Surface engineering enabled highly sensitive humidity sensors in two-dimensional hexagonal boron nitride nanosheets

Humidity sensors have attracted considerable attention for their capability for real-time, continuous monitoring of critical physiological information, thus offering valuable insights into human health. Two-dimensional hexagonal boron nitride (h-BN) has emerged as an attractive material for humidity sensing due to its high specific surface area and excellent chemical stability. However, the low hydrophilicity of h-BN limits its ability to adsorb water molecules, resulting in reduced sensitivity and slow response times. Herein, capacitive humidity sensors consisted of amine-functionalized h-BN nanosheets have been developed. The introduction of amine groups modulates the hydrophilicity of pristine h-BN by forming hydrogen bonds, promoting interactions with water molecules. The h-BN-based sensor shows significantly improved performance, including high sensitivity (124,136 pF/%RH), large response (5,268,192%), and rapid response and recovery time (2.39 s/1.77 s). These findings demonstrate that amine functionalization can effectively enhance both water adsorption capacity and sensor performance, providing a promising approach for highly sensitive and responsive humidity sensors.