Method of eluting metal nanoparticles from the surface of structured metal oxide through intense pulsed light process and a method of manufacturing a gas sensor using the same

Abstract

The present invention relates to a method for leaching metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process and a method for manufacturing a gas sensor using the same, wherein metal nanoparticles are leached onto a porous structured metal oxide doped with metal ions derived from a metal-organic framework (MOF) doped with heterogeneous metal ions through a photothermal treatment process, thereby enabling the effective manufacturing of a gas sensor with excellent gas detection characteristics and stability through a simplified process. The method for leaching metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to the present invention comprises the steps of: synthesizing a metal-organic framework doped with heterogeneous metal ions; and heat-treating the metal-organic framework doped with heterogeneous metal ions to convert it into a structured metal oxide doped with heterogeneous metal ions. The method is characterized by comprising the step of performing a photothermal treatment process on a structured metal oxide doped with heterogeneous metal ions to elute metal nanoparticles to the surface of the structured metal oxide.

Description

Technology Field

[0001] The present invention relates to a method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process and a method for manufacturing a gas sensor using the same. More specifically, the invention relates to a method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process and a method for manufacturing a gas sensor using the same, wherein metal nanoparticles are dissolved through a photothermal treatment process onto a porous structured metal oxide doped with metal ions derived from a metal-organic framework (MOF) doped with heterogeneous metal ions, thereby enabling the effective manufacturing of a gas sensor with excellent gas detection characteristics and stability through a simplified process. Background Technology

[0003] Gas sensors utilizing metal oxide semiconductors are devices that detect specific gases by leveraging the characteristic change in the electrical conductivity of the metal oxide semiconductor upon gas adsorption. These metal oxide semiconductor-based gas sensors have the advantages of low manufacturing costs and excellent response characteristics to gases.

[0004] A technology has been proposed to further improve gas detection characteristics by immobilizing metal nanoparticles with excellent catalytic properties on metal oxides. For example, Korean Registered Patent No. 1400605 (Patent Document 1) presents a technology that introduces a metal salt into a metal oxide nanostructure and binds a metal catalyst in the form of nanoparticles to the metal oxide nanostructure through a photothermal sintering process.

[0005] Although gas detection characteristics can be improved through the introduction of metal nanoparticles, in order to increase the sensitivity of the gas sensor, the amount of gas molecules adsorbed onto the support of the gas sensor must first be increased. Since a porous structure support facilitates the adsorption of gas molecules, various types of porous structure supports have been proposed. For example, Korean Published Patent No. 2023-0072069 (Patent Document 2) uses a yarn-structured nanofiber with a number of pores as a support, and Korean Registered Patent No. 1887281 (Patent Document 3) applies a metal oxide nanosheet with nanopores to enable rapid movement and adsorption of gas.

[0006] Meanwhile, since gas sensors are mostly used to detect hazardous gases and are repeatedly exposed to harsh chemical environments for extended periods, they must possess physical and chemical stability in addition to gas detection capabilities.

[0007] In addition, in the case of gas sensors equipped with metal nanoparticles, most methods involve immobilizing the metal nanoparticles on a support through high-temperature heat treatment. This leads to problems such as deformation of the support due to the high-temperature heat treatment or the constraint that the support must be composed of a material capable of withstanding the high-temperature heat treatment. Prior art literature

[0009] Korean Registered Patent Publication No. 1400605 (Published May 27, 2014) Korean Published Patent Publication No. 2023-0072069 (Published May 24, 2023) Korean Registered Patent Publication No. 1887281 (Published Aug 9, 2018) Korean Registered Patent Publication No. 2530282 (Published May 9, 2023)

[0010] J Mater. Chem. A, 2023,11, 18195-18206. 'Atomically mixed catalysts on a 3D thin-shell TiO2 for dual-modal chemical detection and neutralization' The problem to be solved

[0011] The present invention has been devised to solve the above-mentioned problems, and aims to provide a method for leaching metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process and a method for manufacturing a gas sensor using the same, wherein metal nanoparticles are leached onto a porous structured metal oxide derived from a metal-organic framework (MOF) through a photothermal treatment process, thereby enabling the effective manufacturing of a gas sensor with excellent gas detection characteristics and stability through a simplified process. means of solving the problem

[0013] A method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to the present invention for achieving the above objective comprises: a step of synthesizing a metal-organic framework containing heterogeneous metal ions; a step of heat-treating the metal-organic framework containing heterogeneous metal ions to convert it into a structured metal oxide doped with heterogeneous metal ions; and a step of performing a photothermal treatment process on the structured metal oxide doped with heterogeneous metal ions to dissolve metal nanoparticles onto the surface of the structured metal oxide.

[0014] The step of synthesizing a metal-organic framework doped with heterogeneous metal ions comprises: a process of preparing a mixed solution of a metal-organic framework precursor, an organic ligand, and a metal precursor; and a process of synthesizing a metal-organic framework doped with heterogeneous metal ions by inducing a hydrothermal reaction of the mixed solution.

[0015] In the step of converting a metal-organic framework doped with heterogeneous metal ions into a structured metal oxide doped with heterogeneous metal ions by heat treatment, the organic ligands of the metal-organic framework are removed by heat treatment, and pores are formed in the regions where the organic ligands were removed.

[0016] The step of performing a photothermal treatment process on a structured metal oxide doped with heterogeneous metal ions to elute metal nanoparticles to the surface of the structured metal oxide comprises: a process of grinding the structured metal oxide doped with heterogeneous metal ions into a powder form; and a process of applying pulsed light to the powder-form structured metal oxide doped with heterogeneous metal ions to convert the heterogeneous metal ions existing in a doped form in the structured metal oxide into metal nanoparticles through photothermal conversion and simultaneously elute them to the surface of the structured metal oxide.

[0017] Metal nanoparticles leached to the surface of structured metal oxides are single metals or multi-component alloys.

[0018] The metal-organic framework is ZIF-8.

[0019] The structured metal oxide is structured ZnO.

[0020] The metal nanoparticles are any one of Pt, Pd, Ru, or a combination thereof.

[0021] A method for manufacturing a gas sensor according to the present invention comprises the steps of: preparing a structured metal oxide from which metal nanoparticles have been eluted; preparing a dispersion solution in which the structured metal oxide from which metal nanoparticles have been eluted is dispersed; coating the dispersion solution onto a substrate equipped with an electrode; and removing the solvent from the dispersion solution to immobilize the structured metal oxide from which metal nanoparticles have been eluted onto the substrate. Effects of the invention

[0023] The method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to the present invention and the method for manufacturing a gas sensor using the same have the following effects.

[0024] By doping metal ions during the synthesis of metal-organic frameworks, a separate process for introducing metal nanoparticles is not required, and since the metal nanoparticles are eluted to the surface of the structured metal oxide by a photothermal treatment process, the process time for realizing the elutation of metal nanoparticles can be significantly shortened. Brief explanation of the drawing

[0026] FIG. 1 is a flowchart illustrating a method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to one embodiment of the present invention. FIG. 2 is a flowchart for explaining a method for manufacturing a gas sensor according to one embodiment of the present invention. Figure 3 shows SEM images of ZIF-8 prepared by Experimental Example 1, structured ZnO, and photothermally treated structured ZnO, respectively. Figure 4 shows SEM images of Pt-doped structured ZnO (Pt-ZnO), Pt and Pd-doped structured ZnO (PtPd-ZnO), and Pt, Pd and Ru-doped structured ZnO (PtPdRu-ZnO), respectively, prepared according to Experimental Example 1, before and after photothermal treatment. Figure 5 shows the XRD analysis results before and after photothermal treatment of Pt-doped structured ZnO (Pt-ZnO), Pt and Pd-doped structured ZnO (PtPd-ZnO), and Pt, Pd and Ru-doped structured ZnO (PtPdRu-ZnO), respectively, prepared according to Experimental Example 1. Figure 6 shows the XPS analysis results before and after photothermal treatment of Pt-doped structured ZnO (Pt-ZnO), Pt and Pd-doped structured ZnO (PtPd-ZnO), and Pt, Pd and Ru-doped structured ZnO (PtPdRu-ZnO), respectively, prepared according to Experimental Example 1. Figure 7 shows TEM images of Pt-doped structured ZnO (Pt-ZnO), Pt and Pd-doped structured ZnO (PtPd-ZnO), and Pt, Pd and Ru-doped structured ZnO (PtPdRu-ZnO), respectively, prepared according to Experimental Example 1, before and after photothermal treatment. Figure 8 shows the EDS analysis results after photothermal treatment of Pt-doped structured ZnO (Pt-ZnO), Pt and Pd-doped structured ZnO (PtPd-ZnO), and Pt, Pd and Ru-doped structured ZnO (PtPdRu-ZnO), respectively, prepared according to Experimental Example 1. Figures 9a to 9d are experimental results showing the gas detection characteristics of the gas sensor manufactured according to Experimental Example 2. Specific details for implementing the invention

[0027] The present invention provides a technology for manufacturing a gas sensor with excellent gas adsorption and gas detection characteristics by causing metal nanoparticles to be eluted onto the surface of a structured metal oxide having a stable porous structure.

[0028] In the present invention, 'structured metal oxide' refers to a metal-organic framework (MOF) formed by heat treatment. A metal-organic framework is a crystalline porous material in which metal ions or metal oxides are interconnected by organic ligands, and is known to exhibit excellent adsorption properties for gases, metal ions, etc. through a high specific surface area (see Patent Document 4).

[0029] When such a metal-organic framework is heat-treated at a certain temperature, the organic ligands of the metal-organic framework are oxidized and removed, and the regions where the organic ligands have been removed form pores. In the present invention, a metal-organic framework from which organic ligands have been removed by heat treatment is referred to as a "structured metal oxide," and the structured metal oxide possesses a number of pores formed by the removal of organic ligands. As the metal-organic framework itself exhibits high specific surface area characteristics as described above, the structured metal oxide acquires a very excellent porous structure as additional pores are formed by the removal of organic ligands from the metal-organic framework. Furthermore, as the pores are formed by the removal of organic ligands connecting metals to metals, the pores formed in the structured metal oxide are uniformly distributed throughout the entire structured metal oxide. This uniform distribution of pores induces uniform adsorption of the target gas, thereby improving the stability of gas detection.

[0030] Metal nanoparticles are provided on the surface of a structured metal oxide, and these metal nanoparticles exhibit catalytic properties to enhance gas sensing characteristics. That is, in addition to the adsorption of gas molecules into the pores of the structured metal oxide, as gas molecules are adsorbed onto the metal nanoparticles provided on the surface of the structured metal oxide, the gas sensing [(R g -R a ) / R a ] The characteristics are improved.

[0031] Metal nanoparticles are provided in a form leached onto the surface of a structured metal oxide, which is a case where metal ions existing in a doped form inside the structured metal oxide have leached to the surface of the structured metal oxide.

[0032] Metal ions are included during the preparation of the metal-organic framework (MOF) and are doped into the structured metal oxide in the form of metal ions during the heat treatment of the MOF. That is, when manufacturing a MOF using a MOF precursor, a metal precursor is mixed with the MOF precursor to provide the finished MOF in the form of metal ions; when the MOF containing metal ions is heat-treated, a structured metal oxide is formed in which the metal ions exist in a doped form. Furthermore, the metal ions doped into the MOF are heterogeneous to the materials constituting the MOF.

[0033] Metal ions existing in a doped form in a structured metal oxide are leached to the surface of the structured metal oxide by a photothermal treatment process. Intense pulsed light (IPL) is a technology that induces a momentary temperature rise through photothermal conversion by applying pulsed light with a wide wavelength range (300–1000 nm) for a short period of time (<1 s). When pulsed light from this photothermal treatment process is applied to a structured metal oxide, a momentary temperature rise of more than 1000 K occurs due to photothermal conversion, and as a result, metal ions existing in a doped form in the structured metal oxide are converted into metal nanoparticles and leached to the surface of the structured metal oxide.

[0034] When there are various types of metal ions doped into a structured metal oxide, for example, when Pt, Pd, Ru, etc. are mixed, Pt, Pd, Ru, etc. are leached to the surface of the structured metal oxide and converted into multi-component metal nanoparticles in the form of an alloy.

[0035] As explained above, the process of the present invention is a method in which metal ions exist in a form doped into a structured metal oxide, and the doped metal ions are leached to the surface of the structured metal oxide by a photothermal treatment process. When compared to the prior art, as mentioned earlier in the 'Technology forming the background of the invention,' the prior art requires a process of introducing a metal salt onto a metal oxide to form metal nanoparticles (see Patent Document 1), and high-temperature heat treatment is applied to leach out the metal nanoparticles (see Patent Document 4). However, the present invention allows the metal ions to exist in a form doped into a structured metal oxide, thereby eliminating the need for a separate process of introducing a metal salt. Furthermore, since the leaching of metal nanoparticles can be induced within a very short process time, the process time can be significantly shortened compared to the high-temperature heat treatment method, which requires a very long time.

[0036] Hereinafter, with reference to the drawings, a method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to an embodiment of the present invention and a method for manufacturing a gas sensor using the same will be described. First, a method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to an embodiment of the present invention will be described as follows.

[0037] Referring to FIG. 1, a metal-organic framework containing metal ions is prepared. To this end, a metal-organic framework precursor, an organic ligand, and a metal precursor are mixed in a solvent (S101). In one embodiment, the metal-organic framework precursor and the organic ligand are mixed in methanol, and a metal precursor is additionally added and mixed. Various materials can be used as the metal-organic framework precursor, and in one embodiment, Zn(NO3)2·6H2O can be used. In addition, in one embodiment, 2-methylimidazole (MIM) can be used as the organic ligand. One or multiple types of metal precursors can be added. In one embodiment, at least one of the precursors containing Pt, Pd, and Ru can be added as the metal precursor.

[0038] Next, a metal-organic framework (MOF) containing metal ions is synthesized by inducing a hydrothermal reaction in a solution mixed with a metal-organic framework precursor, an organic ligand, and a metal precursor (S102). In one embodiment, a solution mixed with a metal-organic framework precursor, an organic ligand, and a metal precursor may be loaded into an autoclave and a certain temperature applied to allow the metal-organic framework to be synthesized by a hydrothermal reaction. In one embodiment, the hydrothermally synthesized metal-organic framework may be ZIF-8. Once the synthesis of the metal-organic framework is complete, the metal-organic framework is separated by centrifugation or the like.

[0039] As the metal-organic framework synthesis process proceeds with the metal-organic framework precursor and the metal precursor mixed together, metal ions are provided in a uniform distribution within the metal-organic framework.

[0040] Under these conditions, the metal-organic framework is heat-treated to convert it into a structured metal oxide (S103). Through the heat treatment of the metal-organic framework, the organic components of the metal-organic framework, namely organic ligands, are removed, and the metal-organic framework is converted into a metal oxide. At this time, as the organic ligands of the metal-organic framework are removed and the metal oxide is formed, the framework of the metal-organic framework is maintained to a certain extent in the metal oxide. Therefore, pores are formed in the areas where free ligands were removed, and pores with uniform distribution characteristics are formed in the metal oxide.

[0041] In addition, during the process of converting a metal-organic framework into a structured metal oxide, the metal ions contained in the metal-organic framework exist in a doped form within the structured metal oxide. In one embodiment, ZIF-8 containing metal ions can be heat-treated to convert it into structured ZnO doped with metal ions.

[0042] When the preparation of the structured metal oxide doped with metal ions is completed, the process of dissolving metal nanoparticles through a photothermal treatment process is carried out (S104). Specifically, pulsed light is applied to the structured metal oxide doped with metal ions to induce a momentary temperature rise through photothermal conversion, thereby dissolving the metal ions doped in the structured metal oxide to the surface of the structured metal oxide. In one embodiment, the wavelength of the pulsed light may be 300 to 1000 nm, and the application time of the pulsed light may be less than 1 second, and any one of Pt, Pd, Ru, or an alloy thereof may be dissolved to the surface of the structured metal oxide by the photothermal treatment process.

[0043] Through the above process, the preparation of a structured metal oxide with eluted metal nanoparticles is completed.

[0044] Next, a method for manufacturing a gas sensor according to one embodiment of the present invention will be described.

[0045] Referring to FIG. 2, a structured metal oxide dispersion solution in which metal nanoparticles are eluted is prepared (S201). The structured metal oxide dispersion solution in which metal nanoparticles are eluted is a solution in which a structured metal oxide in which metal nanoparticles are eluted is dispersed, and the structured metal oxide in which metal nanoparticles are eluted can be prepared according to the above example. That is, according to the above example, the preparation of a metal-organic framework, the preparation of a structured metal oxide, and the preparation of a structured metal oxide in which metal nanoparticles are eluted through a photothermal treatment process are carried out sequentially to prepare a structured metal oxide in which metal nanoparticles are eluted through a photothermal treatment process, and the structured metal oxide in which metal nanoparticles are eluted can be prepared by dispersing it in a solvent. In one example, ethanol may be used as the solvent.

[0046] Next, a structured metal oxide dispersion solution from which metal nanoparticles have been eluted is coated onto a substrate equipped with an electrode (S202). At this time, any one of drop coating, spin coating, spray coating, or layer-by-layer coating can be used as the coating method.

[0047] The above substrate is not limited in its material and shape. For example, a flexible substrate made of a material such as a polymer may be used, or the substrate may be composed of ceramics such as Al2O3 or SiO2, or glass, and the shape of the substrate may be selectively processed depending on the application. In addition, the electrode provided on the substrate is intended to measure the change in electrical resistance of a structured metal oxide from which metal nanoparticles have been eluted, and a measuring device (not shown) for measuring the change in electrical resistance is connected to one side of the electrode. The above electrode may be provided in various forms, and in one embodiment, the electrode may be provided in the form of an interdigitated electrode (IDT) in which the cathode and the anode form an interlocked shape.

[0048] When a structured metal oxide dispersion solution from which metal nanoparticles have been eluted is coated on a substrate, the method for manufacturing a gas sensor according to one embodiment of the present invention is completed by removing the solvent component of the dispersion solution, and the structured metal oxide from which metal nanoparticles have been eluted from which the solvent component has been removed forms a state of being immobilized on the substrate (S203).

[0049] For the above, a method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to one embodiment of the present invention and a method for manufacturing a gas sensor using the same have been described. Below, the present invention will be explained in more detail through experimental examples.

[0051] Experimental Example 1: Preparation of Structured Metal Oxide with Eluted Metal Nanoparticles

[0052] Zn(NO3)2·6H2O and 2-methylimidazole (MIM) were mixed in methanol, and then Pt precursor, Pd precursor, and Ru precursor were additionally mixed. For comparison, the Pt precursor alone, the Pt precursor and Pd precursor mixture, and the Pt precursor, Pd precursor, and Ru precursor mixture were performed, respectively. H2PtCl6·6H2O was used for the Pt precursor, K2PdCl4 for the Pd precursor, and RuCl3·xH2O for the Ru precursor.

[0053] Metal ion-doped ZIF-8 was synthesized by placing the mixed solution into a PTFE-lined stainless steel autoclave, completely sealing it, and heating it in an oven at 120°C for 4 hours. Subsequently, the metal ion-doped ZIF-8 was separated by centrifugation. Then, the metal ion-doped ZIF-8 was ground into a powder and heat-treated at 550°C for 1 hour to produce structured ZnO with the organic components of ZIF-8 removed.

[0054] After spreading the structured ZnO powder widely, a photothermal treatment process was performed. A xenon lamp was used during the photothermal treatment process, and the voltage applied to the light source was set to 640V, the pulsed light irradiation time to 10ms, and the current to 1500mA, and the pulsed light irradiation was repeated 10 times.

[0056] Experimental Example 2: Preparation of a Gas Sensor

[0057] The structured ZnO powder (IPL_PtPdRu-ZnO) finally prepared according to Experimental Example 1 was dispersed in ethanol and then drop-coated onto a SiO2 substrate equipped with an IDE (interdigitated electrode) electrode pattern. Subsequently, the ethanol was removed to manufacture a gas sensor.

[0059] Experimental Example 3: Structural Characteristics of ZIF-8, Structured ZIF-8, and Photothermal-treated ZIF-8

[0060] The morphology and crystallinity of ZIF-8 prepared by Experimental Example 1, structured ZnO, and photothermally treated structured ZnO were analyzed.

[0061] Figure 3 shows SEM images of ZIF-8, structured ZnO, and photothermal-treated structured ZnO prepared according to Experimental Example 1, respectively. It can be seen that the structured ZnO forms a porous structure as organic ligands are removed by heat treatment of ZIF-8. On the other hand, it can be seen that the structured ZnO shows almost no morphological change even after photothermal treatment.

[0062] SEM and XRD analysis were performed on the Pt-doped structured ZnO (Pt-ZnO), Pt and Pd-doped structured ZnO (PtPd-ZnO), and Pt, Pd and Ru-doped structured ZnO (PtPdRu-ZnO) prepared according to Experimental Example 1, before and after photothermal treatment.

[0063] Referring to Fig. 4, almost no morphological changes were observed before and after photothermal treatment, similar to the results in Fig. 3. In addition, XRD analysis was performed on the structured ZIF-8 before and after photothermal treatment (see Fig. 5), and it was confirmed that no additional secondary phases were generated due to photothermal treatment.

[0065] Experimental Example 4: Analysis of Metal Nanoparticle Elution by Photothermal Treatment

[0066] In order to determine whether metal nanoparticles were leached from the surface of the structured ZnO after photothermal treatment, XPS analysis was performed on the structured ZnO prepared according to Experimental Example 1 and the photothermal-treated structured ZnO.

[0067] XPS analysis was performed on the Pt-doped structured ZnO (Pt-ZnO), Pt and Pd-doped structured ZnO (PtPd-ZnO), and Pt, Pd and Ru-doped structured ZnO (PtPdRu-ZnO) prepared according to Experimental Example 1, before and after photothermal treatment (see Fig. 6), and it was confirmed that there was no significant difference in the Zn peak before and after photothermal treatment.

[0068] On the other hand, in the case of the O peak, O after photothermal treatment - As the peak increases, O - Wow O 2- It can be confirmed that the ratio of liver changes. O - The increase in the peak indicates an increase in the amount of atmospheric oxygen adsorbed onto the structured ZnO, which indirectly proves that metal nanoparticles have leached from the surface of the structured ZnO. This is because the amount of adsorbed oxygen increases due to the spillover effect in the presence of metal nanoparticles.

[0069] Furthermore, referring to Table 1 below, it can be seen that the amount of adsorbed oxygen increases when Pt-Pd binary nanoparticles and Pt-Pd-Ru ternary nanoparticles are formed compared to when Pt alone is formed, and through this, it can be seen that elution proceeds actively when Pt-Pd binary nanoparticles and Pt-Pd-Ru ternary nanoparticles are formed.

[0071] [Table 1]

[0072] O before and after photothermal treatment according to metal nanoparticle doping form - / O 2- Growth rate >

[0073]

[0075] To further confirm whether metal nanoparticles were leached, TEM and EDS analyses were performed.

[0076] Referring to Fig. 7, it can be seen that metal nanoparticles (Pt, PtPd, PtPdRu) are leached and formed on the surface of ZnO after photothermal treatment. In addition, as a result of performing both TEM and EDS analysis at the same location (see Fig. 8), it can be seen that various types of metal nanoparticles exist in an overlapping manner among the leached multi-component metal nanoparticles, which means that the multi-component metal nanoparticles were leached in the form of an alloy.

[0078] Experimental Example 5: Characteristics of Gas Sensor

[0079] The gas detection characteristics of the gas sensor manufactured according to Experimental Example 2 were analyzed. H2S gas was supplied as the target gas for detection, and then purified air with an RH of 30% was supplied at a flow rate of 1000 sccm while measuring the change in resistance. In addition, to analyze the characteristics of the change in resistance according to temperature, the measurement environment was set to 300℃, 350℃, and 400℃, respectively.

[0080] Referring to Fig. 9a, it can be observed that the resistance of the gas sensor decreases upon contact with the structured ZnO, which exhibits n-type semiconductor characteristics, when H2S, a strong reducing gas, is injected, while the resistance increases upon the injection of air. Additionally, referring to Figs. 9b and 9c, it can be observed that as the measurement temperature increases to 300°C, 350°C, and 400°C, the response time decreases by 58 seconds, 31 seconds, and 20 seconds, respectively. Here, the response time refers to the time required to reach a resistance value corresponding to 90% of the maximum sensitivity value.

[0081] Meanwhile, when ZnO before and after photothermal treatment was applied to a gas sensor and H2S gas was detected (see Fig. 9d), it was confirmed that the gas sensor with ZnO from which PtPdRu had been eluted (IPL_PtPdRu-ZnO) showed a detection accuracy more than 6 times greater than that of the structured ZnO before photothermal treatment.

Claims

Claim 1 A step of synthesizing a metal-organic framework containing heterogeneous metal ions; a step of heat-treating the metal-organic framework containing heterogeneous metal ions to convert it into a structured metal oxide doped with heterogeneous metal ions; The method comprises the step of performing a photothermal treatment process on a structured metal oxide doped with heterogeneous metal ions to elute metal nanoparticles to the surface of the structured metal oxide; wherein the step of synthesizing a metal-organic framework containing heterogeneous metal ions comprises the steps of preparing a mixed solution of a metal-organic framework precursor, an organic ligand, and a metal precursor, and inducing a hydrothermal reaction of the mixed solution to synthesize a metal-organic framework containing heterogeneous metal ions; and the step of converting a metal-organic framework containing heterogeneous metal ions into a structured metal oxide doped with heterogeneous metal ions by heat treatment, wherein the organic ligand of the metal-organic framework is removed by heat treatment and pores are formed in the region where the organic ligand was removed, the metal-organic framework is ZIF-8, the structured metal oxide is structured ZnO, and the metal nanoparticles are any one of Pt, Pd, Ru or a combination thereof. A method for leaching metal nanoparticles to a surface. Claim 2 delete Claim 3 delete Claim 4 A method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process according to claim 1, wherein the step of performing a photothermal treatment process on a structured metal oxide doped with heterogeneous metal ions to dissolve metal nanoparticles onto the surface of the structured metal oxide comprises: a process of grinding the structured metal oxide doped with heterogeneous metal ions into a powder form; and a process of applying pulsed light to the structured metal oxide doped with heterogeneous metal ions in powder form to convert the heterogeneous metal ions existing in a doped form in the structured metal oxide into metal nanoparticles by photothermal conversion and simultaneously dissolving them onto the surface of the structured metal oxide. Claim 5 A method for dissolving metal nanoparticles onto the surface of a structured metal oxide through a photothermal treatment process, characterized in that, in claim 1, the metal nanoparticles dissolved onto the surface of the structured metal oxide are a single metal or a multi-component alloy. Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 A method for manufacturing a gas sensor comprising: a step of preparing a structured metal oxide from which metal nanoparticles have been eluted; a step of preparing a dispersion solution in which the structured metal oxide from which metal nanoparticles have been eluted is dispersed; a step of coating the dispersion solution onto a substrate equipped with an electrode; and a step of removing the solvent from the dispersion solution to immobilize the structured metal oxide from which metal nanoparticles have been eluted onto the substrate; wherein the structured metal oxide from which metal nanoparticles have been eluted is prepared by the method described in any one of claims 1, 4, and 5.

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