Two-dimensional Cu-doped G/h-BN/G heterostructures for highly sensitive gas detection: an ab initio study.

Abstract

Two-dimensional materials like graphene and h-BN have drawn significant interest for gas sensing applications due to their high surface-to-volume ratio and exceptional physical properties. This study introduces a novel approach involving a 2-D G/h-BN/G heterostructure doped with a Cu atom to develop a highly sensitive gas sensor. The intermediate h-BN layers support the Cu dopant and enhance the electrical sensitivity by constraining the offset current. Density functional theory and non-equilibrium Green's function formalisms are employed to investigate the geometry, stability, and electrical properties of the G/h-BN/G structure with the Cu dopant at various vacancy sites, alongside exploring the adsorption behavior of six different gas molecules (NO2, CO, NH3, PH3, HCN, and HO2). Results reveal that doping Cu in the B vacancy and the Stone-Wales defect yields highly stable structures with promising electrical characteristics for gas sensing applications. Gas molecules exhibit a higher tendency to adsorb onto the Cu-doped structure compared to the pristine G/h-BN/G, demonstrating a stronger impact on current flow. The Cu-doped structures display robust electrical sensitivity toward NO2, CO, NH3, and HCN molecules, and the significant gap in current modulation for each gas indicates the potential for distinguishing different gas molecules. Hence, incorporating the Cu dopant in the G/h-BN/G heterostructures emerges as a promising platform for gas sensing applications.