Defective Graphene as a promising lead pollution absorbent from first-principles study

Abstract

An exhaustive first-principles based density function theory investigation of lead adsorption on single layer graphene has been performed to figure out the graphene geometry with the highest adsorption capacity to adsorb lead pollution in auto exhaust pipe. Pristine graphene, divacancy defected graphene, and stone-wales defected graphene were simulated and analyzed in this study. The result shows divacancy defected graphene with defect concentration of 6.25% has the greatest adsorption energy per carbon atom, which is -0.4322 eV. A relative low adsorption height is found for the adsorption case as 1.49 A. Assuming the temperature in exhaust gas pipe as 500 °C, we calculated the Arrhenius rate constant to be 0.0090 as a measure of adsorption efficiency. The results could serve as a reliable reference for the filter element material design for lead pollution regulation. We have further explored the electronic structure of 2D graphene by plotting band structure and density of states diagrams. An increase of density of states from 0 is observed after the existence of divacancy defect on 2D graphene, implying the significant role of divacancy defect in improving graphene adsorption performance.