3D rGO/MXene Composite Aerogel with p‐p Heterojunction Structure for Enhanced Formaldehyde Detection at Low Temperature

3D rGO/MXene aerogels are fabricated via a one‐step hydrothermal method, forming a p‐p heterojunction structure that effectively improves the performance of gas sensors. Characterization analyses reveal their rich porous structure and large specific surface area, which facilitate the adsorption and desorption of target gases. Gas sensing performance tests demonstrate that the sensor exhibits high sensitivity and good selectivity towards formaldehyde gas. At 120 °C, the response to 100 ppm formaldehyde reaches 22.18%. The response and recovery times are 4 s and 8 s. Additionally, the sensor exhibits a linear response over the concentration range of 5–100 ppm formaldehyde, indicating its potential application value in environmental monitoring and smart home areas. Density functional theory calculations suggest that the strong electronic interaction between 3D rGO/MXene and formaldehyde effectively promotes molecular adsorption and activation. This orbital coupling and charge transfer mechanism form the electronic structure basis for the material's excellent response capability.