Density Functional Theoretical method for modelling Cobalt-doped g-C3N4 sensor for detecting aniline - a cancer biomarker

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-C3N4 systems. The adsorption energy calculations reveal that these biomarkers undergo chemisorption on pristine g-C3N4, resulting in long recovery times, which restricts the suitability of pristine g-C3N4 as a sensor. Alternatively, the band gap of Co-g-C3N4 (0.98 eV) is lower than that of pristine g-C3N4 (1.33 eV), which increases the conductivity of Co-g-C3N4 (5.11 × 10⁻⁹ S/m) compared to pristine g-C3N4 (5.714 × 10⁻¹² S/m) - suggesting obvious selective sensitivity towards the biomarkers. Our results indicate that acetone adsorbs on the Co-g-C3N4 surface via chemisorption process, aniline undergoes physisorption, and ethanol exhibits an intermediate adsorption behaviour. 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. However, the conductivity calculations revealed that aniline exhibits the highest conductivity of 1.72 × 10-7 and the work function calculations manifested stronger sensitivity of Co-g-C3N4 towards aniline compared to acetone and ethanol. These results predict, Co-g-C3N4 as a superior sensor for aniline biomarker due to its physisorption behaviour, lower recovery time, higher conductivity and significant change in work function. The state-of-the-art analysis of Co-g-C3N4 as a promising reusable sensor for detecting aniline in exhaled breath is hitherto unknow to date.