Sensing behavior of Al and Si doped BC3 graphenes to formaldehyde

Electronic sensitivity of pristine, Al- and Si-doped BC3 nanosheets to formaldehyde (H2CO) molecule was investigated by utilizing density functional theory. It was found that H2CO is weakly adsorbed on the sheet, releasing energy of 11.35 kcal/mol, and electronic properties of the sheet are not significantly changed. Although both Al and Si dopings make the sheet more reactive and sensitive to H2CO, Si doping seems to be a better strategy to manufacture H2CO chemical sensors due to the shorter recovery time and higher sensitivity of the Si-doped sheet. Our calculations show that the HOMO/LUMO gap of the Si-doped sheet is significantly decreased from 2.20 to 1.58 eV upon H2CO adsorption, which may increase the electrical conductance of the sheet. Therefore, the doped sheet might convert the presence of H2CO molecules to electrical signal. Moreover, the shorter recovery time of the Si-doped sheet is due to middle adsorption energy of −26.49 kcal/mol in comparison with −40.50 kcal/mol for the Al-doped sheet.