Synergistic sensing properties of standalone graphitic carbon nitride-carbonnanotube film integrated portable prototype for ultra-sensitive and selective acetone detection

Abstract

Selective room temperature detection of ultralow bio marker acetone gas remains challenging due to limited analyte interaction with sensor substrates. Carbon nanotube (CNT)-based sensors, offering high surface area and conductivity, often lack sufficient selectivity for specific gases. To address this limitation, we developed a new method that uses graphitic carbon nitride (g-C₃N₄) to coat CNT films, creating a sensitive and selective sensor for acetone. Two types of g-C₃N₄, synthesize from urea (GCN-U) and thiourea (GCN-T) were used, to enhance the sensor performance. The GCN-U-coated sensor showed exceptional results with a twenty four fold resistance increase upon acetone exposure, limit of detection to 2.3 parts per billion with a quick response and recovery time of 5 and 12 seconds. The enhanced selective performance is attributed to g-C₃N₄ defects (pyrrolic-N and pyridinic-N), which enable selective chemical binding with acetone and reduce diffusional limitations through high-density heterojunctions at CNT- g-C₃N₄ interfaces. A small, portable prototype was made and tested, successfully detecting acetone across a wide range (1–50 ppm) and remaining reliable for six months. This work represents a shift from static sensors to highly interactive sensing platforms, advancing point-of-care VOC monitoring for diagnostic applications.