Developing the sensing mechanism of high-performance N2H4 sensors derived from waste cotton stalk using a one-step process

Abstract

The detection of hydrazine (N₂H₄), a highly toxic and explosive compound, is of paramount importance for ensuring environmental and industrial safety. However, research on chemoresistive gas sensors for N₂H₄ detection, particularly the underlying mechanisms, remains limited. To address this gap, we have prepared carbon materials with a unique morphology and trace K doping through a simple carbonization process, utilizing raw cotton straw (RCS) as the starting material. The CS-400 sensor obtained under calcination at 400 °C exhibited high sensitivity and selectivity for N₂H₄, with a response of 30.6 k% and a detection limit of 0.55 ppm for 500 ppm N₂H₄ at room temperature. Subsequently, the gas sensing mechanism of the straw-based biochar material was focused on, and the roles of cellulose, hemicellulose and lignin in the RCS were analyzed. The interaction between defects and carrier concentration during pyrolysis was elucidated. First-principles calculations confirmed that trace K doping and surface adsorbed oxygen enhance the adsorption of target gases, thereby improving the sensor performance.