JP2009121854A - Separation and determination of copper oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for determining and analyzing copper oxides which enables the highly accurate and separate determination of CuO and Cu<SB>2</SB>O in a copper oxide present in the surface of copper. <P>SOLUTION: One end of an object 13 to be measured is connected to a potentiostat/galvanostat device 20, and the side of its other end is immersed in an electrolytic solution BL to acquire a current-potential curve or a time-potential curve. The amounts of CuO and Cu<SB>2</SB>O are measured on the basis of the curves. An aqueous solution of an alkali metal salt of 0.5 M or above, for example, an LiCl aqueous solution, is especially used as the electrolytic solution. By using a high concentration of the aqueous solution of the alkali metal salt, it is possible to acquire curves in which current and potential are sufficiently different for every compound (CuO and Cu<SB>2</SB>O). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a method for separating and quantifying copper oxide for quantifying Cu ₂ O (cuprous oxide) and CuO (cupric oxide) in copper oxide present on the copper surface. In particular, the present invention relates to a method for separating and quantifying copper oxide that can be quantified with high accuracy.

Copper and copper alloys generally produce copper oxide on the surface when exposed to the atmospheric environment due to the influence of humidity, impurity gases, and the like. Copper and copper alloys are widely used for conductor materials such as electric wires, cables, and printed circuit boards. The presence of the copper oxide may cause defective product appearance and poor conductor resistance. The above copper oxide is mainly composed of CuO and Cu ₂ O, and since these CuO and Cu ₂ O have different properties, it is desirable to accurately quantify both when analyzing the corrosion phenomenon of copper, etc. .

As a method for separating and quantifying CuO and Cu ₂ O, the linear sweep voltammetry method (LSV method, Non-Patent Documents 1 to 3) and the chronopotentiometry method (CP method, Non-Patent Document 4), which are electrochemical analysis methods, have been proposed. ing. These methods measure changes in the amount of electricity such as current and potential when a voltage is applied by immersing a measurement object in an electrolytic solution, and quantify them using a curve indicating the change. Non-Patent Documents 1 to 3 disclose an example using a strong alkaline solution of 6M KOH + 1M LiOH as an electrolyte, and Non-Patent Document 4 discloses an example using a 0.1N KCl solution as an electrolyte. Yes. M represents the molar concentration (mol / liter), N represents the normality (N = nM, n is the valence).

`` Voltammetric Characterization of OxideFilms Formed on Copper in Air '', Journal of The Electrochemical Society, 148 (11), B467-B472, 2001 "Study on standardization of voltammetric measurement of cuprous oxide and cupric oxide formed on copper surface", Analytical Chemistry, Vol.51, No.12, pp.1145-1151 (2002) "Chemical state analysis of copper oxide and hydroxide powder samples by voltammetry", copper and copper alloys, Vol. 43 No. 1 (2004) `` Oxidation of copper in high-humidity environment regarding the discoloration mechanism of copper-plated products '', Journal of Copper-strengthening Technology, (1976) Vol. 15, pp. 211-221

  Since the KCl solution is neutral to weakly alkaline, it is excellent in handling safety for workers. However, with 0.1N KCl solution, it is difficult to perform high-precision quantification, and the development of a method capable of more accurate quantification is desired.

Accordingly, an object of the present invention is to provide a copper oxide separation and quantification method capable of quantifying CuO and Cu ₂ O with high accuracy.

The present invention achieves the above object by using a high concentration electrolytic solution. Specifically, the method for separating and quantifying copper oxide of the present invention measures the change in the amount of electricity when a voltage is applied by immersing the measurement object in an electrolytic solution, and based on the curve indicating this change, on the copper surface. CuO and Cu ₂ O in the existing copper oxide are respectively quantified, and an aqueous solution of an alkali metal salt having a concentration of 0.5 M or more is used as the electrolytic solution.

The method of the present invention can determine CuO and Cu ₂ O with high accuracy by using an electrolytic solution having a higher concentration than conventional ones. Moreover, since the electrolytic solution used in the method of the present invention is neutral to weakly alkaline, handling safety for workers is high.

The electrolytic solution used in the method of the present invention is an aqueous solution in which an alkali metal salt is dissolved in water, that is, a solution containing alkali metal ions such as Li ⁺ (lithium ions). The alkali metal is particularly preferably at least one of Li, Na, and K. Alkali metal salts include chloride salts, sulfate salts, carbonates, etc. Among them, chloride salts and sulfide salts are preferable because they are easily dissolved in water and a high-concentration aqueous solution can be obtained. Specifically, LiCl, NaCl, KCl, Li ₂ SO ₄ , Na ₂ SO ₄ , and K ₂ SO ₄ are preferable, and among these, lithium salts such as LiCl and Li ₂ SO ₄ , especially LiCl, have a higher concentration. Since an aqueous solution is obtained, a curve in which CuO and Cu ₂ O are sufficiently separated (a curve having a large reduction potential difference) is easily obtained, which is preferable.

The concentration of the electrolytic solution is 0.5M or more. The higher the concentration, the easier it is to obtain a curve in which CuO and Cu ₂ O are separated. The concentration can be appropriately selected depending on the type of alkali metal salt. For example, in the case of KCl, NaCl, Na ₂ SO ₄ , K ₂ SO ₄ , 1 M or more, particularly 3 M or more is preferable, and in the case of LiCl, Li ₂ SO ₄ , even at a lower concentration than the above potassium salt or sodium salt, It is easy to obtain a curve in which CuO and Cu ₂ O are separated even at 1M. The upper limit of the concentration is generally determined by the solubility, for example, about 15M for LiCl and about 2M for Li ₂ SO ₄ . By using LiCl with high solubility, an aqueous solution with a very high concentration can be obtained.

  In the present invention, quantification is performed using an electrochemical analysis method such as LSV method or CP method. In the LSV method, a current-potential curve is obtained by immersing the measurement object in an electrolyte and measuring the current change when the potential is changed at a predetermined sweep speed, and quantification is performed using this curve. . The CP method obtains a time-potential curve by immersing a measurement object in an electrolyte and measuring the change in potential over time when a current is passed at a predetermined current density. Do. In particular, since the LSV method provides peak-shaped data as compared with the CP method, it is easy to understand the types of existing compounds and their abundance.

The present invention can use either the LSV method or the CP method, but the inventors changed the electrical conditions (sweep speed and current density) according to the thickness of the copper oxide in each method. The knowledge that it can measure with higher accuracy was obtained. Specifically, when using the LSV method, the sweep rate is changed in the range of 1 mV / s to 100 mV / s according to the thickness of the copper oxide present on the surface of the measurement object, and the copper oxide is thick. Make the sweep speed smaller than when it is thin. That is, when the copper oxide is thin, the sweep speed is increased within the specific range, and when the copper oxide is thick, the sweep speed is decreased within the specific range. On the other hand, when using the CP method, the current density is changed in the range of 0.1 mA / cm ² or more and 10 mA / cm ² or less according to the thickness of the copper oxide present on the surface of the measurement object, and the copper oxide is thick. Make the current density larger than when it is thin. That is, when the copper oxide is thin, the current density is reduced within the specific range, and when the copper oxide is thick, the current density is increased within the specific range.

Here, when copper oxide is produced under various corrosive environments, the copper oxide can have various thicknesses. As described above, the present invention adjusts the sweep rate and the current density to an appropriate size according to the thickness of the copper oxide, thereby quantifying CuO and Cu ₂ O with respect to copper oxide having an arbitrary thickness. Can be performed with high accuracy.

More specifically, when the thickness of the copper oxide is 1 μm or more, a more specific sweep speed is preferably 1 mV / s and its vicinity, and the sweep speed is preferably larger as it becomes thinner than 1 μm, and when the thickness is 0.1 μm or more and less than 1 μm, In the case of about 10 mV / s, less than 0.1 μm, especially 50 nm or less, 100 mV / s and its vicinity are preferable. When the copper oxide is thick, especially 1 μm or more, if the sweep rate is fast, especially if it exceeds 1 mV / s, the entire copper oxide may not be reduced, and appropriate quantification is difficult. If the copper oxide is thin, especially less than 1 μm, especially 50 nm or less, if the sweep speed is slow, especially if it is less than 100 mV / s, there is a possibility that the sensitivity decreases and analysis cannot be performed sufficiently. Note that the “thickness of copper oxide” is not a single thickness of CuO or a single thickness of Cu ₂ O, but a total thickness (total film thickness).

  In setting the sweep rate, the thickness of the copper oxide is measured in advance. The LSV method and CP method can also be used to measure the thickness of copper oxide. Specifically, a sample for preliminary measurement is prepared, and the sample for preliminary measurement is based on a current-potential curve obtained by measuring the current change when the potential is changed at a predetermined sweep speed with respect to this sample. Preliminary measurement for calculating the thickness of the copper oxide at is performed. Then, the thickness obtained by the preliminary measurement is treated as the thickness of the copper oxide to be measured, and the sweep speed of the main measurement is determined according to the thickness, and the main measurement is performed. The sweep speed during the preliminary measurement can be selected as appropriate, but if the speed is increased to some extent (for example, 100 mV / s), a rough film thickness can be easily calculated. Thus, the preliminary measurement and the main measurement can be continuously performed by using the electrochemical analysis for the measurement of the thickness of the copper oxide. Note that the preliminary measurement sample and the measurement target (main measurement sample) used for the main measurement may be prepared separately (for example, two samples are made from the same target), or the same target It may be used for both measurements by masking a part. Similarly, when setting the current density described later, the thickness of the copper oxide of the preliminary measurement sample can be used as the thickness of the copper oxide to be measured.

1 [mu] m and more specific current density, if the thickness of the copper oxide is not less than 1 [mu] m, preferably from 1 mA / cm ² or more 10 mA / cm ² or less, it is preferable current density is small in accordance thinner than 1 [mu] m, 0.1 [mu] m or more If it is less than, 1~0.1mA / cm ^2, less than 0.1 [mu] m, especially in the case of 50nm or less, 0.1 mA / cm ² and its vicinity are preferred. When the copper oxide is thick, especially 1 μm or more, when the current density is small, especially when it is less than 1 mA / cm ² , the measurement time becomes long (approximately 1 hour or more), and it is difficult to perform quick measurement. When the copper oxide is thin, especially less than 1 μm, especially 50 nm or less, if the current density is large, especially if it exceeds 0.1 mA / cm ² , the measurement time will be shortened, and there will be curves with sufficiently different potentials for each compound. It is difficult to obtain. Note that when the current density is low, it tends to be affected by the side reaction of reduction by dissolved oxygen in the measurement target, and the measured value (potential) tends to be higher than the actual value. Therefore, it is preferable to remove the dissolved oxygen using an inert gas such as argon gas or high-concentration nitrogen gas prior to measurement. When the current density is high, particularly when the current density is 1 mA / cm ² or more, since the influence of dissolved oxygen is small, it is not necessary to remove the dissolved oxygen.

An object to be measured includes copper oxide containing CuO and Cu ₂ O on the copper surface. “Copper” includes copper alloy as well as pure copper. The shape of the measurement target is not particularly limited. It may be a rod shape or a plate shape, or may be a powder shape containing fine fragments. In the case of powder, for example, an electrode in which a mixture of powder and carbon paste is attached to the carbon electrode body can be used. Alternatively, by applying a carbon paste on the carbon electrode body and using an electrode in which a powder measurement object is attached to this paste, a reduction in reduction efficiency of the measurement object due to the carbon paste can be suppressed. But it can be quantified with high accuracy.

The copper oxide separation and quantification method of the present invention can quantify each of CuO and Cu ₂ O with high accuracy.

First, a basic procedure for separating and quantifying CuO and Cu ₂ O by an electrochemical analysis method will be described.

  The measurement is performed by configuring a three-electrode electrolytic cell 1 as shown in FIG. The electrolytic cell 1 includes a cell container 10 into which an electrolytic solution BL is injected, a reference electrode (RE) 11 and a counter electrode (CE) 12 that are immersed in the electrolytic solution BL, and a measurement target (WE) 13, and both electrodes 11, 12 and one end of the measurement object 13 are connected to a potentiostat / galvanostat device 20, respectively. Here, Ag / AgCl is used for the reference electrode 11, Pt is used for the counter electrode 12, and a commercially available device 20 is used. When sweeping the potential when using the LSV method, the device 20 is set to the potentiostat mode, and when using the CP method, the device 20 is set to the galvanostat mode when observing a change in potential by applying a constant current. . The device 20 is connected to a control device (not shown) having input means, storage means, calculation means, comparison means, judgment means, display means, etc. (Current-potential curve, time-potential curve) is automatically acquired.

The standard device data is input to the control device in advance, and the control device compares this data with the acquired data to be measured so that CuO and Cu ₂ O can be determined from the acquired curve. . Standard samples are those having a coating made of CuO on a substrate such as a copper plate or copper powder (hereinafter referred to as a CuO sample), those having a coating made of Cu ₂ O on the same substrate (hereinafter referred to as a Cu ₂ O sample) Can be used). A CuO sample is obtained by subjecting a copper plate made of oxygen-free copper (JIS H 3100) to a predetermined chemical treatment. A known process can be used for this process (see, for example, Non-Patent Document 2). For the Cu ₂ O sample, the jumet wire (JIS H 4541) can be used as it is. FIG. 2 shows current-potential curves in the CuO sample and the Cu ₂ O sample (electrolyte: 3M LiCl aqueous solution, sweep rate: 1 mV / s).

The current-potential curve in the LSV method ideally changes from 0A to 0A through the maximum current value from the start of reduction of a certain compound in copper oxide to the end of the reduction. Appears as a peak, and when there are a plurality of different compounds, a shape in which a plurality of peaks exist apart from each other is drawn. Therefore, in the LSV method, a current-potential curve is acquired using the standard sample, and the result is input to the control device so that it can be referred to. Here, when a peak appears in the acquired curve, the control device determines that the compound based on each peak is Cu ₂ O, CuO in order from the side far from OV. Then, the control device obtains the electric quantity Q (unit C) corresponding to the area surrounded by the auxiliary line along the baseline of the acquired curve and the curve of the peak portion, and further, the weight increase amount W per unit area (kg / m ² ) = MQ / nFS, M: Molecular weight (kg / mole), n: Number of reaction electrons, F: Faraday constant, S: Measurement area (m ² ) To do. Further, the thickness can be obtained from the weight increase amount W and the density (or theoretical density) of the compound. As a calculation method, a known method can be used (see, for example, Non-Patent Document 2).

On the other hand, the time-potential curve in the CP method ideally takes a constant potential from the start of reduction of a certain compound in copper oxide to the end of the reduction, that is, becomes flat, and the reduction of this compound. When the process is completed, the potential changes, and the reduction of another compound begins to draw a stepped shape that becomes flat. Therefore, in the CP method, similarly to the LSV method described above, a time-potential curve is acquired using the standard sample, and the result is input to the control device so that it can be referred to. Here, when a flat portion appears in the acquired curve, the control device determines that the compound based on each flat portion is CuO and Cu ₂ O in order from the side closer to OV. And a control apparatus calculates | requires the product of the time equivalent to a flat part, and the applied electric current value, ie, the electric quantity Q. FIG.

<Test Example 1>
Electrolyte solutions with different concentrations were prepared, and changes in potential with time were examined by the CP method using the electrolytic cell shown in FIG.

As a sample (measuring object), a substrate having a copper oxide composed of Cu ₂ O and CuO on the surface of the substrate was used. As the substrate, a jumet wire (JIS H 4541, manufactured by Sumitomo Electric Industries, Ltd., diameter φ0.71 mm) used for glass sealing materials such as fluorescent lamps and cold cathode tubes was used. The above wire has a two-layer structure in which the surface of the base material (core material) made of Fe-Ni alloy is subjected to copper plating with a thickness of about 100 μm, and by further heat treatment, a layer mainly made of Cu ₂ O is plated with copper. Prepare on top. A sample is obtained by immersing this wire in a 0.5 M NaOH aqueous solution at 30 ° C. for 32 hours to generate Cu ₂ O and CuO on the surface of the substrate.

When the SIM image of the cross section of the obtained sample was observed, it was confirmed that a layered film was formed on the substrate surface. When the film was analyzed by X-ray diffraction, it was confirmed that the film on the substrate side was composed of Cu ₂ O and the film on the surface side was composed of CuO. That is, this sample includes a Cu ₂ O film and a CuO film in order from the substrate side.

In preparation of the sample, the thickness of the copper oxide on the substrate surface and the abundance ratio of the compounds (Cu ₂ O, CuO) can be changed by changing the NaOH concentration or changing the immersion time. When the concentration is high or the immersion time is long, the copper oxide tends to be thick. Here, in terms of film thickness, the total thickness of copper oxide is about 1.4 μm, the thickness of the Cu ₂ O film is about 0.8 μm, and the thickness of the CuO film is about 0.6 μm. Each thickness was average and was measured using a SIM image.

The potentiostat / galvanostat device shown in FIG. 1 is set to the galvano mode, and the sample is immersed in various concentrations (0.1 M to 3 M) of electrolytes (KCl aqueous solution, LiCl aqueous solution) to obtain a predetermined current density (here, 1 mA / While the current is applied at cm ² ), the change with time of the potential is measured. The results are shown in FIG. The upper graph in FIG. 3 shows the case where the KCl aqueous solution is used, and the lower graph shows the case where the LiCl aqueous solution is used.

The copper oxide present on the sample surface begins to be reduced when immersed in the electrolytic solution, and since the potential is substantially constant until the reduction is completed, a flat portion appears on the time-potential curve. Since CuO and Cu ₂ O have different reduction potentials, there are two flat portions in the time-potential curve, and it can be said that the larger the reduction potential difference, the more separated and measured.

As shown in FIG. 3, when the concentration is 0.1M, only one flat portion is seen, but when it is 0.5M or more, two flat portions appear, and the higher the concentration, the more sufficiently the flat portion is separated. It can be seen that a reduction potential difference appears greatly. It can also be seen that the KCl aqueous solution is preferably 1 M or more, more preferably 3 M or more. On the other hand, it can be seen that the LiCl aqueous solution clearly separates the two flat portions even at 1M. In both graphs shown in FIG. 3, the flat portion on the left (with a low reduction potential) is based on CuO, and the adjacent flat portion (with a high reduction potential) is based on the presence of Cu ₂ O. Yes (confirmed by X-ray diffraction).

From this test result, it can be seen that a time-potential curve in which CuO and Cu ₂ O are sufficiently separated can be obtained by using a high-concentration alkali metal salt aqueous solution. Therefore, it is expected that CuO and Cu ₂ O can be quantified more accurately when an aqueous solution of a high concentration alkali metal salt is used.

In Test Example 1, the electrolytic solution was replaced with a NaCl aqueous solution, and a time-potential curve by the CP method was examined in the same manner as described above. As a result, almost the same result as that obtained using the KCl aqueous solution was obtained. In the above test example 1, in place of the electrolytic solution in Li ₂ SO ₄ solution, time by CP method in the same manner as described above - it was examined potential curve, the concentration of Li ⁺ (lithium ion) is the same as LiCl Almost the same result as that obtained when the aqueous solution was used was obtained.

<Test Example 2>
Electrolytic solutions with different concentrations were prepared, and the current change was examined by the LSV method using the electrolytic cell shown in FIG.

  As the sample (measurement target), a sample produced in the same manner as the sample used in Test Example 1 was used. The potentiostat / galvanostat device shown in Fig. 1 is set to potentiostat mode, the sample is immersed in various concentrations (0.1M to 3M) of electrolyte (KCl aqueous solution, LiCl aqueous solution), and a predetermined sweep speed (here 1mV) Measure the change in current while sweeping with / s). The results are shown in FIGS. The graph of FIG. 4 shows the case where a KCl aqueous solution is used, and the graph of FIG. 5 shows the case where a LiCl aqueous solution is used.

In this test, when the potential (here, negative potential) of copper oxide existing on the sample surface increases to some extent, current starts to flow (current value increases), and the current change until the end of reduction occurs. Appears as a peak on the current-potential curve. Since CuO and Cu ₂ O have different reduction potentials as described above, it can be said that there are two peaks in the current-potential curve, and the larger the reduction potential difference, the more separated and measured.

As shown in FIGS. 4 and 5, when the concentration is 0.1M, only one peak can be seen, but when it is 0.5M or more, two peaks appear, and the higher the concentration, the more separated the peaks appear. That is, it can be seen that a reduction potential difference appears greatly. It can also be seen that the KCl aqueous solution is preferably 1 M or more, more preferably 3 M or more. On the other hand, the LiCl aqueous solution shows clear peak separation even at 1M. In the graphs shown in FIGS. 4 and 5, the left side (high potential side) peak is based on Cu ₂ O, and the right side (low potential side) peak is based on CuO (X-ray diffraction). Confirmed by).

From this test result, it can be seen that a current-potential curve in which CuO and Cu ₂ O are sufficiently separated can be obtained by using a high-concentration alkali metal salt aqueous solution. Therefore, it is expected that CuO and Cu ₂ O can be quantified more accurately when an aqueous solution of a high concentration alkali metal salt is used.

In Test Example 2, the electrolytic solution was replaced with a NaCl aqueous solution, and a current-potential curve by the LSV method was examined in the same manner as described above. As a result, almost the same result as that obtained using the KCl aqueous solution was obtained. Further, in Test Example 2 above, the electrolyte solution was changed to a Li ₂ SO ₄ aqueous solution, and a current-potential curve by the LSV method was examined in the same manner as described above. As a result, LiCl (Li ⁺ ) concentration was the same. Almost the same result as that obtained when the aqueous solution was used was obtained.

<Test Example 3>
Quantification was performed on the copper oxide powder.

Commercially available CuO powder and Cu ₂ O powder were prepared, the following two types of samples were prepared using these powders, and quantification was performed by the LSV method using the electrolytic cell shown in FIG.

  (Form I) A sample obtained by applying a mixture of each powder (about 0.5 mg) and a predetermined amount of carbon paste to a carbon body of a glassy carbon electrode having a diameter of 3 mmφ and a thickness of about 0.2 mm (hereinafter referred to as a mixed sample) Called). The paste amount is changed as appropriate, and samples with different carbon ratio = (powder mass) / (carbon paste + powder mass) are prepared. Both the carbon paste and the glassy carbon electrode containing a carbon body are commercially available products.

  (Form II) A carbon paste (thickness of about 0.2 mm) is applied to one side of the same carbon body as in the above form I, and each powder (about 0.5 mg) is adhered thereon, and this carbon body is the same as in the above form I. A sample (hereinafter referred to as an adhering sample) mounted on the concave portion of the glassy carbon electrode is used. In this sample, at least a part of the powder surface is exposed.

The potentiostat / galvanostat device is set to potentiostat mode, and each sample of the above forms I and II is immersed in the electrolyte (3M LiCl aqueous solution), and the change in current is measured while sweeping at a sweep rate of 10mV / s. Then, a current-potential curve is obtained. Then, CuO and Cu ₂ O were quantified using the obtained curve, and (recovery amount / weighing value) × 100 = recovery rate (%) was obtained to obtain the recovery rate.

  As a result, in the case of a mixed sample, the recovery rate tends to decrease as the proportion of the carbon paste increases, that is, the quantitative accuracy tends to decrease. On the other hand, when measured in a state where the powder is exposed, the recovery rate is as high as 80 to 90% and can be quantified with high accuracy. From this test, when the object to be measured is a fragment or powder, it is expected that a sample can be prepared in the same manner as the attached sample of Form II, and this sample can be used for the measurement and can be accurately quantified. This test result can be used as a standard sample.

<Test Example 4>
Samples (measuring objects) having different copper oxide thicknesses were prepared, and the relationship between the copper oxide thickness and the current density was examined by the CP method using the electrolytic cell shown in FIG. Samples are prepared in the same manner as those used in Test Example 1, and samples having different coating thicknesses are prepared by changing the immersion time of the NaOH aqueous solution. Then, the potentiostat / galvanostat apparatus is set to the galvanostat mode, the prepared sample is immersed in an electrolytic solution (3M LiCl aqueous solution), a current is passed at an appropriate current density, and a change in potential with time is measured. The current density is selected from 0.1 mA / cm ² , 1 mA / cm ² and 10 mA / cm ² .

From this result, it is preferable to increase the current density when the copper oxide is thicker than when the copper oxide is thin. In particular, when the copper oxide is thin, the smaller the current density, the thicker the thicker, the larger the current density is CuO and Cu ₂ O. Can be clearly separated. Further, if the thickness is less than 0.1 [mu] m, 0.1 mA / cm ² or so, if the thickness is 0.1~1μm, 0.1~1mA / cm ^2, when the thickness is at least 1μm, 1~10mA / cm ² is preferred it is conceivable that.

<Test Example 5>
Samples (measuring objects) with different copper oxide thicknesses were prepared, and the relationship between the copper oxide thickness and the sweep rate was examined by the LSV method using the electrolytic cell shown in FIG. Samples are prepared in the same manner as in Test Example 4. Then, the potentiostat / galvanostat apparatus is set to a potentiostat mode, a sample prepared in an electrolytic solution (3M LiCl aqueous solution) is immersed, and a change in current is measured while sweeping at an appropriate sweep speed. Select the sweep speed from 1mV / s, 10mV / s, and 100mV / s.

From this result, when the copper oxide is thick, it is preferable to make the sweep rate smaller than when the copper oxide is thin. In particular, when the copper oxide is thin, the higher the sweep rate, the thicker the lower the sweep rate, CuO and Cu ₂ O. Can be clearly separated. In addition, it is considered that about 100 mV / s is preferable when the thickness is less than 0.1 μm, about 10 mV / s is preferable when the thickness is 0.1 to 1 μm, and about 1 mV / s is preferable when the thickness is 1 μm or more.

  In addition, this invention is not limited to the above-mentioned embodiment, It can change suitably in the range which does not deviate from the summary of this invention.

Separation and determination method of the present invention copper oxide, industrial products and arts made of copper or a copper alloy, such as in materials deposited CuO or Cu ₂ O, CuO oxide in the copper present in the copper surface, Cu ₂ O of It can utilize suitably for each fixed_quantity | quantitative_assay.

It is a schematic block diagram of the electrolytic cell used for isolation | separation fixed_quantity | quantitative_assay of copper oxide. It is a current-potential curve of two standard samples (CuO, Cu ₂ O). It is the time-potential curve acquired by CP method using the electrolyte solution of various density | concentrations. It is the electric current-potential curve acquired by LSV method using KCl aqueous solution of various density | concentrations. It is the electric current-potential curve acquired by the LSV method using LiCl aqueous solution of various density | concentrations.

Explanation of symbols

1 Electrolysis cell 10 Cell container 11 Reference electrode 12 Counter electrode 13 Object to be measured
20 Potentiostat / galvanostat BL electrolyte

Claims (8)

Measure the change in the quantity of electricity when the voltage is applied while immersing the measurement object in the electrolyte, and quantify CuO and Cu ₂ O in the copper oxide present on the copper surface based on the curve indicating this change, respectively. A method for separating and quantifying copper oxide,
A method for separating and quantifying copper oxide, wherein an aqueous solution of an alkali metal salt having a concentration of 0.5 M or more is used as the electrolytic solution.   2. The method for separating and quantifying copper oxide according to claim 1, wherein the alkali metal salt is LiCl. The curve is obtained by immersing the measurement object in the electrolytic solution and measuring a current change when the potential is changed at a predetermined sweep rate,
The sweep rate is changed in the range of 1 mV / s to 100 mV / s according to the thickness of the copper oxide present on the surface to be measured, and the sweep rate when the copper oxide is thicker than when the copper oxide is thin. 3. The method for separating and quantifying copper oxide according to claim 1, wherein the copper oxide is made smaller. The curve is obtained by immersing the measurement object in the electrolytic solution and measuring a change in potential with time when a current is passed at a predetermined current density.
The current density is changed in the range of 0.1 mA / cm ² or more and 10 mA / cm ² or less depending on the thickness of the copper oxide existing on the surface of the object to be measured. 3. The method for separating and quantifying copper oxide according to claim 1, wherein the copper oxide is made larger than the case. The thickness of the copper oxide to be measured uses the thickness of the copper oxide of the sample for preliminary measurement,
The thickness of the copper oxide of the preliminary measurement sample is based on a current-potential curve obtained by measuring the current change when the sample is immersed in an electrolyte and the potential is changed at a predetermined sweep rate. 4. The method for separating and quantifying copper oxide according to claim 3, wherein the method is calculated. The thickness of the copper oxide to be measured uses the thickness of the copper oxide of the sample for preliminary measurement,
The thickness of the copper oxide of the sample for preliminary measurement is based on a current-potential curve obtained by measuring a change in potential with time when the sample is immersed in an electrolyte and a current is applied at a predetermined current density. 5. The method for separating and quantifying copper oxide according to claim 4, wherein   7. The electrolyte according to any one of claims 1 to 6, wherein the electrolytic solution is an aqueous solution of any alkali metal salt selected from LiCl, NaCl, and KCl having a concentration of 1M or more. Separation and determination method of copper oxide.   When the measurement object is in a powder form, the measurement is performed by attaching the measurement object of the powder to the carbon paste applied on the carbon electrode main body. The method for separating and quantifying copper oxide as described.

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