Co3O4/CQDs Composite for Selective Ammonia Detection in Exhaled Human Breath Analysis

Abstract

Co₃O₄ was synthesized using electrospinning method and different amounts of carbon quantum dots (CQDs) were subsequently doped into the Co₃O₄ matrix via grinding, resulting in Co₃O₄/CQDs composite materials with various ratios. Gas sensing tests revealed that the resulting composite Co₃O₄/CQDs sensors exhibited excellent performance at a low temperature of 50°C, with outstanding selectivity towards ammonia gas and rapid response and recovery characteristics. Specifically, response and recovery time for 50 ppm ammonia gas were 14 s and 164 s, respectively. The outcomes of the exhalation simulation test utilizing sensors composed of this material demonstrate that the sensor's response to simulated chronic kidney disease breath closely approximates that of pure biological samples (1.08), exceeding the average response value of healthy exhaled breath samples (1.0). This demonstrates the sensor's capability to differentiate between healthy individuals and chronic kidney disease patients despite significant water vapor and carbon dioxide interference. This study provides valuable insights for the development of more efficient ammonia sensors and their role in the early detection of chronic kidney disease.