Method for preparing iron-based electrochemical catalyst by using waste metal filings and electrochemical catalyst

Abstract

The invention discloses a method for preparing an iron-based electrochemical catalyst by using waste metal filings and an electrochemical catalyst, and the specific process is as follows: the waste metal filings are subjected to acid leaching to obtain a leachate; adsorbing metal ions in the leachate by using resin to obtain saturated resin; desorbing the saturated resin by using nitric acid to obtain an impurity-free solution; adding an excessive reducing agent into the impurity-free solution for reduction to obtain a solid-liquid mixture; carrying out centrifugal separation on the solid-liquid mixture to obtain a precipitate, and cleaning and drying the precipitate to obtain iron-based catalyst powder; electroplating the pretreated foamed nickel in an impurity-free solution to obtain a catalyst substrate; coating a catalyst substrate with the iron-based catalyst powder, and performing vacuum drying to obtain the iron-based electrochemical catalyst. According to the preparation method disclosed by the invention, the waste metal filings are used as raw materials, so that the preparation cost is greatly reduced, meanwhile, the waste metal filings are recycled, and the prepared electrocatalyst shows an excellent catalytic effect in an oxygen evolution reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of electrocatalysts, and in particular relates to a method for preparing an iron-based electrochemical catalyst by utilizing waste metal chips, and also relates to an electrochemical catalyst. Background Art

[0002] As fossil fuels become depleted and the energy crisis becomes increasingly severe, people are placing greater emphasis on the development of renewable energy. Since the early 1970s, hydrogen has been considered an ideal energy source. Hydrogen has the highest energy density among known fuels and is a clean energy source with zero carbon dioxide emissions. Water electrolysis can also produce oxygen, which is essential for human survival. However, the oxygen evolution half-reaction (OER) in water electrolysis involves the transfer of four electrons and is a kinetically slow reaction. Its overpotential is much higher than that of the hydrogen evolution reaction, which is the main factor limiting the efficiency of water splitting. Therefore, the development of an efficient and readily available oxygen evolution catalyst is of great significance to the development of water electrolysis. However, the preparation cost of currently available oxygen evolution catalysts is relatively high.

[0003] It is well known that the transition metals iron, nickel, and cobalt are all excellent candidates for oxygen evolution catalysts. Scrap metal chips are a common industrial waste material, ubiquitous in factories. If these scrap metal chips are prepared into catalysts and applied to water electrolysis, the cost of electrolysis can be significantly reduced. Therefore, developing and improving methods for efficiently extracting and preparing iron-based electrochemical catalysts from scrap metal chips is of great significance for both scrap metal recycling, environmental protection, and water electrolysis research. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing an iron-based electrochemical catalyst using scrap metal chips. The scrap metal chips are used as raw materials, which greatly reduces the preparation cost and recycles the scrap metal chips.

[0005] Another object of the present invention is to provide an electrochemical catalyst obtained by the above preparation method.

[0006] The technical solution adopted by the present invention is a method for preparing an iron-based electrochemical catalyst using scrap metal chips, which is specifically implemented according to the following steps: Step 1, acid leaching the scrap metal to obtain a leachate and waste residue; Step 2, using resin to adsorb metal ions in the leachate to obtain saturated resin and waste liquid; Step 3, desorbing the saturated resin with nitric acid to obtain a pure solution; Step 4, adding an excess reducing agent to the pure solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture to obtain a precipitate, and washing the precipitate; Step 6, drying the cleaned precipitate to obtain iron-based catalyst powder; Step 7, pre-treating the nickel foam, and electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 to obtain a catalyst substrate; Step 8: coating the iron-based catalyst powder onto the catalyst substrate and vacuum drying the catalyst to obtain an iron-based electrochemical catalyst. The present invention is also characterized in that: In step 1, the acid used for acid leaching is one of nitric acid, hydrochloric acid and sulfuric acid; and the scrap metal chips are iron-containing scrap metal chips or iron-nickel-containing scrap metal chips.

[0007] In step 2, the resin volume filling amount is 80%~90%.

[0008] In step 4, the reducing agent is potassium hydroxide solution or sodium borohydride solution; The concentration of the potassium hydroxide solution is 1 mol / L to 6 mol / L, and the concentration of the sodium borohydride solution is 1.78 mol / L.

[0009] In step 6, the drying temperature is 65° C. to 75° C., and the drying time is 10 h to 14 h.

[0010] In step 7, the pretreatment process is: ultrasonically treat the nickel foam in a 20% mass concentration hydrochloric acid solution, anhydrous ethanol, and deionized water, respectively, and then take it out and dry it for later use.

[0011] In step 7, the electroplating time is 5 minutes to 10 minutes.

[0012] In step 8, the specific process of coating is: mixing the iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black evenly and then coating them on the catalyst substrate; wherein the mass ratio of the iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

[0013] Another technical solution adopted by the present invention is that the electrochemical catalyst is obtained by adopting the above preparation method.

[0014] The beneficial effects of the present invention are: (1) The present invention uses waste metal scraps to prepare iron-based electrochemical catalysts. The raw materials are waste metal scraps containing iron and nickel from factories. These scraps are widely available and inexpensive, greatly reducing the production cost of the catalyst. At the same time, the waste metal scraps containing iron and nickel from factories are recycled, effectively reducing the environmental pollution caused by metal waste. (2) The iron-based electrochemical catalyst prepared by the method of the present invention exhibits excellent catalytic effect in the oxygen evolution reaction, can significantly reduce the oxygen evolution overpotential, and improve the efficiency of water electrolysis. It has broad application prospects in the field of new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of the method of the present invention; Figure 2 1 is a comparison diagram of the LSV curves of the iron-based electrochemical catalysts obtained in Example 1 and Example 2 of the method of the present invention; Figure 3 is the XRD pattern of the iron-based electrochemical catalyst obtained in Example 1 of the method of the present invention; Figure 4 This is a scanning image of the iron-based electrochemical catalyst obtained in Example 2 of the method of the present invention; Figure 5 3 is a comparison diagram of the LSV curves of the iron-based electrochemical catalysts obtained in Example 3 and Example 4 of the method of the present invention; Figure 6 This is a scanning image of the iron-based electrochemical catalyst obtained in Example 3 of the method of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] The present invention uses waste metal chips to prepare an iron-based electrochemical catalyst. Figure 1 As shown, please follow the steps below: Step 1, acid leaching the scrap metal to obtain a leachate and waste residue; The acid used for acid leaching is one of nitric acid, hydrochloric acid and sulfuric acid; the scrap metal chips are iron-containing scrap metal chips or iron-nickel-containing scrap metal chips; Step 2, using resin to adsorb metal ions in the leachate to obtain saturated resin and waste liquid; Among them, the resin volume filling amount is 80%~90%; Step 3, desorbing the saturated resin with concentrated nitric acid to obtain a pure solution; Step 4, adding an excess reducing agent to the pure solution for reduction to obtain a solid-liquid mixture; The reducing agent is potassium hydroxide solution or sodium borohydride solution; the concentration of potassium hydroxide solution is 1 mol / L to 6 mol / L, and the concentration of sodium borohydride solution is 1.78 mol / L; Step 5, centrifuging the solid-liquid mixture at a speed of 5000 r / min to obtain a precipitate, and washing the precipitate with distilled water and anhydrous ethanol 2 to 3 times each, wherein the mass concentration of anhydrous ethanol is 75%; Step 6: drying the cleaned precipitate in an oven at 65°C to 75°C for 10 hours to 14 hours to obtain an iron-based catalyst powder; Step 7, pre-treating the nickel foam, electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 at a current of 90 mA for 5 minutes to 10 minutes to obtain a catalyst substrate; The pretreatment process is as follows: the nickel foam is ultrasonically treated in a 20% hydrochloric acid solution, anhydrous ethanol, and deionized water for 0.5 h, and then taken out and dried in an oven at 65°C to 75°C for 10 h to 14 h for later use; Step 8, the iron-based catalyst powder, organic binder polytetrafluoroethylene, carbon black are evenly mixed and coated on the catalyst substrate, and vacuum dried at 65 ℃ ~ 75 ℃ to obtain an iron-based electrochemical catalyst; Among them, the mass ratio of iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

[0018] Example 1 Step 1: 3 g of iron-containing scrap metal chips are added to 40 ml of 3 mol / L dilute nitric acid and soaked for 1 hour to obtain an iron-nickel leachate and waste residue; Step 2, using resin to adsorb metal ions in the iron-nickel leachate to obtain saturated resin and waste liquid; Among them, the resin volume filling amount is 80%~90%; Step 3, desorbing the saturated resin with concentrated nitric acid to obtain an iron-containing impurity-free solution; Step 4, adding an excess of 1 mol / L potassium hydroxide solution to the iron-containing impurity-free solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture at a speed of 5000 r / min to obtain a precipitate, and washing the precipitate twice with distilled water and anhydrous ethanol, wherein the mass concentration of the anhydrous ethanol is 75%; Step 6: drying the cleaned precipitate in an oven at 70° C. for 12 h to obtain an iron-based catalyst powder; Step 7, pre-treating the nickel foam, electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 at a current of 90 mA for 5 minutes to obtain a catalyst substrate; The pretreatment process is as follows: the nickel foam is ultrasonically treated in a 20% hydrochloric acid solution, anhydrous ethanol, and deionized water for 0.5 h, and then taken out and dried in an oven at 70°C for 12 h for later use; Step 8, the iron-based catalyst powder, organic binder polytetrafluoroethylene, carbon black were evenly mixed and coated on the catalyst substrate, and vacuum dried at 70 ° C for 12h to obtain an iron-based electrochemical catalyst; Among them, the mass ratio of iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

[0019] like Figure 2 As shown, at a current density of 10 mA / cm 2 When , the oxygen evolution overpotential of the iron-based electrochemical catalyst obtained in this embodiment is 279mV; Figure 3 As shown, the iron-based electrochemical catalyst obtained in this example has no characteristic peaks and is an amorphous Fe(OH)3 material.

[0020] Example 2 Step 1: 5 g of iron-containing scrap metal chips and 0.1 g of nickel-containing scrap metal chips are added to 40 ml of 3 mol / L dilute nitric acid and soaked for 4 hours to obtain an iron-containing leachate and waste residue; Step 2, using resin to adsorb metal ions in the iron-containing leachate to obtain saturated resin and waste liquid; Among them, the resin volume filling amount is 80%~90%; Step 3, desorbing the saturated resin with concentrated nitric acid to obtain an iron-containing impurity-free solution; Step 4, adding an excess of 6 mol / L potassium hydroxide solution to the iron-containing impurity-free solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture at a speed of 5000 r / min to obtain a precipitate, and washing the precipitate with distilled water and anhydrous ethanol three times each, wherein the mass concentration of anhydrous ethanol is 75%; Step 6: drying the cleaned precipitate in an oven at 70° C. for 12 h to obtain an iron-based catalyst powder; Step 7, pre-treating the nickel foam, electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 at a current of 90 mA for 5 minutes to obtain a catalyst substrate; The pretreatment process is as follows: the nickel foam is ultrasonically treated in a 20% hydrochloric acid solution, anhydrous ethanol, and deionized water for 0.5 h, and then taken out and dried in an oven at 70°C for 12 h for later use; Step 8: uniformly mix the iron-based catalyst powder, the organic binder polytetrafluoroethylene, and the carbon black, and then coat the mixture on the catalyst substrate, and vacuum dry the mixture at 70° C. for 12 hours to obtain an iron-based electrochemical catalyst; Among them, the mass ratio of iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

[0021] like Figure 2 As shown, at a current density of 10 mA / cm 2 When , the oxygen evolution overpotential of the iron-based electrochemical catalyst obtained in this embodiment is 242mV; Figure 4 As shown, the iron-based electrochemical catalyst obtained in this example has no characteristic peaks and is an amorphous FeNiB material.

[0022] Example 3 Step 1: 6 g of iron-containing scrap metal chips were added to 20 ml of concentrated hydrochloric acid and soaked for 1 hour to obtain an iron-containing leachate and waste residue; Step 2, using resin to adsorb metal ions in the iron-containing leachate to obtain saturated resin and waste liquid; Among them, the resin volume filling amount is 80%~90%; Step 3, desorbing the saturated resin with concentrated nitric acid to obtain an iron-containing impurity-free solution; Step 4: adding an excess of 1.78 mol / L sodium borohydride solution to the iron-containing impurity-free solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture at a speed of 5000 r / min to obtain a precipitate, and washing the precipitate with distilled water and anhydrous ethanol three times each, wherein the mass concentration of anhydrous ethanol is 75%; Step 6: drying the cleaned precipitate in an oven at 70° C. for 12 h to obtain an iron-based catalyst powder; Step 7, pre-treating the nickel foam, electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 at a current of 90 mA for 5 minutes to obtain a catalyst substrate; The pretreatment process is as follows: the nickel foam is ultrasonically treated in a 20% hydrochloric acid solution, anhydrous ethanol, and deionized water for 0.5 h, and then taken out and dried in an oven at 70°C for 12 h for later use; Step 8: uniformly mix the iron-based catalyst powder, the organic binder polytetrafluoroethylene, and the carbon black, and then coat the mixture on the catalyst substrate, and vacuum dry the mixture at 70° C. for 12 hours to obtain an iron-based electrochemical catalyst; Among them, the mass ratio of iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

[0023] like Figure 5 As shown, at a current density of 10 mA / cm 2 When , the oxygen evolution overpotential of the iron-based electrochemical catalyst obtained in this embodiment is 207mV; Figure 6 As shown, the iron-based electrochemical catalyst obtained in this embodiment is a rod-shaped FeB material.

[0024] Example 4 Step 1: 8 g of iron-containing scrap metal chips and 0.5 g of nickel-containing scrap metal chips are added to 30 ml of concentrated hydrochloric acid and soaked for 2 hours to obtain an iron-containing leachate and waste residue; Step 2, using resin to adsorb metal ions in the iron-containing leachate to obtain saturated resin and waste liquid; Among them, the resin volume filling amount is 80%~90%; Step 3, desorbing the saturated resin with concentrated nitric acid to obtain an iron-containing impurity-free solution; Step 4, adding an excess of 1.78 mol / L sodium borohydride solution to the iron-containing impurity-free solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture at a speed of 5000 r / min to obtain a precipitate, and washing the precipitate with distilled water and anhydrous ethanol three times each, wherein the mass concentration of anhydrous ethanol is 75%; Step 6: drying the cleaned precipitate in an oven at 70° C. for 12 h to obtain an iron-based catalyst powder; Step 7, pre-treating the nickel foam, electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 at a current of 90 mA for 5 minutes to obtain a catalyst substrate; The pretreatment process is as follows: the nickel foam is ultrasonically treated in a 20% hydrochloric acid solution, anhydrous ethanol, and deionized water for 0.5 h, and then taken out and dried in an oven at 70°C for 12 h for later use; Step 8: uniformly mix the iron-based catalyst powder, the organic binder polytetrafluoroethylene, and the carbon black, and then coat the mixture on the catalyst substrate, and vacuum dry the mixture at 70° C. for 12 hours to obtain an iron-based electrochemical catalyst; Among them, the mass ratio of iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

[0025] like Figure 5 As shown, at a current density of 10 mA / cm 2 When , the oxygen evolution overpotential of the iron-based electrochemical catalyst obtained in this embodiment is 206 mV.

[0026] Depend on Figure 2 and Figure 4 It can be seen that the oxygen evolution effect of FeNiB is better than that of amorphous Fe(OH)3, and the oxygen evolution effect of FeB is better than that of amorphous Fe(OH)3.

[0027] Example 5 Step 1: 8 g of iron-containing scrap metal chips and 0.5 g of nickel-containing scrap metal chips are added to 30 ml of concentrated hydrochloric acid and soaked for 2 hours to obtain an iron-containing leachate and waste residue; Step 2, using resin to adsorb metal ions in the iron-containing leachate to obtain saturated resin and waste liquid; Among them, the resin volume filling amount is 80%~90%; Step 3, desorbing the saturated resin with concentrated nitric acid to obtain an iron-containing impurity-free solution; Step 4, adding an excess of 4 mol / L potassium hydroxide solution to the iron-containing impurity-free solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture at a speed of 5000 r / min to obtain a precipitate, and washing the precipitate with distilled water and anhydrous ethanol three times each, wherein the mass concentration of anhydrous ethanol is 75%; Step 6: drying the cleaned precipitate in an oven at 65° C. for 14 h to obtain an iron-based catalyst powder; Step 7, pre-treating the nickel foam, electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 at a current of 90 mA for 10 minutes to obtain a catalyst substrate; The pretreatment process is as follows: the nickel foam is ultrasonically treated in a 20% hydrochloric acid solution, anhydrous ethanol, and deionized water for 0.5 h, and then taken out and dried in an oven at 65°C for 14 h for later use; Step 8: uniformly mixing the iron-based catalyst powder, the organic binder polytetrafluoroethylene, and the carbon black, and coating the mixture on the catalyst substrate, and vacuum drying the mixture at 65° C. for 14 h to obtain an iron-based electrochemical catalyst; Among them, the mass ratio of iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

[0028] Example 6 Step 1: 6 g of iron-containing scrap metal chips were added to 20 ml of concentrated hydrochloric acid and soaked for 1 hour to obtain an iron-containing leachate and waste residue; Step 2, using resin to adsorb metal ions in the iron-containing leachate to obtain saturated resin and waste liquid; Among them, the resin volume filling amount is 80%~90%; Step 3, desorbing the saturated resin with concentrated nitric acid to obtain an iron-containing impurity-free solution; Step 4: adding an excess of 1.78 mol / L sodium borohydride solution to the iron-containing impurity-free solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture at a speed of 5000 r / min to obtain a precipitate, and washing the precipitate with distilled water and anhydrous ethanol three times each, wherein the mass concentration of anhydrous ethanol is 75%; Step 6: drying the cleaned precipitate in an oven at 75° C. for 10 h to obtain an iron-based catalyst powder; Step 7, pre-treating the nickel foam, electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 at a current of 90 mA for 7 minutes to obtain a catalyst substrate; The pretreatment process is as follows: the nickel foam is ultrasonically treated in a 20% hydrochloric acid solution, anhydrous ethanol, and deionized water for 0.5 h, and then taken out and dried in an oven at 75°C for 10 h for later use; Step 8: uniformly mixing the iron-based catalyst powder, the organic binder polytetrafluoroethylene, and the carbon black, coating the mixture on the catalyst substrate, and vacuum drying the mixture at 75° C. for 10 h to obtain an iron-based electrochemical catalyst; Among them, the mass ratio of iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:1.

Claims

1. A method for preparing an iron-based electrochemical catalyst using scrap metal, characterized in that: Please follow the steps below to implement: Step 1, acid leaching the scrap metal to obtain a leachate and waste residue; Step 2, using resin to adsorb metal ions in the leachate to obtain saturated resin and waste liquid; Step 3, desorbing the saturated resin with nitric acid to obtain a pure solution; Step 4, adding an excess reducing agent to the pure solution for reduction to obtain a solid-liquid mixture; Step 5, centrifuging the solid-liquid mixture to obtain a precipitate, and washing the precipitate; Step 6, drying the cleaned precipitate to obtain iron-based catalyst powder; Step 7, pre-treating the nickel foam, and electroplating the pre-treated nickel foam in the impurity-free solution obtained in step 3 to obtain a catalyst substrate; Step 8: coating the iron-based catalyst powder onto the catalyst substrate and vacuum drying the catalyst to obtain an iron-based electrochemical catalyst.

2. The method for preparing an iron-based electrochemical catalyst using scrap metal according to claim 1, wherein: In step 1, the acid used for acid leaching is one of nitric acid, hydrochloric acid and sulfuric acid; and the scrap metal chips are iron-containing scrap metal chips or iron-nickel-containing scrap metal chips.

3. The method for preparing an iron-based electrochemical catalyst using scrap metal according to claim 1, wherein: In step 2, the resin volume filling amount is 80%~90%.

4. The method for preparing an iron-based electrochemical catalyst using scrap metal according to claim 1, wherein: In step 4, the reducing agent is potassium hydroxide solution or sodium borohydride solution; The concentration of the potassium hydroxide solution is 1 mol / L to 6 mol / L, and the concentration of the sodium borohydride solution is 1.78 mol / L.

5. The method for preparing an iron-based electrochemical catalyst using scrap metal according to claim 1, wherein: In step 6, the drying temperature is 65° C. to 75° C., and the drying time is 10 h to 14 h.

6. The method for preparing an iron-based electrochemical catalyst using scrap metal according to claim 1, wherein: In step 7, the pretreatment process is: ultrasonically treat the nickel foam in a 20% mass concentration hydrochloric acid solution, anhydrous ethanol, and deionized water, respectively, and then take it out and dry it for later use.

7. The method for preparing an iron-based electrochemical catalyst using scrap metal according to claim 1, wherein: In step 7, the electroplating time is 5 minutes to 10 minutes.

8. The method for preparing an iron-based electrochemical catalyst using scrap metal according to claim 1, wherein: In step 8, the specific process of coating is: mixing the iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black evenly and then coating them on the catalyst substrate; wherein the mass ratio of the iron-based catalyst powder, organic binder polytetrafluoroethylene, and carbon black is 7:2:

1.

9. An iron-based electrochemical catalyst, characterized in that The method according to any one of claims 1 to 8 is used to prepare the compound.

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