Identifying suitable photocatalysts for photocatalytic water splitting to produce hydrogen fuel via sunlight is an arduous task by the traditional try-and-error method.Thanks to the progress of density functional theory one can nowadays accelerate the process of finding candidate photocatalysts. In this work, by ab initio calculations we investigated on 48 two-dimensional (2D) transition metal carbides also referred to as MXenes to understand their photocatalytic property. Our results highlight 2D Zr 2 CO 2 and Hf 2 CO 2 as the candidate single photocatalysts for possible high efficient photocatalytic water splitting. The significantly property of 2D Zr 2 CO 2 and Hf 2 CO 2 is that they exhibit unexpectedly high and directionally anisotropic carrier mobility, which may effectively facilitate the migration and separation of photogenerated electron-hole pairs. Meanwhile, these two MXenes also exhibit very good optical absorption performance in the wavelength ranging approximately from 300 to 500 nm.The stability of 2D Zr 2 CO 2 and Hf 2 CO 2 in liquid water is expected to be good based on ab initio molecular dynamics simulations. Finally, the absorption and decomposition of water molecule on the 2D Zr 2 CO 2 surface and the subsequently followed formation process of hydrogen were studied, which contributes to the unraveling of the micro-mechanism of photocatalytic hydrogen production on MXene.Our findings will open a new way to facilitate the discovery and application of MXenes for photocatalytic water splitting. Fig. 3. The electronic band edge positions with respect to the water reduction and oxidation potential levels.Fig. 4. Imaginary part of the dielectric function of 2D Zr 2 CO 2 and Hf 2 CO 2 .

Intrinsically ferromagnetic 2D semiconductors are essential and highly sought for nanoscale spintronics, but they can only be obtained from ferromagnetic bulk crystals, while the possibility to create 2D intrinsic ferromagnets from bulk antiferromagnets remains unknown. Herein on the basis of ab initio calculations, we demonstrate this feasibility with the discovery of intrinsic ferromagnetism in an emerging class of single-layer 2D semiconductors CrOX (CrOCl and CrOBr monolayers), which show robust ferromagnetic ordering, large spin polarization, and high Curie temperature. These 2D crystals promise great dynamical and thermal stabilities as well as easy experimental fabrication from their bulk antiferromagnets. The Curie temperature of 2D CrOCl is 160 K, which exceeds the record (155 K) of the most-studied dilute magnetic GaMnAs materials, and could be further enhanced by appropriate strains. Our study offers an alternative promising way to create 2D intrinsic ferromagnets from their antiferromagnetic bulk counterparts and also renders 2D CrOX monolayers great platform for future spintronics.

The electroplating of amorphous Ni/W alloys is described. The aqueous plating solution consists of NiSO4, Na2WO4, and Na3Cit at pH = 8.0. The bath is operated at room temperature. By avoiding the use of NH4OH or any ammonium salt, it was possible to prepare alloys containing up to 50 a/o (76 w/o) W. XRD measurements revealed that amorphous alloys were obtained when the concentration of W in the alloy is 20−40 a/o. At lower concentrations of W the fcc substitutional solid solution Ni(1 - x )W x was formed. At higher concentration, an orthorhombic crystal structure corresponding to a 1/1 Ni/W alloy was observed. SEM and STM measurements supported the existence of the amorphous phase. The conditions under which amorphous alloys are expected to be formed preferentially are discussed. Thin films of the amorphous phase were prepared reproducibly at any tungsten concentration in the above range. Therefore, these alloys can be used for barrier or capping layers in the microelectronic industry for ULSI and MEMS applications.

Resistive random access memory (RRAM) is a very promising next generation non-volatile RAM, with quite significant advantages over the widely used silicon-based Flash memories. For RRAM, material with switchable resistance, working as the storage medium, is the most important part for the performance of the memory. In this review, as a start, some general hints for the materials selection are proposed. Then most recent studies on this emerging memory from the perspective of materials science are summarized: various materials with resistance switch (RS) behavior and the underlying mechanisms are introduced; as a complementary to the previous review articles, here the increasingly important role of computational materials science in the research of RRAM is presented and highlighted. By incorporating the framework of high-throughput calculation and multi-scale simulations, design process of new RRAM could be accelerated and more cost-effective.