KR101905256B1 - Preparation method of electrocatalyst using reduced graphene oxide and prussian blue - Google Patents

Abstract

The present invention relates to a method of preparing an electrocatalyst using reduced oxidized graphene and prussian blue, and more particularly, to a method for producing an electrocatalyst using a reduced oxide graphene gel and a reduced oxidized graphene complex (PB) nanostructures were deposited in situ on a PtDT-RGO composite by electrostatic interactions and electroplated on the Pt nanostructures to form RGO-PB / Pt structures (MOR) when used as an electrocatalyst such as a methanol fuel cell and the like, which can realize a synergistic electrochemical catalytic activity and high stability when used as an electrocatalyst such as a methanol fuel cell, Platinum growth and its application to methanol fuel cell electrocatalysts.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrocatalyst using reduced graphene oxide and prussian blue,

The present invention relates to a method of preparing an electrocatalyst using reduced oxidized graphene and prussian blue, and more particularly, to a method for producing an electrocatalyst using a reduced oxide graphene gel and a reduced oxidized graphene complex (PB) nanostructures were deposited in situ on a PtDT-RGO composite by electrostatic interactions and electroplated on the Pt nanostructures to form RGO-PB / Pt structures (MOR) when used as an electrocatalyst such as a methanol fuel cell and the like, which can realize a synergistic electrochemical catalytic activity and high stability when used as an electrocatalyst such as a methanol fuel cell, Platinum growth and its application to methanol fuel cell electrocatalysts.

Prussian blue (PB) is widely used as an intermediary in electrochemical biosensors, and has high selectivity for analytes in electrochemical catalytic activity, stability, porosity and low potential. It is a biologically important synthetic electrophilic peroxidase . In addition, extensive research into PB-based nanocomposites has recently been undertaken in a number of fields, particularly electrochromic devices, catalysis and sensor related fields.

Among many applications, the production of practical devices based on PB is considered to be particularly attractive. For such devices, there is a need for a stable active support capable of immobilizing PB nanoparticles (NPs).

PB is usually the ^{Fe 3 + [Fe (II)} (CN) 6] 4- and mixed, or a ^{Fe 2 + [Fe (III)} (CN) 6] is synthesized by mixing the ^3- (FC), resulting insoluble Of deep blue colloid is obtained. There has also been reported a method of electrodepositioning PB on various substrates from an electrolyte containing anions and cations in the presence of excess supporting electrolyte. However, the above-mentioned reaction proceeds too quickly due to the small solubility constant ( K _sp = 3.3 × 10 ^-41 ) of PB, and as a result, the morphology and size of PB can not be easily controlled.

Graphene (GR) has been shown to be an ideal material for electrochemistry because of its ability to accelerate electron transfer reactions, its high 2D electrical conductivity and surface area, and low cost. There is also a growing interest in GR nano-composites for exploring the functionality of GR. Specifically, platinum (Pt) and PB nanostructures (NSs) are fixed on the GR surface, which can be advantageously applied to catalysts and sensors.

To date, numerous GR-PB, GR-Pt and GR-PB-Pt nanocomposites have been used for catalysis and sensor research. For example, Wang et al. Have reported that GR-PB-Pt nanocomposite, as an electrocatalytic material for methanol oxidation reaction (MOR), performs better than GR-Pt nanocomposite.

In particular, direct methanol fuel cell (DMFC) is a device that converts the chemical energy of methanol into electrical energy. It is environmentally friendly. . However, due to high cost and CO poisoning, application of polycrystalline Pt electrode to DMFC is limited.

Therefore, a method of hybridizing various materials with low-cost, controlled composition and structured film morphology using Pt at the nanoscale level has attracted great attention, and the resulting nanocomposite has a new characteristic .

In short, it is still an important issue to economically and easily manufacture nanocomposites of reduced graphene oxide (RGO) and PB with special electrocatalytic properties.

de Tacconi, N. R .; Rajeshwar, K .; Lezna, R. O. Metal Hexacyanoferrates: Electrosynthesis, in Situ Characterization, and Applications. Chem. Mater. 2003, 15, 3046-3062.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method for producing an electrocatalyst using reduced oxidized graphene and prussian blue, and the use of the electrocatalyst prepared thereby.

Specifically, the present inventors have conducted intensive studies and have found that PB NSs can be added to silicate sol-gel matrix (TPDT) -RGO complex functionalized with an amine through electrostatic interactions between surface-absorbed FC and Fe ²⁺ ions. The Pt / Pt catalyst was prepared by electrodeposition of Pt NPs after in situ growth.

The RGO-PB / Pt catalyst thus produced exhibited synergistic electrochemical catalytic activity against MOR and was able to largely resolve issues related to the growth and stability of PB NSs on the RGO surface.

In addition, while the structure of PB NSs prepared by electrochemical deposition and coprecipitation can not be properly controlled, the growth of PB NSs through electrostatic interactions can solve this problem, It is possible to produce uniform PB NSs.

In addition, a synergistic electrocatalytic effect could be achieved due to the inherent catalytic properties of PB NSs interconnecting the porous nature of TPDT and PB NSs with RGO and Pt NPs.

In order to achieve the above object,

a) forming a complex (TPDT-RGO) layer of an amine functionalized silicate sol-gel matrix (TPDT) and reduced oxidized graphene (RGO) on the electrode;

b) on the TPDT-RGO _{layer, [Fe (CN) 6]} 3- (FC) and through the electrostatic interaction between Fe ^{2 +} prussian blue (PB) of the nanostructures in situ (In situ) to be grown step; And

c) forming a platinum (Pt) nanostructure on the PB nanostructure.

A method for producing an electrocatalyst using reduced oxidized graphene and prussian blue is provided.

That is, the present invention relates to an amine-functionalized silicate sol-gel matrix (TPDT) -RGO complex through electrostatic interactions between FC and Fe ^{2 +} with irreversible electrostatic attraction between TPDT and ferricyanide (FC) PB / Pt catalyst by easily depositing Lu nanoclusters (PB NSs) in situ and electrodepositing Pt nanostructures onto the thus formed ITO / TPDT-RGO-PB electrodes.

The present invention is of importance in that PB NSs are grown in situ by RGO layer interconnection and as a result form a 3D cage-like porous nanostructure, and in the presence of RGO PB showed high operating stability.

Further, the electrode modified according to the present invention was characterized by FESEM, EDAX, XRD, XPS and electrochemical techniques. The RGO / PB / Pt catalyst prepared according to the present invention had a synergistic electrochemical catalytic activity And high stability. It is believed that, along with the Pt nanostructures, the porous nature of TPDT and PB and the PB-specific electron transfer mediator interaction with RGO give synergistic effects on the electrochemical catalytic activity for methanol oxidation.

The electrocatalyst prepared according to the present invention shows excellent catalytic performance and high stability against methanol oxidation reaction (MOR).

The nanocomposites of RGO, metal hexacyano iron salts and metal nanostructures according to the present invention can be applied not only to methanol fuel cells but also to various sensors and energy related fields due to their unique characteristics.

FIG. 1 is a schematic view showing a manufacturing process of an ITO / TPDT-RGO-PB / Pt electrode according to an embodiment of the present invention.
2 is a SEM image of (A, B) ITO / TPDT-PB electrodes; SEM image of (C, D) ITO / TPDT-RGO-PB electrodes; (E) EDAX analysis results of ITO / TPDT-RGO-PB electrodes.
3 is a SEM image of (A, D) ITO / TPDT-PB / Pt electrodes; (B, E) SEM image of ITO / TPDT-RGO-PB / Pt electrode; (C, F) SEM image of ITO / TPDT-RGO / Pt electrode; (G) ITO / TPDT-RGO-PB / Pt electrodes.
(B) ITO / TPDT-RGO-PB, (c) ITO / Pt, (d) ITO / TPDT-PB / Pt, -PB / Pt electrode.
Figure 5 shows the XPS spectra of ITO / TPDT-PB / Pt electrode (a) ITO / TPDT-PB, ITO / TPDT-RGO- .
FIG. 6 is a graph showing the relationship between (A, B) C 1s, (C, D) Fe 2p and (B, D) E, F) N 1s spectra of the samples.
FIG. 7 is a graph showing the relationship between (A, B) C 1s, ((A, B, C, E, G) ITO / TPDT-PB / Pt electrodes and (B, D, F, H) ITO / TPDT-RGO- C, D) Fe 2p, (E, F) Pt 4f and (G, H) N 1s.
Figure 8 shows continuous CVs (* 0.1 M KCl, scan rate 100 mV / s) of ITO / TPDT-FC, ITO / TPDT-PB and ITO / TPDT-RGO-PB electrodes; (D) A comparison of the CVs of ITO / TPDT-FC, ITO / TPDT-PB and ITO / TPDT-RGO-PB electrodes (* 0.1 M KCl, scan rate of 100 mV / s , After 50 potential cycles).
FIG. 9 is a graph showing the relationship between (a) ITO / Pt, ((A)) at (A) 0.5 MH ₂ SO ₄ + scan rate of 50 mV / s, and (B) 1 M CH ₃ OH in 0.5 MH ₂ SO ₄ + scan rate of 20 mV / (b) ITO / TPDT-Pt, (c) ITO / TPDT-RGO-Pt, (d) ITO / TPDT-PB / Pt and (e) ITO / TPDT-RGO-PB / Pt electrodes; (C) CVs of electrodes (a) ITO / TPDT-PB, b) A (b) and c) A (d) electrodes 1 M CH ₃ OH in 0.5 MH ₂ SO ₄ + scan rate 20 mV / s ); (D) (a) ITO / TPDT-RGO-PB, (b) A (c) and (c) A (e) electrode of the CVs (* 0.5 MH ₂ SO ₄ in 1 M CH ₃ OH + scan rate 20 mV / s); (E) CVs (* scan rate 20 mV / s) of the electrode (a) in the absence of CH ₃ OH and (b) in the presence of 1 M CH ₃ OH in 0.5 MH ₂ SO ₄ ; (F) The amperometric it curve observed for 1 M CH ₃ OH in 0.5 MH ₂ SO ₄ at an applied potential of 0.7 V;
10 shows the results of (A) CVs (* 0.5 MH ₂ SO ₄ ) of ITO / TPDT-RGO-PB / Pt electrodes at various scan rates (10, 20, 50, 75, 100, 150, 200 and 250 mV / s) 1 M CH ₃ OH); (B) the corresponding relationship of log j and log ( v ); (C) Peak potential E _p . log ( v ) < / RTI >
11 is a schematic view showing the MOR in the ITO / TPDT-RGO-PB / Pt electrode.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. It should be understood, however, that these examples are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

Example : Reformed  Manufacture of electrodes

(1) Materials and methods

Graphite (powder <20 μm), chloroplatinic acid hexahydrate (H ₂ PtCl ₆ ) and N ¹ - (3-trimethoxysilylpropyl) diethylenetriamine (silane monomer used to make TPDT) were obtained from Sigma-Aldrich And K ₃ [Fe (CN) ₆ ], FeSO ₄ and MeOH were obtained from DaeJung chemicals.

ITO (size 2 x 1 cm) and its modified form were used as the working electrode, Pt wire as the counter electrode, and Ag / AgCl (in the saturated KCl solution) as the reference electrode.

All electrochemical experiments were performed on a single compartment 3-electrode cell using an Ivium Technologies electrochemical workstation.

Prior to each experiment, nitrogen gas (N ₂ ) was bubbled through for 30 minutes.

(2) TPDT Silicate  Synthesis of sol-gel matrix

Under vigorous stirring conditions, 5 μL of 1 M TPDT silane monomer was added to 10 mL of aqueous solution to make a homogeneous 0.5 mM TPDT solution and continued stirring for 60 minutes.

(3) RGO  Nanosheet and TPDT - RGO  Synthesis of complex

Oxide graphene (GO) was prepared from graphite according to the modified Hummers method. For example, RGO may be added to the GO with N ₂ H ₄ , NaOH or NaBH ₄ Adding a reducing agent, and heating at 60 to 100 ° C for 2 to 6 hours for reduction.

Detailed synthesis procedures of RGO nanosheets are described in "Lu, D .; Lin, S .; Wang, L .; Shi, X .; Wang, C .; Zhang, Y. Synthesis of Cyclodextrin-Reduced Graphene Oxide Hybrid Nanosheets for Sensitivity Enhanced Electrochemical Determination of Diethylstilbestrol. Electrochim . Acta 2012 , 85, 131-138. &Quot;

That is, after 20 mL of GO (2 mg / mL) was sonicated for 2 hours to obtain a yellowish brown dispersion, 80 mg of ascorbic acid (AA) was added to the reaction mixture, and the mixture was stirred at room temperature for 48 hours. The resulting black dispersion was centrifuged, washed five times with water, and then dried in an oven.

To prepare the TPDT-RGO complex, RGO (0.1 mg / mL) aliquots were added to the TPDT solution with vigorous stirring for 1 hour and the resulting homogeneous solution was stored in the refrigerator until use.

(4) Reformed  Manufacture of electrodes

The modified electrode was fabricated as shown in Fig.

A predetermined amount (50 μL) of TPDT or TPDT-RGO solution (0.5 mM to 0.1 mg / mL) was drop cast on the surface of the washed ITO electrode and dried in a 37 ° C. incubator for 2 hours. The thickness of the TPDT film was calculated to be 1 μm.

The dried ITO / TPDT or ITO / TPDT-RGO electrode was immersed in an acidic solution (0.01 M HCl) of 3 mM K ₃ [Fe (CN) ₆ ] for 60 minutes, taken out and rinsed in double- Respectively.

The next step was further immersed in 3 mM FeSO ₄ solution for 30 min (characteristic blue color was observed on the electrode surface as PB growth), rinsed out in DDW (double-distilled water) Lt; 0 &gt; C) for 2 hours.

The electrodes were named ITO / TPDT-PB or ITO / TPDT-RGO-PB, respectively.

Subsequently, 3 mM H ₂ PtCl _{6 in} 0.5 MH ₂ SO ₄ A potential of -0.2 V (Ag / AgCl) was applied to the electrolyte for 300 seconds to deposit Pt NSs.

The prepared electrodes were named ITO / TPDT-PB / Pt or ITO / TPDT-RGO-PB / Pt electrodes, respectively.

The current was monitored during the electrodeposition process and the amount of Pt was used to evaluate the amount of Pt.

The mass of Pt was used to calculate the electrochemically active surface area (ECSA) and plot the current density.

The specific mass (M) of Pt was calculated using the charge amount and the following equation (1). The mass-specific peak current (mA / mg _Pt ) was calculated using the peak current density and the specific mass of Pt for the various modified electrodes:

M = Q x MW / (nFA) (1)

F = Faraday's constant, A = electrode ("O" ring), M = number of electrons transferred for electrodeposition, M = number of electrons transferred for electrodeposition, (0.44 cm &lt; ² &gt;)).

(5) Electrochemical research method

The redox behavior of PB was confirmed by cyclic voltammetry (CV) (condition: 0.1 M KCl, -0.2 ~ 1.3 V).

The ECSA of the reformed electrode was calculated from the hydrogen adsorption / desorption curve. (Recording conditions: 0.5 MH ₂ SO ₄ solution (saturated with nitrogen), scan rate 50 mV / s, -0.2-1.3 V).

(* Condition: 1 M CH ₃ OH + 0.5 MH ₂ SO ₄ solution, scan rate 20 mV / s, 0 ~ 0.9 V) was investigated by recording the cyclic voltammetric (CV)

The stability of the catalyst was evaluated using an ammeter i-t curve technique (* application potential 0.7 V, 1500 sec).

Experimental Example : Reformed  Evaluation of electrode characteristics

(One) Reformed  Electrode Morphology  And characterization

Synthesis and stabilization of NPs embedded in a silicate sol-gel matrix has the advantage of single-step production and uniform distribution of nanometer-sized particles. These matrices are very attractive as supports and stabilizers for NPs in both solution and solid phase. Therefore, the present inventors selected TPDT as a solid support for in situ growth of PB NSs.

The morphology of the various modified electrodes was analyzed using field emission scanning electron microscopy (FESEM), and the results are summarized in Figures 2 and 3.

Highly interconnected porous 3D cage-like NSs were observed in the TPDT-RGO-PB nanocomposite, whereas PB NPs of ~100 nm size were clearly distributed in Figures 2A and B (Figure 2C, D ).

This result implies that the PB NSs are attached to the surface of the RGO nanosheets in a pure manner and as a result form an interconnected RGO layer with the PB NSs on both sides of the RGO nanosheets.

Such close-contact and 3D cage-like porous structures are very advantageous for improving catalyst performance.

In addition, the EDAX analysis of the ITO / TPDT-RGO-PB electrode (FIG. 2E) summarizes the element mapping of the electrode, where Fe confirms the presence of PB on the electrode surface.

After Pt NSs was electrodeposited on the ITO / TPDT-RGO-PB electrodes, spherical Pt NPs showed varying sizes ranging from 0.1 to 2 μm on the RGO-PB surface (FIG. 3B, E).

As a result of examining the structural characteristics of Pt NSs in ITO / TPDT-RGO-PB / Pt (FIG. 3B, E) and ITO / TPDT-RGO-Pt (FIG. 3C, F) .

Due to the porosity of the TPDT-PB and TPDT-RGO-PB complexes, the Pt precursor (PtCl ₆ ^{2 -} ) can diffuse without stress, resulting in the growth of uniform spherical Pt NPs.

The EDAX analysis of the ITO / TPDT-RGO-PB / Pt electrode (Fig. 3G) confirms the presence of both PB and Pt NPs on the electrode surface.

In addition, the Fe concentration was higher under the Pt NPs, which also supports the diffusion of the Pt precursor into the porous PB NSs.

The interaction between TPDT and PB NSs is an electrostatic interaction between (+) charged TPDT (due to protonated NH ₃ ⁺ ) and (-) charged FC ions present in the acidic medium. The protonation of the NH ₂ group present in the TPDT occurred when the electrode was dipped into an acidic solution containing FC ions.

In the next step, as the ITO / TPDT-FC electrode was dipped in a solution containing Fe ^{2 +} ions, PB NSs embedded in the TPDT were formed in situ. Saturation growth of blue-related PB NSs was observed after 30 minutes.

The recorded absorption spectra for the ITO / TPDT-FC (a), ITO / TPDT-PB (b) and ITO / TPDT-RGO-PB As observed, this is due to the charge transfer from Fe ^{( II )} to Fe ^{( III )} .

The peaks observed at 21.5, 27.1, 30.2, 35.2, 45.6, 50.6 and 60.4 ° (FIG. 4a, b) of the XRD analysis results (FIG. 4) (222), (400), (422), (440) and (622) planes.

The XRD profile (Fig. 4c) of the ITO / Pt modified electrode showed a sharper Pt (111) peak, which is due to the fact that the Pt loading is high and the peaks observed at 40.6, 46.9 and 68.2 deg. ) And (220) Pt planes.

In the case of ITO / TPDT-PB / Pt (FIG. 4d) and ITO / TPDT-RGO-PB / Pt (FIG. 4e) electrodes, both PB and Pt peaks were clearly visible without peak shift.

This result implies that the Pt NSs were successfully electrodeposited on the PB surface, retain their orientation and do not alter the PB XRD pattern.

In addition, the peaks at 31.1, 35.9, 51.5, and 61.5 ° (FIG. 4, star symbol) are (1 2 1), (1 1 3), (1 4 0) and (4 2 1) plane.

(2) XPS  analysis

In order to obtain detailed information on the chemical composition of the prepared reforming electrode, the XPS spectrum was recorded and summarized in Figures 5-7.

Survey spectrum comparisons confirmed the presence of C, O, N (TPDT-RGO complex), Fe (PB) and Pt.

FIG. 6 is a graph showing the relationship between C 1s (A, B), Fe 2p (C, D) and N (B) of ITO / TPDT-PB (FIG. 6A, C and E) and ITO / TPDT-RGO- 1s (E, F) spectrum.

That is, the C 1s spectrum was fitted with three elements corresponding to carbon atoms bonded to C-Si, CH and In-plane sp ² carbon (C = C).

In the case of PB NSs of ITO / TPDT-PB (Fig. 6C), the binding energies of Fe ^II 2p3 / 2, Fe ^III 2p3 / 2 and Fe ^II 2p1 / 2 were observed at 709.3, 711.6 and 723.4 eV, respectively. The binding energies of Fe ^II 2p3 / 2, Fe ^III 2p3 / 2, Fe ^II 2p1 / 2 and Fe ^III 2p1 / 2 were 709.9, 706.8, 722.9 and 725.9 eV, respectively, in ITO / TPDT-RGO- Observed, which is due to the presence of Fe ^{2 +} and FC of PB NSs.

In the case of N 1s, the peaks were fitted to the three elements at 396.1, 398.3 and 400.3 eV, indicating the presence of CN ([Fe ^{( III )} (CN) ₆ ] ^3- and TPDT in both modified electrodes do.

Spectral analysis of Fe 2p and N 1s of the two electrodes clearly showed that PB NSs were successfully grown in situ on the electrode surface.

In addition, the present inventors paid great attention to analyzing the electronic state of PB NSs after electrodeposition of Pt NPs, and the analysis results are summarized in FIG.

No significant changes were observed for the C 1s and N 1s spectra (Figures 7A, B and G, H, respectively), after Pt electrodeposition, whereas for Fe 2p spectra, Fe ^II 2p3 / 2 &lt; / RTI &gt; (709.3 eV).

These results PtCl ₆ ² during the ^{electro-deposition-diffusion} without the stress and porosity PB NSs and PtCl ₆ ^{2 -} as that to clearly identify the active interaction occurs between, uniform spherical Pt NPs (Fig. 3D, E) further on the It becomes evidence.

7E, F show a Pt 4f profile.

Pt 4f7 / 2 and Pt 4f5 / 2 bond energies were found at 69.58, 72.8 and 75.2 eV for the ITO / TPDT-PB / Pt electrodes and 69.6 and 72.7 for the ITO / TPDT-RGO- And 74.9 eV.

These results ^{Pt 0 (4f7 / 2),} Pt 2 + (4f5 / 2) and Pt ^{4 +} (4f5 / 2) bar which means that the condition exists, Pt ^{2 +} and Pt ^{4 +} state precursor salt or Pt And the interaction of TPDT and PB NSs.

Compared to the standard data of Pt 4f (71.1 and 74.5 eV), a deviation of binding energy was observed at both electrodes suggesting electron transfer between Pt and PB NSs.

This variation in Pt binding energy can contribute to the potential durability increase of the RGO-PB / Pt electrocatalyst.

(3) Reformed  Electrode growth and stability analysis

To understand the electrochemical properties and stability of ITO / TPDT-FC, ITO / TPDT-PB and ITO / TPDT-RGO-PB electrodes, CVs were performed at 0.1 M KCl and the results are shown in FIG.

As the first step of PB NSs growth in TPDT or TPDT-RGO, FC ions were irreversibly absorbed from the acid solution, which was confirmed by CV recording of the ITO / TPDT-FC electrode (Figure 8A, D (a) .

That is, a characteristic surface-restricted redox wave at 0.385 V was observed, and the peak-to-peak separation for the [Fe (CN) ₆ ] ^{3- / 4} redox couple was 92 mV.

After PB NSs were grown on ITO / TPDT-PB (Figure 8B, D (b)) and ITO / TPDT-RGO-PB (Figure 8C, D (c)) electrodes, CVs were 0.265 V, 0.685 V and 0.271 V , And two redox couples at 0.692 V (* peak to peak separation are 117 and 83 mV, respectively), consistent with the characteristic redox process of the reported PBs.

As shown in FIG. 8D (a, b), the redox pair located at about 0.2 V corresponds to the reduction from PB to Prussian white (PW), and the redox pair observed at around 0.7 V is the Berlin Green BG). &Lt; / RTI &gt;

In addition, for the ITO / TPDT-FC electrode (Fig. 8A, D (a)), another peak at 0.709 V (BG) along with the [Fe (CN) ₆ ] ^{3- / 4-} redox peak at 0.385 V Observed, this can be understood from the following equation (2). That is, Fe ^{3 +} generated from the acidic K ₃ [Fe (CN) ₆ ] solution forms BG and is absorbed on the electrode surface:

6HCl + K ₃ [Fe (CN) ₆ ]? 6HCN + FeCl ₃ + 3KCl (2)

It is well known that at pH values above 7 PB is unstable and can be decomposed. Thus, the operational stability of PB coupled electrodes is an important factor in the design of catalysts or sensors.

8B) and the TPDT-RGO complex (Fig. 8C) were added to the PB NSs (Fig. 8A), and the TPDT-RGO complex Was evaluated.

In Figure 8A, the peak current rapidly declines to the scan cycle and gradually decreases to about 37% over 50 cycles, meaning that the FC ions absorbed in the TPDT have moderate stability. In FIG. 8B and C, on the other hand, the peak currents were reduced by only 8.3 and 5.3%, which means that the TPDT and TPDT-RGO provide stable performance and excellent protection for PB NSs.

From the CVs in Fig. 8D, the concentration (Γ) of FC and PB on the electrode surface was calculated based on the following formula 3:

Γ = Q / (nFA) (3)

N = number of electrons involved in the redox process, F = Faraday constant, A = electrode area), where Q = PB to PW (~ 0.2 V).

The amounts of FC and PB bound after 50 cycles were 4.85 × 10 ^-9 , 1.03 × 10 ^-8 and 6.52 × 10 ^{-9 for} ITO / TPDT-FC, ITO / TPDT-PB and ITO / TPDT- mol cm &lt; ^{-2 &} gt ^; .

These results indicate that the PB concentration of the ITO / TPDT-PB electrode is 1.58 times higher than that of the ITO / TPDT-RGO-PB electrode, and that the electrostatic interaction between the TPDT and the FC is generally good.

The influence of the scan speed ( ν ) on the peak currents (i _pa and i _pc ) was investigated in the range of 50 to 500 mV / s. Specifically, CVs (* 0.1 M KCl, potential range -0.2 to 1.3 V) were performed on ITO / TPDT-FC, ITO / TPDT-PB and ITO / TPDT-RGO-PB electrodes.

The corresponding black line between the peak current for the redox reaction and the square root of the scan rate ( v1 ^{/ 2} ) was linear, which means that the electrode process is controlled by diffusion.

These results suggest that PB NSs in TPDT and TPDT-RGO are nucleated across the 3D silicate sol-gel matrix and grow between the RGO layers to act as a charge transport carrier between the substrate and the solution interface.

(4) Methanol oxidation reaction MOR ) analysis

The electrochemical catalytic activity of the RGO-PB / Pt catalyst for MOR was evaluated. The synergistic electrocatalytic capacity of the catalysts described above is also summarized in FIG. 9 in comparison with RGO, PB and Pt-modified electrodes.

The ECSA values were calculated from the following equation 4 by performing CVs (FIG. 9A) at 0.5 MH ₂ SO ₄ and the results are summarized in Table 1:

ECSA = QH / QH * (4)

Where QH = amount of charge collected from the hydrogen adsorption region after double-layer correction, QH * = standard value related to the adsorption of the hydrogen monomolecular layer on the surface of the polycrystalline Pt: 210 μC cm ^-2 ).

[Table 1] MOR-related electrochemical parameters of various modified electrodes

The ECSA of the PB / Pt catalyst was 0.03 cm ² , which was significantly lower than that of the RGO / Pt (0.99 cm ² ) and RGO-PB / Pt (0.55 cm ² ) catalysts with geometric area (0.44 cm ² ).

This is because Pt NPs supported on PB or RGO-PB are larger (~ 700 nm in size) and flat spherical NPs (Figure 3D, F) whereas Pt NPs supported on RGO are relatively small (~ 300 nm in size) Surface (Fig. 3F), and the ECSA is even higher.

The electrochemical catalytic activity for the MOR of the electrode modified by CV (* 0.5 MH ₂ SO ₄ + 1 M CH ₃ OH) was evaluated.

Figures 9B-9D are views showing the comparison of five different Pt NS-modified electrodes, the role of PB and RGO, respectively.

Figure 9E compares the behavior of RGO-PB / Pt catalysts with respect to MOR (a) in the absence of CH ₃ OH and (b) in the presence of 1 M CH ₃ OH.

As shown in FIG. 9B to 9D and Table 1, RGO-PB / Pt ( 0.5086 mA / cm 2 and 88.23 mA / mg _Pt) ECSA- normalized peak forward current density of the catalyst (mA / cm ²⁾ and the mass-normalized Forward peak than the current (mA / mg _Pt) is RGO / Pt (0.1386 mA / cm 2 and 69.5 mA / mg _Pt) catalyst than 3.68 times and 1.26 times, PB / Pt (0.1511 mA / cm 2 and 2.29 mA / mg _Pt) catalyst 3.36 times, and 38.5 times, respectively. This is reasonably inconsistent with their ECSA values, which means that the RGO-PB / Pt catalyst has some synergistic electrocatalytic effect on MOR.

In addition, the presence of PB in the RGO-PB / Pt catalyst increases charge transport to a certain level due to its inherent conductivity.

On the other hand, pure ITO, ITO / TPDT and ITO / TPDT-RGO electrodes showed no specific catalytic activity for MOR.

As shown in FIG. 9F, amperometric curves were recorded in a mixture of 1 M CH ₃ OH and 0.5 MH ₂ SO _{4 at} an application potential of 0.7 V (1500 seconds) and the catalysts for Pt, RGO / Pt and RGO-PB / Pt) were analyzed for stability and durability. These results were consistent with the CV data obtained for MOR.

In the case of the RGO-PB / Pt catalyst (FIG. 9F (c)), the initial current was higher and then the current was slower than other catalysts. The initial rapid decay is due to the formation of CO _ad and CHO _ad intermediate species during MOR.

In order to investigate the kinetics of MOR in the RGO-PB / Pt catalyst, the relationship between the anode peak current ( j _p ) and the peak potential ( E _p ) was analyzed as a function of the scan speed ( ν ) obtained from the forward CV scan, The results are shown in Fig.

Figure 10A shows a RGO-PB / CVs of Pt catalyst _{(* 1 M CH 3 OH +} 0.5 MH 2 SO 4) at various scan rates.

Referring to FIG. 10B, the linear relationship between log j _p and log ( v ) in the RGO-PB / Pt catalyst was shown and the slope was about 0.31, ranging from 0 to 0.5, indicating that the system is a diffusion- it means.

In addition, the linear relationship between E _p and log ( v ) (Figure 10C) implies that the MOR is an irreversible charge-transfer process.

In short, RGO-PB / Pt catalysts exhibited synergistic electrochemical catalytic activity in MOR. This implies that the TPDT-RGO-PB complex served as a perfect platform for accommodating Pt NPs, along with the inherent catalytic properties of PB NSs interconnected with the porosity of TPDT and PB NSs, RGO. Also, as shown in FIG. 11, the porous catalyst system of the present invention promotes the electron transfer and the oxidation removal of CO.

Review results

The present inventors have proposed an easy growth method for binding PB NSs to an amine-functionalized silicate sol-gel matrix (TPDT) -RGO complex through electrostatic interactions and then electroplating Pt NSs to produce an RGO-PB / Pt catalyst Respectively.

The PB thus formed exhibited high operational stability in the presence of RGO and provided 3D cage-like porous NSs by RGO layer interconnection.

On the other hand, this structure could not be achieved through electrochemical deposition or coprecipitation of PB.

In particular, the RGO-PB / Pt nanocomposite prepared according to the present invention exhibited synergistic catalytic activity when applied as an electrocatalyst for methanol oxidation reaction. This is because RGO and Pt NPs And the inherent catalytic properties of interconnected PB NSs.

In addition, it is expected that the nanocomposite comprising the RGO, the metal hexacyano iron salt and the metal NSs proposed by the present invention can be promisingly applied to the sensor and energy field due to its unique characteristics.

Claims (13)

a) forming a complex (TPDT-RGO) layer of an amine functionalized silicate sol-gel matrix (TPDT) and reduced oxidized graphene (RGO) on the electrode;
The ^{_{[Fe (CN) 6] 3-}} (FC charged with) - b) The TPDT-RGO layer is an electrode formed acid _{K 3 [Fe (CN) 6} ] and the TPDT (charged and immersed in a solution (+) ) Ions to form electrostatic interactions between ions;
c) The electrode is washed with distilled water and immersed in a FeSO ₄ solution to form a Prussian blue (PB) nanostructure through electrostatic interactions of [Fe (CN) ₆ ] ^3- (FC) with Fe ²⁺ In situ growth of the substrate; and
d) forming a platinum (Pt) nanostructure on the PB nanostructure,
Wherein the bonding energy of Fe ^II 2p3 / 2 is observed in the electrode, and the bonding energy disappears after electroplating of Pt.
(METHOD FOR MANUFACTURING ELECTROCHROMIC ACID FOR METHANOL OXIDATION REACTION (MOR) USE WITH REDUCED GRAPHIC GRINDING AND PRUSCIAN BLUE.
The method according to claim 1,
Wherein the electrode of step a) is an ITO (indium tin oxide) electrode.
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
The method according to claim 1,
The silicate sol-gel matrix (TPDT) functionalized with an amine of step a) is prepared by using N ¹ - (3-trimethoxysilylpropyl) diethylenetriamine as a silane monomer.
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
The method according to claim 1,
Wherein step a) is performed by drop casting.
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
delete delete The method according to claim 1,
Wherein the step d) is performed by electrodeposition.
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
8. The method of claim 7,
Characterized in that the electrodeposition is carried out in an electrolytic solution containing chloroplatinic acid (H ₂ PtCl ₆ ) and sulfuric acid (H ₂ SO ₄ )
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
The method according to claim 1,
Wherein the PB nanostructures are grown in situ by RGO layer interconnection to form a three-dimensional cage-like porous nanostructure.
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
delete The method according to claim 1,
Wherein the material of the RGO-PB / Pt structure formed on the electrode according to the above production method is used as a catalyst for methanol oxidation reaction (MOR) of a methanol fuel cell.
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
12. The method of claim 11,
Wherein the methanol fuel cell is a Direct Methanol Fuel Cell (DMFC).
Process for the preparation of an electrocatalyst for methanol oxidation reaction (MOR).
















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