Qingxiao Zhou

Adsorption sensitivity of graphane decorated with B, N, S, and Al towards HCN: a first-principles study

The geometric structure, adsorption energy, electronic structure, and magnetic properties of hydrogenated graphene (graphane) with the adsorption of a HCN molecule were investigated by first-principles calculations. Compared with graphane, the adsorption of HCN on H-vacancy defected graphane (VHG) exhibited higher stability, which implied that the H-vacancy improved the sensitivity of graphane. However, the small adsorption energies and large bond distance indicated that the weak adsorption of a HCN molecule on the graphane and VHG substrates was due to physisorption. By introducing dopants (B, N, S, and Al), the activity of graphane was significantly improved. The adsorption of HCN changed to chemisorption on the graphane with dopants. Meanwhile, the opening of band gaps by HCN adsorption can be used as an electronic signal to detect HCN gas. Interestingly, the spin polarized density of states (PDOS) results suggested that the adsorption of HCN on VHG and S-doped VHG exhibited magnetic character and half-metallicity behavior. These results could provide useful information to design gas sensors for HCN or spintronic devices based on graphane.

Adsorption of H2S on graphane decorated with Fe, Co and Cu: a DFT study

Herein, density functional theory (DFT) calculations were performed to investigate the adsorption of a H2S molecule on the surface of hydrogenated graphene (graphane). In our results, we found that the appearance of an H-vacancy significantly improved the reactivity of graphane due to the unpaired electrons of the vacancy site. However, small adsorption energy and low charge transfer indicated that the interaction between the H2S molecule and the pure H-vacancy-defected graphane occurred via physisorption. By introducing transition-metal dopants (Fe, Co, and Cu), the adsorption process of the H2S molecule changed to chemisorption. Furthermore, the adsorption of H2S induced a decrease in the band gaps, which could be seen as signal for the detection of H2S gas.

Influence of vacancy defects and 3d transition metal adatoms on the electronic and magnetic properties of graphene

Based on the density functional theory (DFT) method, we investigated the geometry stability, electronic and magnetic properties of vacancy-defected graphene with and without the adsorption of transition metal (TM) adatoms (V, Cr, and Mn). The results indicated that the appearance of vacancy, which broke the π-band, induced a magnetic property due to the unpaired electrons. After adsorbing the TM atoms, the electronic and magnetic properties were interestingly modified by the impurity states and the spin-polarized electrons of TM atoms. Moreover, the projected density of states (PDOS) results suggested that the magnetism of systems was mainly dominated by the 2p orbitals of C atoms around the vacancy and the 3d orbital of the TM adatoms.