A large-size porous single-crystal iron oxide semiconductor material and its application

Abstract

The invention belongs to the technical field of optoelectronic semiconductor materials, and discloses a large-scale porous single-crystalline iron oxide semiconductor material, which contains pores of a vermicular structure with a size of 5 nm to 1500 nm and uniform distribution; the large-scale porous single-crystalline iron oxide semiconductor material has a rigid self-supporting structure in three-dimensional space and does not require template support; the large-scale porous single-crystalline iron oxide semiconductor material has both a nano single crystal skeleton and a disordered connected open pore structure; the large-scale porous single-crystalline iron oxide semiconductor material is a porous single-crystalline iron oxide film or a porous single-crystalline iron oxide crystal; the surface of the porous single-crystalline iron oxide film has at least one of the (104) crystal plane, (214) crystal plane or (110) crystal plane of the porous single-crystalline iron oxide, and the largest surface of the porous single-crystalline iron oxide crystal has at least one of the (104) crystal plane, (214) crystal plane or (110) crystal plane of the porous single-crystalline iron oxide. The material of the invention can further improve the performance of the porous single-crystalline iron oxide as a semiconductor device.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor materials, and in particular relates to a large-size porous single-crystal iron oxide semiconductor material and application thereof. Background Art

[0002] Iron oxide is an environmentally friendly, abundant and efficient n-type semiconductor material that can utilize visible light. Due to its narrow bandgap, good stability, non-toxicity, abundant reserves and low price, it has become a hot spot in the research of optoelectronic semiconductor materials and has shown good application prospects in the fields of optoelectronic semiconductors and photoelectric catalysis.

[0003] In order to further improve the performance of optoelectronic semiconductor devices made of iron oxide semiconductor materials, many methods have been studied, such as ion doping, heterojunction construction, precious metal deposition, and co-catalyst loading to improve the performance of iron oxide materials. Since the low quantum efficiency and light conversion efficiency of iron oxide limit its practical application, the ordered porous photocatalyst has a large specific surface area and abundant catalytic active sites, which is conducive to improving the light collection efficiency and the separation of photogenerated carriers. Therefore, constructing an ordered porous structure is also an effective improvement method. However, most porous materials are usually polycrystalline or amorphous structures, with defects such as grain boundaries between their grains and low stability. Single crystal materials are three-dimensional macroscopic materials composed of atoms, ions, molecules, etc. in three-dimensional space with periodically arranged and ordered repetitive structures. The materials have unique advantages due to their long-range ordered lattice arrangement, clear structure, no grain boundaries, uniformity and stability. Therefore, single crystal materials have a wide range of applications in optoelectronic semiconductors, photoelectric catalysis, thermoelectric conversion, and energy storage.

[0004] Iron oxide has the disadvantages of poor electrical conductivity, short hole diffusion length, short excited state life, slow water oxidation reaction, etc., resulting in high recombination rate of photogenerated carriers in iron oxide, and low photoelectric performance. Porous single crystal materials introduce pore structure into the original single crystal material, and combine it with structural coherence to achieve material modification, with the characteristics of long-range order of lattice, no grain boundary, clear surface atomic termination layer, adjustable pore structure and high specific surface area, and have the advantages of single crystal material and porous material. Therefore, making iron oxide into porous single crystal structure is an effective method to improve the defects of iron oxide, so as to improve the photoelectric performance of iron oxide. The patent "Preparation method of metal oxide nanoparticles with three-dimensional porous single crystal structure" with publication number CN107539953A specifically discloses the implantation of crystal seeds on a prefabricated template by impregnation method, and then the metal oxide is grown in the template by hydrothermal method, and finally the template is removed to obtain metal oxide nanoparticles with the anti-structure of the prefabricated template. The patent "Single Crystal Porous Iron Oxide Powder Material and Preparation Method thereof" with publication number CN103579581A specifically discloses that the iron source and the fluorine source are dissolved in deionized water according to a certain molar ratio and stirred evenly, and then the fluorine source solution is dripped into the iron source solution. The above mixed solution is subjected to a hydrothermal reaction, and after cooling, a single crystal porous Fe2O3 powder material can be obtained. This method can adjust the average pore size from mesopore to macropore by changing the process.

[0005] In summary, conventional methods for preparing nanoporous single crystal materials in the prior art include chemical etching, chemical vapor deposition, template method, resonant permeation method, etc. The preparation methods are complex and require the introduction of different elements, and the maximum crystal size that can be prepared is only at the micrometer level, while the growth of centimeter-level porous single crystals on a macroscopic scale is still a major challenge in international technology. Therefore, it is necessary to prepare large-size porous single crystal iron oxide and use it as a photoelectric semiconductor material and photoelectric catalyst. Summary of the invention

[0006] In response to the problems in the above-mentioned prior art, especially porous single crystal semiconductor materials, the present invention provides a new large-scale porous single crystal iron oxide semiconductor material, which has adjustable pore size in three-dimensional space and a self-supporting structure, and can further improve the performance of the porous single crystal iron oxide material as a semiconductor device.

[0007] The present invention provides the following technical solutions:

[0008] The present invention provides a large-size porous single-crystal iron oxide semiconductor material, which contains a size of 5 nm to 1500 nm. The large-scale porous single-crystalline iron oxide semiconductor material has a rigid self-supporting structure in three-dimensional space and does not require template support; the large-scale porous single-crystalline iron oxide semiconductor material has both a nano single-crystalline skeleton and a disordered connected open pore structure; the large-scale porous single-crystalline iron oxide semiconductor material is a porous single-crystalline iron oxide film or a porous single-crystalline iron oxide crystal; the surface of the porous single-crystalline iron oxide film has at least one of the (104) crystal plane, (214) crystal plane or (110) crystal plane of the porous single-crystalline iron oxide, and the largest surface of the porous single-crystalline iron oxide crystal has at least one of the (104) crystal plane, (214) crystal plane or (110) crystal plane of the porous single-crystalline iron oxide; the large-scale porous single-crystalline iron oxide semiconductor material is prepared by placing a large-scale non-porous single crystal of a compound containing an iron source as a single crystal substrate in a raw material atmosphere, wherein the raw material atmosphere is oxygen-argon or air, at a high temperature of 473 K to 1173 K and a constant negative pressure of 0.5 Torr to 900 The decomposition and replacement reaction are carried out under Torr conditions, and non-iron atoms are removed by breaking bonds, while iron atoms and oxygen atoms form bonds and secondary crystallization is carried out to extend and grow, thereby obtaining a porous single crystal iron oxide semiconductor material; the large-size non-porous single crystal of the compound containing the iron source is a ferrous carbonate single crystal or an iron-containing sulfide compound single crystal.

[0009] Preferably, the iron-containing chalcogenide single crystal is at least one of an iron disulfide single crystal, a ferrous selenide single crystal or a ferrous telluride single crystal.

[0010] Preferably, the raw material atmosphere is selected according to different single crystal substrates, and is at least one of argon, oxygen argon and air, and the atmosphere flow rate satisfies the following conditions respectively:

[0011] The flow rate of oxygen and argon is not less than 0.009 SLM and not more than 100 SLM;

[0012] The air flow rate shall not be less than 0.009 SLM and not more than 100 SLM.

[0013] Among them, oxygen-argon is a mixture of 5% oxygen and 95% argon, and air is a mixture of 20% oxygen and 80% nitrogen.

[0014] SLM is the abbreviation of Standard Litre Per Minute, which means a flow rate of 1 L / min under standard conditions.

[0015] Preferably, the pyrolysis reaction conditions are:

[0016] The reaction temperature is 473 K~1173 K, the constant negative pressure is 0.5 Torr~900 Torr, and the reaction time is 10 min~500 h.

[0017] When nonporous single crystal of ferrous carbonate is selected as the single crystal substrate, the reaction temperature is 473 K~1173 K, the constant negative pressure is 1 Torr~700 Torr, and the reaction time is 30 min~100 h;

[0018] When nonporous single crystal of iron disulfide is selected as the single crystal substrate, the reaction temperature is 573 K~1173 K, the constant negative pressure is 10 Torr~700 Torr, and the reaction time is 30 min~100 h;

[0019] When nonporous single crystal of FeSe was selected as the single crystal substrate, the reaction temperature was 573 K~1123 K, the constant negative pressure was 10 Torr~700 Torr, and the reaction time was 10 min~400 h.

[0020] When non-porous single crystal of ferrous telluride is selected as the single crystal substrate, the reaction temperature is 523 K~1023 K, the constant negative pressure is 0.5 Torr~900 Torr, and the reaction time is 10 min~300 h.

[0021] Preferably, the porous single crystal iron oxide film has a thickness of 10 nm to 100 μm.

[0022] Preferably, the porous single crystal iron oxide crystal has a size of 0.1 cm to 20 cm, which refers to the macroscopic maximum length of the porous single crystal iron oxide crystal.

[0023] The present invention also provides the use of the large-size porous single-crystal iron oxide semiconductor material as a photoelectric semiconductor material in the fields of photoelectric conversion, photoelectric catalysis and electrochemical energy storage.

[0024] Large-size porous single-crystal iron oxide semiconductor materials can be used as sensitive media of sensors to make semiconductor gas-sensitive sensing elements.

[0025] Large-size porous single-crystalline iron oxide semiconductor materials can be used as energy storage materials. The porous structure can increase the active specific surface area and energy storage performance of the electrode and can be used in new solar cells.

[0026] Large-sized porous single-crystalline iron oxide semiconductor materials can be used in the field of environmental protection. The high specific surface area and porous single-crystalline structure of porous single-crystalline iron oxide crystals give them good adsorption and catalytic properties, and can be used to catalytically degrade organic pollutants.

[0027] Large-sized porous single-crystalline iron oxide semiconductor materials can be used as photoelectric catalysts. The porous structure provides more reactive sites for photoelectric catalytic reactions to improve their catalytic activity. It has good application prospects in low-temperature CO oxidation and photocatalytic water splitting to produce hydrogen.

[0028] Large-sized porous single-crystalline iron oxide semiconductor materials can be used as magnetoelectric devices and small spin electronic devices, and have good application prospects in the electronics industry, power switches, output transformers and other fields.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. The present invention provides single crystals of ferrous carbonate and single crystals of iron-containing sulfide compounds (single crystals of iron disulfide, single crystals of ferrous selenide and single crystals of ferrous telluride) as single crystal substrates. Under high temperature and raw material atmosphere, single crystals of iron-containing source compounds are reconstructed and crystallized from the outside to the inside. Under the premise that the size of the single crystal substrate remains unchanged, non-iron atoms escape and volatilize through specific channels of the single crystal lattice in different raw material atmospheres, while oxygen atoms enter the single crystal lattice. The remaining elements recrystallize on the surface of the single crystal substrate due to the reduction of relative atomic mass to construct a porous single crystal iron oxide with disordered nanoscale interconnected channels in a three-dimensional structure. Among them, the porous structure exhibits a three-dimensional percolation that is conducive to species diffusion, the single crystal skeleton maintains the photoelectric catalytic activity of the nanocrystal, and the porous single crystal iron oxide semiconductor material combines stability and activity, so that it has good application prospects in photoelectric semiconductors, photoelectric conversion and photoelectric catalysis.

[0031] 2. In the present invention, ferrous carbonate single crystals and iron-containing sulfide single crystals (iron disulfide single crystals, ferrous selenide single crystals and ferrous telluride single crystals) are used as single crystal substrates to prepare porous single crystal iron oxide semiconductor materials by breaking CO, Fe-S bonds, Fe-Se bonds or Fe-Te bonds and forming Fe-O bonds at the same time. Other iron-containing compounds have serious segregation, difficulty in removing non-iron elements, and large chemical bond breaking energy. For example, copper iron disulfide (FeCuS2) reacts with oxygen at high temperature to generate a mixture of iron oxide and copper oxide. The two are difficult to separate, so pure porous single crystal iron oxide crystals cannot be obtained. CaKFe4As4 single crystals are prone to generate impurities such as FeAs, KFe2As2 or CaO during growth, and are prone to generate holes and cracks, which affects the subsequent preparation and application of porous single crystal iron oxide semiconductor materials. The method of the present invention overcomes the defect that the electron transport of the traditional polycrystalline or granular iron oxide materials prepared from iron-based halogen compounds and iron oxyhydroxide is reduced by grain boundary losses, and greatly improves the performance of the porous single crystal iron oxide material as a device in the fields of optoelectronic semiconductors, photoelectric conversion, photoelectric catalysis and electrochemical energy storage.

[0032] 3. The present invention uses low-cost, abundant raw materials, overcomes the conventional method of introducing dopants or templates and manufacturing porous structures through calcination, more precisely controls the material morphology and pore structure, and does not introduce any impurity elements, providing a porous single-crystal iron oxide substrate with simple preparation conditions, simple preparation methods and good repeatability for iron oxide-based devices, thereby greatly improving the performance of large-size iron oxide-based materials as optoelectronic semiconductor devices.

[0033] 4. The present invention overcomes the challenges of growing large-scale centimeter-level porous single-crystalline iron oxide in the prior art and the technical difficulties in the growth and processing of related material systems. The centimeter-level large-scale porous single-crystalline iron oxide on a macroscopic scale can be used to make optoelectronic semiconductor devices, such as transistors, integrated circuits, etc. The growth of large-scale porous single crystals is of great significance for improving the performance of semiconductor devices, improving the efficiency of optoelectronic equipment, optimizing the photoelectric properties of photoelectric catalysts, and promoting the research and application of new materials. The preparation conditions of the present invention are simple and have good repeatability. According to the actual application direction, the porosity and pore size in the porous single crystal structure can be adjusted by optimizing the growth reaction conditions, such as reaction temperature, reaction chamber pressure, type and flow rate of the raw gas introduced, reaction time, etc., in the preparation process of porous single crystal iron oxide, so as to obtain a porous single crystal structure suitable for specific applications, thereby achieving the best performance of the material.

[0034] 5. The large-scale porous single-crystal iron oxide semiconductor material provided by the present invention, firstly, has a self-supporting structure, has its own skeleton, has a certain strength and rigidity, can maintain the stability of the material and the internal porous structure does not collapse without relying on external support conditions, and can maintain the shape and good stability as a whole; secondly, the semiconductor material of the present invention introduces a pore structure inside the large-scale iron oxide single crystal structure, which has the advantages of both porous materials and single crystal materials. The porous structure combines porosity and structural coherence, combines porosity and structural consistency, and the porous architecture also enhances light The ion scattering has a higher photoelectrocatalytic activity; and the single crystal skeleton minimizes the energy loss at the grain boundaries; from the XRD diagram in the attached figure, it can be seen that the material structure of the present invention is a single crystal, which retains the advantages of long-range order of the single crystal lattice, few crystal defects, no grain boundaries, and a clear surface atomic termination layer; from the SEM diagram, it can be seen that the iron oxide has a porous structure, which increases its specific surface area. Therefore, the porous single crystal iron oxide combines the advantages of single crystal materials and porous materials, and has the advantages of long-range order of the lattice, few crystal defects, no grain boundaries, a clear surface atomic termination layer and a higher specific surface area. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the self-supporting structure of the large-sized porous single crystal iron oxide of the present invention;

[0036] Figure 2For sample 1 in Example 1 # XRD pattern of large-sized (214) crystal plane porous single-crystalline iron oxide crystals;

[0037] Figure 3 For sample 2 in Example 2 # XRD pattern of large-sized (104) crystal plane porous single-crystalline iron oxide crystals;

[0038] Figure 4 For sample 2 in Example 2 # SEM image of large-scale (104) crystal plane porous single-crystalline iron oxide crystal;

[0039] Figure 5 For sample 5 in Example 4 # XRD pattern of large-sized (104) crystal plane porous single-crystalline iron oxide crystals;

[0040] Figure 6 For sample 5 in Example 4 # SEM image of large-scale (104) crystal plane porous single-crystalline iron oxide crystal;

[0041] Figure 7 For sample 5 in Example 4 # Raman spectrum of large-scale (104) crystal plane porous single-crystalline iron oxide crystal;

[0042] Figure 8 For sample 8 in Example 5 # SEM image of large-scale (104) crystal plane porous single-crystalline iron oxide crystal;

[0043] Fig. 9 For sample 11 in Example 6 # SEM image of large-scale (104)-plane porous single-crystalline iron oxide crystals. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Unless otherwise specified, the raw materials in the following examples were purchased from commercial sources.

[0046] The large-sized single crystal referred to in the present invention is a centimeter-sized single crystal with excellent physical and chemical properties. The growth of large-sized single crystals refers to the process of growing a large-sized single crystal from a melt or solution by a specific technical method. The existing methods include Czochralski method, molten salt method, crucible descent method, zone melting method, etc. The large-sized single crystals in the following embodiments are large-sized ferrous carbonate single crystals, large-sized iron disulfide single crystals, large-sized ferrous selenide single crystals, and large-sized ferrous telluride single crystals that have been grown according to the existing technical methods.

[0047] Large-sized nonporous single crystals of ferrous carbonate are commercially available.

[0048] Large-sized non-porous iron disulfide single crystals were prepared according to the method in the literature [RJ The preparation of single crystals of FeS2, CoS2, and NiS2 pyrites by chlorine transport[J]. Journal of Crystal Growth 2 (1968) 40-44].

[0049] The large-sized non-porous ferrous selenide single crystal was prepared according to the method in the literature [Mingwei Ma, Dongna Yuan, Yue Wu, Huaxue Zhou, Xiaoli Dong and Fang Zhou Flux-free growth of largesuperconducting crystal of FeSe by traveling-solvent floating-zone technique[J]. Supercond. Sci. Technol,27 (2014) 122001].

[0050] Large-sized pore-free ferrous telluride single crystals were prepared according to the method in the literature [BC Sales, AS Sefat, MAMcGuire, RY Jin, and D. Mandrus. Bulk superconductivity at 14K in singlecrystals of Fe1+yTexSe1−x[J]. PHYSICAL REVIEW B 79, 094521(2009)].

[0051] The analysis method in the following examples is:

[0052] The samples were analyzed using a JEOL JSM 6330F scanning electron microscope.

[0053] The phase structure analysis was carried out using a Bruker D8 Advance X-ray diffractometer.

[0054] The chemical properties and structure of the material surface were analyzed using the Horiba Soiontific LanRam HR Evolution Raman spectrometer.

[0055] Example 1

[0056] This embodiment provides a method for preparing a porous single crystal iron oxide film or a porous single crystal iron oxide crystal using a single crystal of ferrous carbonate as a single crystal substrate, comprising the following steps:

[0057] A 2 cm-sized single crystal of ferrous carbonate with a (214) crystal plane was used as a single crystal substrate and placed on a high-purity alumina boat, which was then placed in an ultra-sensitive controllable temperature and pressure reaction chamber. The raw material atmosphere was maintained in the reaction chamber, and the system was heated to 853 K. The system pressure was maintained at 300 Torr. Under this condition, a solid-solid phase transition from the outer lattice to the inner lattice was performed to form a semiconductor material.

[0058] The raw material atmosphere is air, which is composed of 20% oxygen and 80% nitrogen, with a flow rate of 0.1 SLM;

[0059] When preparing large-sized porous single-crystalline iron oxide thin films, the contact reaction time between the ferrous carbonate single crystal substrate and the raw material atmosphere is 30 min~20 h. After 300 min of decomposition reaction, the non-iron atoms escape and volatilize, and the iron atoms and oxygen atoms re-generate a porous single-crystalline iron oxide thin film on the surface of the ferrous carbonate single crystal substrate. After testing, the film thickness is 500 nm, recorded as sample M1#.

[0060] When preparing large-sized porous single-crystalline iron oxide crystals, the time for the ferrous carbonate single crystal substrate to contact the raw material atmosphere is 10 h to 100 h. In this embodiment, the decomposition reaction time is 20 h. Non-iron atoms escape and volatilize, and iron atoms and oxygen atoms regenerate porous single-crystalline iron oxide crystals on the surface of the ferrous carbonate single crystal substrate. The crystal size is 2 cm, which is recorded as sample 1#. Figure 2 As shown, after XRD testing, the prepared large-size porous single-crystalline iron oxide film sample 1# has a (214) crystal plane.

[0061] Example 2

[0062] The difference between Example 2 and Example 1 is that:

[0063] When a large-scale porous single-crystalline iron oxide film was prepared using a 2 cm-sized ferrous carbonate single crystal with a (104) crystal plane as a single crystal substrate, the raw material atmosphere was oxygen-argon, consisting of 5% oxygen and 95% argon, and the oxygen-argon flow rate was 0.1 SLM; the reaction system temperature was 823 K, the system pressure was 200 Torr, the decomposition reaction time was 20 h, and the thickness of the obtained porous single-crystalline iron oxide film was 500 nm, recorded as sample M2 # ;

[0064] When a large-sized porous single-crystalline iron oxide crystal was prepared using a 2 cm-sized ferrous carbonate single crystal with a (104) crystal face as a single crystal substrate, the raw material atmosphere was oxygen-argon, consisting of 5% oxygen and 95% argon, and the oxygen-argon flow rate was 0.1 SLM; the reaction system temperature was 823 K, the system pressure was 200 Torr, the decomposition reaction time was 15 h, and the obtained porous single-crystalline iron oxide crystal size was 2 cm, recorded as sample 2#. Figure 3 As shown in Figure 2, the XRD test shows that the crystal plane of the prepared large-scale porous single-crystal iron oxide film sample 2# has a (104) crystal plane. The morphology of sample 2# was characterized by scanning electron microscopy, and the results are shown in Figure 2. Figure 4 As shown, the large-scale porous single-crystalline iron oxide with (104) crystal plane has a porous self-supporting skeleton structure uniformly distributed at the nanoscale. Figure 1 shown.

[0065] Example 3

[0066] Sample M3 # Sample 3 # All of them use single crystals of ferrous carbonate with (104) crystal plane as single crystal substrates. The basic preparation steps of large-scale porous single crystal iron oxide thin films and large-scale porous single crystal iron oxide crystals are the same as those in Example 1. Different samples are obtained by changing the substrate and reaction conditions. The relationship between the sample numbers and the reaction conditions is shown in Table 1.

[0067] Table 1

[0068]

[0069] After testing, sample M3 # The thickness of sample 3 is in the range of 10 nm~100 μm. # The morphology of sample 1 # similar.

[0070] Example 4

[0071] This embodiment provides a method for preparing a porous single crystal iron oxide film or a porous single crystal iron oxide crystal using an iron disulfide single crystal as a single crystal substrate. The basic steps are the same as those in Embodiment 1. Different samples are obtained by changing the type of single crystal substrate and the reaction conditions, namely, Sample M5.# ~Sample M7 # Sample 5 # ~Sample 7 # ; The corresponding relationship between sample number, substrate and reaction conditions is shown in Table 2;

[0072] Table 2

[0073]

[0074] Sample M5 # 、M6 # 、M7 # The thickness of sample 5 is in the range of 10 nm~100 μm. # Sample 6 # and sample 7 # The morphology of sample 5 is similar. # For representatives, such as Figure 5 As shown, according to the XRD pattern, a strong diffraction peak is shown at 33.446°, corresponding to the (104) crystal plane of the porous single crystal iron oxide crystal; Figure 6 As shown, it is a SEM image of the (104) crystal plane porous single crystal iron oxide crystal prepared by it. It can be seen from the figure that the large-sized porous single crystal iron oxide crystal has a porous self-supporting skeleton structure uniformly distributed at the nanoscale; Figure 7 As shown, Raman spectra show that the prepared samples are all porous iron oxide single crystals.

[0075] Example 5

[0076] This embodiment provides a method for preparing a porous single crystal iron oxide film or a porous single crystal iron oxide crystal using a single crystal of ferrous selenide as a single crystal substrate. The basic steps are the same as those in Embodiment 1. Different samples are obtained by changing the type of single crystal substrate and the reaction conditions, namely, Sample M8. # ~Sample M10 # Sample 8 # ~Sample 10 # ; The corresponding relationship between sample number, substrate and reaction conditions is shown in Table 3;

[0077] Table 3

[0078]

[0079] Sample M8 # ~M10 # The thickness of sample 8 is in the range of 10 nm~100 μm. # ~Sample 10 # The morphology is similar to that of sample 8. # For representatives, such as Figure 8As shown, it is a SEM image of the (104) crystal plane large-sized porous single-crystalline iron oxide crystal prepared by it. It can be seen from the figure that the large-sized porous single-crystalline iron oxide crystal has a porous self-supporting skeleton structure uniformly distributed at the nanometer level.

[0080] Example 6

[0081] A porous single crystal iron oxide film and a porous single crystal iron oxide crystal are prepared using a single crystal of ferrous telluride as a single crystal substrate. The basic steps are the same as those in Example 1. Different samples are obtained by changing the type of single crystal substrate and the reaction conditions, namely, sample M11. # ~Sample M13 # 、Sample 10 # ~Sample 13 # ; The corresponding relationship between sample number, substrate and reaction conditions is shown in Table 4;

[0082] Table 4

[0083]

[0084] Sample M11 # ~Sample M113 # The thickness of samples 11 is in the range of 10 nm~100 μm. # ~Sample 13 # The morphology of sample 11 is similar. # For representatives, such as Fig. 9 As shown, it is a SEM image of the (104) crystal plane large-sized porous single-crystalline iron oxide crystal prepared by it. It can be seen from the figure that the large-sized porous single-crystalline iron oxide crystal has a porous self-supporting skeleton structure uniformly distributed at the nanometer level.

[0085] In summary, sample M1 # ~Sample M13 # The scanning electron microscope images of sample 1 # ~Sample 13 # Similarly, the pore size of the samples is in the range of 5 nm to 1500 nm.

[0086] The atomic structure of the samples was characterized by X-ray crystal diffraction, and the results showed that the samples prepared by the present invention were all porous single crystal iron oxide materials.

[0087] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A large-scale porous single-crystal iron oxide semiconductor material, characterized by: The invention relates to a method for preparing a large-scale porous single-crystalline iron oxide semiconductor material, wherein the large-scale porous single-crystalline iron oxide semiconductor material has a rigid self-supporting structure in three-dimensional space and does not require template support; the large-scale porous single-crystalline iron oxide semiconductor material has both a nano-single-crystal skeleton and a disordered connected open-pore structure; the large-scale porous single-crystalline iron oxide semiconductor material is a porous single-crystalline iron oxide film or a porous single-crystalline iron oxide crystal; the surface of the porous single-crystalline iron oxide film has at least one of the (104) crystal plane, (214) crystal plane or (110) crystal plane of the porous single-crystalline iron oxide, and the largest surface of the porous single-crystalline iron oxide crystal has at least one of the (104) crystal plane, (214) crystal plane or (110) crystal plane of the porous single-crystalline iron oxide; the large-scale porous single-crystalline iron oxide semiconductor material is prepared by placing a large-scale non-porous single crystal of a compound containing an iron source as a single crystal substrate in a raw material atmosphere, wherein the raw material atmosphere is at least one of oxygen, argon or air, at a high temperature of 473 K to 1173 K. The method comprises the following steps: performing decomposition and replacement reactions under conditions of K and a constant negative pressure of 0.5 Torr to 900 Torr, removing non-ferrous atoms by bond breaking, and forming bonds with iron atoms and secondary crystallization for extended growth to obtain a porous single crystal iron oxide semiconductor material; the large-size non-porous single crystal of the iron source-containing compound is a ferrous carbonate single crystal or an iron-containing chalcogenide single crystal.

2. The large-scale porous single-crystal iron oxide semiconductor material according to claim 1, characterized in that: The iron-containing chalcogenide single crystal is at least one of an iron disulfide single crystal, a ferrous selenide single crystal, and a ferrous telluride single crystal.

3. The large-scale porous single-crystalline iron oxide semiconductor material according to claim 1, characterized in that: The raw material atmosphere is selected according to different single crystal substrates and is at least one of oxygen, argon and air. The atmosphere flow rates meet the following conditions: the flow rate of oxygen and argon is not less than 0.009 SLM and not more than 100 SLM, and the flow rate of air is not less than 0.009 SLM and not more than 100 SLM.

4. The large-scale porous single-crystalline iron oxide semiconductor material according to claim 1, wherein: The high-temperature decomposition reaction time is 10 min~500 h.

5. The large-scale porous single-crystalline iron oxide semiconductor material according to claim 1, wherein: The thickness of the porous single crystal iron oxide film is 10 nm to 100 μm.

6. The large-scale porous single-crystalline iron oxide semiconductor material according to claim 1, wherein: The porous single crystal iron oxide crystal has a size of 0.1 cm to 20 cm.

7. The large-scale porous single-crystalline iron oxide semiconductor material according to claim 1 is used as a photoelectric semiconductor material in the fields of photoelectric conversion, photoelectrocatalysis and electrochemical energy storage.

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