CN107195917A - A kind of AuPdNWs superfine nano forest elctro-catalysts of the vertical-growth on FTO glass and preparation method thereof - Google Patents

Abstract

The invention discloses an AuPdNWs ultrafine nano-forest electrocatalyst grown vertically on FTO glass. Fluorine _SnO2 substrate (FTO glass), AuPdNWs grow along the direction perpendicular to the substrate, the diameter can reach 10 nm. The invention has the following advantages: the AuPdNWs ultra-fine nano-forests synthesized by the method and grown vertically with FTO glass react at normal temperature and medium temperature, and have the characteristics of low cost, good reproducibility, simple preparation process and short experimental period, and have The unique array-ordered nano-forest structure and alloying make it have excellent catalytic performance. It has good application prospects in the fields of electrochemistry and fuel cells.

Description

A vertically grown AuPdNWs ultrafine nanoforest electrocatalyst on FTO glass and its preparation method

technical field

The invention relates to a preparation method for vertically growing AuPdNWs ultrafine nano-forest electrocatalyst on FTO glass, belonging to the technical field of fuel cells. Especially related to the synthesis of nanomaterials and their electrocatalytic applications in the oxidation of alcohols.

Fuel cells have higher fuel conversion and electrical efficiency than conventional fuel or power generation technologies. Compared with other fuels, liquid fuels such as methanol and ethanol have the advantages of high volumetric energy density, easy handling, anti-toxicity and renewable properties, thus bringing great development of direct alcohol fuel cells (DAFCs). DAFCs rely on the reaction of a fuel (methanol or ethanol) at the anode and an oxidant at the cathode. Regardless of the cathode or anode, high-efficiency catalysts are required to reduce the overpotential in electrocatalytic reactions. Today, Pt is recognized as the best anode catalyst, but its usage rate is still limited by its cost. Compared with Pt, Pd is abundant in reserves and has good catalytic activity for ethanol oxidation, so replacing Pt with Pd as an electrocatalyst has great application prospects.

In order to further improve the ethanol oxidation performance of Pd to reach the level of Pt, the alloying method can increase the electrocatalytic active surface area of Pd while maintaining good electrode conductivity and material transport performance. Pd-based catalysts are supported on one-dimensional nanostructures or on high-aspect-ratio supports such as carbon nanotubes, graphene, and activated carbon. However, these methods can only slightly improve the catalytic performance of Pd for ethanol oxidation. Therefore, it needs to be improved from the nanomaterial itself. The present invention uses the seed solution method to prepare an AuPdNWs ultrafine nano-forest electrocatalyst grown vertically on FTO glass. This method makes it have a synergistic effect on catalytic activity. In addition, the vertically growing nano-forest can promote the diffusion of substances and increase its electron transfer rate, and the unique growth method of this nano-forest can fully increase the surface area of the electrode by enlarging the area of FTO glass, thus providing a great opportunity for the field of electrocatalysis and possible The development of portable equipment provides a new direction.

Contents of the invention

The primary purpose of the present invention is to provide a preparation method for vertically growing AuPdNWs ultrafine nano-forest electrocatalyst on FTO glass.

Another object of the present invention is to provide the application of the above-mentioned AuPdNWs ultrafine nano-forest in the field of electrocatalysis.

For realizing the above-mentioned purpose of the invention, the technical scheme of the present invention is as follows:

A preparation method for vertically growing AuPdNWs ultrafine nano-forests on FTO glass, comprising the following steps:

(1) Add chloroauric acid aqueous solution, sodium citrate solution, and sodium borohydride solution to deionized water in sequence, and stir while adding to synthesize gold nanoparticle solution (Au NSs). The concentration of chloroauric acid in the mixed solution was 10 mg/mL-17 mg/mL, the mass fraction of sodium citrate was 1 wt%-10 wt%, and the concentration of sodium borohydride was 2 mg/mL-5 mg/mL.

(2) Soak the FTO glass in APTES (3-aminopropyltriethoxysilane) solution for 10 to 30 minutes, take it out, wash the FTO glass with deionized water for 3 to 6 times, and then immerse the FTO glass in (1) In the gold nanoparticles (Au NSs) solution, soak for 1 to 2 hours, that is, to modify the gold nanoparticles on the surface of the FTO glass.

(3) The gold nanoparticle-modified FTO glass in (2) was immersed in deionized water for 2 to 3 times, and then immersed in the growth solution for 10 to 30 minutes, wherein the growth solution was composed of chloroauric acid, 4-MBA (4 -Mercaptobenzoic acid), AA (ascorbic acid) in a molar ratio of 5:4:12, and ethanol as a solvent. Finally, the grown FTO glass was immersed in ethanol and water, and stored at room temperature for future use.

(4) Put the product of (3) in a solution of MAA (mercaptoacetic acid) and incubate for 2 to 3 hours under heating at a temperature of 60 to 80°C, wherein the MAA solution is made of DMF (N,N-dimethylformamide) As a solvent, rinse with deionized water afterwards.

(5) Immerse the product in (4) in the Pd growth solution at room temperature, wherein the Pd growth solution is made of deionized water as a solvent, an aqueous solution of chloropalladium acid, PVP (polyvinylpyrrolidone), and AA (ascorbic acid). The concentration of chloropalladium acid is 10 mM ~ 40 mM, and the concentration of PVP is 10 mg/mL ~ 40 mg/mL. The concentration of AA is 10 mM ~ 40 mM. Finally, the prepared AuPdNWs ultrafine nano-forests were stored in deionized water for later use.

The above-mentioned ultrafine nano-forest of AuPdNWs grown vertically on FTO glass has a core-shell structure with good dispersion and an average size diameter of 5–8 nm.

The aforementioned AuPdNWs ultrafine nanoforest electrocatalysts are grown vertically to the substrate.

The number of Au and Pd atoms in the above-mentioned AuPdNWs ultrafine nano-forest electrocatalyst is 1:1.

The above-mentioned AuPdNWs ultrafine nano-forest electrocatalyst grown vertically on FTO glass can be used in electrocatalysis-related fields such as alcohol oxidation.

A test method for electrocatalytic oxidation of ethanol by AuPdNWs ultrafine nano-forests grown vertically on FTO glass, characterized in that it comprises the following steps:

(1) Directly use the AuPdNWs ultrafine nano-forest grown on FTO as the working electrode, drop 5 µL of Nafion (5 wt %) on the surface of the electrode, let it dry naturally at room temperature, and use the saturated calomel electrode as the reference electrode, Pt wire The electrode acts as a counter electrode to form a three-electrode system.

(2) Under alkaline conditions, the ethanol oxidation activity of AuPdNWs ultrafine nano-forests grown vertically on FTO glass was tested by cyclic voltammetry, the electrolyte solution was 1M NaOH + 1M C ₂ H ₅ OH, and the CV was tested under N ₂ atmosphere curve, the scan rate is 50 mV/s, and the scan range is from 0 V to 1.4 V (vs RHE).

(3) Cyclic voltammetry was used to test the ethanol oxidation activity of AuPdNWs ultrafine nano-forests grown vertically on FTO glass under acidic conditions. The electrolyte solution was 0.5 M H ₂ SO ₄ + 1M C ₂ H ₅ OH in N ₂ atmosphere Test the CV curve with a scan rate of 50 mV/s. The scanning range is 0 V ~ 1.2 V (vs RHE).

Compared with the prior art, the present invention has the following advantages:

The AuPdNWs ultrafine nano-forests grown vertically with FTO glass synthesized by this method react at room temperature and medium temperature, and have the characteristics of low cost, good reproducibility, simple preparation process, short experimental period, and unique array-sorted nano-forests The structure and alloying make it have excellent catalytic performance. It has good application prospects in the fields of electrochemistry and fuel cells.

Description of drawings:

Figure 1 shows FTO glass, FTO glass grown with AuNWs ultrafine nano-forest, and FTO glass grown with AuPdNWs ultrafine nano-forest from left to right.

Figure 2 is a scanning electron microscope image of the ultrafine nanoforest of AuNWs.

Figure 3 is a scanning electron microscope image of the ultrafine nanoforest of AuPdNWs.

Figure 4 is a transmission electron microscope image of the AuNWs ultrafine nanowires exfoliated from the substrate FTO glass.

Figure 5 is a transmission electron microscope image of the AuPdNWs ultrafine nanowires exfoliated from the substrate FTO glass.

Figure 6 is the CV curves of AuPdNWs ultrafine nano-forest, Pd/C, and AuPdNWs ultrafine nanowires exfoliated from the substrate FTO glass (alkaline condition).

Fig. 7 is the chronocurrent curve of AuPdNWs ultrafine nano-forest and Pd/C electrode.

Figure 8 is the CV curve (acidic condition) of AuPdNWs ultrafine nano-forest, Pd/C, and AuPdNWs ultrafine nanowires exfoliated from substrate FTO glass.

detailed description

The present invention will be further described below through specific embodiments, but the embodiments of the present invention are not limited thereto.

Example 1

(1) Add 100 µL of chloroauric acid aqueous solution (17 mg/mL), 160 µL of sodium citrate solution (1 wt%), and 620 µL of sodium borohydride solution (5 mg/mL) into 20 mL of deionized water in sequence, Add while stirring to form a gold nanoparticle solution (AuNSs).

(2) Soak FTO glass (2 cm ² ) in APTES (3-aminopropyltriethoxysilane, 1 µL/mL, ethanol: water = 1:1) solution for 15 minutes, take it out, and rinse with deionized water Clean the FTO glass 5 times, then immerse the FTO glass in the gold nanoparticle solution (AuNSs) solution in (1) for 1 hour, that is, modify the gold nanoparticles on the surface of the FTO glass.

(3) The gold nanoparticle-modified FTO glass in (2) was immersed in deionized water to wash twice, and then immersed in the growth solution for 10 minutes, wherein the growth solution was composed of 150 µL chloroauric acid solution (17 mg/mL), 600 µL of 10 mM 4-MBA (4-mercaptobenzoic acid) and 900 µL of 20 mM AA (ascorbic acid) were mixed at a molar ratio of 5:4:12, and 2.1 mL of ethanol was used as a solvent. Finally, the grown FTO glass was immersed in ethanol and water, and stored at room temperature for later use, and finally the AuNWs ultrafine nano-forest modified FTO glass electrocatalytic electrode was prepared.

Figure 2 is a scanning electron micrograph of the AuNWs ultrafine nano-forest grown vertically on the FTO glass prepared in this example. It can be seen that the nano-forest grows along the direction perpendicular to the substrate FTO glass, dense and uniformly arranged, and the length can reach µm level .

FIG. 4 is a transmission electron microscope image of the AuNWs ultrafine nanowires peeled from the substrate FTO glass prepared in Example 1. The diameter is between 3 and 5 nm.

Example 2

(1) Add 100 µL of chloroauric acid aqueous solution (10 mg/mL), 160 µL of sodium citrate solution (1 wt%), and 620 µL of sodium borohydride solution (3.8 mg/mL) into 20 mL of deionized water in sequence, adding While stirring, a gold nanoparticle solution (AuNSs) was formed.

(2) Soak FTO glass (2 cm ² ) in APTES (3-aminopropyltriethoxysilane, 1 µL/mL, ethanol: water = 1:1) solution for 15 minutes, take it out, and rinse with deionized water Clean the FTO glass 5 times, then immerse the FTO glass in the gold nanoparticle solution (AuNSs) solution in (1) for 1 hour, that is, modify the gold nanoparticles on the surface of the FTO glass.

(3) The gold nanoparticle-modified FTO glass in (2) was immersed in deionized water to wash twice, and then immersed in the growth solution for 30 minutes, wherein the growth solution was composed of 150 µL chloroauric acid solution (17 mg/mL), 600 µL of 10 mM 4-MBA (4-mercaptobenzoic acid) and 900 µL of 20 mM AA (ascorbic acid) were mixed at a molar ratio of 5:4:12, and 2.1 mL of ethanol was used as a solvent. Finally, the grown FTO glass was immersed in ethanol and water, and stored at room temperature for future use.

(4) Put the product of (3) in 1 µL/mL of MAA (mercaptoacetic acid) solution and incubate at 70 °C for 2 hours, where the MAA solution uses DMF (N,N-dimethylformamide) as a solvent, and then Then rinse with deionized water.

(5) Immerse the product in (4) in the Pd growth solution, which consists of 200 µL of H ₂ PdCl ₄ (20 mM, H ₂ O), 40 µL of PVP (20 mg/mL, H ₂ O), 400 µL of AA (10 mM, H ₂ O) and 2 mL of deionized water were used as solvents, and finally the AuPdNWs ultrafine nano-forest-modified FTO glass was immersed in deionized water for later use.

(6) Directly use the AuPdNWs ultrafine nano-forest grown on FTO as the working electrode, drop 5 µL of Nafion (5 wt%) on the surface of the electrode, dry the electrode naturally at room temperature, and use the saturated calomel electrode as the reference electrode, Pt wire The electrode acts as a counter electrode to form a three-electrode system. Prepare AuPdNWs ultra-fine nanowire electrodes and Pt/C electrodes free from FTO glass, mix them with ethanol and deionized water 1:1, add 5 µL of Nafion (5 wt%) dropwise, and then coat the surface of the glassy carbon electrode. Blow dry before use. The loading capacity of Pd on AuPdNWs ultrafine nanowires and Pd/C electrode is 17.6 μg/cm ² , the surface area of working electrode is 0.28 cm ² , and 1M NaOH+1M C ₂ H ₅ OH solution is used as the electrolyte solution.

Figure 1 shows the actual pictures of FTO glass, AuNWs ultrafine nano-forest modified FTO glass, and AuPdNWs ultrafine nano-forest modified FTO glass from left to right.

Figure 3 is a scanning electron micrograph of the AuPdNWs ultrafine nano-forest electrocatalyst grown vertically on FTO glass prepared in this example. It can be seen that the nano-forest grows along the direction perpendicular to the FTO glass and is densely and uniformly arranged.

Figure 5 is a transmission electron microscope image of the AuPdNWs ultrafine nanowires peeled off from the substrate FTO glass prepared in this example. The diameter is between 5 and 8 nm.

In this example, cyclic voltammetry was used to evaluate the electrocatalytic activity of the vertical nano-forest electrocatalyst for ethanol oxidation under alkaline conditions, and the scan rate was 50 mV/s. Figure 6 shows the CV curves of the AuPdNWs ultrafine nano-forest grown on FTO glass and the AuPdNWs ultrafine nanowires and Pd/C electrodes detached from the FTO substrate. It can be seen from the figure that the ethanol oxidation peak is at 1.0V (vs. RHE), and the mass specific current density of the ethanol oxidation peak of AuPdNWs ultrafine nano-forest grown vertically on FTO glass is 2237.7 A/g, and the ethanol oxidation of Pd/C electrode The peak mass specific current density is 172.6 A/g, the former is 12.9 times that of the latter, and the AuPdNWs ultrafine nanowires stripped from the surface of FTO are used as the working electrode, and the oxidation peak mass specific current density of ethanol oxidation is 7.8 times that of Pd/C , indicating that the special vertically grown AuPdNWs ultrafine nanoforest has better electrocatalytic activity for ethanol oxidation due to its unique morphology. Figure 7 is the timing of AuPdNWs ultrafine nanoforest and Pd/C electrode at 0.87 V (vs. RHE) current curve.

Example 3

(1) Add 100 µL of chloroauric acid aqueous solution (14 mg/mL), 160 µL of sodium citrate solution (10wt%), and 620 µL of sodium borohydride solution (2 mg/mL) into 20 mL of deionized water in sequence, adding While stirring, a gold nanoparticle solution (AuNSs) was formed.

(2) Soak FTO glass (2 cm ² ) in APTES (3-aminopropyltriethoxysilane, 1 µL/mL, ethanol: water = 1:1) solution for 15 minutes, take it out, and rinse with deionized water Clean the FTO glass 5 times, then immerse the FTO glass in the gold nanoparticle solution (AuNSs) solution in (1) for 1 hour, that is, modify the gold nanoparticles on the surface of the FTO glass.

(3) The gold nanoparticle-modified FTO glass in (2) was immersed in deionized water to wash twice, and then soaked in the growth solution for 15 minutes. The growth solution was composed of 150 µL chloroauric acid solution (17 mg/mL), 600 µL of 10 mM 4-MBA (4-mercaptobenzoic acid) and 900 µL of 20 mM AA (ascorbic acid) were mixed at a molar ratio of 5:4:12, and 2.1 mL of ethanol was used as a solvent. Finally, the grown FTO glass was immersed in ethanol and water, and stored at room temperature for future use.

(4) Put the product of (3) in a solution of 1 µL/mL of MAA (thioglycolic acid) and incubate at 80 °C for 2 hours, where the MAA solution uses DMF (N,N-dimethylformamide) as a solvent, and then Then rinse with deionized water. Afterwards, the FTO glass modified with _{AuNWs ultrafine} nano _- forest was placed in the Pd growth solution at room temperature. , H ₂ O), 400 µL of AA (10 mM, H ₂ O) and 2 mL of deionized water as solvents, and finally the AuPdNWs ultrafine nano-forest modified FTO glass was immersed in deionized water for later use. (5) Directly use the AuPdNWs ultrafine nano-forest grown on FTO as the working electrode, drop 5 µL of Nafion (5 wt%) on the surface of the electrode, dry the electrode naturally at room temperature, and use the saturated calomel electrode as the reference electrode, Pt wire The electrode acts as a counter electrode to form a three-electrode system. Prepare the AuPdNWs ultrafine nanowire working electrode and Pd/C electrode stripped from FTO glass, mix them with ethanol and deionized water 1:1, add 5 µL of Nafion (5 wt%) dropwise, and then coat the surface of the glassy carbon electrode. Allow to dry naturally before use. The loading capacity of Pd on AuPdNWs ultra-fine nanowires and Pd/C electrode is 17.6 μg/cm ² , the surface area of the working electrode is 0.28cm ² , and 0.5 MH ₂ SO ₄ + 1M C ₂ H ₅ OH solution is used as the electrolyte solution .

In this example, cyclic voltammetry was used to evaluate the electrocatalytic activity of the vertical nano-forest electrocatalyst for ethanol oxidation under acidic conditions, with a scan rate of 50 mV/s. Figure 8 shows the CV curves of AuPdNWs ultrafine nano-forests grown on FTO glass, AuPdNWs ultrafine nanowires stripped from FTO glass, and commercial Pd/C electrodes. According to ECSA=Q _H /0.45*[Au], ECSA=Q _PdO /0.405*[Pd], where the Au ₂ O ₃ reduction peak is around 1.15V (vs.RHE), and the PdO reduction peak is at 0.70 (vs.RHE) about. [Au] and [Pd] are the loadings of Au and Pd on the electrode surface, which can be calculated: vertically grown AuPdNWs ultrafine nano-forests, AuPdNWs ultrafine nanowires exfoliated from FTO glass, and the electrochemically active area of Pd/C They are 110.1 m ² /g, 81.8 m ² /g, and 43.3 m ² /g, respectively. It shows that the special vertically grown AuPdNWs ultrafine nano-forest also has good electrocatalytic activity for ethanol oxidation under acidic conditions.

The above-mentioned embodiment is a relatively preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above-mentioned embodiment, and other methods such as changes, modifications, substitutions and combinations on the basis of the principles of the present invention are all within the protection scope of the present invention .

Claims (8)

1. the AuPdNWs superfine nano forest elctro-catalysts of a kind of vertical-growth on FTO glass, it is characterised in that described AuPdNWs superfine nano forests are that wherein conductive substrates are fluorine dopeds based on seed solution method vertical-growth in conductive substrates SnO₂Substrate（FTO glass）, AuPdNWs grows along the direction vertical with substrate, and diameter can reach 10 nm.

2. a kind of AuPdNWs elctro-catalysts of vertical-growth according to claim 1, it is characterised in that its synthetic method It is seed solution method, its specific synthesis step is as follows：

（1）The aqueous solution, sodium citrate solution, sodium borohydride solution of gold chloride are sequentially added into deionized water, side edged is stirred Mix, synthesize solution of gold nanoparticles（Au NSs）, gold chloride concentration is the mg/mL of 10 mg/mL ~ 17, lemon in mixed solution Sour sodium mass fraction is the wt% of 1 wt% ~ 10, and sodium borohydride concentration is the mg/Ml of 2 mg/mL ~ 5；

（2）FTO glass is immersed into APTES（3- aminopropyl triethoxysilanes）Take out, use after being soaked 10 ~ 30 minutes in solution Deionized water cleaning FTO glass 3 ~ 6 times, then FTO glass is immersed（1）In golden nanometer particle（Au NSs）In solution, leaching Bubble 1 ~ 2 hour, i.e., by golden nanometer particle modification in FTO glass surfaces；

（3）Will（2）In golden nanometer particle modification FTO glass immersion deionized water in clean 2 ~ 3 times, then immerse in growth-promoting media Immersion 10 ~ 30 minutes, wherein growth-promoting media is by gold chloride, 4-MBA（4- mercaptobenzoic acids）、AA（Ascorbic acid）According to mole Than for 5:4:12 mixing, ethanol is mixed as solvent.

3. last immerse the FTO glass grown in second alcohol and water, room temperature storage is standby；

（4）Will（3）Product is put in MAA（TGA）Solution in heating hatching 2 ~ 3 hours, heating-up temperature be 60 ~ 80 DEG C, Wherein MAA solution is cleaned with deionized water again afterwards by DMF (DMF) as solvent；

（5）Will（4）Middle product is in room immersion Pd growth-promoting medias, and wherein Pd growth-promoting medias are cooked solvent, the water of chlorine palladium acid by deionized water Solution, PVP（Polyvinylpyrrolidone）、AA（Ascorbic acid）Mix, be most made what is grown on FTO glass at last AuPdNWs preserves standby in deionized water.

4. a kind of AuPdNWs superfine nano forest elctro-catalysts of vertical-growth on FTO glass according to claim 2 Apply in oxidation of ethanol catalytic field.

5. a kind of AuPdNWs superfine nano forest electro-catalysis of the vertical-growth on FTO glass is to the method for testing of oxidation of ethanol, Its feature comprises the following steps：

（1）The AuPdNWs superfine nanos forest grown in FTO is directly added dropwise 5 μ L's as working electrode toward electrode surface Nafion（5 wt %）, dry naturally at room temperature, saturated calomel electrode is as reference electrode, and Pt electrodes are as to electrode, group Into three-electrode system.

6.（2）The AuPdNWs superfine nano forests of the vertical-growth on FTO glass are tested under alkalescence condition using cyclic voltammetry Alcohol oxidation activity, electrolyte solution be 1M NaOH+1M C₂H₅OH, in N₂CV curves are tested under atmosphere, sweep speed is 50 mV/s, scanning range is in the V of 0 V ~ 1.4（vs RHE）.

7.（3）The AuPdNWs superfine nano forests of the vertical-growth on FTO glass are tested under acid condition using cyclic voltammetry Alcohol oxidation activity, electrolyte solution be 0.5 M H₂SO₄ + 1M C₂H₅OH, in N₂CV curves, scanning speed are tested under atmosphere Rate is 50 mV/s.

8. scanning range is in the V of 0 V ~ 1.2（vs RHE）.