Platinum disulfide (PtS2 ), a new member of the group-10 transition-metal dichalcogenides, is studied experimentally and theoretically. The indirect bandgap of PtS2 can be drastically tuned from 1.6 eV (monolayer) to 0.25 eV (bulk counterpart), and the interlayer mechanical coupling is almost isotropic. It can be explained by strongly interlayer interaction from the pz orbital hybridization of S atoms.

a great deal of research interest for diverse applications such as field effect transistors, optoelectronic devices, catalysis, energy storage, and conversion. [1][2][3][4][5] Benefiting from the features of atomic thickness, large specific surface area, intrinsic quantum confined electrons, and high ratio of surface atoms to entire atoms, the ultrathin 2D materials exhibit unique physicochemical properties, such as planar conductivity, electronic anisotropy, tunable energy band structure, and high surface activity. [6,7] When the thickness of bulk materials is reduced to the atomic level, the local atomic structures will suffer from obvious distinctions including coordination number, bond angle, bond length, and disorder degree of the surface atoms and may even result in the formation of numerous surface defects. As a consequence, the ultrathin 2D materials can not only display improved inherent properties of the bulk materials but also give birth to new properties that the corresponding bulk materials do not possess. [8,9] Semiconductor photocatalysis has attracted massive research interest since it has been regarded as one of the most promising solutions to deal with the energy shortage and environmental-pollution issues. [10][11][12][13][14] With the solar light as the external driving force, the semiconductor could split water into hydrogen and oxygen, reduce the CO 2 to chemicals and valuable fuel, as well as completely eliminate pollutants. [15][16][17][18] Generally, the major critical steps in the photocatalytic process can be classified as light absorption, charge separation and migration, as well as surface redox reactions. Under the irradiation, the photocatalysts can absorb the solar light and are excited to produce electron-hole pairs when the photon energy equal to or higher the bandgap, leaving the electrons in the conduction band (CB) and holes in the valence band (VB), respectively. Subsequently, the photogenerated electrons and holes will diffuse to the materials surface and further migrate to the surface active sites before involving in the surface reactions. During this process, the recombination of charge carriers will happen and the crystal structure, crystallinity, particle size, surface atomic structure, etc., will strongly affect the separation efficiency. Finally, the target molecule will be adsorbed on the materials surface, and will undergo charge injection process and desorption to form the ultimate products. [19] Up to now, hundreds of semiconductor materials are available for different photocatalytic applications with the help As a sustainable technology, semiconductor photocatalysis has attracted considerable interest in the past several decades owing to the potential to relieve or resolve energy and environmental-pollution issues. By virtue of their unique structural and electronic properties, emerging ultrathin 2D materials with appropriate band structure show enormous potential to achieve efficient photocatalytic performance. Here, the state-of-the-art progress on ultrathin 2D...

Semiconductor p-n junctions are the elementary building blocks of most electronic and optoelectronic devices. The need for their miniaturization has fuelled the rapid growth of interest in two-dimensional (2D) materials. However, the performance of a p-n junction considerably degrades as its thickness approaches a few nanometres and traditional technologies, such as doping and implantation, become invalid at the nanoscale. Here we report stable non-volatile programmable p-n junctions fabricated from the vertically stacked all-2D semiconductor/insulator/metal layers (WSe/hexagonal boron nitride/graphene) in a semifloating gate field-effect transistor configuration. The junction exhibits a good rectifying behaviour with a rectification ratio of 10 and photovoltaic properties with a power conversion efficiency up to 4.1% under a 6.8 nW light. Based on the non-volatile programmable properties controlled by gate voltages, the 2D p-n junctions have been exploited for various electronic and optoelectronic applications, such as memories, photovoltaics, logic rectifiers and logic optoelectronic circuits.

Two-dimensional (2D) magnets with intrinsic ferromagnetic/antiferromagnetic (FM/AFM) ordering are highly desirable for future spintronic devices. However, the direct growth of their crystals is in its infancy. Here we report a chemical vapor deposition approach to controllably grow layered tetragonal and non-layered hexagonal FeTe nanoplates with their thicknesses down to 3.6 and 2.8 nm, respectively. Moreover, transport measurements reveal these obtained FeTe nanoflakes show a thickness-dependent magnetic transition. Antiferromagnetic tetragonal FeTe with the Néel temperature ( T N ) gradually decreases from 70 to 45 K as the thickness declines from 32 to 5 nm. And ferromagnetic hexagonal FeTe is accompanied by a drop of the Curie temperature ( T C ) from 220 K (30 nm) to 170 K (4 nm). Theoretical calculations indicate that the ferromagnetic order in hexagonal FeTe is originated from its concomitant lattice distortion and Stoner instability. This study highlights its potential applications in future spintronic devices.

Solar-driven reduction of CO , which converts inexhaustible solar energy into value-added fuels, has been recognized as a promising sustainable energy conversion technology. However, the overall conversion efficiency is significantly limited by the inefficient charge separation and sluggish interfacial reaction dynamics, which resulted from a lack of sufficient active sites. Herein, Bi O Cl superfine nanotubes with a bilayer thickness of the tube wall are designed to achieve structural distortion for the creation of surface oxygen defects, thus accelerating the carrier migration and facilitating CO activation. Without cocatalyst and sacrificing reagent, Bi O Cl nanotubes deliver high selectivity CO evolution rate of 48.6 μmol g h in water (16.8 times than of bulk Bi O Cl ), while maintaining stability even after 12 h of testing. This paves the way to design efficient photocatalysts with collaborative optimizing charge separation and CO activation towards CO photoreduction.