Based on first-principles simulations,we revisit the crystal structures,electronic structures,and structural stability of the layered transition metal dichalcogenides(TMDCs)NbS2,and shed more light on the crucial role...Based on first-principles simulations,we revisit the crystal structures,electronic structures,and structural stability of the layered transition metal dichalcogenides(TMDCs)NbS2,and shed more light on the crucial roles of the van der Waals(vdW)interactions.Theoretically calculated results imply that the vdW corrections are important to reproduce the layered crystal structure,which is significant to correctly describe the electronic structure of NbS2.More interestingly,under hydrostatic pressure or tensile strain in ab plane,an isostructural phase transition from two-dimensional layered structure to three-dimensional bulk in the I4/mmm phase has been uncovered.The abnormal structural transition is closely related to the electronic structure instability and interlayer bonding effects.The interlayer Nb-S distances collapse and the interlayer vdW interactions disappear,concomitant with new covalent bond emerging and increasing coordination number.Present work highlights the significance of the vdW interactions,and provides new insights on the unconventional structural transitions in NbS2,which will attract wide audience working in the hectic field of TMDCs.展开更多
The oxysulfide La3NbS2O5 was synthesized by sulfurization using H2S and characterized by X-ray diffraction （XRD）, UV-Vis diffuse reflectance spectroscopy （DRS） and field emission scanning electron microscopy （FE-...The oxysulfide La3NbS2O5 was synthesized by sulfurization using H2S and characterized by X-ray diffraction （XRD）, UV-Vis diffuse reflectance spectroscopy （DRS） and field emission scanning electron microscopy （FE-SEM）. The relationship between the sulfurization conditions and the photocatalytic activities for H2 evolution was investigated. Sulfurization method allowed for synthesis of La3NbS2O5 at much lower temperatures and significantly shortened reaction time of 1 h compared with conventional solid-state techniques. The particle morphologies were regular platelike with sizes of 0.1-0.6μm and smooth surfaces. The highest activity for H2 evolution was obtained at 1073 K for 1 h, which was about 1.83 times that of La3NbS2O5 prepared by solid-state method.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11864008)Guangxi Natural Science Foundation,China(Grant Nos.2018GXNSFAA138185 and 2018AD19200)High performance computational resources provided by LvLiang Cloud Computing Center of China and National Supercomputer Center on TianHe-2 are gratefully acknowledged.
文摘Based on first-principles simulations,we revisit the crystal structures,electronic structures,and structural stability of the layered transition metal dichalcogenides(TMDCs)NbS2,and shed more light on the crucial roles of the van der Waals(vdW)interactions.Theoretically calculated results imply that the vdW corrections are important to reproduce the layered crystal structure,which is significant to correctly describe the electronic structure of NbS2.More interestingly,under hydrostatic pressure or tensile strain in ab plane,an isostructural phase transition from two-dimensional layered structure to three-dimensional bulk in the I4/mmm phase has been uncovered.The abnormal structural transition is closely related to the electronic structure instability and interlayer bonding effects.The interlayer Nb-S distances collapse and the interlayer vdW interactions disappear,concomitant with new covalent bond emerging and increasing coordination number.Present work highlights the significance of the vdW interactions,and provides new insights on the unconventional structural transitions in NbS2,which will attract wide audience working in the hectic field of TMDCs.
基金Projects(11JJ3020,10JJ9015)supported by Hunan Provincial Natural Science Foundation of ChinaProject supported by the Construct Program of the Key Discipline in Hunan Province,China
文摘The oxysulfide La3NbS2O5 was synthesized by sulfurization using H2S and characterized by X-ray diffraction （XRD）, UV-Vis diffuse reflectance spectroscopy （DRS） and field emission scanning electron microscopy （FE-SEM）. The relationship between the sulfurization conditions and the photocatalytic activities for H2 evolution was investigated. Sulfurization method allowed for synthesis of La3NbS2O5 at much lower temperatures and significantly shortened reaction time of 1 h compared with conventional solid-state techniques. The particle morphologies were regular platelike with sizes of 0.1-0.6μm and smooth surfaces. The highest activity for H2 evolution was obtained at 1073 K for 1 h, which was about 1.83 times that of La3NbS2O5 prepared by solid-state method.
