Superior sensitivity of metal functionalized boron carbide (BC₃) monolayer towards carbonaceous pollutants

The sensitivity of light metal functionalized boron carbide (BC₃) sheets towards selected carbonaceous gases like CO, CO₂, and CH₄ is investigated by using first principles density functional theory calculations. We find that functionalization with alkali (Li, Na, K) and alkaline earth metals (Be, Mg, Ca), is a useful strategy to improve the sensitivity of graphene-like BC₃ towards the mentioned gases. A semiconductor-to-metal transformation of BC₃ is observed upon the introduction of metal dopants. Gas molecules are adsorbed on the metallized BC₃ through weak chemisorption, which is an ideal scenario for gas sensing under practical working conditions. We find that the adsorption energies (E_ads) of CO molecule are found to be 1.71, 0.48, 0.34, 0.35, 0.96, and 0.84 eV on Be-, Li-, Na-, K-, Mg-, and Ca-doped BC₃, respectively. Similarly, CO₂ binds to Li-, Be-, Mg-, and Ca- doped BC₃ with E_ads of 0.54, 0.87, 0.61, and 0.43 eV, respectively. For CH₄, an E_ads value of 0.74 eV turns out to be the strongest in case of Be-BC₃. Bader charge analysis divulges that the transfer of charges results in the adsorption mechanism of the gases to the metallized BC₃. In addition to feasible E_ads, change in the work function upon the adsorption of gas molecules further confirms good sensitivity of the metallized BC₃ towards CO, CO₂ and CH₄. Based on our findings, we deduce that metal-doped BC₃ is an excellent candidate for the efficient sensing of harmful pollutants.