An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Two-dimensional van der Waals heterostructures with multiple tunable approaches in electronic and optical properties are highly superior for photocatalysis and novel devices. By applying first-principles calculations, we systematically studied the electronic structure, optical absorption, carrier mobility and solar-to-hydrogen efficiency of PtSe2/GaN heterostructures, which are affected by different thicknesses, varying directions of polarization of the GaN nanosheets and applied mechanical strain of the whole system. The results indicate that these heterostructures exhibit thermodynamic stability at room-temperature (300 K), and most configurations have type-II band alignment, among which the heterostructure consisting of GaN trilayers and PtSe2 shows high visible-light absorption (1.71 × 105 cm-1) and ultra-wide range of pH values (pH = 0-14) for the photocatalytic water splitting reaction and exceedingly high overpotential for the hydrogen evolution reaction (3.375 eV). Simultaneously, being two of the most significant parameters of photocatalysis and devices, the carrier mobility and solar-to-hydrogen efficiency have also been calculated, respectively, reaching up to 1601 cm2 V-1 s-1 and 17.2%. Moreover, the photoelectrical properties can be highly tuned through further biaxial strain engineering; especially, the visible-light absorption can be enhanced to 2.85 × 105 cm-1 by applying 6% compression strain. Thus, the PtSe2/GaN heterostructure we proposed shows a broad prospect for photocatalytic water splitting.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
In this work, a sulfur and nitrogen co-doping technique has been demonstrated for diamond epilayer growth by microwave plasma chemical vapor deposition (MPCVD). Results show that the nitrogen concentration in films could be tailored by co-doping of sulfur. At a certain growth condition, single nitrogen-vacancy (NV) colour centers could be achieved. A competition mechanism between sulfur and nitrogen incorporation in the H2/CH4 plasma is proposed to explain the efficient suppression of the incorporated nitrogen. Briefly, adding H2S decreases the growth rate and the resulting (S or S2) species could react with the dissociated nitrogen atoms to form S and N-containing clusters. Hence, the concentration of the NV centers in diamond is decreased. Meanwhile, density functional theory (DFT) calculations indicate an increment of the NV formation energy in the presence of sulfur, which confirms that sulfur has a suppression effect on the formation of the NV centers. This study provides a new method to adjust the concentration of the NV centers in the diamond films.
Using the first-principles method based on the density functional theory (DFT), the work function of seven different GaN (0001) (1×1) surface models is calculated. The calculation results show that the optimal ratio of Cs to O for activation is between 3∶1 and 4∶1. Then, Cs/O activation and stability testing experiments on reflection-mode negative electron affinity GaN photocathodes are performed. The surface model [GaN (Mg): Cs] Cs-O after being activated with cesium and oxygen is used. The experiment results illustrate that the adsorption of O contained in the residual gas increases the surface potential barrier and the reduction of the effective dipole quantity is the basic cause of the quantum efficiency decay.
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