NH3, PH3, AsH3 adsorption and sensing on rare earth metal doped graphene: DFT insights

To explore new sensor materials towards hazardous gases NH3, PH3, and AsH3, their adsorptions on pristine graphene and rare earth metal (REM = La, Ce, Nd, Pm, Sm, Eu and Gd) doped graphenes were studied by using density functional theory calculations. The adsorption energies show that pristine graphene exhibits weak physisorption towards the NH3, PH3, and AsH3 gas molecules. Almost no changes appear on the geometrical structures, charge populations and DOSs of pristine graphene. However, the rare earth metal element modifications lead to enhanced chemisorption towards NH3 and weakened adsorption towards AsH3, accompanied with significant electron redistribution and orbital hybridization. The electrical conductivity of the graphenic substrate is also increased, leading to higher sensor response towards NH3. Facile sensitivity and recovery time reveals Ce doped graphene is an ideal candidate for room temperature monitoring of NH3.