Preparation method of Nafion/mesoporous silicon dioxide composite proton exchange film

[0011] Example 1: 0.5 mol of Pluronic P123 was added to 100 ml of an ethanol solution of tetraethoxysilane, the concentration of tetraethoxysilane was 0.5 mol/L, the pH was adjusted to 2, and then it was sonicated for 30 minutes. The Nafion 117 film was immersed in the aforementioned silicon source sol at a rate of 30 mm/s, and then the silicon source sol was pulled out at this rate. At this time, the silicon source sol is adsorbed on the surface of the Nafion 117 membrane. After the film to be coated with the silicon source sol is aged in the air for 2-6 hours at 10°C, the composite film is cleaned 3 times with ethanol to remove the surfactant. The Nafion/mesoporous silica composite proton exchange membrane was obtained. The surface of the obtained composite film has a network structure of nano-scale mesoporous silica. It can effectively block the permeation of methanol. The proton conductivity of the composite membrane remains at the same order of magnitude as that of the Nafion membrane.

[0012] Example 2: 0.005 mol of Pluronic F127 was added to 1000 ml of tetraethoxysilane in ethanol, the concentration of tetraethoxysilane was 0.5 mol/L, the pH was adjusted to 2, and then it was sonicated for 30 minutes. The Nafion 115 film was immersed in the aforementioned silicon source sol at a rate of 100 mm/s, and then the silicon source sol was pulled out at this rate. At this time, the silicon source sol is adsorbed on the surface of the Nafion 112 membrane. After that, repeat the above-mentioned immersion and pulling process after 5 minutes respectively, repeating 4 times in total. After the film coated with the silicon source sol is aged for 2-6 hours in the air at room temperature at 15° C., the composite film is cleaned 3 times with ethanol to remove the surfactant. The Nafion/mesoporous silica composite proton exchange membrane was obtained. The surface of the obtained composite film has a network structure of five layers of nano-scale mesoporous silica. The methanol permeability of the composite membrane is 10 times lower than that of the unmodified membrane, while the proton conductivity remains at the same order of magnitude as that of the Nafion membrane.

[0013] Example 3 0.01 mol of CTAB was added to 200 ml of tetraethoxysilane in ethanol, the concentration of tetraethoxysilane was 0.5 mol/L, the pH was adjusted to 3, and then ultrasonic for 30 minutes. The Nafion 112 film was immersed in the aforementioned silicon source sol at a rate of 120 mm/s, and then the silicon source sol was pulled out at this rate. At this time, the silicon source sol is adsorbed on the surface of the Nafion 112 membrane. After that, the above-mentioned immersion and pulling process was repeated at an interval of 60 minutes, a total of 2 times. After the film coated with the silicon source sol is aged in the air at 25° C. for 2-6 hours, the composite film is cleaned 3 times with ethanol to remove the surfactant. The Nafion/mesoporous silica composite proton exchange membrane was obtained. The surface of the obtained composite membrane has a network structure of three layers of nano-scale mesoporous silica. The methanol permeability of the composite membrane is 2 times lower than that of the unmodified membrane, while the proton conductivity remains comparable to that of the Nafion membrane.