Interface Growth of PANI-ZnO Nanohybrids on a Self-Formed Grapefruit Peel Aerogel to Construct a Quick Self-Restored Gas Sensor

A series of gas sensors based on compound conductive polymers and metal oxides with p–n heterojunctions have received a lot of interest. Also, the gas response is significantly enhanced using three-dimensional (3D) porous structured aerogels as carriers. Here, we report a sustainable and highly sensitive gas sensor based on self-formed grapefruit peel aerogel (GPA) loaded with polyaniline (PANI)-ZnO nanohybrids (PANI-ZnO@GPA). ZnO nanorods are produced in situ on the GPA surface (with a porosity of 93.8%) skeleton, adsorbing PANI nanoparticles (NPs) evenly to construct PANI-ZnO nanohybrids. PANI-ZnO@GPA demonstrates excellent gas sensing behaviors for ethanol, acetic acid, ammonia, and formaldehyde gases and high structural stability with 10% linear compression rebound and steady sensing properties even at 50% compression. It is shown that composite aerogel can successfully detect formaldehyde at the 10–1000 ppm level and with a sensitivity of 0.134% ppm–1. Furthermore, it is capable of restoring the initial sensing performance after only 3 min of sunlight exposure. This work is expected to provide new ways to expand the sustainable sensors in the rapid and sustainable detection of volatile organic compounds (VOCs).