Silk protein nanofibers for highly efficient, eco-friendly, optically translucent, and multifunctional air filters

New types of air filter technologies are being called because air pollution by particulate matters (PMs) and volatile organic compounds has raised serious concerns for public health. Conventional air filters have limited application and poor degradability and they become non-disposable wastes after use. Here, we report a highly efficient, eco-friendly, translucent, and multifunctional air purification filter that is highly effective for reducing air pollution, protecting the environment, and detecting hazardous chemical vapors encountered in everyday life. Uniform silk protein nanofibers were directly generated on a window screen by an electrospinning process. Optical properties (translucence and scattering) of the silk nanofibrous air filters (SNAFs) are advantageous for achieving viewability and controlling the room temperature. Air filtration efficiencies of the fabricated SNAFs could reach up to 90% and 97% for PMs with sizes under 2.5 and 10 μm, respectively, exceeding the performances of commercial semi-high-efficiency particulate air (semi-HEPA) filters. After use, the SNAFs could be naturally degraded. Furthermore, we demonstrate the ability of SNAFs impregnated with organic dyes to sense hazardous and volatile vapors encountered in everyday life.