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Density functional theory was used to investigate the effects of doping alkaline earth metal atoms (beryllium, magnesium, calcium and strontium) on graphene. Electron transfer from the dopant atom to the graphene substrate was observed and was further probed by a combined electron localization function/non-covalent interaction (ELF/NCI) approach. This approach demonstrates that predominantly ionic bonding occurs between the alkaline earth dopants and the substrate, with beryllium doping having a variant characteristic as a consequence of electronegativity equalization attributed to its lower atomic number relative to carbon. The ionic bonding induces spin-polarized electronic structures and lower workfunctions for Mg-, Ca-, and Sr-doped graphene systems as compared to the pristine graphene. However, due to its variant bonding characteristic, Be-doped graphene exhibits non-spin-polarized p-type semiconductor behavior, which is consistent with previous works, and an increase in workfunction relative to pristine graphene. Dirac half-metal-like behavior was predicted for magnesium doped graphene while calcium doped and strontium doped graphene were predicted to have bipolar magnetic semiconductor behavior. These changes in the electronic and magnetic properties of alkaline earth doped graphene may be of importance for spintronic and other electronic device applications.

In this study, we investigated the effect of impurities—carbon (C), nitrogen (N), and fluorine—on the electronic properties of a Si/SiO2 interface by measuring the atomic layer-resolved partial local density of states using first-principles simulations. Our results show that C and N impurity atoms with dangling bonds (DBs) induce midgap states at the interface. If DBs are terminated by hydrogen atoms, the formation of midgap states is effectively suppressed even in the presence of impurity atoms at the interface. If DBs are terminated by an oxygen (O) atom, both π bonding and π ∗ antibonding orbitals of C=O are occupied and such occupied antibonding orbital forms a midgap state at the interface, increasing the leakage current. Based on these observations, we propose that preparation of the SiO2 substrate with oxygen-rich conditions prior to Si deposition is important in realizing a defect-tolerant interface. In addition, hydrogen treatment after Si deposition recovers the pure band structure by terminating the midgap states, thereby preventing leakage current. [ABSTRACT FROM AUTHOR]

Hydrogen boride (HB), a freestanding 2D hydrogenated‐borophene (borophane) polymorph, is synthesized via ion exchange. HB sheets with a B/H atomic ratio of 1.0 are confirmed to contain three‐center–two‐electron B–H–B bonds and two‐center–two‐electron terminal B–H bonds. The optical properties of HB sheets are expected to be tunable by changing the BHB/BH bond ratio, which alters the electronic structure of HB sheets; however, this is not yet achieved. This study demonstrates that controlling the BHB/BH bond ratio in the HB sheets is possible without altering the hydrogen content by adjusting the volume of ion‐exchange resin during synthesis, thus enabling the tuning of the photoinduced H2 release under UV irradiation. Furthermore, the fluorescence intensity correlates with the absorbance ratio of the BHB and BH vibrational modes. Increasing the BHB/BH bond ratio enhances the luminescence intensity, whereas reducing it enhances the photoinduced H2 release rate under UV irradiation. The ability to control the BHB/BH bond ratio of HB sheets provides new avenues for optimizing their properties for various applications, including hydrogen storage and photocatalysis. [ABSTRACT FROM AUTHOR]

We present a density functional theory study of atomic and molecular adsorption on a single Pt atom deposited at the edges of graphene. We investigate geometric and electronic structures of atoms (H, C, N, and O) and molecules (O2, CO, OH, NO, H2O, and OOH) on a variety of Pt deposited graphene edges and compare the adsorption states with those on a Pt(111) surface and on a Pt single atom. Furthermore, using the calculated adsorption energy and simple kinetic models, the catalytic activities of a Pt single-atom catalyst for the oxygen reduction reaction and CO oxidation are discussed. [ABSTRACT FROM AUTHOR]