Formation of SiO₂-Encapsulated Ag Nanoparticles on SiO₂ Nanofibers and Their Application as Robust, Flexible Pressure Sensor Working under High Temperatures

Lightweight, flexible pressure sensors working under high temperatures have intrigued great research interest owing to their potential in firefighting, aerospace technology, and automotive and petroleum industries. Here, we propose a strategy to prepare SiO 2 shell-coated Ag nanoparticles on SiO 2 nanofiber membranes (SNFs), which prohibit nanoparticle migration and fusion. The reduction treatment of the nanofiber membrane promotes the in situ reduction of AgNO 3 into Ag seeds, which further grow as Ag nanoparticles in the following wet-chemical treatment. Then, a protective silica layer is fabricated on the Ag nanoparticles, which effectively prevents the nanoparticles’ migration and fusion; we propose that metal–support interaction (MSI) may help to form the silica coatings on the Ag nanoparticles. The as-formed Ag nanoparticles with a SiO 2 coating layer are sinter-resistant and show much higher thermal stability than bare Ag nanoparticles on the nanofibers. The as-assembled pressure sensors using these SNFs as active materials can continuously work at 350 °C without performance decay. After annealing the SNF at 600 °C for 2 h, the SNF can still maintain its performance as a pressure sensor. The high-sensitivity, high-temperature-resistant, and robust SNF may provide a platform for unconventional pressure sensor construction. The strategies used in this study may bring insights into both the design and application of these sinter-resistant nanostructures.