关键词: 静电纺丝, 二氧化硅, 柔性, 水诱导发电, 大孔, 溶胶-凝胶法

Abstract:  Nowadays, the development and utilization of clean and renewable energy has received tremendous attention due to the growing demand with the continuous improvement of social living standards. There are a lot of untapped energy sources, and water can be seen everywhere; therefore, the rational use and development of water resource has become an important issue that needs to be addressed. Converting water in the environment into electrical energy is a hot research direction today. SiO2 is one of the extremely important inorganic new materials, especially nanoscale SiO2 has been widely used in many disciplines and fields owing to its small particle size, abundant micropores, large specific surface area, strong surface adsorption, large surface energy, high chemical purity, good dispersion performance, superior stability and other specific performance.
In this experiment, a flexible macroporous SiO2 nanofiber membrane with mesoporous structures was prepared by sol-gel electrospinning to explore its performance in water-induced power generation. Firstly, TEOS was hydrolyzed, then mixed with PVA solution, and PS was added as a pore making agent to prepare a precursor solution. Composite precursor nanofibers were prepared by electrospinning, and afterwards, flexible macroporous SiO2 nanofibers were obtained through calcination. By controlling the proportions of pore-forming agents, PS microspheres, and the adjustment of calcination temperatures, the influence of PS proportion on the microscopic and macroscopic morphology, mesopore and macropore contents of SiO2 nanofibers was explored. Then the charge property analysis of SiO2 nanofibers was conducted through the adsorption comparison of anion MB and cationic CR dyes. Half of the obtained SiO2 nanofiber membrane was placed in NaCl aqueous solution, the other half was exposed to air, and its output voltage was measured at both ends, and then its performance of water-induced power generation was tested. 
It is found that the addition of PS nanospheres could contribute to the preparation of flexible macroporous SiO2 nanofibers with mesoporous structures. The adsorption properties of SiO2 nanofibers to anionic MB and cationic CR dyes were very different. It showed that the adsorption rate of MB was about 77%–78%, and the adsorption rate of CR was only 16%–20%, which indicated that the SiO2 nanofibers were negatively charged. Therefore, SiO2 nanofibers can be applied to water-induced power generation. The composite nanofiber membranes without calcination did not have the performance of water-induced power generation. After calcination, the water-induced power generation performance of SiO2 nanofiber membrane was improved. When the temperature was 500 °C, the output voltage was the highest, up to 0.46 V. It is speculated that the water-induced power generation voltage of SiO2 nanofibers with negative charges is related to the contents of pore structures, and too much or too little will both lead to the decrease in the output voltage, illustrating that the flexible macroporous SiO2 nanofibers can be applied in water energy conversion to electrical energy.

Key words: electrospinning, silica, flexible, water-induced power generation, macroporous , sol-gel method