Device for detecting lead ions

A polypyrrole and electrode technology, applied in the field of heavy metal detection, can solve the problems of unfavorable heavy metal enrichment, easy stacking, high sensitivity, etc., achieve excellent electrochemical performance, reduce experimental cost, and improve the effect of electrical conductivity

Inactive Publication Date: 2018-07-17

TIANJIN UNIV

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AI-Extracted Technical Summary

Problems solved by technology

co 3 o 4 The nanosheet and nanosphere structures have been applied in the field of heavy metal detection, but these structures are prone to s...

Abstract

The invention discloses a device for detecting Pb<2+>. The device adopts a three-electrode system; a working electrode is a three-dimensional array electrode of a polypyrrole coated Co3O4 nanowire; anauxiliary electrode is a Pt wire electrode; a reference electrode is a Ag/AgCl electrode; acetic acid-sodium acetate serves as a buffer solution; the three-dimensional array electrode of the polypyrrole coated Co3O4 nanowire is a three-dimensional array prepared by taking foam copper as a base and loading polypyrrole coated Co3O4 nanowire on the base, the length of the Co3O4 nanowire is 1 to 1.8[mu]m, the diameter is 100 to 130 nm, the thickness of the polypyrrole coating layer is 10 to 15 nm, and the Co3O3 nanowire has a polycrystalline structure. The device reduces the experiment cost, issimple and convenient to operate, improves the conductivity of the Co3O4 by utilizing the three-dimensional array structure, increases the specific surface area and the active site of the electrode material, introduces the nitrogen-containing polypyrrole to further improve the conductivity of the electrode material, enables the nitrogen-containing group to be effectively complexed with the Pb<2+>,is favorable for Pb<2+> enrichment during detection, and further improves improvement on the Pb<2+> detection sensitivity and reduce on the detection limit by a sensor.

Application Domain

Material electrochemical variables

Technology Topic

Auxiliary electrodeIon +16

Image

Examples

Experimental program(4)

Example Embodiment

[0032] Example 1

[0033] Soak the foamed copper in hydrochloric acid, acetone, distilled water and absolute ethanol successively, and ultrasonically clean it to remove the oily dirt, oxide layer and insoluble matter on the foamed copper, and place the foamed copper in a vacuum drying oven at 60℃ for drying. .

[0034] Cut the pre-treated foamed copper to a size of 1×2cm 2 As a substrate, grow Co on this substrate 3 O 4 Precursor nanowire array structure. Weigh 0.58 g of cobalt nitrate, 0.1389 g of ammonium fluoride, and 0.56 g of urea, add them to 40 ml of distilled water, and stir for 10 minutes to obtain a bright and uniform pink liquid. Pour this pink liquid into a hydrothermal kettle, and suspend the foamed copper in the pink liquid. Hydrothermal reaction was carried out at 100°C for 8 hours. After the reaction, the reaction kettle was taken out to cool to room temperature, and the foamed copper substrate was taken out. The pink substance was attached to the foamed copper substrate. The foamed copper substrate was washed repeatedly with distilled water and ethanol and dried at room temperature.

[0035] Transfer the sample to a muffle furnace and calcinate in air for 2 hours at a calcining temperature of 200℃ to obtain Co 3 O 4 Nanowire array.

[0036] Using chemical vapor deposition polymerization method in Co 3 O 4 The surface of the nanowire array is coated with an ultra-thin polypyrrole (PPy) film: Weigh 0.66g ammonium persulfate and 0.01g SDS into distilled water, and ultrasonically make it fully dissolved. Will Co 3 O 4 Soak the nanowire array in the above-mentioned mixed solution for 30 minutes, take it out, and place it in a petri dish. Add 30μL of pyrrole monomer to the petri dish without direct contact between the two. Cover the petri dish. The pyrrole monomer volatilizes in the petri dish to produce pyrrole. Steam. Take it out after 10 minutes, rinse the surface repeatedly with distilled water and ethanol to obtain Co 3 O 4 @PPy Nanowire array electrode.

[0037] in figure 1 It can be seen that the nanoneedle structure is uniformly distributed and consistent. The diameter of the nanoneedle is about 120nm and the length is 1.5μm. The needle-like morphology can be clearly observed. figure 2 It shows that polypyrrole coated Co was successfully prepared 3 O 4 The transmission image of the nanowire array electrode shows that the thickness of the PPy layer is about 12nm, which proves that the method of chemical vapor polymerization can obtain an extremely thin polypyrrole layer.

Example Embodiment

[0038] Example 2

[0039] Soak the foamed copper in hydrochloric acid, acetone, distilled water and absolute ethanol successively, and ultrasonically clean it to remove the oily dirt, oxide layer and insoluble matter on the foamed copper, and place the foamed copper in a vacuum drying oven at 60℃ for drying. .

[0040] Cut the pre-treated foamed copper to a size of 1×2cm 2 As a substrate, grow Co on this substrate 3 O 4 Precursor nanowire array structure. Weigh 0.29 g of cobalt nitrate, 0.1389 g of ammonium fluoride, and 0.3 g of urea, add them to 40 ml of distilled water, and stir for 10 minutes to obtain a bright and uniform pink liquid. Pour this pink liquid into a hydrothermal kettle, and suspend the foamed copper in the pink liquid. Hydrothermal reaction was carried out at 120°C for 5 hours. After the reaction, the reactor was taken out to cool to room temperature, and the foamed copper substrate was taken out. The pink substance was attached to the foamed copper substrate. The foamed copper substrate was rinsed repeatedly with distilled water and ethanol and dried at room temperature.

[0041] Transfer the sample to the muffle furnace and calcinate in the air for 2h at a calcining temperature of 400℃ to obtain Co 3 O 4 Nanowire array.

[0042] Using chemical vapor deposition polymerization method in Co 3 O 4 The surface of the nanowire array is coated with an ultra-thin polypyrrole (PPy) film: Weigh 0.23g ammonium persulfate and 0.03g SDS into distilled water, and ultrasonically make it fully dissolved. Will Co 3 O 4 Soak the nanowire array in the above mixed solution for 20 minutes, take it out, and place it in a petri dish. Add 10μL of pyrrole monomer to the petri dish without direct contact between the two. Cover the petri dish. The pyrrole monomer volatilizes in the petri dish to produce pyrrole. Steam. Take it out after 10 minutes, rinse the surface repeatedly with distilled water and ethanol to obtain Co 3 O 4 @PPy Nanowire array electrode.

[0043] To study Co 3 O 4 @PPy The crystal structure of the nanowire array, the growth of Co on the foamed copper substrate 3 O 4 @PPy nanowire array has been tested by XRD, such as image 3 As shown, the characteristic peaks 2θ=43.3°, 50.3°, 74° are the characteristic peaks of the foamed copper substrate, and the diffraction characteristic peaks 2θ=31.1°, 36.6°, 59.3°, 65.1° correspond to Co 3 O 4 (220), (311), (511), (440) crystal planes, this result proves the successful synthesis of Co 3 O 4 The polycrystalline structure.

[0044] Figure 4 For three electrode foam copper, Co 3 O 4 And Co 3 O 4 @PPy's CV curve, the three electrode curves all show the redox peak of CV, and the peak position is basically the same, the foam copper grows Co 3 O 4 After the nanoneedles, the peak redox current has decreased, which is due to Co 3 O 4 As a semiconductor, the conductivity is worse than that of foamed copper, so the peak current is reduced, but due to Co 3 O 4 The nanoneedle array structure increases the active catalytic sites to a certain extent, making the peak current drop not obvious. Co obtained after coating with polypyrrole 3 O 4 The CV peak current of the @PPy nanowire array has increased significantly. This is due to the increased conductivity of the material after polypyrrole coating. Co 3 O 4 @PPy nanowire array has good catalytic activity.

Example Embodiment

[0045] Example 3

[0046] Soak the foamed copper in hydrochloric acid, acetone, distilled water and absolute ethanol successively, and ultrasonically clean it to remove the oily dirt, oxide layer and insoluble matter on the foamed copper. Place the foamed copper in a vacuum drying oven at 70℃ for drying. .

[0047] Cut the pre-treated foamed copper to a size of 1×2cm 2 As a substrate, grow Co on this substrate 3 O 4 Precursor nanowire array structure. Weigh 0.87 g of cobalt nitrate, 0.074 g of ammonium fluoride, and 0.3 g of urea, add them to 40 ml of distilled water, and stir for 20 minutes to obtain a bright and uniform pink liquid. Pour this pink liquid into a hydrothermal kettle, and suspend the foamed copper in the pink liquid. Hydrothermal reaction was carried out at 80°C for 8 hours. After the reaction, the reaction kettle was taken out to cool to room temperature, and the foamed copper substrate was taken out. It can be seen that pink substance was attached to the foamed copper substrate. The foamed copper substrate was rinsed repeatedly with distilled water and ethanol and dried at room temperature.

[0048] Transfer the sample to a muffle furnace and calcinate in the air for 2h at a calcining temperature of 300℃ to obtain Co 3 O 4 Nanowire array.

[0049] Using chemical vapor deposition polymerization method in Co 3 O 4 The surface of the nanowire array is coated with an ultra-thin polypyrrole (PPy) film: weigh 0.45g ammonium persulfate and 0.02g SDS into distilled water, and ultrasonically make it fully dissolved. Will Co 3 O 4 Soak the nanowire array in the above-mentioned mixed solution for 30 minutes, take it out, and place it in a petri dish. Add 20μL of pyrrole monomer to the petri dish without direct contact between the two. Cover the petri dish. The pyrrole monomer volatilizes in the petri dish to produce pyrrole. Steam. Take it out after 15min, rinse the surface repeatedly with distilled water and ethanol to obtain Co 3 O 4 @PPy Nanowire array electrode.

[0050] Figure 5 Co 3 O 4 And Co 3 O 4 @PPy nanowire array electrode contains 0.3μM Pb 2+ In the SWASV curve of the ABS (pH=5), it can be seen that the current response peak appears at -0.59V for both electrodes, Co 3 O 4 The SWASV current response peak of the nanoneedle array electrode is around 19μA, while the Co 3 O 4 The @PPy nanowire array electrode has a peak current value of 24.8μA at -0.59V. This is because the coating of polypyrrole improves the overall conductivity of the electrode material. The nitrogen-containing groups in the polypyrrole can also complex lead ions. , Increasing the active sites of the electrode material, making Co 3 O 4 @PPyThe sensitivity of the nanowire array electrode has been improved, proving that Co 3 O 4 The structure of the @PPy nanowire array can improve the sensitivity of the electrochemical sensor for lead ion detection.

PUM

Property	Measurement	Unit
Length	1.0 ~ 1.8	µm
Diameter	100.0 ~ 130.0	nm
Thickness	10.0 ~ 15.0	nm

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