Electrochemical sensor for detecting urea and preparation method
Electrochemical sensors are prepared by electrodepositing carbon paper of NiW nanoalloy, which solves the problems of indefinite reactions of existing urea detection methods and complex material preparation, and achieves efficient, sensitive and low-cost urea detection effect.
Patent Information
- Application Number
- CN202410337663.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-24
- Publication Date
- 2025-03-04
AI Technical Summary
The existing urea detection methods have problems such as inconspicuous reactions and large odors during heating, and the electrochemical detection methods still have room for improvement in the material preparation process and high cost.
Carbon paper with electrodeposited NiW nanoalloy was used as working electrode, combined with platinum sheet counter electrode and silver/silver chloride reference electrode, and electrodeposited NiW nanoalloy was electrodeposited on carbon paper by cyclic voltammetry to prepare an electrochemical sensor with high electrocatalytic activity, stability, sensitivity and selectivity.
It realizes efficient detection of urea, with extremely high electrocatalytic activity, stability, sensitivity and selectivity, and is simple in preparation process and low in cost.
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Figure CN119555768A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of electrochemistry, and in particular to an electrochemical sensor for detecting urea and a preparation method thereof. Background Art
[0002] Urea is the end product of amino acid decomposition and metabolism in the body. Hepatocytes can convert ammonia into urea, and the liver is the main organ for producing urea. Urea is the main component of non-protein nitrogen in the blood, accounting for about 50% of the total non-protein nitrogen under normal circumstances. Urea is mainly excreted by the kidneys. All urea in the blood is filtered by the glomeruli, and 30% to 40% is reabsorbed by the renal tubules. The renal tubules also secrete a small amount of urea, and the secretion amount increases in severe renal failure. The determination of serum urea is one of the commonly used indicators to measure glomerular function. Urea concentration is affected by the rate of protein decomposition, the amount of protein intake in food, and the excretion function of the kidneys. In clinical practice, urea examination is used as a routine item in renal function examination.
[0003] Commonly used methods for urea detection include: enzyme coupling method and diacetyl monoxime method. Enzyme coupling method: urease is used to hydrolyze urea to generate ammonium salts, which can be colored by enzyme coupling reaction. Its advantages are that the reaction is specific and strong, it is not affected by urea analogs, and it is easy to automate analysis. The disadvantage is that it is affected by ammonia in the receptor fluid. Diacetyl monoxime method: Urea and diacetyl monoxime are heated under strong acid conditions to generate pink diazine compounds. The color is compared at 540nm, and the depth of the color is proportional to the content. This method has high sensitivity and stable color; the disadvantage is that the reaction is not specific and there is a strong odor when heated.
[0004] Electrochemical detection of urea has a simple electrode material preparation process and has the characteristics of low cost, high sensitivity, good selectivity, rapid response, excellent reproducibility and stability. It is a promising method for clinical detection of urea. Summary of the invention
[0005] In order to make up for the shortcomings of conventional clinical urea detection methods, the present invention aims to produce a simple and convenient electrochemical sensor to achieve efficient detection of urea, using carbon paper with electrodeposited NiW nanoalloy as the working electrode, platinum sheet as the counter electrode, and silver / silver chloride as the reference electrode to achieve efficient detection of urea.
[0006] The present invention is implemented by the following technical scheme. First, a method for preparing a working electrode by electrodepositing NiW alloy on carbon paper is provided, comprising the following steps: (1) 1 cm × 1 cm carbon paper was ultrasonically pretreated with isopropanol, deionized water, 0.1 M hydrochloric acid, and deionized water for 30 min respectively to clean the carbon paper surface; (2) Dissolve 4.41 g of trisodium citrate dihydrate, 0.46 g of sodium bromide, 1.19 g of sodium tungstate dihydrate, 0.12 g of nickel chloride, and 0.86 g of ammonium chloride in 30 ml of deionized water, stir evenly, and aerate (Ar) for 10 minutes. Place the cleaned carbon paper in the solution and stir for 30 minutes.
[0007] (3) Prepare electroplating solutions with different NiW ratios, change the amounts of nickel chloride and sodium tungstate dihydrate in step b, keep the amounts of other chemicals unchanged, stir evenly, aerate (Ar) for 10 minutes, and use cyclic voltammetry to electrodeposit NiW nanoalloy on carbon paper in the range of −1.5 V to −0.4 V, with a scan rate of 100 mV / s and 70 scans. Obtain a NiW / CP electrode.
[0008] from Figure 1 It can be seen that compared with various ratios of electrodeposited Ni:W, the electrodeposited Ni:W ratio of 3:4 shows a higher current response to urea oxidation. It is speculated that this is mainly because Ni atoms and W atoms are uniformly deposited on the surface of the working electrode during the electrodeposition process, and Ni atoms are fully exposed on the working electrode, which facilitates efficient urea oxidation and thus obtains a higher current response.
[0009] from Figure 2 It can be seen that, using a working electrode with an electrodeposited Ni:W ratio of 3:4, in different concentrations of potassium hydroxide electrolyte, as the concentration increases, the current response of urea oxidation increases rapidly when the potassium hydroxide concentration is 1 M. A potassium hydroxide solution with a concentration of 2 M can also obtain a higher current response, but a high concentration potentially increases the detection cost, so a potassium hydroxide solution with a concentration of 1 M is preferably used as the electrolyte for urea detection.
[0010] One of the preferred solutions is that the ratio of electrodeposited Ni:W is 3:4. When applied to the present invention, a NiW / CP electrode with the best detection effect can be prepared.
[0011] One of the preferred solutions is that the optimal concentration of potassium hydroxide is 1 mol / L. When applied to the present invention, the best detection effect can be obtained.
[0012] The present invention further provides a method for detecting urea, using the aforementioned electrochemical sensor for detecting urea, one end of the working electrode, the counter electrode and the reference electrode are respectively connected to an electrochemical workstation, and the other ends of the working electrode, the counter electrode and the reference electrode are respectively placed in the electrolyte in the electrolytic cell.
[0013] The detection method further comprises: Linear sweep voltammetry was selected on the electrochemical workstation with a voltage range of 0 V-0.9 V. The current-voltage curve of urea oxidation was used to measure the peak current of urea oxidation under different concentrations of potassium hydroxide solution, and the optimal potassium hydroxide concentration was screened out. Urea was detected at the optimal potassium hydroxide concentration.
[0014] The beneficial effects of the present invention compared to the prior art include: The electrochemical sensor for detecting urea described in the present invention has high electrocatalytic activity, stability, sensitivity, good selectivity and reproducibility in alkaline electrolyte, simple preparation process and low cost ( Figure 3 ).
[0015] With reference to the following description and the accompanying drawings, the specific embodiments of the present invention are disclosed in detail, indicating the manner in which the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope thereby.
[0016] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.
[0017] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying creative labor.
[0019] Figure 1 This is a comparison chart of urea detection by NiW / CP electrodes with different Ni:W ratios in an alkaline environment.
[0020] Figure 2 This is a comparison chart of urea detection by NiW / CP electrode with Ni:W=3:4 at different potassium hydroxide concentrations.
[0021] Figure 3 This is the linearity plot of urea detection at 1 M potassium hydroxide concentration using the NiW / CP electrode with Ni:W=3:4. DETAILED DESCRIPTION
[0022] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.
[0023] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.
[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0025] Example 1 A method for preparing a working electrode by electrodepositing NiW nano alloys in different proportions on carbon paper comprises the following steps: a. 1 cm × 1 cm carbon paper was ultrasonically pretreated with isopropanol, deionized water, 0.1 M hydrochloric acid, and deionized water for 30 min respectively to clean the surface of the carbon paper; b. Dissolve 4.41 g of trisodium citrate dihydrate, 0.46 g of sodium bromide, 1.19 g of sodium tungstate dihydrate, 0.12 g of nickel chloride, and 0.86 g of ammonium chloride in 30 ml of deionized water, stir evenly, aerate (Ar) for 10 minutes, and place the cleaned carbon paper in the solution and stir for 30 minutes.
[0026] c. Prepare electroplating solutions with different NiW ratios, change the amount of nickel chloride and sodium tungstate dihydrate in step b, keep the amount of other chemicals unchanged, stir evenly, aerate (Ar) for 10 minutes, and use cyclic voltammetry to electrodeposit NiW nanoalloy on carbon paper in the range of −1.5 V to −0.4 V, with a scan rate of 100 mV / s and 70 scans. Obtain a NiW / CP electrode.
[0027] from Figure 1It can be seen that compared with various ratios of electrodeposited Ni:W, the electrodeposited Ni:W ratio of 3:4 shows a higher current response to urea oxidation. It is speculated that this is mainly because Ni atoms and W atoms are uniformly deposited on the surface of the working electrode during the electrodeposition process, and Ni atoms are fully exposed on the working electrode, which facilitates efficient urea oxidation and thus obtains a higher current response.
[0028] from Figure 2 It can be seen that, using a working electrode with an electrodeposited Ni:W ratio of 3:4, in different concentrations of potassium hydroxide electrolyte, as the concentration increases, the current response of urea oxidation increases rapidly when the potassium hydroxide concentration is 1 M. A potassium hydroxide solution with a concentration of 2 M can also obtain a higher current response, but a high concentration potentially increases the detection cost, so a potassium hydroxide solution with a concentration of 1 M is preferably used as the electrolyte for urea detection.
[0029] Example 2 Linear sweep voltammetry was selected on the electrochemical workstation with a voltage range of 0 V to 0.9 V. The current-voltage curve of urea oxidation was used to measure the peak current of urea oxidation under different concentrations of potassium hydroxide solution, and the optimal potassium hydroxide concentration was screened out. Urea was detected at the optimal potassium hydroxide concentration.
[0030] Any numerical value cited herein includes all values of lower and upper values that increase by one unit from the lower limit to the upper limit, and there is at least a two-unit interval between any lower value and any higher value. For example, if the value of the quantity of a component or a process variable (such as temperature, pressure, time, etc.) is set forth to be from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, the purpose is to illustrate that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in the specification. For values less than 1, one unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1. These are merely examples that are intended to be clearly expressed, and it can be considered that all possible combinations of numerical values listed between the lowest value and the highest value are clearly set forth in the specification in a similar manner.
[0031] Unless otherwise indicated, all ranges include the endpoints and all numbers between the endpoints. "About" or "approximately" used with a range applies to both endpoints of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", including at least the specified endpoints.
[0032] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but should be determined with reference to the appended claims and the full scope of equivalents possessed by such claims. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of the subject matter, nor should it be considered that the inventors did not consider the subject matter to be part of the disclosed inventive subject matter.
Claims
1. A method for preparing a working electrode by electrodepositing different proportions of NiW nano alloys on carbon paper, characterized in that: The following steps are involved: a. ultrasonically pretreating the carbon paper with isopropyl alcohol, deionized water, hydrochloric acid and deionized water respectively to clean the surface of the carbon paper; b. Dissolve trisodium citrate dihydrate, sodium bromide, sodium tungstate dihydrate, nickel chloride and ammonium chloride in deionized water, stir evenly and aerate; c. The amounts of nickel chloride and sodium tungstate dihydrate in step b were changed, and the amounts of other chemicals remained unchanged to prepare electroplating solutions with different NiW ratios, which were stirred evenly and then aerated; the cleaned carbon paper was then placed in the electroplating solutions with different NiW ratios and stirred for 30 minutes, and then NiW nano-alloys were electrodeposited on the carbon paper by cyclic voltammetry in the range of −1.5 V to −0.4 V, with a scan rate of 100 mV / s~1 and a scan number of more than 50 circles, to obtain a NiW / CP electrode.
2. The method for preparing a working electrode by electrodepositing NiW nano alloys in different proportions on carbon paper according to claim 1, characterized in that: The step a is specifically implemented as follows: ultrasonically pre-treating the carbon paper of 1 cm×1 cm with isopropanol, deionized water, 0.1 M hydrochloric acid and deionized water for 30 minutes respectively to clean the surface of the carbon paper.
3. The method for preparing a working electrode by electrodepositing NiW nano alloys in different proportions on carbon paper according to claim 1, characterized in that: The step b is specifically implemented as follows: 4.41 g of trisodium citrate dihydrate, 0.46 g of sodium bromide, 1.19 g of sodium tungstate dihydrate, 0.12 g of nickel chloride, and 0.86 g of ammonium chloride are dissolved in 30 ml of deionized water, stirred evenly, and then aerated for 10 minutes.
4. The method for preparing a working electrode by electrodepositing NiW nano-alloys in different proportions on carbon paper according to claim 1, characterized in that: The step c is specifically implemented as follows: changing the dosage of nickel chloride and sodium tungstate dihydrate in step b, keeping the dosage of other chemicals unchanged to prepare electroplating solutions with different NiW ratios, stirring evenly, aerating for 10 minutes, placing the cleaned carbon paper in the electroplating solutions with different NiW ratios and stirring for 30 minutes, and then electrodepositing NiW nano alloy on the carbon paper by cyclic voltammetry, in the range of −1.5 V to −0.4 V, with a scanning rate of 100 mV / s~1 and a scanning number of 70 circles, to obtain a NiW / CP electrode.
5. A working electrode for electrodepositing NiW nano alloys in different proportions on carbon paper, characterized in that: The electrode is prepared by the above preparation method.
6. An electrochemical sensor for detecting urea, characterized in that: The sensor is composed of an electrochemical workstation, an electrolytic cell, a working electrode, a counter electrode and a reference electrode; a platinum sheet is used as the counter electrode, silver / silver chloride is used as the reference electrode, and the working electrode is the working electrode described in claim 5.
7. A method for detecting urea, characterized in that: An electrochemical sensor for detecting urea according to claim 6 is used, wherein one end of the working electrode, the counter electrode and the reference electrode are respectively connected to an electrochemical workstation, and the other ends of the working electrode, the counter electrode and the reference electrode are respectively placed in the electrolyte in the electrolytic cell.
8. A method for detecting urea according to claim 7, characterized in that: The electrolyte is a potassium hydroxide solution containing urea.
9. A method for detecting urea according to claim 8, characterized in that: The concentration of urea is 0.02 mol / L to 0.1 mol / L, and the concentration of potassium hydroxide is 0.1 M to 2 M.
10. A method for detecting urea according to claim 7, 8 or 9, characterized in that: Linear sweep voltammetry was selected on the electrochemical workstation with a voltage range of 0 V to 0.9 V. The current-voltage curve of urea oxidation was used to measure the peak current of urea oxidation under different concentrations of potassium hydroxide solution, and the optimal potassium hydroxide concentration was screened out. Urea was detected at the optimal potassium hydroxide concentration.