A DFT STUDY ON THE STRUCTURAL AND ELECTRONIC PROPERTIES OF SMALL TOXIC GASES ON B- AND Al- DOPED C20 FULLERENE

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 C-20 and AlC19 is the most reactive cage. This provides a theoretical basis to fabricate B- and Al-doped C-20-based gas sensors.