CN111424301A - Method for improving conversion efficiency of CuO photoelectrocatalysis CO2 in pulse potential mode - Google Patents

Abstract

The invention relates to the field of photoelectrocatalysis, in particular to a method for improving CuO photoelectrocatalysis CO in a pulse potential mode₂And (3) a method for converting the efficiency. The method comprises the following steps: anodic oxidation: taking the pretreated titanium sheet as an anode, carrying out constant potential anodic oxidation on the titanium sheet to obtain a pre-matrix, and annealing the pre-matrix to obtain a matrix; electro-deposition: immersing the substrate in copper-containing electrolyte, and electrodepositing on the surface of the substrate by pulse electrodepositionCopper, and then carrying out heat treatment to obtain a CuO/TNTs composite electrode; and (3) pulse potential mode reduction: the obtained CuO/TNTs composite electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and the counter electrode is immersed in electrolyte and continuously introduced with CO₂The xenon lamp is used as a light source, and CO is reduced in a pulse potential mode by setting different potentials₂. The invention greatly improves the electro-deposition precision, has low requirement on manufacturing equipment, has the advantages of low cost, high efficiency, easy realization and the like, and can well realize mass production.

Description

Method for improving conversion efficiency of CuO photoelectrocatalysis CO2 in pulse potential mode

Technical Field

The invention relates to the field of photoelectrocatalysis, in particular to a method for improving CuO photoelectrocatalysis CO in a pulse potential mode₂And (3) a method for converting the efficiency.

Background

The CuO film is a classical semiconductor, has a forbidden band width of about 1.6eV, and a conduction band potential of-0.8 eV, and can effectively remove CO in an aqueous solution under illumination₂Reducing the organic matter into organic matter and being widely applied to the field of photoelectrocatalysis. However, the potential of the conduction band covers the self reduction potential, so that the CO is reduced in photoelectrocatalysis₂The catalyst itself can be reduced, which greatly limits the application of the catalyst. At home and abroad, scholars usually combine CuO with other semiconductors and cover the CuO with n-type semiconductors to prepare composite electrodes for photoelectrocatalysis. On one hand, the prepared p-n junction enables electrons to be transmitted in a single direction, so that the photoelectrocatalysis efficiency of the p-n junction is improved; on the other hand, the chemical property of the covered semiconductor is more stable, and the whole service life can be prolonged to a certain extent. However, the n-type semiconductor is uniformly covered on the surface of CuO, expensive equipment and complex process are required, and the prepared composite semiconductor electrode still has obvious performance attenuation phenomenon.

In order to overcome the defects, a pure Ti plate is used as a substrate, and an anodic oxidation method is used for preparing TiO₂A nano tube array (TNTs), a CuO/TNTs composite electrode is prepared by compounding CuO and TNTs through an electrodeposition method, and a proper catalysis mode is adopted to improve CuO CO₂The conversion efficiency. At present, CuO is used as a main catalyst to reduce CO₂The modes include photocatalysis, electrocatalysis and photoelectrocatalysis. The photocatalysis is most widely applied, and the catalyst in the photocatalysis exists in a powder form, so that CuO can be compounded with more semiconductors, but the problem of CuO stability cannot be solved; electrocatalysis usually needs to apply a relatively negative potential, CuO is reduced to pure Cu at the potential, and the semiconductor characteristic of CuO is lost; the pulse potential photoelectrocatalysis can effectively combine light and electricity, and is different from the traditional photoelectrocatalysis that CuO is gradually reduced by pulse potentialThe mode photoelectrocatalysis can oxidize the carbon dioxide by intermittent positive potential, thereby having long service life and improving CO₂However, the pulse potential photoelectrocatalysis mode cannot completely reduce the used CuO/TNTs into the original composition, and further optimization is needed.

The Chinese patent office discloses TiO in 2019, 1 month and 25 days₂-CuO/g-C₃N₄Synthesis method of composite nano material and CO₂The patent application for the application of the photocatalysis reduction has the application publication number of CN 109261189A. The invention adopts a sol-gel method to synthesize TiO in different dispersion media₂-CuO/g-C₃N₄The composite material has more active surfaces due to irregular surface, the yield of the methanol produced by photocatalysis reaches 0.702mg/g-cat/min, but the inventor does not give a change curve of the yield along with the time, and the stability of the composite material cannot be explained.

In addition, the China patent office issued an invention patent of a regeneration method of AgBr/CuO visible light photocatalytic material and application thereof in 2016, 1, 27, with the publication number of CN 104190446B. The high-activity AgBr/CuO composite catalyst is prepared by taking CuO as a raw material through a deposition method, has excellent visible light catalytic performance, and Ag is used after the catalyst is used for a long time⁺Will be reduced to Ag causing its failure and the inventors regenerated it with 3% bromine water. Although the technical scheme can regenerate the catalyst, the regeneration process is complex, the regeneration and the catalysis cannot be carried out simultaneously, and the large-scale application is difficult.

Disclosure of Invention

In order to solve a series of problems of short service life and poor stability of the existing CuO catalyst, complicated operation, low efficiency and the like of the existing regeneration method, the invention provides a pulse potential mode for improving the CuO photoelectrocatalysis CO₂And (3) a method for converting the efficiency. The invention aims to: the method has the advantages that the limitation of the existing photoelectric composite material in application is reduced, and the applicability and universality of the photoelectric composite material are improved; secondly, the performance of the photoelectric catalytic material is improved, and a better photoelectric catalytic effect is generated; thirdly, the service life of the CuO photoelectrocatalysis material is prolonged, and the CO is treated₂Optimizing the catalytic performance; fourthlyThe CuO/TNTs composite photoelectric composite material with better performance is provided; and fifthly, the preparation and operation difficulty is reduced, and the method is suitable for industrial production and application.

In order to achieve the purpose, the invention adopts the following technical scheme.

Pulse potential mode for improving CuO photoelectrocatalysis CO₂A method for the conversion of a protein into a protein,

the method comprises the following steps:

1) anodic oxidation: taking the pretreated titanium sheet as an anode, carrying out constant potential anodic oxidation on the titanium sheet to obtain a pre-matrix, and annealing the pre-matrix to obtain a matrix;

2) electro-deposition: dipping the substrate in copper-containing electrolyte, electrodepositing copper on the surface of the substrate in a pulse electrodeposition mode, and performing heat treatment to obtain a CuO/TNTs composite electrode;

3) and (3) pulse potential mode reduction: the obtained CuO/TNTs composite electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and the counter electrode is immersed in electrolyte and continuously introduced with CO₂The xenon lamp is used as a light source, and CO is reduced in a pulse potential mode by setting different potentials₂。

In the method, firstly, the titanium sheet is subjected to anodic oxidation treatment, and a TNTs structure is prepared on the surface to improve the specific surface area of the TNTs structure. Then annealing to form a matrix suitable for loading CuO, depositing Cu on the surface of the TNTs structure in an electrodeposition mode, and further performing heat treatment to obtain CuO, and performing photoelectrocatalysis reduction on CO by using the prepared CuO/TNTs electrode as a working electrode in combination with illumination and pulse potential₂. Compared with photocatalysis and common constant potential photoelectrocatalysis, the pulse potential mode photoelectrocatalysis can give consideration to CO₂The reduction performance and the stability of the electrode can keep the CuO catalytic performance, and greatly improve the photocatalytic performance of the CuO composite material.

By fixing the negative pulse and changing the positive pulse potential and time, the composition of Cu oxide can be effectively maintained, the Cu oxide is ensured not to be completely reduced into simple substance Cu, and the Cu oxide can reduce CO₂Simultaneously, the regeneration is realized, the two-step process is not wrong, the efficiency is high, the continuity is realized, and the photoelectric composite material is greatly improvedThe service life and the stability of the material produce excellent technical effects.

As a preference, the first and second liquid crystal compositions are,

step 1) the pretreatment comprises chemical polishing;

the polishing solution adopted by the chemical polishing comprises 45-90 g/L of chromium oxide, 45-90 m L/L of 38-42 wt% of hydrogen fluoride solution and the balance of water;

the chemical polishing time is 10-20 min, and the polishing temperature is 50-60 ℃.

In addition to chemical polishing, the pretreatment may include any one or more of conventional degreasing, grinding, cleaning, and drying steps.

The titanium sheet is subjected to the above-mentioned special pretreatment, which is mainly embodied in the aspect of chemical polishing. The component proportion of the polishing solution is critical, the titanium sheet surface is seriously corroded by the over-concentrated hydrofluoric acid, and the polishing efficiency is low and the surface cannot be smooth due to the over-diluted hydrofluoric acid. Therefore, the chemical polishing of the special pretreatment in the present invention is one of the most critical steps in the pretreatment, and the composition of the polishing solution and the polishing parameters need to be strictly controlled.

As a preference, the first and second liquid crystal compositions are,

step 1) during the anodic oxidation: taking a graphite electrode or a platinum electrode as a cathode, and taking 1-5 wt% of hydrofluoric acid solution as electrolyte;

the anodic oxidation temperature is 25-40 ℃, the anodic oxidation voltage is 15-35V, and the anodic oxidation time is 5-25 min.

By combining the anodic oxidation conditions (namely various parameters) recorded in the anodic oxidation system, a TNTs array structure with controllable growth rule, length and density can be prepared, and the subsequent electrodeposited copper is ensured to have good uniformity. In addition, under the action of hydrofluoric acid, the time required by the formed TNTs structure is shorter, and the length of the titanium oxide nanotube is shorter, so that the conductivity of the titanium oxide nanotube is more excellent.

As a preference, the first and second liquid crystal compositions are,

the purity of the titanium sheet is more than or equal to 99.0 percent.

The high-purity titanium sheet can avoid the introduction of impurities, and the photoelectrocatalysis effect of the prepared photoelectric composite material is ensured.

As a preference, the first and second liquid crystal compositions are,

the annealing temperature in the step 1) is 450-550 ℃, the heating rate is 5-10 ℃/min, and the temperature is kept for 2-4 h after the annealing temperature is reached.

The matrix obtained by annealing under the condition can be well used for loading the copper oxide foam, and good technical effects are generated.

As a preference, the first and second liquid crystal compositions are,

step 2), the copper-containing electrolyte is a soluble copper salt aqueous solution containing 0.1-1.0 mol/L bivalent copper ions;

step 2) in the pulse electrodeposition: negative pulse is-0.01 to-0.1A, duration is 0.002 to 0.1s, positive pulse is 0.01 to 0.1A, and duration is 0.002 to 0.1 s.

Compared with the conventional constant current electrodeposition, the pulse current electrodeposition is more suitable for electrodeposition in the titanium dioxide nanotube, copper can be electrodeposited into the titanium dioxide nanotube or a tube seam, and the copper deposited outside the tube is dissolved to prepare the embedded structure. The structure is more stable and is more beneficial to photoelectrocatalysis.

As a preference, the first and second liquid crystal compositions are,

the soluble copper salt is any one or more of copper sulfate, copper chloride and copper nitrate.

Most preferably, the soluble copper salt is copper sulfate. The copper sulfate solution is a common solution for electrodepositing copper, is stable, has low cost and is suitable for large-scale application.

As a preference, the first and second liquid crystal compositions are,

step 3) the reduction of CO in the pulse potential mode₂The medium-negative pulse is-0.2 to-0.7V, the duration is 80 to 100s, the positive pulse is 1.0 to 2.5V, and the duration is 10 to 50 s.

Pulsed potential mode reduction of CO₂Has the advantage that it can reduce CO₂The active components on the surface of the electrode can be kept relatively stable through a pulse potential mode, so that CO is reduced₂The efficiency is improved and the service life of the electrode is prolonged.

As a preference, the first and second liquid crystal compositions are,

step 3) the electrolyte is NaHCO₃An aqueous solution having a concentration of 0.05 to 0.2 mol/L;

step 3) irradiating the xenon lamp onto the electrode to generate energy density of 50-120 mw/cm²。

NaHCO in photoelectrocatalysis₃The most common aqueous solution is one with neutral pH and alkaline pH, and can effectively dissolve CO as buffer solution₂And also contributes to the stability of the electrode. Simultaneous NaHCO₃The aqueous solution is also an excellent conductive salt, so that the photocurrent transmission is faster and more stable. The power of the xenon lamp is 250W, the illumination wavelength range of the xenon lamp comprises ultraviolet visible light and infrared light, the xenon lamp is closest to a solar light source, the catalysis performance of the photoelectrode under the solar illumination is approximately obtained by simulating the illumination energy by the xenon lamp, and the reference significance is realized.

As a preference, the first and second liquid crystal compositions are,

step 3) reduction of CO in a pulse potential mode₂A saturated calomel electrode is also arranged as a reference electrode.

The saturated calomel electrode has good stability.

The invention has the beneficial effects that:

1) the electro-deposition precision is greatly improved, the requirement on manufacturing equipment is low, the manufacturing method has the advantages of low cost, high efficiency, easiness in implementation and the like, and mass production can be well realized;

2) the photoelectrocatalysis conditions are optimized, so that the photoelectrocatalysis of CO is realized₂The reduction efficiency is higher, and the performance is more durable;

3) for photoelectrocatalytic reduction of CO₂Provides a new thought and has important significance for the development of the field of photoelectrocatalysis.

Drawings

FIG. 1 is an SEM image of the surface and cross section of a CuO/TNTs composite electrode prepared according to an embodiment of the present invention;

FIG. 2 is an XRD pattern of the surface and cross section of a CuO/TNTs composite electrode fabricated according to an embodiment of the present invention;

FIG. 3 is a graph showing the relationship between the methanol yield and the pulse potential under the fixed negative pulse condition of the CuO/TNTs composite electrode manufactured by the embodiment of the present invention;

FIG. 4 is a graph showing the relationship between the methanol yield and the pulse time under the fixed forward pulse condition of the CuO/TNTs composite electrode manufactured by the embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to specific embodiments and the attached drawing figures. Those skilled in the art will be able to implement the invention based on these teachings. Moreover, the embodiments of the present invention described in the following description are generally only some embodiments of the present invention, and not all embodiments. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention.

Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all those known to those skilled in the art.

Example 1

Pulse potential mode for improving CuO photoelectrocatalysis CO₂A method of converting efficiency, the method comprising the steps of:

1) pretreating, namely pretreating 99.5% of flake-shaped foamed titanium, wherein the pretreatment comprises oil removal, chemical polishing, cleaning and drying, the foamed titanium is firstly placed in mixed solution of acetone and absolute ethyl alcohol in a ratio of 1: 1 for ultrasonic cleaning for 10min, then the chemical polishing is carried out, polishing solution used for the chemical polishing contains 90 g/L of zirconium oxide and 38 wt% of hydrogen fluoride solution with the concentration of 90m L/L, the solvent is water, the polishing temperature is 50 ℃, the polishing time is 10min, finally, deionized water is used for cleaning, the polished titanium is placed in protective atmosphere for drying, and the specially pretreated foamed titanium is obtained after the drying;

2) anodic oxidation: taking a specially pretreated titanium sheet as an anode, and carrying out constant potential anodic oxidation on the titanium sheet to obtain a pre-matrix, wherein the specially pretreated titanium foam is taken as the anode, a graphite electrode is taken as a cathode, a 2 wt% hydrofluoric acid solution is taken as an electrolyte, the oxidation temperature is 25 ℃, the oxidation voltage is 20V, and the oxidation time is 20min,

and annealing it. Wherein the annealing time is 2h, the annealing temperature is 450 ℃, the heating rate is 5 ℃/min, and the substrate is obtained after furnace cooling;

3) and (3) electrodeposition, namely, immersing the substrate in a copper-containing electrolyte for 10min, wherein the electrolyte contains 1 mol/L copper sulfate, then carrying out pulse galvanic electrodeposition on the substrate by a pulse program of-0.1A, 0.1s, 0.1A and 0.002s, circulating for 200 times, heating the composite electrode at the heating rate of 10 ℃/min after deposition, and carrying out heat treatment on the composite electrode at the temperature of 450 ℃ for 4h to obtain the CuO/TNTs composite electrode.

Photoelectrocatalysis reduction of CO₂Performing on CHI660C electrochemical workstation, placing CuO/TNTs composite electrode as working electrode, platinum electrode as counter electrode, and saturated calomel electrode as reference electrode at 0.05 mol/L mol of NaHCO₃Continuously bubbling CO into the solution₂A gas. After 20min, a xenon lamp is turned on to adjust the light energy density of the photoelectrode to 120mw/cm²And simultaneously switching on a power supply to carry out photoelectrocatalysis reduction on CO₂Wherein in the pulse potential mode, the negative pulse is-0.5V and 100s, the positive pulse is 2.0V and 20s, and the running time is 5h in total.

Taking part of the substrate prepared in the step 3), and carrying out SEM detection and XRD detection on the surface of the substrate to obtain an SEM picture as shown in figure 1, wherein a is the front surface and b is the cross section, and the CuO in the prepared composite electrode can be found to be tightly embedded in TiO from the front surface and the cross section₂Inside the nanotubes, which facilitates the photoelectrocatalysis in step 4); FIG. 2 is a comparison between the XRD detection result of this example and TNTs, and it can be seen from the XRD pattern in FIG. 2) that the phase composition obtained by the preparation contains TiO₂And CuO;

for CO in step 4)₂The results of the studies comparing the methanol production by reduction with the methanol production at different forward pulse potentials (all maintained for a forward pulse duration of 20 s) are shown in fig. 3. It can be found that the methanol yield is different for different forward pulse potentials, and the methanol yield is integrally in a trend of increasing and then falling along with the increase of the pulse potential. Subsequently, the yield of methanol produced at different forward pulse durations (each maintaining a forward pulse potential of 2.0V) was further investigated, and the resultsAs shown in fig. 4, it is evident from the graph that the overall methanol production shows a tendency to increase and then fall as the duration of the forward pulse is increased.

Example 2

The procedure was the same as in example 1, except that the chemical polishing process in the special pretreatment was changed, the polishing solution used in this example contained chromium oxide at a concentration of 45 g/L and a hydrogen fluoride solution at a concentration of 45m L of 42 wt%, i.e., a hydrogen fluoride solution at a concentration of 45m L/L of 40 wt%, was added to each liter of the polishing solution, and the chemical polishing time was 20min and the polishing temperature was 60 ℃.

Example 3

The specific procedure was the same as in example 1, except that the potentiostatic anodic oxidation conditions and the annealing conditions were changed. In this example, the anodic oxidation voltage is 35V, the anodic oxidation time is 5min, and the electrolyte is a 5 wt% hydrofluoric acid solution; the annealing temperature is 550 ℃, the heating rate is 5 ℃/min, and the annealing time is 2 h.

Example 4

The procedure was the same as in example 1, except that the conditions for potentiostatic anodization were changed. In this example, the anodization voltage was 15V, the anodization time was 25mi, the anodization temperature was 40 ℃, and the electrolyte was a 1 wt% hydrofluoric acid solution.

Example 5

The procedure was the same as in example 1, except that the composition of the electrolyte was changed, in this example, the electrolyte was 0.1 mol/L aqueous solution of copper chloride.

Example 6

The procedure was the same as in example 5, except that the electrodeposition conditions were changed. In this example, the electrodeposition pulse program was-0.01A, 0.05s, 0.01A, 0.1 s.

Example 7

The procedure was the same as in example 1 except that the electrodeposition conditions were changed. In this example, the electrodeposition pulse program was-0.1A, 0.002s, 0.03A, 0.002 s.

Example 8

Comprises the following stepsThe procedure was as in example 1, except that the xenon lamp power and NaHCO were varied₃Concentration of aqueous solution. In this example, the xenon lamp irradiated energy to the electrode surface was 50mW/cm²；NaHCO₃The concentration of the aqueous solution was 0.2 mol/L.

Example 9

The specific procedure was the same as in example 1, except that the pulse potential was changed, wherein the forward pulse was changed to 1.0V for a duration of 20 s; the negative going pulse becomes-0.2V for a duration of 80 s.

Example 10

The specific procedure was the same as in example 1, except that the pulse potential was changed, wherein the forward pulse was changed to 2.5V for a duration of 20 s; the negative going pulse was-0.7V and the duration was 80 s.

Example 11

The procedure was the same as in example 1, except that the pulse potential was changed, wherein the forward pulse was changed to 2.0V for a duration of 30 s.

Example 12

The procedure was the same as in example 1, except that the pulse potential was changed, wherein the forward pulse was changed to 2.0V for a duration of 10 s.

Example 13

The procedure was the same as in example 1, except that the pulse potential was changed, wherein the forward pulse was changed to 2.0V for a duration of 50 s.

Comparative example 1

The procedure was as in example 1, except that the reduction potential pattern in step 4) was changed. Wherein the reduction mode is constant potential reduction, the potential is constant-0.5V, and the duration is 5 h.

Comparative example 2

The specific procedure was the same as in example 1, except that the electrodeposition pattern in step 3) was changed. In which electrodeposition was carried out in a constant current mode, with a current of-0.01A for 150 s.

Comparative example 3

The specific procedure was the same as in example 1, except that the photocatalytic reduction of CO was carried out by xenon lamp irradiation only₂And (6) processing.

And (3) detection:

and (3) characterization of micro morphology and methanol yield: the same characterization as in example 1 was performed for examples 2 to 17 and comparative examples 1 to 2, and the results of the characterization are shown in Table 1 below in combination with macroscopic observation.

TABLE 1 morphology characterization and methanol yield results

As is apparent from Table 1 above, the method of the present invention is very effective in increasing the ratio of CuO to CO₂The effect of generating formaldehyde by photocatalytic conversion.

Claims (10)

1. Pulse potential mode for improving CuO photoelectrocatalysis CO₂A method for converting an efficiency, characterized in that,

the method comprises the following steps:

1) anodic oxidation: taking the pretreated titanium sheet as an anode, carrying out constant potential anodic oxidation on the titanium sheet to obtain a pre-matrix, and annealing the pre-matrix to obtain a matrix;

2) electro-deposition: dipping the substrate in copper-containing electrolyte, electrodepositing copper on the surface of the substrate in a pulse electrodeposition mode, and performing heat treatment to obtain a CuO/TNTs composite electrode;

3) and (3) pulse potential mode reduction: the obtained CuO/TNTs composite electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and the counter electrode is immersed in electrolyte and continuously introduced with CO₂The xenon lamp is used as a light source, and CO is reduced in a pulse potential mode by setting different potentials₂。

2. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 1₂A method for converting an efficiency, characterized in that,

step 1) the pretreatment comprises chemical polishing;

the polishing solution adopted by the chemical polishing comprises 45-90 g/L of chromium oxide, 45-90 m L/L of 38-42 wt% of hydrogen fluoride solution and the balance of water;

the chemical polishing time is 10-20 min, and the polishing temperature is 50-60 ℃.

3. A pulsed potential mode enhanced CuO photoelectrocatalytic CO according to claim 1 or 2₂A method for converting an efficiency, characterized in that,

step 1) during the anodic oxidation: taking a graphite electrode or a platinum electrode as a cathode, and taking 1-5 wt% of hydrofluoric acid solution as electrolyte;

the anodic oxidation temperature is 25-40 ℃, the anodic oxidation voltage is 15-35V, and the anodic oxidation time is 5-25 min.

4. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 1₂A method for converting an efficiency, characterized in that,

the purity of the titanium sheet is more than or equal to 99.0 percent.

5. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 1₂A method for converting an efficiency, characterized in that,

the annealing temperature in the step 1) is 450-550 ℃, the heating rate is 5-10 ℃/min, and the temperature is kept for 2-4 h after the annealing temperature is reached.

6. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 1₂A method for converting an efficiency, characterized in that,

step 2), the copper-containing electrolyte is a soluble copper salt aqueous solution containing 0.1-1.0 mol/L bivalent copper ions;

step 2) in the pulse electrodeposition: negative pulse is-0.01 to-0.1A, duration is 0.002 to 0.1s, positive pulse is 0.01 to 0.1A, and duration is 0.002 to 0.1 s.

7. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 6₂A method for converting an efficiency, characterized in that,

the soluble copper salt is any one or more of copper sulfate, copper chloride and copper nitrate.

8. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 1₂A method for converting an efficiency, characterized in that,

step 3) the reduction of CO in the pulse potential mode₂The medium-negative pulse is-0.2 to-0.7V, the duration is 80 to 100s, the positive pulse is 1.0 to 2.5V, and the duration is 10 to 50 s.

9. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 1 or 8₂A method for converting an efficiency, characterized in that,

step 3) the electrolyte is NaHCO₃An aqueous solution having a concentration of 0.05 to 0.2 mol/L;

step 3) irradiating the xenon lamp onto the electrode to generate energy density of 50-120 mw/cm²。

10. The pulsed potential mode enhanced CuO photoelectrocatalytic CO of claim 1₂A method for converting an efficiency, characterized in that,

step 3) reduction of CO in a pulse potential mode₂A saturated calomel electrode is also arranged as a reference electrode.

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