다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

The family of 2D transition metal carbides, carbonitrides and nitrides (collectively referred to as MXenes) has expanded rapidly since the discovery of Ti3C2 in 2011. The materials reported so far always have surface terminations, such as hydroxyl, oxygen or fluorine, which impart hydrophilicity to their surfaces. About 20 different MXenes have been synthesized, and the structures and properties of dozens more have been theoretically predicted. The availability of solid solutions, the control of surface terminations and a recent discovery of multi-transition-metal layered MXenes offer the potential for synthesis of many new structures. The versatile chemistry of MXenes allows the tuning of properties for applications including energy storage, electromagnetic interference shielding, reinforcement for composites, water purification, gas- and biosensors, lubrication, and photo-, electro- and chemical catalysis. Attractive electronic, optical, plasmonic and thermoelectric properties have also been shown. In this Review, we present the synthesis, structure and properties of MXenes, as well as their energy storage and related applications, and an outlook for future research. More than twenty 2D carbides, nitrides and carbonitrides of transition metals (MXenes) have been synthesized and studied, and dozens more predicted to exist. Highly electrically conductive MXenes show promise in electrical energy storage, electromagnetic interference shielding, electrocatalysis, plasmonics and other applications.

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2D metal carbides and nitrides (MXenes) for energy storage

Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China

Understanding TiO2 photocatalysis: mechanisms and materials.

Antiferromagnetic skyrmion crystal (AF-SkX), a regular array of antiferromagnetic skyrmions, is a fundamental phenomenon in the field of condensed-matter physics. So far, only very few proposals have been made to realize the AF-SkX, and most based on three-dimensional (3D) materials. Herein, using first-principles calculations and Monte-Carlo simulations, we report the identification of AF-SkX in two-dimensional lattice of Janus monolayer CrSi 2 N 2 As 2 . Arising from the broken inversion symmetry and strong spin-orbit coupling, large Dzyaloshinskii–Moriya interaction is obtained in Janus monolayer CrSi 2 N 2 As 2 . This, combined with the geometric frustration of its triangular lattice, gives rise to the skyrmion physics and long-sought AF-SkX in the presence of external magnetic field. More intriguingly, this system presents two different antiferromagnetic skyrmion phases, and such phenomenon is distinct from those reported in 3D systems. Furthermore, by contacting with Sc 2 CO 2 , the creation and annihilation of AF-SkX in Janus monolayer CrSi 2 N 2 As 2 can be achieved through ferroelectricity. These findings greatly enrich the research on antiferromagnetic skyrmions.

Antiferromagnetic skyrmion crystal in Janus monolayer CrSi2N2As2

Monoclinic bismuth vanadate (BiVO4) is an attractive material with which to fabricate photoanodes due to its suitable band structure and excellent photoelectrochemical (PEC) performance. However, the poor PEC stability originating from its severe photo-corrosion greatly restricts its practical applications. In this paper, pristine and Mo doped BiVO4 ceramics were prepared using the spark plasma sintering (SPS) method, and their photoelectrochemical properties as photoanodes were investigated. The as-prepared 1% Mo doped BiVO4 ceramic (Mo-BVO (C)) photoanode exhibited enhanced PEC stability compared to 1% Mo doped BiVO4 films on fluorine doped Tin Oxide (FTO) coated glass substrates (Mo-BVO). Mo-BVO (C) exhibited a photocurrent density of 0.54 mA/cm2 and remained stable for 10 h at 1.23 V vs. reversible hydrogen electrode (RHE), while the photocurrent density of the Mo-BVO decreased from 0.66 mA/cm2 to 0.11 mA/cm2 at 1.23 V vs. RHE in 4 h. The experimental results indicated that the enhanced PEC stability of the Mo-BVO (C) could be attributed to its higher crystallinity, which could effectively inhibit the dissociation of vanadium in BiVO4 during the PEC process. This work may illustrate a novel ceramic design for the improvement of the stability of BiVO4 photoanodes, and might provide a general strategy for the improvement of the PEC stability of metal oxide photoanodes.

BiVO4 Ceramic Photoanode with Enhanced Photoelectrochemical Stability

Coupling nontrivial topological physics to ferroelectricity in two-dimensional lattice is highly desirable in both fundamental research and devices applications. Here, using first-principles calculations, we report that in a multiferroic heterobilayer consisting of a antiferromagnetic layer MnSe and a ferroelectric layer ${\mathrm{In}}_{2}{\mathrm{S}}_{3}$, the typical type-III band alignment can be realized. Upon introduction of spin-orbit coupling, a band gap is created, giving rise to a nontrivial antiferromagnetic topological phase. By reversing ferroelectric polarization, the nontrivial antiferromagnetic topology of $\mathrm{MnSe}/{\mathrm{In}}_{2}{\mathrm{S}}_{3}$ can be annihilated, yielding a wide-gap antiferromagnetic semiconductor with trivial physics. It thus proves to be a feasible approach to realize purely electric-field control of antiferromagnetic topological physics in this heterobilayer. The physical mechanism of such phenomenon is further unveiled to be related to the interlayer charge transfer between the two layers. These findings shed light on the design and control of antiferromagnetic topological physics in two dimensions. 

Electric-field switching of the antiferromagnetic topological state in a multiferroic heterobilayer

Electrochemical water splitting is an environmentally friendly and effective energy storage method. However, it is still a huge challenge for preparing no-noble metal based-electrocatalysts which possess high activity and long-term durability to realize efficient water splitting. Here, we put forward a novel method of low-temperature phosphating to prepare CoP/Co3O4 heterojunction nanowires catalyst on titanium mesh (TM) substrate for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and overall water splitting. CoP/Co3O4@TM heterojunction showed an excellent catalytic performance and long-term durability in 1.0 M KOH electrolyte. The overpotential of CoP/Co3O4@TM heterojunction was only 257 mV at 20 mA cm-2 during the OER process, and it could work stably more than 40 h at 1.52 V versus reversible hydrogen electrode (vs. RHE). During the HER process, the overpotential of CoP/Co3O4@TM heterojunction was only 107 mV at -10 mA cm-2.  More importantly, when CoP/Co3O4@TM heterojunction were used as anodic and cathodic electrocatalysts, respectively, they displayed 10 mA cm-2 at 1.59 V. The Faradaic efficiencies of OER and HER were 98.4% and 99.4%, respectively. It was more excellent than the Ru/Ir-based noble metal electrocatalysts and other non-noble metal electrocatalysts which have been reported for overall water splitting.

In-Situ Formation of CoP/Co3O4 Heterojunction for Efficient Overall Water Splitting.

In order to achieve valley polarization, breaking the time-reversal symmetry in two-dimensional hexagonal lattices with inversion asymmetry is the heart of current valleytronic research, which, however, has caused studies to stagnate due to the inevitable drawbacks. In this work, we go beyond the conventional paradigm and demonstrate the novel valley physics caused by lowering the crystalline symmetry instead of breaking the time-reversal symmetry. In particular, we translate our concept into concrete nonmagnetic LaOMX2 monolayers with a tetragonal lattice, confirming that a spontaneous structure distortion can cause the long-sought, considerably large valley polarization. In detail, the physics of valley-orbital coupling, valley-orbital-layer coupling, valley-contrasting linear dichroism, and interlayer exciton valleytronics are discussed.

Ying Dai

Papers

Antiferromagnetic skyrmion crystal in Janus monolayer CrSi2N2As2

BiVO4 Ceramic Photoanode with Enhanced Photoelectrochemical Stability

Electric-field switching of the antiferromagnetic topological state in a multiferroic heterobilayer

In-Situ Formation of CoP/Co3O4 Heterojunction for Efficient Overall Water Splitting.

Spontaneous Valley Polarization Caused by Crystalline Symmetry Breaking in Nonmagnetic LaOMX2 Monolayers.