CATALYST FOR GENERATING HYDROGEN PEROXIDE INDUCED BY TEMPERATURE DIFFERENCE AND METHOD FOR ENVIRONMENTAL DISINFECTION USING SAME

Abstract

A catalyst adapted for generating hydrogen peroxide induced by a temperature difference and a method for environmental disinfection using the same are provided. The catalyst includes a thermoelectric material distributed on a substrate. The thermoelectric material induces a reaction between water vapor and oxygen contained in the air through a temperature difference to generate hydrogen peroxide, to serve a sterilization function through the hydrogen peroxide generated. The method for environmental disinfection using the catalyst includes the following. The catalyst is placed in an environment with a temperature difference. The catalyst is caused to induce a reaction between water vapor and oxygen contained in air through the temperature difference to generate hydrogen peroxide without applying power, and serve a sterilization function through the hydrogen peroxide generated.

Claims

1. A catalyst for generating hydrogen peroxide induced by a temperature difference, the catalyst comprising: a thermoelectric material, being distributed on a substrate and inducing a reaction between water vapor and oxygen contained in air through a temperature difference to generate hydrogen peroxide (H.sub.2O.sub.2) to serve a sterilization function through the hydrogen peroxide generated.

2. The catalyst as described in claim 1, wherein a form of the thermoelectric material comprises a nanomaterial or a bulk.

3. The catalyst as described in claim 2, wherein the nanomaterial comprises a nanoparticle, a nanoplate, or a nanowire.

4. The catalyst as described in claim 1, wherein the thermoelectric material is at least one material selected from a group consisting of a metal composite oxide, a polymer, a silicide, skutterudite, a Half-Heusler alloy, and a compound containing tellurium (Te).

5. The catalyst as described in claim 4, wherein the thermoelectric material comprises bismuth telluride (Bi.sub.2Te.sub.3), antimony telluride (Sb.sub.2Te.sub.3), or lead telluride (PbTe).

6. The catalyst as described in claim 1, wherein the substrate comprises a sheet substrate, a porous substrate, or a mesh substrate.

7. The catalyst as described in claim 1, wherein a concentration of the hydrogen peroxide generated is modulated through a content of the thermoelectric material and/or a magnitude of the temperature difference.

8. The catalyst as described in claim 1, wherein the thermoelectric material is formed on the substrate by coating, spraying, or soaking.

9. A method for environmental disinfection using the catalyst as described in claim 1, the method comprising: placing the catalyst in an environment with a temperature difference; and causing the catalyst to induce a reaction between water vapor and oxygen contained in air through the temperature difference to generate hydrogen peroxide without applying power, and serve a sterilization function through the hydrogen peroxide generated.

10. The method as described in claim 9, wherein the environment with the temperature difference comprises an air outlet of an air conditioner, a heater, a fan, or a stove.

11. The method as described in claim 9, wherein the environment with the temperature difference comprises a surface of a mask.

12. The method as described in claim 9, wherein the environment with the temperature difference comprises an exterior wall or a window of a building.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0024] FIG. 1 is a schematic diagram of a thermocatalysis mechanism of a thermoelectric material according to an embodiment of the disclosure.

[0025] FIG. 2A is a schematic diagram of a catalyst for generating hydrogen peroxide induced by a temperature difference according to an embodiment of the disclosure.

[0026] FIG. 2B is a schematic diagram of an air conditioner applying the catalyst of the disclosure.

[0027] FIG. 2C is a schematic diagram of a mask applying the catalyst of the disclosure.

[0028] FIG. 3A is a bar graph of generation efficiency by different thermoelectric materials and a photocatalyst TiO.sub.2 with or without a temperature difference in Experimental Example 1.

[0029] FIG. 3B is a bar graph of generation efficiency by a bulk Bi.sub.2Te.sub.3 of Experimental Example 1 under different temperature differences.

[0030] FIG. 3C is a bar graph of disinfection performance of the bulk Bi.sub.2Te.sub.3 of Experimental Example 1 under different temperature differences.

[0031] FIG. 3D is a line graph of changes of H.sub.2O.sub.2 concentration and weight of Bi.sub.2Te.sub.3 of the bulk Bi.sub.2Te.sub.3 of Experimental Example 1 under different thermal cycles.

[0032] FIG. 3E is a line graph of a change of H.sub.2O.sub.2 concentration of the bulk Bi.sub.2Te.sub.3 of Experimental Example 1 under a change of temperature.

[0033] FIG. 4A is an SEM image of a nanomaterial Bi.sub.2Te.sub.3 of Experimental Example 2.

[0034] FIG. 4B is a bar graph of H.sub.2O.sub.2 concentration of and generation efficiency by the nanomaterial Bi.sub.2Te.sub.3 of Experimental Example 2 under different temperature differences.

[0035] FIG. 4C is a bar graph of disinfection performance of the nanomaterial Bi.sub.2Te.sub.3 of Experimental Example 2 after three thermal cycles under different temperature differences.

[0036] FIG. 5 is a bar graph of H.sub.2O.sub.2 concentration of a nanomaterial Bi.sub.2Te.sub.3 of Experimental Example 3 in different gas environments.

[0037] FIG. 6A is a temperature profile of a catalyst of Experimental Example 4 during exposure to cold air.

[0038] FIG. 6B is a temperature profile of the catalyst of Experimental Example 4 during exposure to hot air.

[0039] FIG. 6C is a bar graph of disinfection performance of the catalyst and a substrate of Experimental Example 4 under the temperature difference of FIG. 6A.

[0040] FIG. 6D is a bar graph of disinfection performance of the catalyst and a substrate of Experimental Example 4 under the temperature difference of FIG. 6B.

[0041] FIG. 7A is an SEM image of a catalyst of Experimental Example 5.

[0042] FIG. 7B is an SEM image of the catalyst of Experimental Example 5 after 30 days of use.

[0043] FIG. 7C is a bar graph of disinfection performance of the catalyst of Experimental Example 5 during the 30 days of use.

DESCRIPTION OF THE EMBODIMENTS

[0044] Exemplary embodiments of the disclosure with reference to the drawings will be comprehensively described below. However, the disclosure may still be embodied in many different forms and should not be interpreted as being limited to the embodiments described herein. For clarity in the drawings, sizes and shapes of structures and materials are possibly not drawn to actual scale.

[0045] First, in the disclosure uses thermoelectric material as the sterilization function of the catalyst's thermocatalysis mechanism as shown in FIG. 1.

[0046] With reference to FIG. 1 on the left, generally, the conduction band potential of a thermoelectric material 100 is more negative than the redox potential of O.sub.2/.O.sub.2.sup.−. Therefore, because of the relatively large potential difference present between the conduction band of thermoelectric material 100 and the redox potential of O.sub.2/.O.sub.2.sup.−, free charges present on the surface of the thermoelectric material 100 quickly exhaust before reacting with the bacteria, and no significant catalytic activity is present.

[0047] However, with the generation of a temperature difference, with reference to of FIG. 1 on the right, the band energy decreases at the positive potential side and increases at the negative potential side, such that the conduction band and the valence band of the thermoelectric material 100 tilt, negative charges rush from the code end to the hot end of the thermoelectric material 100 and produce a potential difference between the hot end and the cold end, and at the same time, the conduction band of the thermoelectric material 100 is also close to the redox potential of O.sub.2/.O.sub.2.sup.−. Consequently, electrons from the conduction band migrate to the surface of the thermoelectric material 100, and generate hydrogen peroxide (H.sub.2O.sub.2) via reaction formula (1) below.

.O.sub.2.sup.−+e.sup.−+2H.sup.+.fwdarw.H.sub.2O.sub.2  formula (1)

[0048] In the disclosure, the form of the thermoelectric material 100 may be a bulk or a nanomaterial. The term “bulk” herein represents a material with a micron-scale size, such as 0.5 cm to microns. The term “nanomaterial” herein represents a material with a nano-level size, and the nanomaterial includes a nanoparticle, a nanoplate, or a nanowire. For the thermoelectric material 100, common thermoelectric materials or materials prepared in a laboratory, at least one material selected from a group consisting of a metal composite oxide, a polymer, a silicide, skutterudite, a Half-Heusler alloy, and a compound containing tellurium (Te), for example, may be used. In some embodiments, the thermoelectric material 100 may include but is not limited to bismuth telluride (Bi.sub.2Te.sub.3), antimony telluride (Sb.sub.2Te.sub.3), or lead telluride (PbTe).

[0049] FIG. 2A is a schematic diagram of a catalyst for generating hydrogen peroxide induced by a temperature difference of an embodiment according to the disclosure.

[0050] With reference to FIG. 2A, a catalyst 200 of this embodiment includes a thermoelectric material 202, which is distributed on a substrate 204. The thermoelectric material 202 may be formed on the substrate 204 by coating, spraying, or soaking. For the form of the thermoelectric material 202, reference may be made to the description of the thermoelectric material 100, which will not be repeated. The substrate 204 may include a sheet substrate, a porous substrate, or a mesh substrate. For example, the substrate 204 in FIG. 2A is a mesh substrate similar to a woven cloth, and the thermoelectric material 202 is a nanomaterial. However, the disclosure is not limited thereto. Depending on the environmental temperature, the type of each of the substrate 204 and the thermoelectric material 202 may be selected as appropriate to serve as a sterilization device.

[0051] For example, due to factors such as global warming, seasons with a relatively high temperature are present in whichever of the tropical, subtropical, or temperate zones. Accordingly, in the need of an air conditioner or a fan for cooling down, the thermoelectric material 202 may be formed on the surface of the substrate 204 such as a filter or woven cloth, and then mounted at the air outlet of the air conditioner as shown in FIG. 2B, to induce a reaction between water vapor and oxygen contained in the air by the environmental temperature difference to generate hydrogen peroxide. On the other hand, sub-zero temperatures often occur in the temperate or frigid zone, so a heater or stove is needed for increasing the temperature. Therefore, the thermoelectric material 202 may also be formed on the surface of the substrate 204, and then mounted at the air outlet of the air conditioner as shown in FIG. 2B, to induce generation of hydrogen peroxide by the environmental temperature difference. In this embodiment, the thermoelectric material 202 may be selected as appropriate depending on the temperature difference and the environmental temperature.

[0052] In addition, if the catalyst 200 is applied to an epidemic prevention product such as a mask as shown in FIG. 2C, generation of hydrogen peroxide for disinfection and sterilization may similarly be catalyzed by the temperature difference. Moreover, according to the content of the thermoelectric material 202 and/or the magnitude of the temperature difference, the concentration of the generated H.sub.2O.sub.2 may be modulated. Specifically, as the thermoelectric material 202 increases in content, the H.sub.2O.sub.2 increases in concentration; and as the temperature difference increases, the H.sub.2O.sub.2 also increases in concentration. Therefore, depending on the application area of the catalyst 200, the temperature difference may be first determined, and the content of the thermoelectric material 202 may then be changed to strike a balance between the requirements of sterilization function and prevention from a hazard to the human body.

[0053] The method for environmental disinfection of the disclosure include the following. The catalyst 200 of FIG. 2A is placed in an environment with a temperature difference. The catalyst is caused to induce a reaction between water vapor and oxygen contained in air through the temperature difference to generate hydrogen peroxide (H.sub.2O.sub.2) without applying power, and serve a sterilization function through the hydrogen peroxide generated.

[0054] In an embodiment, the environment with the temperature difference includes an air outlet of an air conditioner, a heater, a fan, or a stove.

[0055] In another embodiment, the environment with the temperature difference includes a surface of a mask.

[0056] In still another embodiment, the environment with the temperature difference includes an exterior wall or a window of a building.

[0057] Some experiments will be provided below to verify the effects of the disclosure, but the disclosure is not limited to the following content.

<Experimental Example 1> Analysis on Thermoelectric Material (Bulk)

[0058] The following thermocatalysis test was carried out using thermoelectric materials Bi.sub.2Te.sub.3, Sb.sub.2Te.sub.3, and PbTe (each purchased from Alfa Aeser) and a photocatalyst TiO.sub.2, each in a bulk form.

[0059] 1. Thermocatalysis Test

[0060] The generation of superoxide radicals during the thermocatalysis reaction was estimated quantitatively by using XTT (2, 3-bis (2-methoxy-4-nitro-5-sulfophehyl)-2H-tetrazolium-5-carboxanilide) assay to obtain the generation efficiency.

[0061] Generally, an aqueous dispersion of the bulk was mixed with XTT (50 μM), and then the mixed solution was subjected to different temperature differences in a water bath. After the reaction, the bulk was separated by centrifugation, and the absorbance spectrum of the supernatant was detected at 470 nm. The estimated data is shown in FIG. 3A.

[0062] FIG. 3A is a bar graph of generation efficiency by different thermoelectric materials and the photocatalyst TiO.sub.2 at a temperature difference of 0 and at a temperature difference of 20K. From FIG. 3A, it can be found that the thermoelectric material bulks each have capability of generating hydrogen peroxide through thermocatalysis, while TiO.sub.2 hardly generates hydrogen peroxide under a temperature difference.

[0063] Next, the bulk Bi.sub.2Te.sub.3 with a higher generation efficiency in FIG. 3A was adopted for the following analysis.

[0064] First, based on the thermocatalysis test, the aqueous dispersion of the bulk Bi.sub.2Te.sub.3 was mixed with XTT (50 μM), and then the mixed solution was subjected to different temperature differences in a water bath. After the reaction, the bulk was separated by centrifugation, and the absorbance spectrum of the supernatant was detected at 470 nm. The estimated data is shown in FIG. 3B.

[0065] FIG. 3B is a bar graph of generation efficiency by the bulk Bi.sub.2Te.sub.3 (50 mg) under different temperature differences, which shows that a greater temperature difference indicates a higher generation efficiency. For example, the H.sub.2O.sub.2 generation efficiency at a temperature difference of 40K reached about 0.34 μM/mg.

[0066] Then, to verify the antibacterial effect of the generated H.sub.2O.sub.2, the following experiment was performed.

[0067] 2. Disinfection (Antibacterial) Experiment

[0068] First, E. coli K12 cells were grown in a lysogeny broth (LB) medium for 16 h at 37° C. Then, the E. coli K12 cells were diluted to an optical density of 0.06 at 670 nm (OD670=0.06). Further, the bacterial cell suspension was diluted 10 times with 0.85% sodium chloride, which was equal to 2×10.sup.7 CFU per 1 mL for antibacterial investigation.

[0069] Next, the bulk Bi.sub.2Te.sub.3 (50 mg) was added into 1 mL of the bacterial solution (2×10.sup.6 CFU per 1 mL) and was subjected to 3 thermal cycles, respectively denoted as C1, C2, and C3.

[0070] In each thermal cycle, the material was first allowed to react at a specific temperature (15° C./35° C./45° C.) for 5 minutes, and then was returned to room temperature (25° C.) for 5 minutes. In addition, one group with no temperature difference (under room temperature) served as a control group.

[0071] Then, aliquots of 100 μL of the bacterial solution were collected and plated on an aseptic plate. The bacterial colonies were counted from the plate after 24 hours of incubation at 37° C. The survival rates were determined by using the formula C/C.sub.0×100%, where C.sub.0 is the concentration of the bacteria solution before thermal treatment, and C is the remaining concentration of the bacteria after the thermal treatment. The results are shown in FIG. 3C.

[0072] FIG. 3C is a bar graph of disinfection performance of the bulk Bi.sub.2Te.sub.3 (50 mg) under different temperature differences. From FIG. 3C, it can be found that as the number of thermal cycles increases from 1 (C1) to 3 (C3), the disinfection performance of the bulk Bi.sub.2Te.sub.3 increases gradually. This result also indicates that the disinfection performance has a positive correlation with the amount of hydrogen peroxide generated. In other words, higher hydrogen peroxide production caused by a greater temperature difference results in a better thermocatalytic effect, and in turn a greater disinfection performance.

[0073] To verify that the thermoelectric material as a catalyst does not participate in the reaction, the following H.sub.2O.sub.2 concentration detection was first performed, and then the weight of the bulk Bi.sub.2Te.sub.3 was measured to observe the change in weight of the bulk Bi.sub.2Te.sub.3 before and after the reaction.

[0074] 3. H.sub.2O.sub.2 Concentration Detection

[0075] An Amplex Red reagent with an HRP enzyme was used for H.sub.2O.sub.2 detection. In general, Amplex Red reacts with H.sub.2O.sub.2 to produce a red-fluorescent oxidation product, i.e., resorufin.

[0076] First, two different stock solutions were prepared. One was 0.4 mg Amplex Red powder dissolved in 3.1 mL dimethyl sulfoxide (DMSO), and the other was 0.5 mg of HRP dissolved in phosphate-buffered saline (PBS, pH 5.8). Then, the bulk was first added into 1 mL of a sodium chloride (0.85% NaCl) solution, and then the solution was placed in a water bath for 15 minutes at a temperature difference of 20K.

[0077] After the temperature treatment, the solution was filtered by a 0.2 μm PVDF membrane filter, and 270 μL of the filtrate solution was added into a mixture of 30 μL of the Amplex Red solution and 3 μL of the HRP solution. A photoluminescence spectrophotometer (HITACHI F-7000) was used to detect the generated fluorescent product. That is, the sample was excited at 530 nm, and the emission spectrum was scanned from 560 to 750 nm. The H.sub.2O.sub.2 concentrations under different thermal cycles obtained are shown in FIG. 3D.

[0078] FIG. 3D also shows the measured weight of the bulk Bi.sub.2Te.sub.3 after different thermal cycles. Accordingly, it can be found from FIG. 3D that, for the bulk Bi.sub.2Te.sub.3 of Experimental Example 1, as the number of thermal cycles increases from 1 to 10, the H.sub.2O.sub.2 concentration increases gradually, but the weight of the bulk Bi.sub.2Te.sub.3 is substantially maintained at 50 mg. Therefore, the thermoelectric material serves as a catalyst during the process of H.sub.2O.sub.2 generation.

[0079] In addition, during the detection process of the adopted H.sub.2O.sub.2 concentration detection, the temperature difference was only present in the first 15 minutes, while the environmental temperature was subsequently kept constant, and a line graph of a change of the H.sub.2O.sub.2 concentration of the bulk Bi.sub.2Te.sub.3 under a temperature change is obtained in FIG. 3E. From FIG. 3E, it can be observed that once no temperature difference is present, the H.sub.2O.sub.2 concentration is substantially unchanged, which indicates that barely any more H.sub.2O.sub.2 is produced since the 15.sup.th minute. Therefore, the temperature difference obviously affects H.sub.2O.sub.2 generation through thermocatalysis.

<Preparation Example 1> Preparation of a Nanomaterial Bi.SUB.2.Te.SUB.3

[0080] First, a stock solution was prepared by dissolving 0.8 g of sodium hydroxide in 10 mL of ethylene glycol at 45° C. in a water bath. Then, 0.1 g of bismuth nitrate pentahydrate, 0.067 g of sodium telluride, and 0.235 g of polyvinylpyrrolidone (PVP) were loaded into a 25 mL three-necked flask, into which 10 mL of the stock solution was added. The mixture was stirred for 10 minutes at room temperature.

[0081] After that, the three-neck flask was placed in a water bath at 45° C. for 20 minutes. Until the precursors were dissolved in the solution, the three-neck flask was kept in an oil bath and stirred for 3 hours at 190° C. After the reaction, 30 mL of isopropyl alcohol and 10 ml of acetone were added into the solution, and the mixture was centrifuged at 6700×g for 10 minutes. The supernatant was discarded, and the process was repeated 3 times. Finally, the filtered Bi.sub.2Te.sub.3 nanoplate was redispersed in 30 mL of isopropyl alcohol and was used for further experiments.

<Experimental Example 2> Analysis of Thermoelectric Material (Nanomaterial)

[0082] First, the Bi.sub.2Te.sub.3 nanoplate obtained in Preparation Example 1 was observed with a field emission scanning electron microscope (FESEM), which is shown in FIG. 4A. From FIG. 4A, it can be observed that Bi.sub.2Te.sub.3 is a uniform hexagonal nanoplate-like nanomaterial.

[0083] Then, the thermocatalysis test and H.sub.2O.sub.2 concentration detection of Experimental Example 1 were used, in which the bulk was changed into the Bi.sub.2Te.sub.3 nanoplate (5 mg) obtained in Preparation Example 1, and the H.sub.2O.sub.2 concentration and production efficiency of the nanomaterial Bi.sub.2Te.sub.3 under different temperature differences can be obtained, which are shown in FIG. 4B. From FIG. 4B, it can be found that a greater temperature difference indicates both a greater H.sub.2O.sub.2 concentration and a higher generation efficiency. Moreover, H.sub.2O.sub.2 can be generated regardless of whether the temperature difference is positive or negative. For example, at a temperature difference of 30K, only 5 mg of a Bi.sub.2Te.sub.3 nanoplate can reach a H.sub.2O.sub.2 concentration of about 30 μM. Therefore, in terms of generation efficiency, a Bi.sub.2Te.sub.3 nanoplate exhibits a more than 20 times higher generation efficiency than a bulk Bi.sub.2Te.sub.3.

[0084] In addition, the disinfection (antibacterial) experiment of Experimental Example 1 was used, in which the bulk was changed into the Bi.sub.2Te.sub.3 nanoplate (5 mg) obtained in Preparation Example 1, and the disinfection performance of the nanomaterial Bi.sub.2Te.sub.3 after three thermal cycles under different temperature differences can be obtained, which is shown in FIG. 4C. From FIG. 4C, it can be found that as the number of thermal cycles increases, the disinfection performance of the nanomaterial Bi.sub.2Te.sub.3 increases gradually.

Experimental Example 3

[0085] First, a surface potential analysis of the Bi.sub.2Te.sub.3 nanoplate was carried out by Kelvin probe force microscopy (KPFM), and it was observed that the surface of the Bi.sub.2Te.sub.3 nanoplate did not show any surface potential in the thermal equilibrium. However, a response voltage of ˜280 mV was observed at a temperature of 60° C.

[0086] In addition, the H.sub.2O.sub.2 concentration (at a temperature difference of 20K) was tested for Bi.sub.2Te.sub.3 under different environmental conditions (including O.sub.2, N.sub.2, and air), and the results are shown in FIG. 5. From FIG. 5, it can be found that an N.sub.2-filled environment led to the lowest amount of H.sub.2O.sub.2 generated, and an O.sub.2-filled environment led to the greatest amount of H.sub.2O.sub.2 generated, verifying that superoxide radicals from O.sub.2 decomposition are a key factor in H.sub.2O.sub.2 generation.

<Preparation Example 2> Preparation of Bi.SUB.2.Te.SUB.3.@CFF

[0087] To clean the surface of a carbon fiber fabric (CFF), the carbon fiber fabric was soaked in acetone, isopropanol, and deionized water for 5 minutes, respectively. Then, the carbon fiber fabric was cut into a size of 1×1 cm and dipped in 100 μL of a Bi.sub.2Te.sub.3 nanoplate (1 mM; Bi.sub.2Te.sub.3 nanoplate of Preparation Example 1) solution. Finally, the prepared carbon fiber was dried in a hot air oven to completely remove the water.

Experimental Example 4

[0088] To prove that Bi.sub.2Te.sub.3@CFF serves as a catalyst with an antibacterial performance, the following test was carried out.

[0089] First, a bacterial solution (2×10.sup.6 CFU/mL) was prepared by the method in the disinfection (antibacterial) experiment of Experimental Example 1. Then, 1 mL of the bacterial solution was added into each of 1×1 cm Bi.sub.2Te.sub.3@CFF and 1×1 cm commercially available CFF, and further treated for a total time of 20 minutes under the temperature difference created by a hairdryer and a cooling fan. Control experiments were also performed under the same conditions without the temperature difference. FIG. 6A is a temperature profile of the tested samples during exposure to cold air, and FIG. 6B is a temperature profile of the tested samples during exposure to hot air.

[0090] The treated Bi.sub.2Te.sub.3@CFF and CFF were immersed into 1 mL of 0.85% sodium chloride solution. Then, aliquots of 100 μL of the bacterial solution were collected and plated on an aseptic plate. The bacterial colonies were counted from the plate after 24 hours of incubation at 37° C. The survival rates were determined by using the formula C/C.sub.0×100%, where C.sub.0 is the concentration of the bacteria solution before thermal treatment, and C is the remaining concentration of the bacteria after the thermal treatment. The results are shown in FIG. 6C and FIG. 6D.

[0091] FIG. 6C is a bar graph of disinfection performance of the catalyst (Bi.sub.2Te.sub.3@CFF) and the substrate (CFF) under the temperature difference of FIG. 6A, and FIG. 6D is a bar graph of disinfection performance of the catalyst (Bi.sub.2Te.sub.3@CFF) and the substrate (CFF) under the temperature difference of FIG. 6B. From FIG. 6C and FIG. 6D, it can be observed that the CFF without Bi.sub.2Te.sub.3 exhibits a poor sterilization effect with regardless heating or cooling, while the catalyst of the disclosure has an obvious sterilization effect regardless of whether the temperature difference is positive or negative.

[0092] In order to verify the reusability of the catalyst of the disclosure, the following test was performed.

<Experimental Example 5> Reusability Test

[0093] First, Bi.sub.2Te.sub.3@CFF with dimensions of 8×15 cm was prepared based on Preparation Example 2 and observed with an FESEM, and an image of FIG. 7A was obtained. From FIG. 7A, it is evident that the Bi.sub.2Te.sub.3 nanoplate was uniformly deposited on the CFF.

[0094] Then, the Bi.sub.2Te.sub.3@CFF was mounted on an indoor unit of a split air conditioner. The temperature of the air conditioner was set to 17° C. (different from the 25° C. room temperature by 8° C.), where the temperature difference is similar to that generated by the use of cooling fan in Experimental Example 4.

[0095] A disinfection (antibacterial) experiment was performed by using the same bacterial concentration (2×10.sup.6 CFU/mL) and environment (air) as in Experimental Example 4 and was repeated for 30 days. In addition, the survival rates of the bacteria were detected on different days. The results are shown in FIG. 7C.

[0096] FIG. 7B is an SEM image of Bi.sub.2Te.sub.3@CFF after 30 days of use, with nearly no difference compared with FIG. 7A. Moreover, with XRD and Raman spectroscopy tests, the results show that after 30 days of test, the initial spectral property of Bi.sub.2Te.sub.3@CFF is still maintained as before the test.

[0097] From FIG. 7C, it can be found that Bi.sub.2Te.sub.3@CFF exhibits similar disinfection performance and about 60% bacterial degradation across the 30 days of use, same as the results of Experimental Example 4 shown in FIG. 6C. Therefore, through this experiment, it can be verified that the long-term stability and robustness of the disclosure for practical disinfection applications.

[0098] In summary of the foregoing, the catalyst of the disclosure may serve to realize a low-cost antibacterial device that requires no external power source during its operation, and can be widely used in various daily necessities and equipment with good potential for development.

[0099] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.