Method for preparing silver nano-catalyst by recovering retired crystalline silicon battery

Abstract

The invention discloses a method for preparing a silver nano-catalyst by recycling a decommissioned crystalline silicon solar cell. According to the method, silver organic acid salt obtained by treating the decommissioned crystalline silicon solar cell is adopted as one of raw materials. The preparation method of the silver nanoparticle catalyst comprises the following steps: dissolving the obtained silver organic salt in an organic solvent, adding carbon powder, and carrying out ultrasonic dispersion, drying and grinding to prepare catalyst precursor powder; and wrapping the precursor powder with carbon cloth, carrying out rapid thermal shock treatment in an argon atmosphere, and carrying out a heating-quenching reaction to obtain the silver nanoparticle catalyst. The prepared silver nanoparticle catalyst can be used for catalytic reduction of carbon dioxide. According to the method, the preparation process is simplified, and the catalyst which is larger in electrochemical reaction active area, better in stability and excellent in catalytic performance can be obtained. The catalyst can be used for catalytic reduction of carbon dioxide and has important environmental protection significance. And in addition, the silver salt is leached by using organic acid, so that generation of harmful gas in the leaching process of inorganic acid is avoided.

Description

Technical Field

[0001] The present invention relates to the fields of resource recycling and electrocatalysis, and particularly to the recovery of valuable components in crystalline silicon cells and the method for carbon dioxide reduction catalysts. Background Art

[0002] Electrochemical conversion is an effective way to construct a "zero-carbon network" cycle of chemical energy. Among them, silver (Ag) is considered to be a good noble metal catalyst due to its rich reserves and high selectivity. Researchers have found that using nano-silver and its alloy catalysts can reduce carbon dioxide to CO, and its performance is superior to other metal or non-metal catalysts. Although Ag has a high CO selectivity, its reduction overpotential is usually also high. Therefore, it is necessary to modify the silver crystal plane size, morphology and surface to regulate its overpotential, thereby improving the performance of silver nano-catalysts. At present, the main methods for preparing nano-silver include dealloying method, electrochemical method and redox method, etc. Most of these methods are relatively complex, costly and not green enough. Therefore, it is particularly important to explore a simpler and more efficient method for preparing nano-silver alloy catalysts.

[0003] The thermal shock method is considered to be a relatively low-cost and convenient method for preparing nano-silver alloy materials (CN118028871A). The two main raw materials of its precursor solution are silver salt aqueous solution and carbon powder. Among them, the silver salt aqueous solution is prepared by adding a specific sodium salt to silver nitrate prepared from silver and nitric acid, which is costly and has a complex process. Researchers have found that based on the silver leaching solution of retired photovoltaic cell slices, a short-process method can be designed to prepare nano-silver alloy catalysts, which can not only solve the problem of recycling retired photovoltaic modules, but also further reduce the preparation cost of catalysts, which has great practical significance.

[0004] The existing wet recycling methods for retired photovoltaic cells are mainly nitric acid leaching or mixed acid leaching based on nitric acid. Although these methods can obtain a high leaching rate, they will produce a large amount of nitrogen oxides, causing serious environmental pollution. Moreover, nitric acid has strong acidity and is easy to leach other heavy metal elements in the battery slices, resulting in a decrease in the purity of silver salts in the leaching solution, which cannot meet the preparation requirements of nano-silver alloy catalysts. Therefore, it is of great significance to explore a highly selective leaching method to obtain a high-purity silver leaching solution for preparing nano-silver alloy catalysts for efficient silver recovery and low-cost electrocatalysis. Summary of the Invention

[0005] The purpose of the present invention is to propose a method for recycling waste crystalline silicon cells to produce silver catalysts containing silver nanoparticles, and to obtain a simple and efficient carbon dioxide conversion catalyst.

[0006] The present invention includes the following steps:

[0007] A: Take a certain amount of retired crystalline silicon solar cell powder, add an organic weak acid and an oxidant to leach the crystalline silicon solar cell powder, dissolve the silver element to obtain an aqueous solution of silver organic acid salt, and obtain silver organic acid salt crystal powder after vacuum drying;

[0008] B: Calcinate carbon black at high temperature in an argon atmosphere to obtain carbon powder, wherein the carbon black is one or both of GS carbon and VGCF carbon;

[0009] C: Dissolve the silver organic acid salt crystal powder obtained in step A in an organic solvent, add a certain amount of the carbon powder in step B, perform ultrasonic dispersion, vacuum drying, and grinding on it to obtain a precursor powder;

[0010] D: Take a certain amount of the precursor powder obtained in step C and evenly sprinkle it on carbon cloth, pass a direct current in an argon atmosphere, perform a thermal shock treatment on the precursor powder, and undergo a heating-quenching reaction to obtain a silver nanoparticle-containing catalyst. The silver nanoparticle-containing catalyst uses GS carbon or VGCF carbon as a carrier, and the silver content is 20 wt%-90 wt%.

[0011] Preferably, in step A, the organic weak acid is one or both aqueous solutions of oxalic acid and citric acid monohydrate, and the oxidant is one or more of hydrogen peroxide, sodium sulfite, and sodium peroxide.

[0012] Preferably, in step A, the drying temperature is 50-300 °C.

[0013] Preferably, in step B, the calcination temperature is 500-1500 °C.

[0014] Preferably, in step C, the silver organic acid salt crystal powder is one or both of silver oxalate and silver citrate monohydrate.

[0015] Preferably, in step C, the organic solvent is one or more of methanol, ethanol, isopropanol, DMF, DMSO, and NMP.

[0016] Preferably, in step C, the drying temperature of the mixed solution is 100-500 °C.

[0017] Preferably, in step D, the voltage of the direct current power supply is 10-50 V, and the current is 10-50 A.

[0018] Preferably, in step D, the silver nanoparticle-containing catalyst is used for catalytic reduction of carbon dioxide.

[0019] The technical principle adopted in the present invention is as follows:

[0020] 1. Wet leaching: Use an organic mixed acid to selectively leach silver in crystalline silicon solar cells. Silver is first oxidized by an oxidant and then reacts with an organic weak acid. This method can effectively reduce the entry of elements such as lead, aluminum, selenium, and silicon in crystalline silicon solar cell wafers into the leaching solution; at the same time, using an organic mixed acid as the leaching agent can avoid the generation of nitrogen-containing waste gas caused by using nitric acid; vacuum dry the aqueous solution of silver organic salt. As water evaporates, the salt gradually becomes supersaturated and crystallizes in the aqueous solution.

[0021] 2. Preparation of precursor powder: Ultrasonically disperse silver organic salt and carbon powder in an organic solvent. The silver organic salt is soluble in the organic solvent, and the carbon powder can be evenly dispersed; after vacuum drying the dispersion liquid, the salt precipitates supersaturated in the aqueous solution, which can increase the uniformity of mixing with the carbon powder. After grinding, a homogeneous precursor powder can be obtained.

[0022] 3. Preparation of silver nanoparticle catalyst: Evenly sprinkle a certain amount of precursor powder (a mixture of silver organic salt and carbon powder) on carbon cloth. The high specific surface area of the carbon powder material can provide more active sites for silver nanoparticles; under an argon atmosphere, pass a direct current to perform a thermal shock treatment on the precursor powder, which can convert the silver organic salt into silver nanoparticles; by adjusting the ratio of silver salt / carbon powder, current, and voltage values, silver nanoparticle catalysts with different catalytic effects can be obtained.

[0023] Compared with the existing silver nanoparticle catalyst preparation technology, the present invention has the following beneficial effects: The raw materials are rich and easy to obtain, the preparation process is simplified, the economic and environmental effects are high, organic acids are used to leach silver salts, the recovery system is green, and at the same time, a thermal shock method is used to prepare silver nanoparticle catalysts, which significantly improves the electrocatalytic reduction performance of silver catalysts for carbon dioxide, and constructs a green, complete, and efficient preparation system. Brief Description of the Drawings

[0024] The following further describes the present invention in detail with reference to the drawings and specific embodiments, but does not constitute any limitation to the present invention.

[0025] Figure 1 is the process flow chart of preparing silver nano-catalyst of the present invention;

[0026] Figure 2 is the TEM image of the silver nanoparticle catalyst prepared in Example 1. Detailed Embodiments

[0027] Example 1: Preparation of VGCF-C6H5Ag3O7-HT-65 silver nanoparticle catalyst

[0028] 1. Take a certain amount of retired crystalline silicon cell wafers and put them into a beaker, add C6H 10 O8 and H2O2, C6H 10The concentration of O8 is 1.5 mol / L, the dosage of 30% H2O2 is controlled at 375 ml / L, and the solid-liquid ratio is 20:1. The reaction time is controlled at 2 h and the reaction temperature is 50 °C. Stir continuously during the leaching process to obtain the leaching solution. Filter the leaching solution and place it in a vacuum oven at 100 °C to dry until uniformly dried silver citrate monohydrate crystals are formed.

[0029] 2. Take a certain amount of VGCF carbon black, introduce argon into a tubular furnace, calcine at 800 °C for two hours, and then naturally cool to room temperature and take it out.

[0030] 3. Dissolve a certain amount of silver citrate monohydrate in 10 ml of methanol, add a certain amount of carbon powder, control the silver salt content at 65 wt%, ultrasonically disperse for 3 hours, pour the mixture into a petri dish, and place it in a vacuum oven at 333 K until completely dry to obtain the precursor powder, and grind it thoroughly.

[0031] 4. Cut the carbon cloth into 2.0×2.0 cm 2 Ultrasonically wash it in ethanol and deionized water for 15 minutes respectively, and after washing, put it in an oven to dry. Uniformly wrap the precursor powder (6 mg each time) with the substrate carbon cloth to prevent splashing. Place the carbon cloth wrapped with the precursor powder in a glove box with an argon atmosphere, clamp a conductive clip at each end of the carbon cloth and connect them to the two electrodes of a DC power supply correspondingly. Apply a voltage of 25 V and a current of 20 A to conduct rapid thermal shock. During this process, the material undergoes an extremely fast heating-quenching process and emits a dazzling flash. Finally, a silver nanoparticle-containing catalyst is obtained.

[0032] Example 2: Preparation of GS-Ag2C2O4-HT-85 silver nanoparticle-containing catalyst

[0033] 1. Take a certain amount of retired crystalline silicon solar cell wafers and put them into a beaker, add H2C2O4 and H2O2, the concentration of H2C2O4 is 2 mol / L, the dosage of 30% H2O2 is controlled at 450 ml / L, and the solid-liquid ratio is 30:1. Control the reaction time at 2 h and the reaction temperature at 50 °C. Stir continuously during the leaching process to obtain the leaching solution. Filter the leaching solution and place it in a vacuum oven at 100 °C to dry until uniformly dried silver oxalate crystals are formed.

[0034] 2. Take a certain amount of GS carbon black, introduce argon into a tubular furnace, calcine at 800 °C for two hours, and then naturally cool to room temperature and take it out.

[0035] 3. Dissolve a certain amount of silver oxalate in 10 ml of methanol, add a certain amount of carbon powder, control the silver salt content at 85 wt%, ultrasonically disperse for 3 hours, pour the mixture into a petri dish, and place it in a vacuum oven at 333 K until completely dry to obtain the precursor powder, and grind it thoroughly.

[0036] 4. Cut the carbon cloth into 2.0×2.0 cm 2 Ultrasonically wash it in ethanol and deionized water for 15 minutes respectively. After washing, put it into an oven for drying. Wrap the precursor powder (8 mg each time) evenly with the substrate carbon cloth to prevent splashing. Put the carbon cloth wrapped with the precursor powder into a glove box with an argon atmosphere, clamp a conductive clip at each end of the carbon cloth and connect them to the two electrodes of a DC power supply correspondingly. Apply a voltage of 22 V and a current of 18 A to conduct rapid thermal shock. During this process, the material undergoes an extremely rapid heating-quenching process and emits a dazzling flash. Finally, a silver nanoparticle-containing catalyst is obtained.

Claims

1. A method for recycling and preparing a silver nanocatalyst from retired crystalline silicon solar cells, characterized in that, It includes the following steps: A: Take a certain amount of retired crystalline silicon solar cell powder, add an organic weak acid and an oxidant to leach the crystalline silicon solar cell powder, dissolve the silver element to obtain an aqueous solution of silver organic acid salt, and obtain silver organic acid salt crystal powder after vacuum drying; B: Calcinate carbon black at high temperature in an argon atmosphere to obtain carbon powder, wherein the carbon black is one or both of GS carbon and VGCF carbon; C: Dissolve the silver organic acid salt crystal powder obtained in step A in an organic solvent, add a certain amount of the carbon powder in step B, perform ultrasonic dispersion, vacuum drying, and grinding on it to obtain a precursor powder; D: Take a certain amount of the precursor powder obtained in step C and evenly sprinkle it on a carbon cloth, pass a direct current in an argon atmosphere, perform a thermal shock treatment on the precursor powder, and undergo a heating-quenching reaction to obtain a silver nanoparticle catalyst. The silver nanoparticle catalyst uses GS carbon or VGCF carbon as a carrier, and the silver content is 20wt%-90wt%.

2. The method according to claim 1, wherein In step A, the organic weak acid is one or both aqueous solutions of oxalic acid and citric acid monohydrate, and the oxidant is one or more of hydrogen peroxide, sodium sulfite, and sodium peroxide.

3. The method according to claim 1, wherein In step A, the drying temperature is 50-300°C.

4. The method according to claim 1, wherein In step B, the calcination temperature is 500-1500°C.

5. The method according to claim 1, wherein In step C, the silver organic acid salt crystal powder is one or both of silver oxalate and silver citrate monohydrate.

6. The method according to claim 1, characterized in that, In step C, the organic solvent is one or more of methanol, ethanol, isopropanol, DMF, DMSO, and NMP.

7. The method according to claim 1, wherein In step C, the drying temperature of the mixed solution is 100-500°C.

8. The method according to claim 1, wherein In step D, the voltage of the direct current power supply is 10-50V, and the current is 10-50A.

9. The method according to claim 1, wherein In step D, the silver nanoparticle catalyst is used for catalytic reduction of carbon dioxide.

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