A zinc oxide modified nanoporous gold and its preparation method and application

Abstract

The present invention provides a zinc oxide modified nanoporous gold and a preparation method and application thereof. The preparation method of the zinc oxide modified nanoporous gold comprises: placing gold as a working electrode in a zinc salt solution, performing electrochemical alloying / de-alloying treatment to obtain a gold-zinc porous alloy; and heat treating the gold-zinc porous alloy to obtain the zinc oxide modified nanoporous gold. The present invention constructs a zinc oxide modified nanoporous gold by an in-situ alloying and dealloying method. When the zinc oxide modified nanoporous gold is used as an electrode in an electrochemical analysis sensor, rapid and highly sensitive monitoring of low-concentration heavy metal trivalent arsenic ions can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of nanomaterials, and in particular to zinc oxide modified nanoporous gold and a preparation method and application thereof. Background Art

[0002] Arsenic is highly toxic, especially trivalent arsenic ions, which are 56 times more toxic than other arsenic ions. Trivalent arsenic is widely present in groundwater. Long-term exposure to trivalent arsenic will cause various adverse effects on the human body, so highly sensitive sensors are needed for detection.

[0003] Electrochemical catalysts play an important role in electrochemical reaction systems, which can accelerate electron transfer and reduce the activation energy of reactions. For many years, researchers have been committed to developing electrochemical catalysts with high catalytic activity, such as increasing specific surface area, electrochemically active sites, or regulating the mass transfer and diffusion of reactants at the electrode-electrolyte interface. Among them, porous metal materials with three-dimensional interlaced network structures have attracted widespread attention in electrochemical catalysis due to their unique properties. Porous metal materials have a good catalytic structure, and their interlaced network structure can effectively promote the mass transfer and diffusion of reactants; the highly curved structure inside the network can expose multiple crystal faces, thereby providing a variety of electrochemically active sites. Zinc oxide also exhibits excellent performance in the detection of trivalent arsenic due to its unique adsorption and catalytic effects.

[0004] At present, a variety of technical means have been applied to construct porous metal materials, such as dealloying methods, electrochemical deposition methods, template synthesis methods, etc. Among them, the dealloying method is widely used. It often uses binary or ternary alloys composed of precious metals and active metals as initial reactants, and dissolves active metals in multiple steps under strong acid or strong alkaline conditions to form a porous structure of precious metals. This method has harsh conditions and requires the use of strong acid and strong alkaline conditions, and lacks certain controllability in the construction of ordered porous structures. Therefore, the development of controllable and inexpensive nanoporous structure materials is still a major challenge and of great significance. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a zinc oxide-modified nanoporous gold and a preparation method and application thereof. A zinc oxide-modified nanoporous gold is constructed by in-situ alloying and dealloying methods. When it is used as an electrode in an electrochemical analysis sensor, it can achieve rapid and highly sensitive monitoring of low-concentration heavy metal trivalent arsenic ions.

[0006] The present invention provides a method for preparing zinc oxide modified nanoporous gold, comprising the following steps:

[0007] S1, placing gold as a working electrode in a zinc salt solution, and performing electrochemical alloying / de-alloying treatment to obtain a gold-zinc porous alloy;

[0008] S2. After heat treatment of the gold-zinc porous alloy, the zinc oxide-modified nanoporous gold is obtained.

[0009] Preferably, step S1 further includes using zinc as an auxiliary electrode and a reference electrode.

[0010] Preferably, in step S1, the gold microdisc is placed in a zinc salt solution as a working electrode.

[0011] In the present invention, gold microdisks as working electrodes have higher mass transfer efficiency than gold wires, etc., reduce diffusion and convection, and are helpful for the loading and modification of zinc, and ultimately zinc oxide-modified nanoporous gold microdisks with high surface area and uniform porous structure can be obtained.

[0012] Preferably, in step S1, the zinc salt solution is a zinc salt alcohol solution;

[0013] Preferably, the zinc salt is zinc chloride, and the alcohol is ethylene glycol.

[0014] Preferably, the electrochemical alloying / dealloying treatment is to perform cyclic scanning on the working electrode using linear voltammetry, and the completion of the cathode scanning is regarded as the end of the last cyclic scanning;

[0015] In the present invention, alloying and dealloying are carried out on the gold surface by using a cyclic voltammetry method, thereby preparing a nanoporous gold-zinc alloy: in a cathode potential scan, zinc ions can be reduced and electrodeposited on the surface of a gold working electrode, and AuZn alloy is formed on the surface of the gold working electrode; in a subsequent anode potential scan, the reduced zinc is gradually oxidized to form zinc ions and dissolves and diffuses into an electrolyte; zinc migrates on the surface of the gold working electrode and causes synchronous migration of gold atoms; the subsequent cathode reduction / anodic oxidation cycle can repeat the electrodeposition, migration and dissolution of zinc ions, thereby preparing gold with a three-dimensional nanoporous structure, namely, nanoporous gold. The nanoporous gold greatly increases the specific surface area and roughness of gold, and has a synergistic sensitization mechanism of precious metal nanoparticles and porous nanostructures, and when used as an electrode, has a very high current density and charge transfer electron speed; at the same time, the present invention further stops the last cycle before the start of the anode scan, namely, stops the cycle when the potential is scanned to 0 V before the start of the anode scan, so that the zinc deposited on the porous nano-gold will not dissolve again, thereby preparing a nanoporous gold-zinc alloy.

[0016] The nanoporous gold-zinc alloy is subjected to high-temperature heat treatment to obtain zinc oxide-modified nanoporous gold, which has excellent performance in analyzing ions, and thus can realize the detection of toxic heavy metal trivalent arsenic ions.

[0017] Preferably, the voltage of the cyclic scanning is -0.8-1.8V, the rate of the cyclic scanning is 8-12mV / s, the temperature of the cyclic scanning is 90-130°C, and the number of cyclic scanning is 2-20 times;

[0018] Preferably, the potential of the cathode scan is -0.8-0V.

[0019] In the present invention, by controlling parameters such as cyclic voltammetry and cycle time, the specific surface area of ​​the obtained zinc oxide-modified nanoporous gold is effectively changed, and the electrochemical sensitive response of trace analytes is improved.

[0020] Preferably, before step S1, the method further comprises cyclically scanning the working electrode using linear voltammetry to activate the gold working electrode;

[0021] Preferably, the electrolyte for the cyclic scanning is a sulfuric acid solution, the voltage for the cyclic scanning is 0-1.5V, the rate for the cyclic scanning is 40-60mV / s, and the number of cyclic scanning is 4-6 times.

[0022] Preferably, in step S2, the heat treatment temperature is 130-170°C and the time is 80-160min;

[0023] Preferably, the heat treatment is performed in an air atmosphere.

[0024] The invention provides a zinc oxide modified nanoporous gold, which is prepared by the above preparation method.

[0025] The present invention provides an electrochemical catalyst, which comprises the zinc oxide modified nanoporous gold.

[0026] The present invention also provides an electrochemical analysis sensor, which includes the electrochemical sensing electrode constructed by the zinc oxide modified nanoporous gold;

[0027] Preferably, the electrochemical analysis sensor is used to detect toxic heavy metal ions;

[0028] Preferably, the toxic heavy metal ions are trivalent arsenic ions.

[0029] The present invention treats a gold working electrode by an electrochemical method and prepares zinc oxide modified nanoporous gold by a cyclic scanning technology; specifically, a gold-zinc porous alloy with an active zinc element is subjected to an in-situ reduction method and then subjected to a high-temperature heat treatment to obtain zinc oxide modified nanoporous gold.

[0030] The present invention uses the zinc oxide modified nanoporous gold as an electrochemical sensing electrode, which can be effectively applied to the detection of toxic heavy metal trivalent arsenic ions. Through testing, it is found that the zinc oxide modified nanoporous gold of the present invention has significantly improved electrochemical detection performance of heavy metal trivalent arsenic ions compared with bare gold with a smooth surface. At the same time, the electrochemical treatment technology significantly increases the specific surface area of ​​gold, and its roughness is significantly increased compared with bare gold with a smooth surface.

[0031] The zinc oxide-modified nanoporous gold prepared by electrochemical and in-situ reduction-oxidation methods has high catalytic activity and large specific surface area, realizes highly sensitive detection of heavy metal trivalent arsenic ions, and effectively solves the problem of difficult electrochemical capture and low sensitivity of trivalent arsenic ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 SEM images of the gold microdisc and zinc oxide modified nanoporous gold prepared in the embodiments of the present invention: (a) is a SEM image of the gold microdisc, and (b) is a SEM image of the zinc oxide modified nanoporous gold electrode;

[0033] Figure 2 XRD patterns of gold microdisks, gold-zinc porous alloys, and zinc oxide-modified nanoporous gold prepared in the embodiments of the present invention;

[0034] Figure 3 The cyclic voltammetry curves of the gold-zinc porous alloy prepared under different cyclic scanning numbers in sulfuric acid of the present invention are shown;

[0035] Figure 4 The sensitivity detection diagram of the zinc oxide modified nanoporous gold prepared in the embodiment of the present invention to trivalent arsenic ions when used in an electrochemical analysis sensor: (a) is the square wave dissolution curve of the zinc oxide modified nanoporous gold to trivalent arsenic ions when used in an electrochemical analysis sensor; (b) is the linear fitting diagram of Figure a;

[0036] Figure 5 The sensitivity detection diagram of the nanoporous gold prepared in the comparative example of the present invention to trivalent arsenic ions when used in an electrochemical analysis sensor: (a) is the square wave dissolution curve of the nanoporous gold to trivalent arsenic ions when used in an electrochemical analysis sensor; (b) is the linear fitting diagram of Figure a;

[0037] Figure 6 The following are diagrams showing the repeatability of the detection of 100 ppb trivalent arsenic ions by the zinc oxide-modified nanoporous gold prepared in the embodiment of the present invention when used in an electrochemical analysis sensor: (a) is a square wave dissolution curve and a peak current line graph when the zinc oxide-modified nanoporous gold repeatedly detects 100 ppb trivalent arsenic ions; (b) is a bar graph showing the current response of the zinc oxide-modified nanoporous gold prepared in different batches when detecting 100 ppb trivalent arsenic ions;

[0038] Figure 7 This is a test diagram of the anti-interference performance of the zinc oxide-modified nanoporous gold prepared in an embodiment of the present invention for detecting trivalent arsenic ions when used in an electrochemical analysis sensor. DETAILED DESCRIPTION

[0039] The technical solutions of the present invention are described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention. Example

[0040] A method for preparing zinc oxide modified nanoporous gold comprises the following steps:

[0041] (1) Take a gold wire with a diameter of 25 μm, a length of 30 mm and a smooth surface, place it in a high-borosilicate glass tube with one end condensed into a small hole by high temperature, insert one end of the gold wire into the small hole, make the end of the gold wire close to the small hole and perform high-temperature treatment, so that the end of the gold wire is sealed at the mouth of the glass tube, then vacuum treat the high-borosilicate glass tube, and seal a part of the gold wire in the glass tube in a high-temperature atmosphere, and then grind the mouth of the glass tube into a disc shape with a grinding wheel to make the surface of the gold micro-disc smooth; take another copper wire and wrap one end of it with silver paste, insert the end wrapped with silver paste into the glass tube, connect it to the unsealed end of the gold wire in the glass tube, put it in an oven for drying, take it out after drying and use a multimeter to measure whether it is conductive. After measuring that the conductivity is good, seal the end of the glass tube with AB glue, and after naturally drying, prepare a gold micro-disc;

[0042] (2) placing 5 mL of 0.1 M sulfuric acid solution in an electrolytic cell, introducing nitrogen for 15 min, and then exhausting the air in the sulfuric acid solution; then using the gold microdisc prepared in step (1) as a working electrode, Ag / AgCl as a reference electrode, and a platinum wire as a counter electrode, the three electrodes are placed in the sulfuric acid solution and connected to an electrochemical workstation, and a three-electrode cyclic voltammetry method is used to perform cyclic scanning to activate the working electrode, wherein the starting voltage is 0 V, the ending voltage is 1.5 V, and the scanning rate is 50 mV / s. After 5 cycles of cyclic scanning, an activated gold microdisc is obtained;

[0043] (3) placing 1.022 g of zinc chloride and 5 mL of ethylene glycol in an electrolytic cell, and ultrasonically treating the zinc chloride until the zinc chloride is dissolved to form a transparent clear solution, thereby obtaining a zinc salt solution; then polishing the zinc sheet and the zinc rod to a bright finish to remove the surface oxide film, and ultrasonically cleaning the zinc sheet and the zinc rod in ethanol for 5 min to obtain the cleaned zinc sheet and the zinc rod; immersing the zinc salt solution in silicone oil and heating it to 110° C., and then using the gold microdisc activated in step (2) as a working electrode, the cleaned zinc rod as a counter electrode, the cleaned zinc sheet as a counter electrode, and the zinc rod as a reference electrode, the three electrodes are placed in the zinc salt solution, and connected to an electrochemical workstation, and cyclic scanning is performed using a three-electrode cyclic voltammetry method, with a starting voltage of 0.2 V, a minimum voltage of -0.8 V, a maximum voltage of 1.8 V, a scanning rate of 10 mV / s, and 10 cycles of cyclic scanning. At the 10th cycle of the cyclic scanning, the cyclic scanning is stopped after the cathode scanning is completed, the working electrode is removed, and the organic solvent remaining on the surface is rinsed with anhydrous ethanol, thereby obtaining a gold-zinc porous alloy;

[0044] (4) The gold-zinc porous alloy prepared in step (3) is heat treated at 150° C. for 2 h in an air atmosphere and cooled to room temperature to obtain the zinc oxide-modified nanoporous gold.

[0045] The gold microdiscs and zinc oxide modified nanoporous gold prepared in the examples were examined by scanning electron microscopy. Figure 1 As shown, Figure 1 The SEM images of the gold microdisc and zinc oxide modified nanoporous gold prepared in this example are shown in FIG. Figure 1 It can be seen that after electrochemical alloying / dealloying treatment, a uniform nanoporous structure is formed on the surface of the smooth gold microdisc.

[0046] X-ray powder diffraction analysis was performed on the gold microdiscs and zinc oxide modified nanoporous gold prepared in the examples. The results are as follows: Figure 2 As shown, Figure 2 The XRD patterns of the gold microdisc, gold-zinc porous alloy and zinc oxide-modified nanoporous gold prepared in this example. Figure 2 XRD patterns of gold microdiscs (NPG), gold-zinc porous alloy (Zn / NPG), and zinc oxide modified nanoporous gold (ZnO / NPG) are shown, with the strong peaks at 2θ = 38.2, 44.4, 64.5, 77.5, and 81.7° assigned to the (111), (200), (220), (311), and (221) planes of face-centered cubic Au (JCPDS No. 04-0784). Figure 2It can be seen that the Zn / NPG obtained at 0.0V during the electrochemical alloying / de-alloying treatment clearly showed new peaks near 28.4, 40.6, 50.2, 58.7, 66.5 and 73.8°; when further calcined in an air atmosphere, compared with NPG, additional peaks at 31.7, 34.4, 36.2, 47.5, 56.6, 62.8, 67.9 and 69.1° were clearly observed, which are consistent with the (100), (002), (101) hexagonal structure of ZnO (102), (110), (103), (112) and (201) planes; it can be seen that the nanoporous gold modified with zinc oxide has the diffraction characteristic peaks of both gold and zinc oxide.

[0047] Except that only 0, 2, 5, 15, and 20 cycles of scanning are performed in step (3) of the embodiment, other operations are the same as those of the embodiment, and the gold-zinc porous alloys with 0, 2, 5, 15, and 20 cycles of scanning are obtained respectively. The gold-zinc porous alloy obtained in the embodiment is 10 cycles of scanning.

[0048] The gold-zinc porous alloy obtained after 0, 2, 5, 10, 15, and 20 cycles of the above-mentioned cyclic scanning was used as the working electrode, respectively, in a 0.1M sulfuric acid solution, with Ag / AgCl as the reference electrode and platinum wire as the counter electrode, connected to an electrochemical workstation, and cyclic scanning was performed using a three-electrode cyclic voltammetry method until a stable cyclic voltammetry curve was obtained, wherein the starting voltage was 0V, the ending voltage was 1.5V, and the scanning rate was 50mV / s; the results are as follows Figure 3 As shown, Figure 3 The cyclic voltammetry curves of the gold-zinc porous alloy prepared under different cyclic scanning numbers in sulfuric acid are shown in the figure.

[0049] Reference Figure 3 It can be seen that compared with the gold microdisk (cycle scan 0), the oxidation and reduction peaks of the obtained gold-zinc porous alloy increased significantly after 2 cycles of electrochemical alloying / dealloying treatment, and the broad oxidation peak of gold and the sharp oxide reduction peaks around 1.3V and 0.9V can be clearly observed, which are derived from the formation of gold oxide and the reduction of gold oxide. In addition, after 5 cycles of electrochemical alloying / dealloying treatment, the oxidation and reduction peaks of the gold-zinc porous alloy (NPG-μE) increased significantly with the expansion of the double electric layer; but when the number of cycles was increased from 10 to 20, the oxidation and reduction peaks of the gold-zinc porous alloy were almost stable or slightly decreased.

[0050] Comparative Example

[0051] A method for preparing nanoporous gold comprises the following steps:

[0052] (1) Take a gold wire with a diameter of 25 μm, a length of 30 mm and a smooth surface, place it in a high-borosilicate glass tube with one end condensed into a small hole by high temperature, insert one end of the gold wire into the small hole, make the end of the gold wire close to the small hole and perform high-temperature treatment, so that the end of the gold wire is sealed at the mouth of the glass tube, then vacuum treat the high-borosilicate glass tube, and seal a part of the gold wire in the glass tube in a high-temperature atmosphere, and then grind the mouth of the glass tube into a disc shape with a grinding wheel to make the surface of the gold micro-disc smooth; take another copper wire and wrap one end of it with silver paste, insert the end wrapped with silver paste into the glass tube, connect it to the unsealed end of the gold wire in the glass tube, put it in an oven for drying, take it out after drying and use a multimeter to measure whether it is conductive. After measuring that the conductivity is good, seal the end of the glass tube with AB glue, and after naturally drying, prepare a gold micro-disc;

[0053] (2) placing 5 mL of 0.1 M sulfuric acid solution in an electrolytic cell, introducing nitrogen for 15 min, and then exhausting the air in the sulfuric acid solution; then using the gold microdisc prepared in step (1) as a working electrode, Ag / AgCl as a reference electrode, and a platinum wire as a counter electrode, the three electrodes are placed in the sulfuric acid solution and connected to an electrochemical workstation, and a three-electrode cyclic voltammetry method is used to perform cyclic scanning to activate the working electrode, wherein the starting voltage is 0 V, the ending voltage is 1.5 V, and the scanning rate is 50 mV / s. After 5 cycles of cyclic scanning, an activated gold microdisc is obtained;

[0054] (3) 1.022 g of zinc chloride and 5 mL of ethylene glycol are placed in an electrolytic cell, and the zinc chloride is ultrasonically dissolved to form a transparent clear solution to obtain a zinc salt solution; the zinc sheet and the zinc rod are polished to a bright finish to remove the surface oxide film, and ultrasonically cleaned in ethanol for 5 min to obtain the cleaned zinc sheet and the zinc rod; the zinc salt solution is immersed in silicone oil and heated to 110° C., and the gold microdisc activated in step (2) is used as a working electrode, the cleaned zinc rod is used as a counter electrode, the cleaned zinc sheet is used as a counter electrode, and the zinc rod is used as a reference electrode. The three electrodes are placed in the zinc salt solution and connected to an electrochemical workstation, and a three-electrode cyclic voltammetry method is used for cyclic scanning, with a starting voltage of 0.2 V, a minimum voltage of -0.8 V, a maximum voltage of 1.8 V, a scanning rate of 10 mV / s, and a cyclic scanning of 10 circles. The working electrode is removed and the organic solvent remaining on the surface is rinsed with anhydrous ethanol, and then dried to obtain the nanoporous gold.

[0055] Test example:

[0056] The electrochemical analysis test was carried out using the zinc oxide modified nanoporous gold prepared in the example as the working electrode, Pt wire and Ag / AgCl as the counter electrode and reference electrode to form a three-electrode test system, 0.1M phosphate buffer (pH 5) as the electrolyte, and toxic heavy metal trivalent arsenic ions (As 3+) is the analyte. Before the test, inert nitrogen was introduced into the electrolyte for 20 min to remove the oxygen dissolved in the electrolyte. Square wave anodic stripping voltammetry was used as the analysis method. The experimental conditions were: deposition potential and time were -0.4V, 120s; desorption potential and time were 0.6V, 150s; step voltage was 4mV; amplitude was 25mV; frequency was 25Hz; the electrolyte was scanned; trivalent arsenic solution was then added with a concentration of 1-260ppb, the electrolyte was stirred evenly, and scanned under the same conditions. The scanning results are shown in the figure. Figure 4 As shown, Figure 4 The sensitivity detection diagram of zinc oxide modified nanoporous gold prepared in an embodiment of the present invention to trivalent arsenic ions when used in an electrochemical analysis sensor: (a) is the square wave dissolution curve of zinc oxide modified nanoporous gold to trivalent arsenic ions when used in an electrochemical analysis sensor; (b) is the linear fitting diagram of Figure a.

[0057] Reference Figure 4 It can be seen that the nanoporous gold modified with zinc oxide prepared in the embodiment of the present invention has a -0.1V resistance to As 3+ It exhibits strong electrochemical oxidation behavior.

[0058] The nanoporous gold prepared in the comparative example was used as the working electrode for electrochemical analysis. The test conditions were the same as above, except that a trivalent arsenic solution with a concentration of 1-150 ppb was added and scanned under the same conditions. The scanning results are shown in FIG. Figure 5 As shown, Figure 5 The sensitivity detection diagram of the nanoporous gold prepared in the comparative example of the present invention to trivalent arsenic ions when used in an electrochemical analysis sensor: (a) is the square wave dissolution curve of the nanoporous gold to trivalent arsenic ions when used in an electrochemical analysis sensor; (b) is the linear fitting diagram of Figure a.

[0059] Reference Figure 5 It can be seen that compared with the nanoporous gold microdisk electrode prepared in the comparative example, the zinc oxide modified nanoporous gold microdisk electrode prepared in the embodiment has a better effect on As 3+ The electrochemical response sensitivity was increased by 6.3 times, indicating that ZnO-modified nanoporous gold has higher electrocatalytic activity.

[0060] The same conditions were used for 100 ppb As 3+ Repeatability test, the results are as follows Figure 6 As shown, Figure 6 The following are diagrams showing the repeatability of the detection of 100 ppb trivalent arsenic ions by the zinc oxide-modified nanoporous gold prepared in an embodiment of the present invention when used in an electrochemical analysis sensor: (a) is a square wave dissolution curve and a peak current line graph of the repeated detection of 100 ppb trivalent arsenic ions by the zinc oxide-modified nanoporous gold; (b) is a bar graph of the current response of the zinc oxide-modified nanoporous gold prepared in different batches when detecting 100 ppb trivalent arsenic ions.

[0061] Reference Figure 6 It can be seen that the zinc oxide modified nanoporous gold prepared in the embodiment of the present invention exhibits good repeatability.

[0062] When the zinc oxide modified nanoporous gold prepared in the embodiment of the present invention was used to detect 100 ppb trivalent arsenic ions, 5 times the concentration of anti-interference ions was added, and the detection results were as follows: Figure 7 As shown, Figure 7 This is a test diagram of the anti-interference performance of the zinc oxide-modified nanoporous gold prepared in an embodiment of the present invention for detecting trivalent arsenic ions when used in an electrochemical analysis sensor.

[0063] Reference Figure 7 It can be seen that the zinc oxide modified nanoporous gold prepared in the embodiment of the present invention exhibits good anti-interference performance.

[0064] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing zinc oxide modified nanoporous gold, It is characterized in that The steps include: S1, placing gold as a working electrode in a zinc salt solution, and performing electrochemical alloying / de-alloying treatment to obtain a gold-zinc porous alloy; S2, heat-treating the gold-zinc porous alloy to obtain the zinc oxide-modified nanoporous gold; In step S1, the electrochemical alloying / dealloying treatment is to perform cyclic scanning on the working electrode using linear voltammetry, and the completion of the cathode scanning is regarded as the end of the last cyclic scanning; The voltage of the cyclic scanning is -0.8-1.8V, the rate of the cyclic scanning is 8-12mV / s, the temperature of the cyclic scanning is 90-130°C, and the number of cycles of the cyclic scanning is 2-20 times; The voltage of the cathode scanning is -0.8-0V.

2. The method for preparing zinc oxide modified nanoporous gold according to claim 1, It is characterized in that Step S1 also includes using zinc as an auxiliary electrode and a reference electrode.

3. The method for preparing zinc oxide modified nanoporous gold according to claim 1 or 2, It is characterized in that In step S1, a gold microdisk is placed in a zinc salt solution as a working electrode.

4. The method for preparing zinc oxide modified nanoporous gold according to claim 1 or 2, It is characterized in that In step S1, the zinc salt solution is a zinc salt alcohol solution, the zinc salt is zinc chloride, and the alcohol is ethylene glycol.

5. The method for preparing zinc oxide modified nanoporous gold according to claim 1 or 2, It is characterized in that Before step S1, the method further includes performing cyclic scanning on the working electrode using linear voltammetry to activate the gold working electrode.

6. The method for preparing zinc oxide modified nanoporous gold according to claim 5, It is characterized in that The electrolyte of the cyclic scanning is a sulfuric acid solution, the voltage of the cyclic scanning is 0-1.5V, the rate of the cyclic scanning is 40-60mV / s, and the number of cyclic scanning is 4-6 times.

7. The method for preparing zinc oxide modified nanoporous gold according to claim 1 or 2, It is characterized in that In step S2, the heat treatment temperature is 130-170°C and the time is 80-160 minutes.

8. The method for preparing zinc oxide modified nanoporous gold according to claim 7, It is characterized in that The heat treatment is performed in an air atmosphere.

9. A zinc oxide modified nanoporous gold, It is characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. An electrochemical catalyst, It is characterized in that It comprises the zinc oxide modified nanoporous gold as claimed in claim 9.

11. An electrochemical analysis sensor, It is characterized in that The invention comprises the electrochemical sensing electrode constructed by the zinc oxide modified nanoporous gold as claimed in claim 9.

12. The electrochemical analysis sensor according to claim 11, It is characterized in that The electrochemical analysis sensor is used for detecting toxic heavy metal ions.

13. The electrochemical analysis sensor according to claim 12, It is characterized in that The toxic heavy metal ions are trivalent arsenic ions.

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