A method for the photocatalytic preparation of platinum black from WO3

Abstract

A method for preparing platinum black by WO3 photocatalysis, comprising the following steps: (1) configuring a chloroplatinic acid solution with a certain concentration, adding a certain amount of ethanol into the solution, and adjusting the pH value of the solution to 1.0 by using 3 M dilute hydrochloric acid; (2) adding WO3 semiconductor nanoparticles with a particle size of 50 nm into the solution in step (1), stirring in the dark state for 30 minutes, and after reacting for a certain time under ultraviolet light, separating and drying by suction filtration to obtain Pt / WO3 particles; (3) dispersing the Pt / WO3 particles obtained in step (2) in a 0.1 M NaOH solution for alkali leaching, stirring at room temperature for 12 h, and after centrifugal washing and vacuum drying, obtaining elemental platinum black nanoparticles.

Description

TECHNICAL FIELD

[0001] The application relates to a WO3 photocatalytic method for preparing platinum black and belongs to the field of preparation of new energy materials. BACKGROUND

[0002] Fine powder of metal platinum is black, so it is called platinum black, and the particle size is usually nanoscale, and should be less than 10 nm in a strict sense. Platinum black is widely used in electronic materials and chemical catalysis industry, and nanoscale platinum black has high catalytic activity for many chemical reactions, and with the vigorous development of chemical catalysis industry, the demand for platinum black is also increasing.

[0003] At present, the traditional methods for preparing platinum black mainly include formaldehyde reduction, sodium borohydride reduction, zinc powder reduction and electrolytic reduction method, but formaldehyde, sodium borohydride and other solutions have toxicity and have certain pollution to the environment; the electrolytic process is relatively complex and it is difficult to efficiently and quickly prepare platinum black. Therefore, it is urgent to develop a new method for preparing platinum black which is efficient, green and simple in process.

[0004] Preparation of platinum black mainly selects a precursor of platinum to realize nucleation and growth through a reduction process, and photocatalysis is a new technology which can be used for oxidation-reduction reaction by using sunlight in recent years, and application of the photocatalysis to photochemical reduction preparation of platinum black will be a very effective means. Patent CN201711367678.3 proposes a high-purity platinum black with large specific surface area and a preparation method thereof, and the platinum black is prepared by an atomization granulation method and a microwave calcination reduction method, and the preparation process is relatively complex, and the average particle size of the platinum black is 2 mu m, which does not belong to platinum black in a strict sense. Patent CN202210270146.2 proposes a method for refining platinum and preparing platinum black, and the method needs to use high temperature of 90 DEG C, dispersing agent and hydrogen peroxide which are flammable and explosive reagents. The present technology proposes to use acidic WO3 as a semiconductor photoreduction agent to prepare platinum black by a photochemical reduction method, and the main advantages are as follows: ① WO3 has high photochemical activity and can realize rapid photochemical reduction of Pt ions; ② WO3 is stable under acidic conditions and can be used for reduction and enrichment of noble metal Pt, and under alkaline conditions, WO3 can be dissolved and used for preparation of platinum black; ③ the present technology is efficient, green and simple in process. The present technology can complete enrichment and extraction of noble metal Pt in 20-60 min in a relatively wide concentration range (2-200 mg / L) of Pt solution, so as to prepare platinum black, the extraction efficiency can reach 99%, the average particle size is about 3.43 nm, and the purity is more than 99%. SUMMARY

[0005] The application aims to provide a method for preparing platinum black by WO3 photocatalysis.

[0006] The application is a method for preparing platinum black by WO3 photocatalysis, which comprises the following steps:

[0007] Step (1) configure a certain concentration of chloroplatinic acid solution, the concentration is 0.1-10 mM; a certain amount of ethanol is added to the solution, the concentration of ethanol is 0.05-0.5 M, and the pH value of the solution is adjusted by 3 M dilute hydrochloric acid, and the pH value is 1.0;

[0008] Step (2) add WO3 semiconductor nanoparticles with a particle size of 50 nm to the above solution, the concentration is 0.5 g / L, dark state stirring for 30 minutes, and reaction under ultraviolet lamp light for 20 minutes, and then separation by suction filtration to obtain Pt / WO3 particles;

[0009] Step (3) the Pt / WO3 particles obtained above are dispersed in 0.1 M NaOH solution for alkali leaching, stirring at room temperature for 12 h, centrifugal washing and vacuum drying to obtain elemental platinum black nanoparticles.

[0010] The beneficial effects of the application are that the enrichment and extraction of noble metal Pt can be completed in 20-60 min in a wide concentration range (2-200 mg / L) of Pt solution to prepare platinum black, the extraction efficiency can reach 99%, the average particle size is about 3.43 nm, and the purity is above 99%. The technology directly utilizes ultraviolet light or sunlight to drive the reaction, is simple to operate, green and pollution-free; on the other hand, it has universality, and the raw material sources include various secondary resources of noble metal Pt, electronic waste, automobile exhaust catalyst, industrial waste catalyst and low-grade ore, etc. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is an optical photo of the platinum black prepared in Example 2; Figure 2 It is an XRD graph; Figure 3 It is a TEM graph, Figure 4 It is an HRTEM graph; Figure 5 It is a particle size distribution graph of the prepared platinum black. IMPLEMENTATION

[0012] The application is a method for preparing platinum black by WO3 photocatalysis, which comprises the following steps:

[0013] Step (1) configure a certain concentration of chloroplatinic acid solution, and add a certain amount of ethanol to the solution, and adjust the pH value of the solution by 3 M dilute hydrochloric acid, and the pH value is 1.0;

[0014] Step (2) add WO3 semiconductor nanoparticles with a particle size of 50 nm to the solution in step (1), dark state stirring for 30 minutes, and reaction under ultraviolet lamp light for a certain time, and then separation by suction filtration to obtain Pt / WO3 particles;

[0015] Step (3) Pt / WO3 particles obtained in step (2) were dispersed in 0.1 M NaOH solution for alkaline leaching, stirred at room temperature for 12 h, washed by centrifugation and dried in vacuum to obtain elemental platinum black nanoparticles.

[0016] In the above-mentioned method for preparing platinum black by WO3 photochemistry, the concentration of chloroplatinic acid solution in step (1) is 0.01-10.0 mM; the concentration of ethanol is 0.1-2.0 M; the concentration of WO3 in step (2) is 0.25-1.0 g / L; and the reaction time is 20-120 minutes.

[0017] In the above-mentioned method for preparing platinum black by WO3 photochemistry, the extraction efficiency of elemental platinum black is more than 99%, the purity is more than 99%, and the average particle size is 3.43 nm.

[0018] The following are specific examples of the present application, and the technical solutions of the present application are further described in combination with the examples, but the present application is not limited to these examples. Example

[0019] In this example, the concentration of chloroplatinic acid is 0.1 mM, the concentration of WO3 particles is 0.5 g / L, the concentration of ethanol is 0.2 M, the pH value of the solution is 1.0, and after 20 minutes of photodeposition, Pt / WO3 particles are obtained by centrifugal washing and drying. After dissolving WO3 by adding 0.1 M NaOH solution, elemental platinum black nanoparticles are obtained by centrifugal washing and vacuum drying. Example

[0020] In this example, the concentration of chloroplatinic acid is 10.0 mM, the concentration of WO3 particles is 0.5 g / L, the concentration of ethanol is 0.2 M, the pH value of the solution is 1.0, and after 1 hour of photodeposition, Pt / WO3 particles are obtained by centrifugal washing and drying. After dissolving WO3 by adding 0.1 M NaOH solution, elemental platinum black nanoparticles are obtained by centrifugal washing and vacuum drying.

[0021] As Figure 2 The platinum black enriched and extracted by the present application is pure element, and the purity is more than 99%, as shown by XRD. Figure 3 TEM, Figure 4 The HRTEM graph shows that the platinum black particles are small and uniform, with some agglomeration. Figure 5 The average particle size of the prepared platinum black is 3.43 nm.

Claims

1. A method for preparing platinum black by photocatalysis of WO3, characterized in that, It consists of the following steps: Step (1) Prepare a chloroplatinic acid solution of a certain concentration, add a certain amount of ethanol to the solution, and adjust the pH value of the solution with 3 M dilute hydrochloric acid to 1.0; Step (2) Add WO3 semiconductor nanoparticles with a particle size of 50 nm to the solution in step (1), stir in the dark for 30 minutes, react under ultraviolet light for a certain period of time, filter and dry to obtain Pt / WO3 particles. Step (3) The Pt / WO3 particles obtained in step (2) are dispersed in 0.1 M NaOH solution for alkaline leaching, stirred at room temperature for 12 h, centrifuged, washed and vacuum dried to obtain elemental platinum black nanoparticles.

2. The method for preparing platinum black by photocatalysis of WO3 according to claim 1, characterized in that, The concentration of chloroplatinic acid solution in step (1) is 0.01~10.0 mM; the concentration of ethanol is 0.1~2.0 M; the concentration of WO3 in step (2) is 0.25~1.0 g / L; and the reaction time is 20~120 minutes.

3. The method for preparing platinum black by photocatalysis of WO3 according to claim 1, characterized in that, The extraction efficiency of elemental platinum black is over 99%, the purity is >99%, and the average particle size is 3.43 nm.

Images