An S-mechanism indium oxide / cadmium indium sulfur heterophase / heterojunction nanosheet photocatalyst and preparation method thereof

Abstract

The present invention discloses an S-scheme indium oxide / cadmium indium sulfide heterogeneous / heterojunction nanosheet photocatalyst and a preparation method thereof. Using an inorganic cadmium source, an indium source, and urea as raw materials, a transparent and uniform liquid is obtained by heating, and then thiourea is added and stirred to form a uniform yellow liquid. The obtained yellow liquid is transferred to a porcelain boat, and then the porcelain boat is placed in a nickel tube furnace. A pyrolysis reaction is carried out using nitrogen as a protective gas, and then it is cooled, washed, and dried to obtain an S-scheme rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst. This heterogeneous / heterojunction nanosheet catalyst is composed of a stack of multiple ultrathin sheets, endowing the nanosheets with more exposed active sites, higher charge migration efficiency, and strong redox ability. The preparation method of this heterogeneous / heterojunction has low cost and simple process. It shows excellent photocatalytic activity and stability in aspects such as photocatalytic water splitting for hydrogen production, environmental purification, photocatalytic degradation of formaldehyde and harmful gases, photocatalytic degradation of organic wastewater, and inhibition of the generation of bacteria and molds.

Description

Technical Field

[0001] The present invention belongs to the field of new energy and environmental purification, and is a photocatalyst used for hydrogen new energy and environmental purification. It relates to an S-mechanism indium oxide / cadmium indium sulfur heterogeneous / heterojunction nanosheet photocatalyst and a preparation method thereof. Specifically, it relates to a heterogeneous / heterojunction nanosheet photocatalyst composed of multiple layers of tightly coupled ultrathin sheets and a preparation method thereof. Background Art

[0002] Visible light-driven photocatalytic hydrogen production is considered to be a cost-effective green technology for converting solar energy into chemical energy and an ideal solution to the energy crisis and environmental pollution problems. So far, a large number of semiconductors have been synthesized and used as photocatalysts. Among various photocatalysts, cadmium indium sulfur bimetallic sulfide CdIn2S4 has attracted the attention of researchers due to its visible light response, high chemical stability, narrow band gap and suitable band edge position. However, high carrier recombination rate, slow charge transfer kinetics and fewer exposed active sites hinder its practical application.

[0003] To date, many strategies have been developed to enhance the photocatalytic performance of photocatalysts, such as morphology regulation, element doping, noble metal loading, defect engineering, and heterostructure construction. Among these strategies, constructing semiconductor heterojunctions is one of the most effective strategies to improve the photocatalytic efficiency.

[0004] In recent years, indium oxide (In2O3) has become a promising catalyst due to its good reduction potential and excellent chemical stability in photocatalytic hydrogen production. There are two types of indium oxide: hexagonal indium oxide (rh-In2O3) and cubic indium oxide (c-In2O3). The preparation of heterojunctions by combining indium oxide with CdIn2S4 can effectively improve the photocatalytic efficiency. However, the currently prepared In2O3 / CdIn2S4 heterojunction photocatalysts either have few exposed surface active sites, or CdIn2S4 is prone to photocorrosion, or it is difficult to construct S-mechanism heterophase / heterojunctions, resulting in low separation efficiency of photogenerated electrons and holes and failure to obtain high redox ability. Summary of the invention

[0005] The present invention aims at the shortcomings of the In2O3 / CdIn2S4 heterojunction photocatalyst prepared in the prior art, such as few exposed surface active sites, low specific surface area, easy photocorrosion, low separation efficiency of photogenerated electrons and holes, difficulty in preparing heterophase / heterojunction in one step, and inability to obtain high redox ability. A preparation method for constructing S-mechanism rh / c-In2O3 / CdIn2S4 heterophase / heterojunction nanosheet photocatalyst is proposed. The present invention adopts the following technical solutions to achieve this:

[0006] An S-mechanism indium oxide / cadmium indium sulfur heterogeneous / heterojunction nanosheet photocatalyst and a preparation method thereof, characterized in that the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction is formed by two crystalline indium oxides of hexagonal structure rh-In2O3 and cubic structure c-In2O3 to form a rh / c-In2O3 heterogeneous junction, and is compounded with CdIn2S4 to form a rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction, and the migration of photogenerated carriers in the heterogeneous / heterojunction follows the S mechanism; the S-mechanism rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet is obtained by synchronous pyrolysis, oxidation, and sulfurization of a liquid precursor, and is composed of multiple layers of ultra-thin sheets stacked and coupled, giving the nanosheet more exposed active sites, and the photocatalyst has higher charge migration efficiency and strong redox ability. The preparation method specifically comprises the following steps:

[0007] (1) Weigh 0.1-5.0 g CdCl2·2.5H2O, 0.1 g-5.0 g InCl3 and 0.5-10 g urea, place in an oil bath, heat and stir at 60-80°C for 10-40 min, and the mixture forms a transparent and uniform liquid.

[0008] (2) Add 0.1-5.0 g of thiourea to the liquid obtained in step (1) above, and stir for 0.5-2 h to form a uniform yellow liquid.

[0009] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, and heated to 550-850°C at a rate of 1-15°C / min using nitrogen as a protective gas, and kept warm at this temperature for 1-4 hours, and then cooled to room temperature and washed three times with water and ethanol respectively, and dried at 40-60°C to obtain S-mechanism rh / c-In2O3 / CdIn2S4 heterophase / heterojunction nanosheet photocatalyst.

[0010] The advantages of the present invention are: the preparation method is low in cost and simple in process; the rh / c-In2O3 / CdIn2S4S-mechanism heterogeneous / heterojunction nanosheet photocatalyst constructed by one-step method is composed of multiple layers of ultra-thin sheets stacked and coupled, giving the nanosheet more exposed active sites, which is conducive to the rapid migration in and out of the electrolyte, the multi-site adsorption of protons and the rapid escape of the generated H2. In addition, the construction of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction with S-mechanism and the built-in electric field greatly improves the charge migration efficiency, shows strong redox ability, and effectively avoids photocorrosion. It is used in photocatalytic decomposition of water to produce hydrogen, purify the environment, photocatalytic degradation of formaldehyde and harmful gases, photocatalytic degradation of organic wastewater, inhibition of the production of bacteria and molds, etc., and shows excellent photocatalytic activity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the XRD spectrum and PDF standard spectrum of the rh / c-In2O3 / CdIn2S4 heterophase / heterojunction nanosheet photocatalyst prepared in Example 1.

[0012] Figure 2 This is the SEM photo of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared in Example 1.

[0013] Figure 3 TEM photos of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared in Example 1: (a) low-magnification photo, (b) high-magnification photo.

[0014] Figure 4 This is the HRTEM image of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared in Example 1.

[0015] Figure 5 These are the STEM photos and element distribution photos of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared in Example 1.

[0016] Figure 6 The UV-visible diffuse reflectance spectra of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared in Example 1, and the samples of Control Example 1 and Control Example 2 are shown.

[0017] Figure 7 This is the hydroxyl radical experiment of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared in Example 1.

[0018] Figure 8 This is the superoxide radical experiment of the rh / c-In2O3 / CdIn2S4 nanosheet heterojunction photocatalyst prepared in Example 1.

[0019] Fig. 9 This is a graph showing the relationship between the amount of hydrogen produced from photocatalytic water decomposition and time for the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1, the rh / c-In2O3 prepared by the method described in Control Example 1, and the CdIn2S4 photocatalyst prepared by the method described in Control Example 2.

[0020] Fig.10This is a test graph of the cyclic stability of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1 under the irradiation of a simulated visible light xenon lamp (λ≥420nm) for photocatalytic decomposition of water to produce hydrogen.

[0021] Fig.11 This is a graph showing the relationship between the photocatalytic degradation of formaldehyde and time by the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1, the rh / c-In2O3 prepared by the method described in Control Example 1, and the CdIn2S4 photocatalyst prepared by the method described in Control Example 2 under the irradiation of a simulated visible light xenon lamp (λ≥420nm). DETAILED DESCRIPTION

[0022] The present invention is further described in detail below through embodiments:

[0023] Embodiment 1:

[0024] (1) Weigh 0.57 g of CdCl2·2.5H2O, 0.55 g of InCl3, and 1.0 g of urea, and place them in an oil bath and heat at 80°C. After stirring for 30 min, the mixture forms a transparent and uniform liquid.

[0025] (2) Add 0.57 g of thiourea to the liquid obtained in step (1) above and stir for 2 h to form a uniform yellow liquid.

[0026] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 750°C at a rate of 5°C / min using nitrogen as a protective gas, and maintained at this temperature for 4 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 40°C.

[0027] Embodiment 2:

[0028] (1) Weigh 0.34 g of CdCl2·2.5H2O, 0.77 g of InCl3, and 1.0 g of urea, and place them in an oil bath and heat at 80°C. After stirring for 20 min, the mixture forms a transparent and uniform liquid.

[0029] (2) Add 0.57 g of thiourea to the liquid obtained in step (1) above and stir for 2 h to form a uniform yellow liquid.

[0030] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 750°C at a rate of 5°C / min using nitrogen as a protective gas, and maintained at this temperature for 4 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 40°C.

[0031] Embodiment three:

[0032] (1) Weigh 0.80 g of CdCl2·2.5H2O, 0.33 g of InCl3, and 1.0 g of urea, and place them in an oil bath and heat at 80°C. After stirring for 40 min, the mixture forms a transparent and uniform liquid.

[0033] (2) Add 0.57 g of thiourea to the liquid obtained in step (1) above and stir for 2 h to form a uniform yellow liquid.

[0034] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 750°C at a rate of 5°C / min using nitrogen as a protective gas, and maintained at this temperature for 4 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 40°C.

[0035] Embodiment 4:

[0036] (1) 1.71 g of CdCl2·2.5H2O, 1.65 g of InCl3 and 5.0 g of urea were weighed and then placed in an oil bath and heated at 60°C. After stirring for 20 min, the mixture formed a transparent and uniform liquid.

[0037] (2) Add 2.28 g of thiourea to the liquid obtained in step (1) above and stir for 1 h to form a uniform yellow liquid.

[0038] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 650°C at a rate of 5°C / min using nitrogen as a protective gas, and maintained at this temperature for 4 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 40°C.

[0039] Embodiment five:

[0040] (1) 3.64 g of CdCl2·2.5H2O, 0.88 g of InCl3 and 4.0 g of urea were weighed and then placed in an oil bath and heated at 80°C. After stirring for 30 min, the mixture formed a transparent and uniform liquid.

[0041] (2) Add 1.71 g of thiourea to the liquid obtained in step (1) above and stir for 1 h to form a uniform yellow liquid.

[0042] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 850°C at a rate of 15°C / min using nitrogen as a protective gas, and maintained at this temperature for 2 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 50°C.

[0043] Embodiment six:

[0044] (1) 1.14 g of CdCl2·2.5H2O, 1.10 g of InCl3 and 4.0 g of urea were weighed and then placed in an oil bath and heated at 70°C. After stirring for 20 min, the mixture formed a transparent and uniform liquid.

[0045] (2) Add 1.71 g of thiourea to the liquid obtained in step (1) above and stir for 2 h to form a uniform yellow liquid.

[0046] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 750°C at a rate of 5°C / min using nitrogen as a protective gas, and maintained at this temperature for 3 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 60°C.

[0047] Embodiment seven:

[0048] (1) Weigh 2.28 g of CdCl2·2.5H2O, 2.2 g of InCl3, and 6.0 g of urea, and place them in an oil bath and heat at 80°C. After stirring for 20 min, the mixture becomes a transparent and uniform liquid.

[0049] (2) Add 1.80 g of thiourea to the liquid obtained in step (1) above and stir for 1 h to form a uniform yellow liquid.

[0050] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 700°C at a rate of 5°C / min using nitrogen as a protective gas, and maintained at this temperature for 4 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 40°C.

[0051] Comparative Example 1:

[0052] (1) Weigh 1.10 g of InCl3 and 1.0 g of urea, place in an oil bath, and heat at 80°C. After stirring for 30 min, the mixture becomes a transparent and uniform liquid.

[0053] (2) Add 0.57 g of thiourea to the liquid obtained in step (1) above and stir for 2 h to form a uniform yellow liquid.

[0054] (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, heated to 750°C at a rate of 5°C / min using nitrogen as a protective gas, and maintained at this temperature for 4 hours, and then cooled to room temperature, washed three times with water and ethanol respectively, and dried at 40°C.

[0055] Comparative Example 2:

[0056] (1) 0.123 g Cd(NO3)2·4H2O, 0.222 g In(NO2)3 and 2.40 g thioacetamide were dissolved in 30 ml of a mixed solution of deionized water and ethanol (volume ratio 1:1). The resulting solution was then transferred to a 50 mL Teflon-lined stainless steel autoclave and reacted at 160 °C for 16 h. After cooling to room temperature, the product was washed three times with deionized water and ethanol respectively and dried to obtain the CdIn2S4 photocatalyst.

[0057] Figure 1 The XRD spectrum of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1. Figure 1 As shown, the characteristic peaks at 23.24°, 27.31°, 32.99°, 40.75°, 43.31° and 47.42° correspond to the (220), (311), (400), (422), (511) and (440) crystal planes of cubic phase CdIn2S4 (JCPDS No. 27-0060), indicating that cubic phase CdIn2S4 was prepared by the method described in Comparative Example 2. The diffraction peaks of cubic phase c-In2O3 (JCPDS No. 06-0416) and characteristic peaks of hexagonal phase rh-In2O3 (JCPDS No. 22-0336) in the figure indicate that rh / c-In2O3 heterophase In2O3 was prepared by the method described in Example 1. As expected, all characteristic peaks of the sample prepared by the method described in Example 1 can be attributed to c-In2O3, rh-In2O3 and cubic CdIn2S4, respectively, without other impurity diffraction peaks. XRD results show that the present invention successfully synthesized rh / c-In2O3 / CdIn2S4 heterophase / heterojunction.

[0058] Figure 2 This is a SEM photo of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1. As can be seen from the figure, the obtained catalyst is a uniform and regular nanosheet structure with a thickness of about 20-30nm.

[0059] Figure 3TEM photos of rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalysts prepared by the method described in Example 1 at different magnifications. As can be seen from Figure a, the nanosheets are formed by the stacking and coupling of ultrathin nanosheets, and the stacked ultrathin nanosheet structure can be more clearly seen in Figure b. Under the action of capillary forces, water molecules can more easily enter the interlayer gaps between ultrathin nanosheets. This unique layer stacking structure gives the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction photocatalyst a larger surface area and more reaction sites.

[0060] Figure 4 This is a HRTEM image of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1. Figure 4 It can be seen that the lattice fringe spacing of 0.282nm corresponds to the (104) crystal plane of rh-In2O3 (JCPDS No. 22-0336), and the lattice fringe of 0.292nm matches well with the (222) crystal plane of c-In2O3 (JCPDS No. 06-0416). The lattice spacing of 0.383nm corresponds to the (220) crystal plane of CdIn2S4 (JCPDS No. 27-0060). In addition, it can be clearly observed that the interface is closely coupled, which is conducive to electron transfer and the formation of built-in electric field. This provides a good foundation for the establishment of S-type heterojunction.

[0061] Figure 5 The STEM image and element distribution image of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1. The STEM element distribution shows that the four elements In, Cd, O and S are evenly distributed on the sample surface.

[0062] Figure 6 UV-Vis diffuse reflectance spectra of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1, and the samples of Reference Example 1 and Reference Example 2. The absorption edge of rh / c-In2O3 is at 422nm. In contrast, pure CdIn2S4 shows better visible light absorption, with an absorption edge at 595nm, which may be attributed to its narrow band gap. The absorption band edge of the rh / c-In2O3 / CdIn2S4 catalyst is located at 580nm, and the visible light absorption is significantly enhanced compared to rh / c-In2O3. In short, the formation of the heterojunction effectively changes the optical absorption of rh / c-In2O3, which directly improves the photocatalytic performance of the catalyst.

[0063] Figure 7This is a hydroxyl radical experiment on the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1. It can be seen that in the dark, no DMPO-·OH signal was observed on the rh / c-In2O3 / CdIn2S4 photocatalyst. Upon light irradiation, both rh / c-In2O3 and rh / c-In2O3 / CdIn2S4 showed four representative DMPO-·OH signals with an intensity ratio of 1:2:2:1. However, for CdIn2S4 under light irradiation, there was no DMPO-·OH signal. This is attributed to the valence band position ratio of CdIn2S4·OH / OH - At a more negative potential (1.99 V vs NHE), the generation of ·OH is thermodynamically limited. The resulting accumulation of holes in the valence band of rh / c-In2O3 excludes the possibility of a type-II heterojunction, further confirming that the rh / c-In2O3 / CdIn2S4 photocatalyst follows the S mechanism charge transfer route.

[0064] Figure 8 This is the superoxide radical experiment of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1. It can be seen that in the dark, no DMPO-·O2 was observed on the rh / c-In2O3 / CdIn2S4 photocatalyst. - Upon light irradiation, rh / c-In2O3, CdIn2S4, and rh / c-In2O3 / CdIn2S4 all showed six DMPO-·O2 - signal, and DMPO-·O2 of rh / c-In2O3 / CdIn2S4 - The signal was the strongest, which further confirmed that the rh / c-IO / CIS photocatalyst followed the S mechanism charge transfer route.

[0065] Fig. 9 The relationship between the amount of hydrogen produced by photocatalytic decomposition of water and time of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1, the rh / c-In2O3 prepared by the method described in Comparative Example 1, and the CdIn2S4 photocatalyst prepared by the method described in Comparative Example 2 under the irradiation of a simulated visible light xenon lamp (λ≥420nm). It can be seen that the hydrogen production of the rh / c-In2O3 / CdIn2S4 photocatalyst obtained in Example 1 is as high as 28mmol·g -1 , the hydrogen production rate reached 4.7mmol·g -1 ·h -1 , respectively, than CdIn2S4 (1.3mmol·g -1 ·h -1 ) and rh / c-In2O3(0.6mmol·g-1 ·h -1 ) are 3.6 and 7.8 times higher.

[0066] Fig.10 This is a test diagram of the cyclic stability of the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1 under the irradiation of a simulated visible light xenon lamp (λ≥420nm). The experimental results show that the heterogeneous / heterojunction nanosheet photocatalyst achieves good cyclic stability while maintaining high performance. During the 30-hour cycle test, the hydrogen evolution activity did not decrease significantly.

[0067] Fig.11 The figure is a relationship between the photocatalytic degradation of formaldehyde and time by the rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the method described in Example 1 under the irradiation of a simulated visible light xenon lamp (λ≥420nm). The experimental results show that the degradation rate of formaldehyde by the rh / c-In2O3 / CdIn2S4 photocatalyst obtained in Example 1 reaches 91.4% in 60 minutes, indicating that the S-mechanism rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the present invention can effectively remove formaldehyde harmful gas in the air.

[0068] In addition, under the irradiation of a simulated visible light xenon lamp (λ≥420nm), the S-mechanism rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the present invention is used for photocatalytic degradation of various organic dye wastewaters. The UV-vis absorption experimental results show that the organic dyes are rapidly degraded under the irradiation of simulated visible light and can be used for degradation of organic wastewater. Adding it to the coating can avoid the formation of mold in a humid environment and can well remove formaldehyde, ammonia and hydrogen sulfide gas in the air, indicating that the S-mechanism rh / c-In2O3 / CdIn2S4 heterogeneous / heterojunction nanosheet photocatalyst prepared by the present invention can be used in environmental purification fields such as air purification and sterilization and antibacterial.

[0069] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, substitutions, simplifications, etc. made without departing from the principles and process of the present invention are equivalent replacements and should be included in the protection scope of the present invention.

Claims

1. A method for preparing an S-mechanism indium oxide / cadmium indium sulfur heterophase / heterojunction nanosheet photocatalyst, characterized in that: The indium oxide / cadmium indium sulfur heterogeneous / heterogeneous junction is formed by two crystal forms of indium oxide, hexagonal indium oxide rh-In2O3 and cubic indium oxide c-In2O3, forming a rh / c-In2O3 heterogeneous junction, and compounding with cadmium indium sulfur CdIn2S4 to form a rh / c-In2O3 / CdIn2S4 heterogeneous / heterogeneous junction. The migration of photogenerated carriers in the heterogeneous / heterogeneous junction follows the S mechanism; the S mechanism rh / c-In2O3 / CdIn2S4 heterogeneous / heterogeneous junction nanosheet is obtained by simultaneous pyrolysis, oxidation and sulfurization of a liquid precursor, and is composed of a plurality of ultra-thin sheets stacked and coupled. The preparation method specifically comprises the following steps: (1) Weigh 0.1-5.0 g CdCl2·2.5H2O, 0.1 g-5.0 g InCl3 and 0.5-10 g urea, place in an oil bath, heat and stir at 60-80°C for 10-40 min, and the mixture forms a transparent and uniform liquid; (2) adding 0.1-5.0 g of thiourea to the liquid obtained in step (1) above, stirring for 0.5-2 h to form a uniform yellow liquid; (3) The yellow liquid obtained in step (2) is transferred to a porcelain boat, and then the porcelain boat is placed in a tube furnace, and heated to 550-850°C at a rate of 1-15°C / min using nitrogen as a protective gas, and kept warm at this temperature for 1-4 hours, and then cooled to room temperature and washed three times with water and ethanol respectively, and dried at 40-60°C to obtain S-mechanism rh / c-In2O3 / CdIn2S4 heterophase / heterojunction nanosheet photocatalyst.

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