Molecular modeling of Si₆₀ fullerene and Nb-doped Si₆₀ fullerene nanomaterials for SO₂, NO₂ and CO₂ gas sensing

CO₂, NO₂ and SO₂ are by-products from the petrochemical industries that have been associated with both global warming and several respiratory dysfunctions. Hence, several efforts are being put forth to detect their excesses at minimal concentrations. In this regard, this study presents a theoretical analysis based on quantum and molecular mechanical calculations of the sensing efficacy of silicon nanostructures towards the effective detection of these gases at low concentrations. To enhance the attributes of the nanomaterial, transition metal (Nb) was endohedrally doped on the silicon Si₆₀ nanomaterial to enhance the surface conductivity and sensitivity. The results indicate that the metal-doped nanostructures have improved sensitivity towards the studied gases. The adsorption of NO₂, SO₂ and CO₂ followed a declining trend; NO₂@Nb^dopSi59 > SO₂@Nb^dopSi59 > CO₂@Nb^dopSi₅₉ > NO₂@Si₆₀ > SO₂@Si₆₀ > CO₂@Si₆₀ respectively. The computed adsorption enthalpies were found to be −25.36, −136.26 and −183.67 kcal/mol respectively for CO₂@Nb^dopSi₅₉, NO₂@Nb^dopSi₅₉ and SO₂@Nb^dopSi₅₉ systems. Comparatively, SO₂ and NO₂ preferred to be adsorbed on Si₆₀ than CO₂. The results of other electronic properties such as energy gap and conductivity were also found to be in tandem with the adsorption and stability studies. The sensing mechanism and computed desorption times were also found to be within 1.02 s to 2.72 s, clearly indicating a quick desorption from the metal-doped surface. Contrary, desorption from the pristine nanocluster was found to be slower due to strong chemisorption bonds between the gases and surface. While the electronic properties affirmed the conducting and stable nature of the surfaces, molecular dynamics simulation was further employed for stability evaluation. These results also unveiled the stable nature of the nanocluster and confirmed that the studied metal-doped nanoclusters possess the ideal properties to be employed as sensors for SO₂ NO₂ and CO₂ gases.