Method of manufacturing metal nanoparticle-oxide support complex structure based gas sensor

Abstract

Provided is a method of producing a metal nanoparticle-oxide support complex structure, in which metal nanoparticles uniform in size are evenly distributed on the surface of oxide supports. A gas sensor with improved gas sensing ability and durability may be provided by using the same.

Claims

1. A method of producing a metal nanoparticle-oxide support complex structure, the method comprising: a step (step 1) of mixing a precursor of the metal nanoparticle with a precursor of the oxide support to form a first mixture and additionally mixing a mixture of graphene oxide and nanocellulose with the first mixture of the precursor of the metal nanoparticle and the precursor of the oxide support to form a second mixture, wherein the second mixture consists of the precursor of the metal nanoparticle, the precursor of the oxide support, graphene oxide, and nanocellulose; a step (step 2) of preparing a solid solution by calcining and sintering the second mixture of the step 1; and a step (step 3) of forming the metal nanoparticles on the surface of the oxide supports by heat-treating the solid solution of the step 2 in a reducing atmosphere, wherein the graphene oxide and the nanocellulose are removed through the step 2, and wherein the precursor of the metal nanoparticle is an iridium (Ir) salt, and the precursor of the oxide support is a tungsten (W) salt.

2. The method of claim 1, wherein the oxide support is a compound represented by the following Chemical Formula 1:
B.sub.yO.sub.z[Chemical Formula 1] in Chemical Formula 1, B is W, y is 1 to 3, and z is 1 to 4.

3. The method of claim 1, wherein the precursor of the metal nanoparticle and the precursor of the oxide support are mixed at a molar ratio of 5:95 to 1:99.

4. The method of claim 1, wherein the step 2 is performed by raising the temperature from room temperature to 400 C. to 800 C. at a heating rate of 1 C./min to 10 C./min.

5. The method of claim 1, wherein the step 3 is performed by using any one or more of a H.sub.2/Ar mixed gas, a H.sub.2/H.sub.2O mixed gas, a CO/CO.sub.2 mixed gas, and a H.sub.2/N.sub.2 mixed gas.

6. The method of claim 5, wherein a volume ratio of the H.sub.2/Ar mixed gas, the H.sub.2/H.sub.2O mixed gas, the CO/CO.sub.2 mixed gas, or the H.sub.2/N.sub.2 mixed gas is 1/99 to 99/1.

7. The method of claim 1, wherein the step 3 is performed at 200 C. to 600 C.

8. The method of claim 1, wherein the metal nanoparticle-oxide support complex structure is a compound represented by the following Chemical Formula 2:
A.sub.xB.sub.yO.sub.z[Chemical Formula 2] in Chemical Formula 2, A is the metal nanoparticle, B is W, x is 0.005 to 0.1, y is 0.9 to 2.995, and z is 1 to 4.

9. A gas sensor comprising the metal nanoparticle-oxide support complex structure of claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows observation results according to Experimental Example 1 of the present invention;

(2) FIG. 2 shows observation results according to Experimental Example 2 of the present invention;

(3) FIG. 3 shows observation results according to Experimental Example 3 of the present invention; and

(4) FIG. 4 shows observation results according to Experimental Example 4 of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) Hereinafter, the actions and effects of the present invention will be described in more detail with reference to the specific exemplary embodiments. However, these exemplary embodiments are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

EXAMPLE

Example 1

(6) A graphene oxide (GO) solution (1.2 mL, 5 mg/mL) and an aqueous nanocellulose (NC) solution (10 mL) were mixed to prepare a graphene oxide-nanocellulose solution (GO-NC). Thereafter, ammonium metatungstate hydrate ((NH.sub.4).sub.6H.sub.2W.sub.12O.sub.40, 0.123 g) and iridium chloride (IrCl.sub.3.Math.xH.sub.2O, 5 mg) were dissolved in deionized water (24 mL) to prepare a tungsten/iridium solution (W/Ir sol). The prepared tungsten/iridium solution was added to the GO-NC solution, and stirred at 300 rpm for 3 hours to prepare a W/Ir_GO-NC solution.

(7) The prepared W/Ir_GO-NC solution was centrifuged to obtain a pellet, which was then dried at 50 C. for 6 hours. Then, the W/Ir_GO-NC solution in a gel state was heated to 600 C. at 5 C./min, and then calcined for 1 hour to 3 hours to prepare 1 at % Ir-doped WO.sub.3 nanosheets (Ir.sub.0.01W.sub.0.99O.sub.3 NSs). For ex-solution treatment, the prepared Ir.sub.0.01W.sub.0.99O.sub.3 NSs were reduced under conditions of H.sub.2/Ar (4/96, (v/v)), 300 C. for 1 hour to prepare a final IrWO.sub.3 complex structure.

Example 2

(8) An IrWO.sub.3 complex structure was prepared in the same manner as in Example 1, except that the prepared Ir.sub.0.01W.sub.0.99O.sub.3 NSs were reduced at 400 C.

Example 3

(9) An IrWO.sub.3 complex structure was prepared in the same manner as in Example 1, except that the prepared Ir.sub.0.01W.sub.0.99O.sub.3 NSs were reduced at 500 C.

Comparative Example 1

(10) An IrWO.sub.3 complex structure was prepared in the same manner as in Example 1, except that the prepared Ir.sub.0.01W.sub.0.99O.sub.3 NSs were not reduced.

Comparative Example 2

(11) WO.sub.3 NSs were prepared in the same manner as in Example 1, except that the iridium chloride precursor was not used, and reduction using the H.sub.2/Ar gas was not performed. Then, iridium nanoparticles were impregnated in WO.sub.3 NSs at 1 at % by impregnation to prepare an IrWO.sub.3 complex structure (poly_Ir NPs-WO.sub.3).

Experimental Example

Experimental Example 1

(12) During the preparation of Examples 1 to 3 and Comparative Example 1, the surface of each complex structure was observed by TEM, and the results are shown in FIG. 1.

Experimental Example 2

(13) Each of the complex structures of Examples 1 to 3 and Comparative Example 1 was dispersed in ethanol and then coated onto an alumina sensor substrate (2.5 mm2.5 mm) with a gold electrode (width=2.5 m, gap size=150 m) to manufacture each gas sensor.

(14) Then, after stabilization in dry air (30% RH; relative humidity), the gas sensor was exposed to H.sub.2S at 1 ppm to 5 ppm while the sensor was turned on and off at 10 min intervals, and its sensing characteristics were measured. The results are shown in FIG. 2A.

(15) In addition, the sensing characteristics of the complex structure of Example 2 were measured according to the temperature of H.sub.2S, and the results are shown in FIG. 2B.

Experimental Example 3

(16) Each gas sensor was manufactured using the complex structure of Example 2 or Comparative Example 1 in the same manner as in the method of Experimental Example 2.

(17) Then, after stabilization in dry air (30% RH), the gas sensor was exposed to CH.sub.3SH, C.sub.3H.sub.6O, C.sub.7H.sub.8, CO, NH.sub.3, HCHO, or H.sub.2S while the sensor was turned on and off at 10 min intervals, respectively, and sensing characteristics thereof were measured. The results are shown in FIG. 3.

Experimental Example 4

(18) Each gas sensor was manufactured using the complex structure of Example 2 or Comparative Example 2 in the same manner as in the method of Experimental Example 2.

(19) Then, after stabilization in dry air (30% RH), the gas sensor was exposed to 1 ppm of H.sub.2S while the sensor was turned on and off at 10 min intervals, and sensing characteristics were measured for a long period of time. The results are shown in FIG. 4.