Super-hydrophobic and resilient hybrid silica aerogels for thermal insulation, energy harvesting, and electrical applications in harsh environments

Abstract

Silica aerogels have attracted considerable attention in the insulation and electrical industries. Nevertheless, their fragility and susceptibility to moisture have hindered widespread adoption. To address these challenges, this study has developed hydrophobic, lightweight, and flexible aerogels with remarkable resilience and electrical properties, enabling them to withstand extreme temperatures in practical application environments. The methodology used involves the sol–gel technique and strategically incorporates vinyltrimethoxysilane (VTMS) into the polymethylhydrosiloxane (PMHS) chain. The findings demonstrate that these innovative materials can endure compressive stress levels of up to 10 MPa and undergo fatigue cycles without noticeable failure. Additionally, these hybrid aerogels exhibit varying thermal conductivity values ranging from 22 to 38 mW m⁻¹ K⁻¹ at room temperature, depending on the percentage of VTMS grafting. Thermogravimetric analysis (TGA) in air reveals their exceptional thermal stability, allowing them to withstand temperatures up to 518 °C in real-world environments without any significant weight loss. Notably, the inclusion of VTMS into the PMHS has led to a remarkable enhancement in both the triboelectric performance and power density of the aerogel-based triboelectric nanogenerator (TENG). Specifically, the triboelectric performance of the aerogel has improved by an impressive 3.7 times, while achieving a considerable power density of 0.723 W m⁻² in the contact-and-separation mode of TENG operation. This pioneering approach holds immense potential for revolutionizing the triboelectric properties of silica aerogels and significantly enhancing their mechanical and thermal stability for mechanical energy harvesting in harsh environments.