Structural, Electronic, and Magnetic Properties of Adatom Adsorptions on Black and Blue Phosphorene: A First-Principles Study

Using first-principles calculations, we investigate the adsorption characteristics of alkali, alkaline-earth, nonmetallic, transition, and noble metal adatoms on phosphorene. The adsorption-induced tunable electronic structures are comparatively studied on two representative structures of phosphorene, i.e., black and blue phosphorus (P) nanosheets. Both black and blue P sheets exhibit good adsorption capability to foreign atoms, on which the binding energies of adatoms are stronger than on the BN, SiC, MoS2, or graphene sheets. On the black P sheet, most adatoms prefer to adsorb on the hollow site, whereas for the blue P sheet, the favored adsorption sites are element-dependent. The majority of alkali, alkaline-earth, and transition-metal adatoms prefer the valley site, noble metal adatoms the hollow site, and nonmetallic adatoms the bridge and top sites instead. The semiconducting behaviors of phosphorene are modified by adatoms, which can cause p-type and n-type doping or induce midgap states into the P sheets. Moreover, surface adsorptions effectively functionalize the phosphorene system with versatile spintronic features: N-/P-decorated blue P sheets are half-metals, B-/Fe-decorated ones become bipolar-semiconductors, and Co-/Au-decorated blue and black P sheets turn into spin-gapless-semiconductors. Our work demonstrates that adatom adsorption is a feasible method of chemical functionalization of phosphorene, which results in peculiar electronic and magnetic properties for potential applications in nanoelectronics and spintronics.