Covalently intercalated MXene/graphene composite film enables ultrasensitive acoustic sensors under extreme conditions

Developing sensors with high sensitivity, capable of running in extreme environments, is highly desirable for specific intelligent technology development. Large MXene layers with high electrical conductivity have been widely used to assemble high-performance sensing films. However, the gaps between the large overlapping MXene layers would degrade mechanical performance and accelerate layer oxidation with air/water. Here, we propose a covalently intercalated MXene-based composite sensing film affording high tensile strength and suppressed air/water penetration, which is achieved by a small graphene layer covalently interconnected with large MXene layers, followed by cross-linking using 3-glycidoxypropyltrimethoxysilane (PGPTMS). As a result, the sensor using this strong and anti-oxidation sensing material could identify featured weak sound signals (<0.27 Pa) with a high sensitivity of 1728 kPa⁻¹ even under extreme conditions (200^oC and 100 % relative humidity). This work provides a robust interfacial engineering approach for building sensors combined with high sensitivity and environmental adaptability.