Metal semiconductor-based composite material, preparation method thereof and application of metal semiconductor-based composite material in arsenic ion detection

Abstract

The invention relates to a metal-semiconductor-based composite material, a preparation method thereof and application of the metal-semiconductor-based composite material in arsenic ion detection. The composite material disclosed by the invention comprises Bi2SeO5-Ag (at) Ag < + > NSs, and comprises a Bi2SeO5-Ag NSs heterojunction and Ag < + >, the Bi2SeO5-Ag NSs heterojunction comprises a Bi2SeO5 nanosheet and silver nanoparticles loaded on the surface of the Bi2SeO5 nanosheet. The preparation method comprises the following steps: preparing a bismuth selenate nanosheet, forming a silver nanoparticle layer on the surface of bismuth selenate, soaking the bismuth selenate nanosheet on the silver nanoparticle layer to combine silver ions, mixing a solution containing arsenic ions with a compound with silver nanoparticles on the surface and an aggregation agent, enriching on the surface of tinfoil, and drying, thereby obtaining the bismuth selenate composite material. And irradiating light to the center of the to-be-detected arsenic ion water drop dripped on the aluminum foil by using a laser light source. And finally, detecting the enriched arsenic ions by using Raman spectrum detection to obtain As (III) As (V) and a specific Raman peak signal.

Description

Technical Field

[0001] The present invention relates to the technical field of arsenic ion detection, and in particular to a metal-semiconductor composite material, a preparation method thereof, and an application thereof in arsenic ion detection. Background Art

[0002] Arsenic contamination of paddy soils is widespread, primarily due to mining activities and irrigation with arsenic-rich groundwater. In the aquatic environment, arsenic occurs primarily as arsenite (As 3+ ) and arsenite (As 5+ ), both of which are easily absorbed by rice and accumulated in the grain, thus entering the human food chain. Among the various exposure routes, dietary intake of rice is the main source of chronic low-dose arsenic exposure for most of the world's population. Arsenic in rice exists mainly in two forms: inorganic arsenic (iAs) and organic arsenic, of which dimethylarsonic acid (DMA) is the most common organic species. Inorganic arsenic, including As(III) and As(V), has been classified as a carcinogen by the World Health Organization. It is worth noting that As(III) is approximately 25 to 60 times more toxic than As(V). Long-term exposure to inorganic arsenic significantly increases the risk of lung, bladder and skin cancers, as well as ischemic heart disease.

[0003] In recent years, aqueous plasmonic nanostructures based on SERS technology have attracted considerable attention due to their high precision, high sensitivity, and simple operation. For effective detection, target molecules must be close to the SERS-active surface to generate a high signal-to-noise ratio Raman signal. However, most inorganic species exhibit weak affinity for noble metal SERS substrates, hindering effective adsorption and thus limiting quantitative detection capabilities. Therefore, achieving specific adsorption of analytes on the substrate surface is crucial for reliable and accurate SERS detection. The emergence of low-dimensional semiconductors, particularly two-dimensional transition metal dichalcogenides (TMDs) and one-dimensional carbon nanotubes, has attracted widespread attention. Due to their unique physical and electronic properties, 2D materials are considered promising candidates for next-generation microelectronic devices, balancing performance and cost. Among them, 2D Bi2SeO5 is an emerging oxide dielectric material. Its crystalline properties suggest a low trap state density, which may lead to high carrier mobility and reduced hysteresis. Furthermore, its high dielectric constant can enhance the local electromagnetic field at the plasmonic interface, potentially improving SERS performance.

[0004] Current research focuses on developing plasmonic materials for arsenic ion detection, typically using silver nanoparticles, gold nanoparticles, and silver nanowires. However, these methods suffer from low sensitivity and significant signal interference. Therefore, a more sensitive method for detecting arsenic ions in rice is urgently needed. Summary of the Invention

[0005] To address the existing problems of low sensitivity and high detection limits in detecting arsenic ions using Raman spectroscopy combined with low-dimensional semiconductors, the present invention provides a metal-semiconductor composite material, its preparation method, and its application in arsenic ion detection. Specifically, a method for enriching and highly sensitively detecting arsenic ions based on surface-enhanced Raman scattering (SERS) is provided. Bismuth selenate nanosheets are prepared, a silver nanoparticle layer is formed on the surface of the bismuth selenate, and silver ions are bound by immersion in the silver nanoparticle layer. An arsenic ion-containing solution is then mixed with the composite having the silver nanoparticles on its surface and an aggregating agent. After enrichment on a tinfoil surface, a laser light source is used to irradiate the center of a water droplet of the arsenic ions to be detected on the aluminum foil. Finally, the enriched arsenic ions are detected using Raman spectroscopy, obtaining specific Raman peak signals for As(III), As(V), and .

[0006] The first object of the present invention is to provide a composite material for detecting arsenic ions, the composite material comprising Bi2SeO5-Ag@Ag + NSs, including Bi2SeO5-Ag NSs heterojunction and Ag + ;Ag + Attached to the surface of Bi2SeO5-Ag NSs heterojunction in a free or weakly bound form; the Bi2SeO5-Ag NSs heterojunction includes Bi2SeO5 nanosheets and silver nanoparticles on the surface. + Attached to the surface of Bi2SeO5-Ag NSs heterojunction.

[0007] In some embodiments of the present invention, the Bi2SeO5-Ag NSs heterojunction and Ag + The mass ratio of (0.84~2.52):(0.17~0.51).

[0008] In some embodiments of the present invention, the mass ratio of the Bi2SeO5 nanosheets to the silver nanoparticles is (0.5-1.5): (0.34-1.02).

[0009] In some embodiments of the present invention, the Bi2SeO5-Ag@Ag + NSs were prepared by the following method:

[0010] Providing a mixture of a bismuth salt and a selenite salt;

[0011] Adding a reducing agent to the mixed solution and mixing to obtain a mixed solution; heating the obtained mixed solution to obtain Bi2Se3 NSs;

[0012] The obtained Bi2Se3 NSs were heat treated to obtain Bi2SeO5 NSs;

[0013] The Bi2SeO5 NSs are dispersed in a solvent to obtain a dispersion, which is then mixed with a first silver salt solution, and an ascorbic acid AA solution is added to react to obtain Bi2SeO5-AgNSs;

[0014] The Bi2SeO5-Ag NSs were immersed in the second silver salt solution to obtain Bi2SeO5-Ag@Ag + NSs.

[0015] In some embodiments of the present invention, the bismuth salt includes one or more of Bi(NO3)3·5H2O, BiCl3, and Bi2(SO4)3;

[0016] The selenium salt includes Na2SeO3 and / or SeO2;

[0017] The first reducing agent and the second reducing agent each independently include one or more of hydrazine hydrate, AA (ascorbic acid), Na2S2O3, Na2SO3 and NaBH4;

[0018] The mass volume ratio of the bismuth salt, selenite and reducing agent is (4-16): (0.7-2.8): (0.5-2) mmol / mmol / mL;

[0019] The mass volume ratio of the Bi2SeO5 NSs to the solvent is (2.5-7.5): (1-3) mg / mL; the solvent is selected from one or more of ethanol, isopropanol, N,N-dimethyl sulfoxide and N,N-dimethylformamide.

[0020] In some embodiments of the present invention, the conditions of the heat treatment are: temperature of 160-180° C., time of 10-14 h;

[0021] Heat treatment conditions: heating rate of 2-5°C / min, heating temperature of 500-600°C, and heating time of 3-5h.

[0022] In some embodiments of the present invention, the mass ratio of the Bi2SeO5 NSs to the first silver salt is (0.5-1.5): (0.34-1.02);

[0023] The concentration of the first silver salt is 10 to 20 mmol / L;

[0024] The concentration of the second silver salt solution is 10 to 20 mmol / L;

[0025] The first silver salt and the second silver salt are each independently selected from silver nitrate.

[0026] The second object of the present invention is to provide an application of the composite material in detecting arsenic ions; the arsenic ions are As3+ and As 5+ .

[0027] In some embodiments of the present invention, the method for detecting arsenic ions is as follows:

[0028] Providing a test solution containing arsenic ions;

[0029] Mixing the solution to be tested, the dispersion containing the composite material and the aggregating agent to obtain a mixed solution to be tested;

[0030] The enhanced Raman spectroscopy signal on the surface of the mixed solution to be tested is collected to detect the arsenic ions.

[0031] In some embodiments of the present invention, the aggregating agent comprises at least one of a Mg(NO3)2 solution, a Ba(NO3)2 solution, a Ca(NO3)2 solution, and a KNO3 solution;

[0032] The concentration of the aggregating agent is 0.1 to 1 mol / L;

[0033] The solution to be tested containing arsenic ions includes As 3+ and As 5+ , As 3+ The concentration is 10 -7 -10 -3 M;As 5+ The concentration is 10 -8 ~10 -3 M;

[0034] The volume ratio of the test solution containing arsenic ions, the dispersion containing the composite material and the aggregating agent is 100-160:25-40:25-40.

[0035] The instrument suitable for enhancing the Raman spectral signal is a Raman spectrometer, and its parameters are as follows: excitation power of 3-30mW, exposure time of 10-12s; laser wavelength of the laser light source of 532-785nm, Raman shift range of 300-1200cm -1 .

[0036] In some embodiments of the present invention, a process for constructing a standard curve between arsenic ion concentration and optical spectral signal is further included, which specifically includes the following steps:

[0037] Providing standard solutions containing arsenic ions at different concentrations and providing a dispersion containing a composite material; mixing the standard solutions containing arsenic ions at different concentrations with the dispersion of the composite material and an aggregating agent to obtain different standard mixed solutions; collecting surface-enhanced Raman spectral signals of the standard mixed solutions using a Raman spectrometer to establish a standard curve between arsenic ion concentration and Raman spectral signal, with Raman shift as the abscissa and spectral signal intensity as the ordinate;

[0038] The different concentrations of As 3+ The standard solution is at 10 -7 ~10 -3 M. Take several standard solutions containing arsenic ions with different concentrations as standard solutions. 5+ The standard solution is at 10 -8 ~10 -3 Several standard solutions containing arsenic ions at different concentrations are taken within the range of M as standard solutions.

[0039] Preferably, the volume ratio of the standard solution, the dispersion of the composite material and the aggregating agent is 100-160:25-40:25-40 μL.

[0040] The present invention is based on As 3+ and As 5+ For the test, Ag + With As 3+ and As 5+ The combined characteristic peaks are at 499 cm -1 and 816cm -1 Therefore, this peak is used as the characteristic peak, and the strength of its corresponding Raman signal is used to determine the content of arsenic ions.

[0041] In the present invention, Bi2SeO5 is used as a low-dimensional semiconductor. Its crystal properties indicate a low density of trap states, which may lead to higher carrier mobility and reduced hysteresis. When Bi2SeO5 nanosheets are combined with silver nanoparticles, their crystal properties promote efficient electron transfer between the nanosheets and the silver nanoparticle surface. The composite material based on localized surface plasmon resonance will more sensitively detect arsenic ions in liquids, especially water, and can improve the sensitivity of Raman detection. In other words, the present invention, by preparing Bi2SeO5 nanosheets and in situ growing silver nanoparticles on their surface, exhibits stronger Raman performance compared to individual silver nanocubes. This is because Bi2SeO5 acts as an electron donor, enabling electron transfer to the surface of AgNPs, providing better synergy with AgNPs. The larger dielectric constant of Bi2SeO5 suppresses the attenuation of electromagnetic waves, further amplifying the SERS performance of the Bi2SeO5-Ag nanostructure.

[0042] The above technical solution of the present invention has the following advantages over the prior art:

[0043] The present invention successfully synthesized a Bi2SeO5-Ag hybrid heterostructure by in-situ reduction of AgNO3 on the Bi2SeO5 surface. Compared with single Ag cube, Bi2Se3 NSs, Bi2SeO5 NSs and Bi2Se3 Ag NSs, the prepared composite showed significantly enhanced SERS activity. Bi2SeO5, as an electron donor, effectively transferred electrons to Ag nanoparticles, enhancing their synergistic effect. In addition, the high dielectric constant of Bi2SeO5 reduced electromagnetic damping, further improving the SERS performance of Bi2SeO5-AgNSs. The hybrid material has good stability and selectivity, and can be combined with Ag by incubation with AgNO3 solution. + , thereby simultaneously detecting As 3+ and As 5+ In the pretreated rice sample, the Bi2SeO5-Ag SERS composite successfully identified and detected As 3+ and As 5+ The present invention provides a new method for the construction of bismuth-based plasmon hybrid heterostructures and highlights their potential for arsenic ion detection in food safety and environmental monitoring.

[0044] The present invention can realize the detection of arsenic ions in rice through the method, thereby avoiding the harm of arsenic ions in rice to human health.

[0045] The present invention can also achieve quantitative detection of arsenic ions in the sample by first constructing a standard curve of arsenic ion concentration and optical spectrum signal. At the same time, by cooperating with the prepared composite material, a detection method with high enrichment and sensitivity is provided.

[0046] The present invention can achieve quantitative detection of arsenic ions in a solution to be tested through the above steps, and further improve the detection accuracy by improving the base material. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0048] Figure 1 This invention Figure 1 4 is a characterization diagram of each material in Example 1 of the present invention.

[0049] In the figures: a. TEM image of Bi2Se3 NSs, inset is a SEM image of Bi2Se3 NSs. b. TEM image of Bi2Se3-Ag NSs. c. TEM image of Bi2SeO5 NSs. d. TEM image of Bi2SeO5-Ag NSs, inset is a SEM image of Bi2SeO5-Ag NSs. e. X-ray diffraction pattern of Bi2Se3 NSs. f. X-ray diffraction pattern of Bi2SeO5 NSs. g. UV-visible absorption spectra of each material in Example 1 of the present invention, inset is a physical image of each material. h. HAADF-STEM elemental mapping image of Bi2SeO5-Ag NSs.

[0050] Figure 2 The Raman spectra of the solutions containing different concentrations of arsenic ions and As 3+ 、As 5+ The standard curve and relative standard deviation were obtained.

[0051] Figure 3 In: a. The present invention detects 10 using different materials -4 SERS spectra of M DPI. b, Ag Cube and Ag@Ag + Cube Detection As 3+ and solid and liquid As 3+ SERS spectra of Ag Cube and Ag@Ag + Cube Detection As 5+ and solid and liquid As 5+ SERS spectrum of Ag. + The combined different materials detected 10 -3 MAs 3+ &As 5+ SERS spectra.

[0052] Figure 4 This paper studies the specificity of Bi2SeO5-Ag heterostructure SERS sensor to As(III) and As(V).

[0053] In the figure: a, Bi2SeO5-Ag@Ag + NSs detection 10 -4 MAs 3+ and As 5+ SERS spectra of mixed solutions (interferences from different coexisting ions). b. As 3+ and As 5+ Comparison of SERS signal intensities under different coexisting ion interferences. DETAILED DESCRIPTION

[0054] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0055] The actual sample to be tested used in the present invention is commercially available rice. Unless otherwise specified, the raw materials used in the present invention are all commercially available commodities.

[0056] Example 1

[0057] This embodiment provides a method for enriching and highly sensitively detecting arsenic ions based on surface-enhanced Raman scattering technology, as shown below:

[0058] 1. Preparation of metal-semiconductor composite materials

[0059] S1: Bismuth selenide nanosheets were synthesized by solvothermal synthesis, dried, and calcined in a muffle furnace to obtain bismuth selenate nanosheets, as shown below:

[0060] 8 mmol Bi(NO3)3·5H2O and 1.4 mmol Na2SeO3 were dissolved in 30 mL of deionized water and ultrasonically dispersed for 30 minutes until completely dissolved. Then, 1 mL of hydrazine hydrate (H4N2·H2O) was added and the solution was thoroughly mixed. The mixture was transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 160°C for 12 hours. After cooling naturally to room temperature, it was washed three times with ethanol and dried at 80°C overnight to obtain Bi2Se3 NSs. The Bi2Se3 NSs precursor was placed in a crucible and heated to 500°C in a muffle furnace at a rate of 2°C / min and maintained there for 3 hours to obtain Bi2SeO5 NSs.

[0061] S2: The Bi2SeO5 NSs described in step S1 are dispersed in an ethanol solvent to obtain a dispersion, the dispersion is mixed with silver nitrate, aged, centrifuged, and washed to obtain a metal semiconductor composite material, as shown below:

[0062] A Bi2SeO5 NSs solution was prepared in ethanol at a concentration of 2.5 mg / mL. 200 μL of Bi2SeO5 NSs solution was added to a 1.5 mL centrifuge tube, followed by the addition of 200 μL of a 10 mM AgNO3 aqueous solution. After thorough mixing, 200 μL of a 0.1 M A solution was quickly added. The reaction was allowed to proceed for 1 hour, and after shaking and dispersion, the reaction was continued for another 1 hour, and the supernatant was removed. The product was washed three times with deionized water to obtain Bi2SeO5-Ag NSs. The Bi2SeO5 Ag NSs were then soaked in 100 μL of a 10 mM AgNO3 solution overnight to obtain Bi2SeO5-Ag@Ag + NSs.

[0063] Figure 1 Figure c shows the TEM image of the bismuth selenate nanosheets. The XRD patterns in Figures c and f are consistent with the Bi2SeO5 standard card surface, indicating that sheet-like Bi2SeO5 NSs with an average size of 425.1±11.6 nm were successfully synthesized in this example. Figure 1 Figure g shows the UV-visible absorption spectrum of Bi2SeO5-Ag NSs. It can be seen from the figure that Bi2SeO5-Ag NSs has a blue shift compared to Bi2SeO5NSs, indicating that Ag NPs have grown on the surface of Bi2SeO5 NSs. In addition, Figure 1 The HAADF-STEM elemental mapping image of Bi2SeO5-Ag NSs in Figure h also shows that Ag NPs were successfully grown on the surface of Bi2SeO5 NSs.

[0064] S3: The aqueous solution containing DPI and the different materials prepared in step S2 (without Ag) + ) dispersion and aggregating agent are mixed to prepare a mixture. The mixture is dropped on aluminum foil to form water droplets, and then waited for them to aggregate.

[0065] The specific method is as follows:

[0066] S3-1: 160 μL of a 10 -4 An aqueous solution containing DPI (4,5-diphenyl-2-imidazolethiol, a Raman beacon molecule), 40 μL Ag Cube, Ag Cube concentrated twice (Ag Cube 2×), Bi2Se3-Ag NSs, the Bi2Se3 NSs and Bi2SeO5 NSs obtained in step (1), and the Bi2SeO5-Ag NSs dispersion obtained in step (2) were mixed with 40 μL of a 1M Mg(NO3)2 aqueous solution to obtain a mixed solution containing an aggregation agent;

[0067] Among them, the preparation method of Ag Cube is:

[0068] Preparation of solution A: 0.2 g of AgNO3 was dissolved in 10 mL of 1,5-pentanediol (PD), and then 35 μL of 8 mg / mL CuCl2 solution was added to obtain solution A.

[0069] Preparation of solution B: 0.2 g of PVP (polyvinyl pyrrolidone) was dissolved in 10 mL of PD. Next, 20 mL of PD was added to a 100 mL round-bottom flask and heated at 190 ° C for 10 minutes. The precursors were then added dropwise in the following order: 250 μL of polyvinyl pyrrolidone (PVP) precursor solution was added dropwise every 30 seconds, and 500 μL of AgNO3 precursor solution was quickly added every minute. This process continued until the green color of the reaction mixture gradually disappeared, and Ag Cube was obtained. The resulting mixture was centrifuged to remove PD, and the Ag Cube was redispersed in 70 mL of ethanol. Finally, the Ag Cube was soaked in 100 μL of 10 mM AgNO3 solution overnight to obtain Ag@Ag + Cube.

[0070] Preparation of Bi2Se3-Ag:

[0071] A Bi2Se3 NSs solution was prepared in ethanol at a concentration of 2.5 mg / mL. 200 μL of Bi2Se3 NSs solution was added to a 1.5 mL centrifuge tube, followed by addition of 200 μL of 10 mM AgNO3 aqueous solution. After thorough mixing, 200 μL of 0.1 MAA solution was quickly added. The reaction was allowed to proceed for 1 hour, and after shaking and dispersion, the reaction was continued for another 1 hour, and the supernatant was removed. The product was washed three times with deionized water to obtain Bi2Se3-Ag NSs. The Bi2Se3-Ag NSs was then soaked in 100 μL of 10 mM AgNO3 solution overnight to obtain Bi2Se3-Ag@Ag + NSs.

[0072] S3-2: Take 40 μL of each of the mixed solutions and drip it onto aluminum foil to form droplets.

[0073] S4: Use a laser light source to irradiate light onto the center of the DPI water droplet to be detected on the aluminum foil.

[0074] S5: Use Raman spectroscopy to detect the enriched DPI and obtain a specific Raman peak signal of DPI.

[0075] 2. Preparation of standard curve:

[0076] Experimental steps:

[0077] S1: Provide standard solution containing arsenic ions; among them, different gradients of As 3+ The concentration of the standard solution was 10 -7 , 10 -6 , 10 -5 , 10 -4 , 10 -3 M, different gradients of As 5+ The concentration of the standard solution is 10-8 , 10 -7 , 10 -6 , 10 -5 , 10 -4 M.

[0078] S2: Take a metal semiconductor composite material dispersion with a concentration of 0.84 mg / 100 μL;

[0079] S3: 160 μL of standard solutions containing arsenic ions at different concentrations were mixed with 40 μL of metal semiconductor composite material dispersion and 40 μL of 1M Mg(NO3)2 aqueous solution aggregating agent to obtain different standard mixed solutions; the surface enhanced Raman spectral signals of the standard mixed solutions were collected by Raman spectrometer to establish a standard curve between arsenic ion concentration and Raman spectral signal.

[0080] The experimental results are shown in Figure 2 ,Depend on Figure 2 It can be seen that Figure 2 The Bi2SeO5-Ag heterostructure shows the effect of arsenic morphology (As 3+ and As 5+ )’s surface enhanced Raman scattering (SERS) detection performance. Figure 2 As shown in a, the SERS spectra of the mixed solutions at different concentrations showed that the -1 and 816cm -1 The characteristic peaks of As(III) and As(V) are shown in Figure 2. As the concentration decreases, the corresponding Raman peak intensity gradually weakens, indicating that the sensor has good sensitivity.

[0081] Figure 2 b and Figure 2 c shows the Raman intensity and As 3+ and As 5+ The linear fitting relationship between the concentration logarithms is obtained. 3+ The standard curve is y = 2034.8 + 14988.3x, R 2 =0.982; As 5+ The standard curve is y = 2164.5 + 17685.8x, R 2 =0.946; where x represents the concentration of the arsenic ion solution and y represents the spectral signal intensity. Both showed good linear correlation, and the coefficient of determination (R 2 ) were 0.982 and 0.946, respectively, indicating that the sensor has good potential for quantitative analysis.

[0082] Figure 2 d and Figure 2 e evaluated in 10 -5 M As(III) and 10 -6The relative standard deviations (RSDs) of the SERS signals at different concentrations of M As(V) were 10.8% and 17.9%, respectively, indicating that the sensor had good signal stability and reproducibility in multiple measurements.

[0083] Specifically, a Renishaw micro-Raman spectrometer and a 785nm argon ion laser were used to measure the Raman spectrum of DPI and obtain the Raman peak signal of DPI. The excitation wavelength of the Raman spectrum was 785nm, the excitation power was 3mW, and the magnification was 500 times (eyepiece 10x, objective lens 50x). The Raman shift range was 600 to 2000cm -1 , the exposure time is 10s, each acquisition is repeated more than 5 times, and the average value is recorded. Figure 3 It can be seen from a that the characteristic peak of DPI is at 1000 cm -1 The peak is most significant, so this peak is used as the characteristic peak, and the SERS performance of the material is determined by the strength of its corresponding Raman signal. Mg(NO3)2 makes the composite material exhibit strong SERS performance. This is because in the salt-induced aggregation process, Mg 2+ It can neutralize negative charge and destroy the double layer. Introducing NO3 - Impurities on the surface of silver nanoparticles were significantly removed, and the contact between DPI molecules and silver nanoparticles was improved for SERS detection.

[0084] Figure 3 Figure b shows Ag Cube and Ag@Ag + Cube detects As 3+ SERS spectra of Ag Cube and Ag@Ag in solid and liquid states. + Cube Detection As 5+ and solid and liquid As 5+ SERS spectrum. S6: Mix the aqueous solution containing arsenic ions, Ag Cube, Ag Cube concentrated twice (Ag Cube 2×), Bi2Se3-Ag NSs, the Bi2Se3 NSs and Bi2SeO5 NSs obtained in step (1), and the dispersion of Bi2SeO5-Ag NSs obtained in step (2) with an aggregating agent to prepare a mixture. Drop the mixture on aluminum foil to form water droplets and wait for them to aggregate. The specific method is as follows:

[0085] S6-1: 160 μL of the above concentration of 10 -3 M aqueous solution containing arsenic ions, 40 μL of different materials prepared in step S2 (containing Ag + ) were mixed with 40 μL of 1 M Mg(NO 3 ) 2 aqueous solution to obtain a mixed solution containing an aggregating agent.

[0086] S6-2: Take 40 μL of each of the mixed solutions and drip it onto aluminum foil to form droplets.

[0087] S7: Use a laser light source to irradiate light onto the center of the arsenic ion droplet to be detected dropped on the aluminum foil.

[0088] S8: The enriched arsenic ions are detected using Raman spectroscopy to obtain specific Raman peak signals of the arsenic ions.

[0089] Specifically, a Renishaw micro-Raman spectrometer and a 785nm argon ion laser were used to measure the Raman spectrum of arsenic ions and obtain the Raman peak signal of arsenic ions. The excitation wavelength of the Raman spectrum was 785nm, the excitation power was 3mW, and the magnification was 500 times (eyepiece 10x, objective lens 50x). The Raman shift range was 300 to 1200cm -1 , the exposure time is 10s, each acquisition is repeated more than 5 times, and the average value is recorded. Figure 3 As d shows, 3+ and As 5+ The combined characteristic peaks are at 499 cm -1 and 816cm -1 The peak is the most significant, so this peak is used as the characteristic peak, and the SERS performance of the material is determined by the strength of its corresponding Raman signal.

[0090] 3. Anti-interference experiment (specificity experiment)

[0091] In order to evaluate the Bi2SeO5-Ag heterostructure SERS sensor for As 3+ and As 5+ The selectivity of Ca 2+ 、Cd 2+ Cr 3+ 、Cu 2+ and Pr 3+ Common interfering metal ions such as α, β, β and β were tested under the same experimental conditions in step 2. Figure 4 As shown in Figure a, 3+ and As 5+ At 499cm -1 and 816cm -1 The characteristic peaks at the ions are still clearly visible, while the Raman signals of other coexisting ions are obviously weaker. Figure 4 Figure b further shows that in the presence of interfering ions, As 3+ and As 5+ The corresponding Raman intensity hardly changes, which fully demonstrates that the SERS sensor has excellent selectivity in arsenic form detection.

[0092] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A composite material based on a metal semiconductor, characterized in that: The composite material includes a Bi2SeO5-Ag NSs heterojunction and Ag + ; The Bi2SeO5-Ag NSs heterojunction includes Bi2SeO5 nanosheets and silver nanoparticles loaded on the surface.

2. The composite material according to claim 1, characterized in that The Bi2SeO5-Ag NSs heterojunction and Ag + The mass ratio is (0.84~2.52):(0.17~0.51).

3. The composite material according to claim 1, characterized in that The mass ratio of the Bi2SeO5 nanosheets to the silver nanoparticles is (0.5-1.5): (0.34-1.02).

4. The composite material according to claim 1, characterized in that The Bi2SeO5-Ag@Ag + NSs were prepared by the following method: Providing a mixture of a bismuth salt and a selenite salt; adding a first reducing agent to the mixed solution and mixing to obtain a mixed solution; heating the obtained mixed solution to obtain Bi2Se3 NSs; The obtained Bi2Se3 NSs were heat treated to obtain Bi2SeO5 NSs; The Bi2SeO5 NSs are dispersed in a solvent to obtain a dispersion, which is then mixed with a first silver salt solution, and a second reducing agent solution is added to react to obtain Bi2SeO5-Ag NSs; The Bi2SeO5-Ag NSs were immersed in the second silver salt solution to obtain Bi2SeO5-Ag@Ag + NSs.

5. The composite material according to claim 4, characterized in that The bismuth salt includes one or more of Bi(NO3)3·5H2O, BiCl3, and Bi2(SO4)3; The selenium salt includes Na2SeO3 and / or SeO2; The first reducing agent and the second reducing agent each independently include one or more of hydrazine hydrate, ascorbic acid, Na2S2O3, Na2SO3, and NaBH4; The molar volume ratio of the bismuth salt, selenite and reducing agent is (4-16): (0.7-2.8): (0.5-2) mmol / mmol / mL; The mass volume ratio of the Bi2SeO5 NSs to the solvent is (2.5-7.5): (1-3) mg / mL; the solvent is selected from one or more of ethanol, isopropanol, N,N-dimethyl sulfoxide, and N,N-dimethylformamide.

6. The composite material according to claim 4, characterized in that The heating treatment conditions are: temperature of 160-180°C and time of 10-14h; Heat treatment conditions: heating rate of 2-5°C / min, temperature of 500-600°C, time of 3-5h.

7. The composite material according to claim 4, characterized in that The mass ratio of the Bi2SeO5 NSs to the first silver salt is (0.5-1.5): (0.34-1.02); The concentration of the first silver salt is 10 to 20 mmol / L; The concentration of the second silver salt solution is 10 to 20 mmol / L; The first silver salt and the second silver salt are each independently selected from silver nitrate.

8. Use of the composite material according to any one of claims 1 to 7 in detecting arsenic ions; the arsenic ions are As 3+ and As 5+ .

9. The use according to claim 8, characterized in that The method for detecting arsenic ions is as follows: Providing a test solution containing arsenic ions; Mixing the solution to be tested, the dispersion containing the composite material and the aggregating agent to obtain a mixed solution to be tested; The enhanced Raman spectroscopy signal on the surface of the mixed solution to be tested is collected to detect the arsenic ions.

10. The use according to claim 9, characterized in that The aggregating agent includes at least one of Mg(NO3)2 solution, Ba(NO3)2 solution, Ca(NO3)2 solution and KNO3 solution; The concentration of the aggregating agent is 0.1 to 1 mol / L; The solution to be tested containing arsenic ions includes As 3+ and As 5+ , As 3+ The concentration is 10 -7 -10 -3 M;As 5+ The concentration is 10 -8 ~10 -3 M; The volume ratio of the test solution containing arsenic ions, the dispersion containing the composite material and the aggregating agent is 100-160:25-40:25-40.

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