Density Functional Theoretical Method for Modelling Cobalt‐Doped g‐C ₃ N ₄ Sensor for Detecting Acetone, Ethanol, and Aniline — Cancer Biomarkers

Abstract Using DFT calculations, we investigated the sensitivity of the lung cancer biomarkers, such as acetone, ethanol, and aniline — on pristine and Cobalt (Co)‐doped g‐C 3 N 4 systems. The adsorption energy calculations reveal that these biomarkers undergo chemisorption on pristine g‐C 3 N 4 , resulting in long recovery times, which restricts the suitability of pristine g‐C 3 N 4 as a sensor. Alternatively, the band gap of Co‐g‐C 3 N 4 (0.98 eV) is lower than that of pristine g‐C 3 N 4 (1.33 eV), which increases the conductivity of Co‐g‐C 3 N 4 (5.11 × 10⁻⁹ S/m) compared to pristine g‐C 3 N 4 (5.714 × 10⁻¹ 2 S/m) – suggesting obvious selective sensitivity toward the biomarkers. Our results indicate that acetone adsorbs on the Co‐g‐C 3 N 4 surface via chemisorption process, aniline undergoes physisorption, and ethanol exhibits an intermediate adsorption behavior. Recovery time analysis revealed that aniline (0.09 s) and ethanol (3.64 s) can be recovered quickly at 398 K, which further accelerates under UV irradiation at 298 K. These results predict, Co‐g‐C 3 N 4 as a superior sensor for aniline biomarker due to its physisorption behavior, lower recovery time, higher conductivity, and significant change in work function. The state‐of‐the‐art analysis of Co‐g‐C 3 N 4 as a promising reusable sensor for detecting aniline in exhaled breath is hitherto unknown to date.