A hydrophobic porous silver sulfide / silver film electrode and a preparation method thereof

Abstract

The invention discloses a hydrophobic porous Ag 2 S / Ag film electrode and preparation method thereof. The porous film material is silver plated on the surface by vacuum evaporation to obtain an Ag@porous film electrode; the Ag@porous film electrode is sulfurized to obtain an Ag@porous film electrode. 2 S / Ag@porous film electrode; the Ag 2 After the S / Ag@ porous film electrode is alkalized, it is immersed in n-octadecylthiol and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane solution to obtain a hydrophobic porous Ag. 2 S / Ag film electrode. This method can greatly improve the Ag 2 The S / Ag film electrode surface is hydrophobic, and this method has mild reaction conditions, low energy consumption, and simple operation, which is conducive to large-scale promotion and application.

Description

Technical Field

[0001] The invention relates to a hydrophobic porous membrane electrode, in particular to a hydrophobic porous silver sulfide / silver membrane electrode and a preparation method thereof, belonging to the technical field of super hydrophobic membrane electrode preparation. Background Art

[0002] Metal sulfide materials and their derivatives have been widely used in photocatalytic and electrocatalytic water splitting to produce hydrogen, CO 2 reduction, lithium-ion batteries and supercapacitors, and in the electrocatalytic CO 2 Hu et al. (Hu L, Zhang Y, Han W. Boosting CO 2 Ag@Ag ... 2 The results showed that these DS-Ag NWs achieved 81% CO Faradaic efficiency and enhanced CO partial current density compared with the original Ag nanowires. 2 The S nanowires are believed to have more active sites than pristine Ag with a smooth surface.

[0003] Membrane electrode in gaseous pollutants (CO 2 , SO 2 , H 2 S, etc.) are widely used in the process of resource utilization, and the hydrophobicity of membrane electrode materials is crucial to the mass transfer between gas and liquid phases during electrolysis. The wetting of the membrane electrode surface is extremely unfavorable for the mass transfer of gas, thereby greatly reducing the service life of the membrane material. Chinese patent CN109355673A discloses a method for preparing Au-Ag / Ag in one step by hydrothermal method 2S heterojunction nano hydrogen evolution catalyst and its preparation method, the catalyst shows good catalytic performance, has a wide range of application prospects in the field of photoelectrocatalytic hydrogen evolution. Chinese patent CN101864571A discloses a method for preparing a copper-based super-hydrophobic surface, the surface treatment process provided by the method from the perspective of biomimetic can prepare an oxide layer with multiple microstructures on the surface of the copper material, and then hydrophobic treatment is carried out by n-octadecyl mercaptan self-assembled film, and a super-hydrophobic surface with a contact angle greater than 150° can be obtained. Chinese patent CN102407220A discloses a method for preparing a super-hydrophobic film on the surface of a zinc substrate, that is, ultrasonic cleaning of a zinc sheet substrate, drying with nitrogen, and then oxidation treatment with a formamide aqueous solution, so that the zinc sheet surface forms a rod-shaped nano zinc oxide array, and finally modified by a low surface energy material to form a super-hydrophobic film on the surface of the zinc sheet substrate.

[0004] At present, although the existing methods for hydrophobic modification of membrane electrode surfaces can prepare super hydrophobic layers on the surfaces of copper-based materials and zinc-based materials, these methods are not suitable for modifying Ag with stable properties. 2 The target hydrophobic effect cannot be achieved at the S / Ag composite interface. Summary of the invention

[0005] In view of the poor surface hydrophobicity of Ag film electrode after sulfurization treatment in the prior art, the traditional hydrophobic modification method is difficult to be applied on stable Ag film. 2 In order to avoid defects such as hydrophobic modification on the S / Ag surface, the traditional hydrophobic modification method usually adopts direct immersion to form a chemical bond between the surface of the substrate material and the hydrophobic agent to achieve the hydrophobic modification effect; however, silver sulfide is stable in nature and has poor binding ability with hydrophobic materials. Therefore, it is difficult to achieve the hydrophobic effect using the traditional hydrophobic modification method.

[0006] The first object of the present invention is to provide a hydrophobic porous silver sulfide / silver film electrode with a contact angle greater than 120°.

[0007] The second object of the present invention is to provide a method for preparing a hydrophobic porous silver sulfide / silver film electrode, the method comprising: 2 The S / Ag interface is alkalized and self-assembled to modify n-octadecyltrichlorosilane and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane to obtain a hydrophobic porous silver sulfide / silver film electrode with good surface hydrophobicity. This method is simple to operate and requires mild conditions, which is conducive to large-scale promotion and application, and breaks through the technology of difficult hydrophobic treatment of traditional metal sulfide film electrode materials.

[0008] In order to achieve the above technical objectives, the present invention provides a hydrophobic porous Ag 2The preparation method of S / Ag film electrode comprises the following steps: silver is plated on the surface of a porous film material by vacuum evaporation to obtain an Ag@porous film electrode; the Ag@porous film electrode is subjected to a sulfurization treatment to obtain an Ag@porous film electrode. 2 S / Ag@porous film electrode; the Ag 2 The S / Ag@ porous film electrode is subjected to alkalization treatment and then immersed in n-octadecylthiol and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane solution to obtain the electrode.

[0009] The key to the present invention is to 2 Before the S / Ag@porous membrane electrode surface is hydrophobically modified, the Ag 2 The surface of S / Ag@porous membrane electrode was pretreated by alkalization. 2 Introduction of OH into S / Ag interface - , while activating Ag 2 S, a small part of n-octadecanethiol or 1H,1H,2H,2H-perfluorodecyltrichlorosilane is physically adsorbed on the metal sulfide, while most of n-octadecanethiol or 1H,1H,2H,2H-perfluorodecyltrichlorosilane is chemically bonded to Ag. 2 The active groups at the S / Ag interface are connected in the form of -SH or -SS-. This bond has good stability, thus fixing the hydrophobic long carbon chain molecules or fluorocarbon chains on Ag. 2 S / Ag@porous film electrode surface reduces the surface energy, thus making Ag 2 S / Ag@porous membrane electrode has high hydrophobicity.

[0010] The technical solution of the present invention firstly forms a uniform silver coating on the surface of the porous membrane electrode substrate by vacuum evaporation, and then performs a sulfurization treatment to generate Ag with higher catalytic activity on the surface of the silver coating. 2 S / Ag heterostructure interface, but the Ag 2 The hydrophilicity of the S / Ag heterostructure interface is significantly enhanced, which is not conducive to the mass transfer between the gas phase and the liquid phase during the electrolysis process. 2 The hydrophobic film of n-octadecethiol formed by self-assembly at the S / Ag heterostructure interface is poor in density. 2 After the S / Ag heterostructure interface is alkaline treated, the film-forming performance of n-octadecyl mercaptan on its surface can be greatly improved, thereby obtaining a dense hydrophobic film layer.

[0011] As a preferred solution, the porous membrane material is PTFE, PEEK, PP, PE, carbon cloth or porous carbon paper. These porous membrane materials are mainly hydrophobic materials and are all commodities that can be directly purchased on the market.

[0012] As a preferred solution, the vacuum evaporation method uses metallic silver as the evaporation material, and the vacuum degree is less than 1.3×10 -7 Pa, the evaporation rate is The cathode voltage is 70-110 V and the current is 1-3 A. Under the preferred evaporation conditions, a uniform silver coating can be formed on the surface of the porous membrane material.

[0013] As a preferred solution, the sulfurization treatment condition is: soaking in a 0.5-1.5 mmol / L sodium sulfide solution for 10-30 min. Under the preferred sulfurization conditions, Ag can be generated in situ on the surface of the Ag@porous membrane electrode. 2 S / Ag heterostructure interface.

[0014] As a preferred solution, the alkalization treatment conditions are: immersing in a 0.1-1.5 mol / L sodium hydroxide solution at a temperature of 40-80°C for 12-30 hours. Under the preferred alkalization treatment conditions, the Ag 2 S / Ag heterostructure interface modified OH - , while activating Ag 2 S is beneficial to improve the octadecylthiol or 1H,1H,2H,2H-perfluorodecyltrichlorosilane on Ag 2 Film-forming effect at the S / Ag heterostructure interface.

[0015] As a preferred solution, the immersion treatment conditions are: immersion in a 0.1-1 mol / L solution of n-octadecylmercaptan and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane for 10-60 minutes. The n-octadecylmercaptan and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane solution is an ethanol solution of n-octadecylmercaptan and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The concentration of n-octadecylmercaptan and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane solution cannot be too low, and the immersion time cannot be too short. If the concentration of n-octadecylmercaptan and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane solution is lower or the immersion time is shorter, n-octadecylmercaptan and 1H,1H,2H,2H-perfluorodecyltrichlorosilane will not be absorbed by Ag. 2 The effect of self-assembly film formation at the S / Ag heterostructure interface is worse.

[0016] The present invention also provides a hydrophobic porous Ag 2 The S / Ag film electrode is prepared by the method.

[0017] The hydrophobic porous Ag of the present invention 2 The preparation method of S / Ag film electrode is as follows:

[0018] 1) Ag@porous membrane electrode was prepared by vacuum evaporation on the surface of commercially purchased hydrophobic porous membrane material substrate. The specific conditions of vacuum evaporation were: using metallic silver as the evaporation material and the vacuum degree was 1.3×10 -7 Pa below, the evaporation rate is The cathode voltage is 70-110V and the current is 1-3A;

[0019] 2) Place the Ag@porous film electrode in a 0.5-1.5 mmol / L sodium sulfide solution for pre-sulfurization for 10-30 min to obtain Ag 2 S / Ag@porous film electrode;

[0020] 3) Ag 2 The S / Ag@porous membrane electrode was treated with a sodium hydroxide solution with a concentration of 0.1 to 1.5 mol / L at a temperature of 40 to 80°C for 12 to 30 hours and then dried.

[0021] 4) The alkalized Ag 2 The S / Ag@porous film electrode is immersed in an ethanol solution of 0.1-1 mol / L n-octadecylthiol and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane for 10-60 min and dried to obtain a hydrophobic porous silver sulfide / silver film electrode.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0023] The technical solution of the present invention is the first to be applied in Ag 2 The surface of the S / Ag film electrode successfully used n-octadecyl mercaptan to self-assemble to form a dense hydrophobic layer, which greatly improved the Ag 2 Hydrophobicity of the S / Ag electrode surface.

[0024] The surface contact angle of the hydrophobic porous silver sulfide / silver film electrode of the present invention is greater than 120 degrees.

[0025] The method for preparing the hydrophobic porous silver sulfide / silver film electrode of the present invention is simple to operate and requires mild conditions, and is conducive to large-scale promotion and application. DETAILED DESCRIPTION

[0026] The following examples are intended to further illustrate the present invention, but are not intended to limit the scope of protection of the claims of the present invention.

[0027] The preparation process of Ag@PTFE membrane electrode in the following examples is as follows: Ag catalyst is loaded on a PTFE porous membrane (commercially purchased with a pore size of 0.22 μm) substrate by vacuum evaporation coating. The specific vacuum evaporation parameters are as follows: the vacuum degree is 1.3×10 -7Pa, Ag was melted under the condition of voltage of 70V and current of 1A, and then the voltage was gradually increased to 110V (10V / 5min), the current to 1.3A, and the evaporation rate was controlled at range, and obtain the Ag / PTFE electrode.

[0028] Example 1

[0029] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The contact angle of S / Ag@PTFE membrane electrode was measured to be 105.35°.

[0030] Will get Ag 2 The S / Ag@PTFE membrane electrode was alkalized with 0.5 mol / L sodium hydroxide solution at 60°C for 24 h and dried, and the contact angle was measured to be 57°.

[0031] The obtained Ag 2 The S / Ag@PTFE membrane electrode was immersed in 0.4 mol / L n-octadecyl mercaptan ethanol solution for 10 min and dried. The contact angle was measured to be 111.73°.

[0032] The alkalized Ag 2 The S / Ag film electrode was immersed in 0.4 mol / L n-octadecyl mercaptan ethanol solution for 10 min, dried, and the contact angle was measured to be 134.27°.

[0033] This example shows that the Ag@PTFE membrane electrode obtained after sulfurization 2 The surface hydrophobicity of S / Ag@PTFE membrane electrode was significantly reduced, but after alkalization treatment and surface modification with n-octadecanethiol, the surface hydrophobicity was greatly improved. 2 If the S / Ag@PTFE membrane electrode is not subjected to alkalization treatment, it is difficult to form a dense and uniform n-octadecethiol film layer on its surface.

[0034] Example 2

[0035] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 0.1 mol / L sodium hydroxide solution at 60 °C for 24 h and dried. 2 The S / Ag film electrode was immersed in a 0.4 mol / L 1-octadecyl mercaptan ethanol solution for 10 min and dried. The contact angle was measured to be 130.09°.

[0036] Example 3

[0037] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 0.2 mol / L sodium hydroxide solution at 60 °C for 24 h and dried. 2 The S / Ag film electrode was immersed in 0.4 mol / L n-octadecyl mercaptan ethanol solution for 10 min and dried. The contact angle was measured to be 127.72°.

[0038] Example 4

[0039] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 1.5 mol / L sodium hydroxide solution at 60°C for 24 h and dried. 2 The S / Ag film electrode was immersed in 0.4 mol / L n-octadecyl mercaptan ethanol solution for 10 min and dried. The contact angle was measured to be 136.93°.

[0040] Example 5

[0041] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 0.5 mol / L sodium hydroxide solution at 60°C for 24 h and then dried. The contact angle was measured to be 94.05°. 2 The S / Ag film electrode was immersed in a 0.1 mol / L 1H,1H,2H,2H-perfluorodecyltrichlorosilane ethanol solution for 10 min and dried. The contact angle was measured to be 125.87°.

[0042] Comparative Example 1

[0043] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 S / Ag@PTFE membrane electrode, the Ag after sulfurization 2 The S / Ag film electrode was immersed in 0.1 mol / L 1H,1H,2H,2H-perfluorodecyltrichlorosilane ethanol solution for 10 min, dried, and the contact angle was measured to be 114°. 2The ability of S / Ag@PTFE membrane electrode to modify the surface with 1H,1H,2H,2H-perfluorodecyltrichlorosilane was significantly improved.

[0044] Example 6

[0045] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 0.1 mol / L sodium hydroxide solution at 60 °C for 24 h and dried. 2 The S / Ag film electrode was immersed in a 0.1 mol / L 1H,1H,2H,2H-perfluorodecyltrichlorosilane ethanol solution for 10 min and dried. The contact angle was measured to be 126.40°.

[0046] Example 7

[0047] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 0.2 mol / L sodium hydroxide solution at 60 °C for 24 h and dried. 2 The S / Ag film electrode was immersed in a 0.1 mol / L 1H,1H,2H,2H-perfluorodecyltrichlorosilane ethanol solution for 10 min and dried. The contact angle was measured to be 125.26°.

[0048] Example 8

[0049] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 1.5 mol / L sodium hydroxide solution at 60°C for 24 h and dried. 2 The S / Ag film electrode was immersed in a 0.1 mol / L 1H,1H,2H,2H-perfluorodecyltrichlorosilane ethanol solution for 10 min and dried. The contact angle was measured to be 112.86°.

[0050] Comparative Example 2

[0051] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 0.1 mol / L sodium hydroxide solution at 25°C for 24 h and dried. 2The S / Ag film electrode was immersed in 0.4 mol / L n-octadecyl mercaptan ethanol solution for 10 min and dried. The contact angle was measured to be 102.92°.

[0052] Comparative Example 3

[0053] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 S / Ag@PTFE membrane electrode, dried, and the treated Ag 2 The S / Ag film electrode was immersed in 0.4 mol / L n-octadecyl mercaptan ethanol solution for 10 min, dried, and the contact angle was measured to be 108.74°.

[0054] Comparative Example 4

[0055] The Ag@PTFE electrode obtained by evaporation was placed in a 1 mmol / L sodium sulfide solution for pre-sulfurization for 25 min to obtain Ag 2 The S / Ag@PTFE membrane electrode was treated with 0.5 mol / L sodium hydroxide solution at 100°C for 24 hours and then dried. The high alkalization temperature destroyed the fiber structure of PTFE, causing the fibers to break.

Claims

1. A hydrophobic porous Ag 2 Preparation method of S / Ag film electrode, Features: The Ag@porous membrane electrode is obtained by silver plating on the surface of the porous membrane material by vacuum evaporation method; the Ag@porous membrane electrode is subjected to sulfurization treatment to obtain Ag@porous membrane electrode. 2 S / Ag@porous film electrode; the Ag 2 The S / Ag@ porous film electrode is subjected to alkalization treatment and then immersed in n-octadecylthiol and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane solution to obtain the electrode.

2. A hydrophobic porous Ag according to claim 1 2 Preparation method of S / Ag film electrode, Features: The porous membrane material is PTFE, PEEK, PP, PE, carbon cloth or porous carbon paper.

3. A hydrophobic porous Ag according to claim 1 or 2 2 Preparation method of S / Ag film electrode, Features: The vacuum evaporation method uses metallic silver as the evaporation material, and the vacuum degree is less than 1.3×10 -7 Pa, the evaporation rate is The cathode voltage is 70 to 110 V and the current is 1 to 3 A.

4. A hydrophobic porous Ag according to claim 1 2 Preparation method of S / Ag film electrode, Features: The conditions of the sulfidation treatment are: soaking in a 0.5-1.5 mmol / L sodium sulfide solution for 10-30 minutes.

5. A hydrophobic porous Ag according to claim 1 2 Preparation method of S / Ag film electrode, Features: The conditions of the alkalinization treatment are: immersing in a 0.1-1.5 mol / L sodium hydroxide solution for 12-30 hours at a temperature of 40-80°C.

6. A hydrophobic porous Ag according to claim 1 2 Preparation method of S / Ag film electrode, Features: The soaking treatment conditions are: soaking in 0.1-1 mol / L n-octadecylthiol and / or 1H,1H,2H,2H-perfluorodecyltrichlorosilane solution for 10-60 minutes.

7. A hydrophobic porous Ag 2 S / Ag film electrode, Features: The invention is prepared by the method according to any one of claims 1 to 6.