A DFT study on the structural and electronic properties of small toxic gases on B- and Al- doped C20 fullerene

Abstract

The structural and electronic properties of semiconducting BC₁₉ and AlC₁₉ heterofullerenes as adsorbents for toxic small gas molecules (H₂S and SO₂) are determined by DFT. Structural parameters, energy gaps, natural population analysis, partial density of state, dipole moments, and vibrational frequencies were extracted. The adsorption process and sensitivity to the gases are increased by doping with B or Al. The results show that AlC₁₉ is the most sensitive structure. The good sensing of AlC₁₉ is related to high charge transfer upon gas adsorption. Adsorption of the H₂S on the BC₁₉ has negligible effects on the electronic properties, to be categorized as “harmless adsorption”. H₂S is weakly adsorbed on BC₁₉ and AlC₁₉. The H₂S and SO₂ molecules act as electron donating and electron withdrawing molecules, respectively. Notably, the adsorption processes are highly exothermic. In general, BC₁₉ is more reactive than C20 and AlC₁₉ is the most reactive cage. This provides a theoretical basis to fabricate B- and Al-doped C20-based gas sensors.