form a homogeneous solution, reacting in an oil bath at 80° C. for 30 min, centrifugally washing and drying to obtain BaTiO3 / In(OH)3, and then calcining at high temperature in a muffle furnace to obtain a BaTiO3 / In2O3 heterojunction; Step 3: Grind the obtained BaTiO3 / In2O3 and NaBH4 in proportion and mix them evenly, and then calcine and wash them in an argon atmosphere in a tube furnace to obtain a BaTiO3 / B-In2O3 heterojunction.

2. The method for preparing a photocatalytic ferroelectric heterojunction having a photothermal-pyroelectric effect according to claim 1, characterized in that: The preparation process of the carboxylated BaTiO3 NPs includes: 0.50 mL, 6.4 mmol, of 3-aminopropyltriethoxysilane was added dropwise to a DMF solution containing succinic anhydride and stirred at room temperature for 3 h to generate N-3-(triethoxysilyl)propyl-4-carboxybutyramide; BaTiO3 NPs were added to the solvent and dispersed in a mixed solvent, stirred at room temperature for 8 h, and then washed with distilled water and ethanol at 5000 rpm for 3 times, and dried at 60°C under vacuum for 10 h to obtain carboxylated BaTiO3 NPs; Among them, succinic anhydride is 0.30 g, 3 mmol, DMF is 20 mL, and the mixed solvent is deionized water and DMF solution with a volume ratio of 1:

5.

3. The method for preparing a photocatalytic ferroelectric heterojunction having a photothermal-pyroelectric effect according to claim 2, characterized in that: In the step 1, the volume ratio of the mixed solution of H2O and ethanol is 1:

3.

4. The method for preparing a photocatalytic ferroelectric heterojunction having a photothermal-pyroelectric effect according to claim 3, characterized in that: In the step 2, the calcination temperature in the muffle furnace is 450° C. and the calcination time is 3 hours.

5. The method for preparing a photocatalytic ferroelectric heterojunction having a photothermal-pyroelectric effect according to claim 4, characterized in that: The step three comprises: BTO / In2O3 and NaBH4 with a mass ratio of 1:2 were ground and mixed evenly, calcined in an argon atmosphere at 400°C in a tube furnace for 3 hours, added with water and stirred for 12 hours, then washed twice with H2O and ethanol and centrifuged until the residual NaBH4 was completely removed, and dried at 60°C to obtain black BTO / B-In2O3.

6. Application of a photocatalytic ferroelectric heterojunction with photothermal-pyroelectric effect, characterized in that: A BaTiO3 / B-In2O3 heterojunction is prepared using the method for preparing a photocatalytic ferroelectric heterojunction with a photothermal-pyroelectric effect as described in any one of claims 1 to 5, wherein the BaTiO3 / B-In2O3 heterojunction is used for a photocatalytic carbon dioxide reduction reaction.

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