Journal of Materiomics 2018年第2期目录

Research on two dimensional (2D) materials, one of the most extensively studied classes of materials, has grown rapidly over the past several years and attracted great attention of thousands of scientists from across materials science, physics, chemistry, engineering, medicine and industry. This research activity has triggered the emergence of a new generation of atomically thin metals, semimetals, semiconductors, nitrides, oxides/hydroxides, transition metal dichalcogenides (TMDs), topological insulators and even polymers, demonstrating the potential for novel properties and technological innovations. The topics of the special issue include TMDs and transition metal oxides (TMOs), graphene and graphene-derived materials, black phosphorus (BP), 2D metals, and related heterostructures/hybrids/composites and their potential applications in energy, environment, electronics, and biology fields.

二维材料是材料科学广泛研究的领域之一。二维材料的研究在过去几年中迅速发展，并引发了来自材料科学，物理学，化学，工程学，医学和工业界的数千名科学家的高度关注。该领域的研究引发了新一代原子级厚度金属，半金属，半导体，氮化物，氧化物/氢氧化物，过渡金属二硫化物（TMD），拓扑绝缘体甚至拓扑结构聚合物的出现，展示了新性能和技术创新的潜力。本期专刊的主题包括TMDs和过渡金属氧化物（TMOs），石墨烯和石墨烯衍生材料，黑磷（BP），二维金属以及相关的异质结构/杂化物/复合材料及其在能源，环境，电子， 和生物学领域的应用潜力。

While two-dimensional layered nanomaterials including transition metal oxides and transition metal dichalcogenides have been widely researched because of their unique electronic and optical properties, they still have some limitations. To overcome these limitations, transition metal oxides and transition metal dichalcogenides based nanocomposites have been developed using various methods and have exhibited superior properties. In this paper, we introduce the photodeposition method and review the photodeposition of metal nanoparticles on the surface of transition metal oxide and transition metal dichalcogenides. Their current applications are also explained, such as photocatalysis, hydrogen evolution reaction, surface enhanced Ramanscattering, etc. This approach for nanocomposites has potential for future research areas such as photocatalysis, hydrogen evolution reaction, surface enhanced Raman scattering, and other applications. This approach for nanocomposite has the potential for future research areas.

二维层状纳米材料，包括过渡金属氧化物和过渡金属二卤代物，由于其独特的电学和光学特性而得到了广泛的研究，但仍存在一些局限性。为了克服这些限制，过渡金属氧化物和过渡金属二硫化物等二维层状纳米材料因其独特的电学和光学性能引发了广泛的研究，但他们仍然存在一些局限性。为克服这些限制，研究者采用各种方法发展了基于过渡金属氧化物和过渡金属二硫化物的纳米复合材料，这些材料表现出了优异的性能。在本文中，我们综述了利用光沉积在过渡金属氧化物和过渡金属二硫化物表面沉积金属纳米颗粒的方法。阐述了该方法在光催化，析氢反应，表面增强拉曼散射等方面的应用。这种制备纳米复合材料的方法在未来的研究领域中具有很大潜力。

Exploring high-activity and earth-abundant electrocatalysts for electrochemical reactions, including the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), etc. are crucial for building future large-scale green energy conversion and storage systems. Recently, some low-cost and resourceful two-dimensional (2D) semiconductor materials such as transition metal dichalcogenides (TMDCs) and layered oxides, have attracted increasing attention in electrocatalysis applications in virtue of their comparable catalytic activity and long-term stability to conventional noble metal-based catalysts (e.g. Pt/C, RuO_2,IrO₂, etc.). However, the intrinsic activity of some 2D materials still cannot meet the increasing requirement for highly efficient and reliable eletrocatalysts for future energy conversion and storage systems. In this context, designing elctrocatalysts with sufficient amount of active sites accessible for electrolyte, high activity of each active sites, and excellent conductivity is of great significance. To this end, defect engineering is a powerful strategy for tailoring the physical and chemical properties of 2D materials for efficient electrocatalysis. In this article, an overview of recent progress on defect engineering in 2D eletrocatalysts for HER, ORR and OER is presented. The effects of defects on the structure and tuned properties of 2D materials in eletrocatalysts applications are also summarized. Additionally, the challenges and opportunities ahead in this emerging field are also proposed.

探索用于电化学反应（包括析氢反应（HER），氧化还原反应（ORR）和析氧反应(OER)等）的高活性，地球丰产的电催化剂对于发展未来大规模绿色能源转化和存储系统至关重要。近年来，过渡金属二硫化物和层状氧化物等二维半导体材料因其具有低成本和资源丰富的特点，并且具有与传统贵金属催化剂（如Pt/C，RuO₂，IrO₂等）相当的催化活性和长期稳定性，吸引了越来越多的关注。然而，一些二维材料的本征活性仍不能满足未来能量转化和存储系统所需的高效高可靠性的要求。鉴于此，设计具有足量，高活性位点以及优异导电性的电催化剂具有重大意义。缺陷工程是调节高效电催化二维材料物理化学性能的有力工具。在本文中，我们介绍了缺陷工程在用于析氢，氧化还原和析氧反应的电催化剂中应用的研究进展。总结了缺陷在二维电催化材料结构和性能调控中的作用，提出了这一新兴领域面临的挑战和机遇。

Recently, graphene-based materials have been successfully fabricated by the electrophoretic deposition (EPD) technique and exhibited various extraordinary properties. Here, research progress of the field of graphene-based materials prepared by the EPD process in recent 5 years is reviewed, including graphene films, graphene/non-metal composites, graphene/metal-based nanoparticles composites, graphene/polymer composites. We also summarize the experimental deposition conditions and the applications of the deposited graphene-based materials that have been reported. It can be concluded that EPD is a simple and reliable manipulation technique and promises a bright future for the production of graphene-based materials in the field of advanced nanocomposite materials. Finally the current issues and outlook of the development direction of EPD in future are also proposed.

近年来，石墨烯基材料已经可以通过电脉冲沉积技术（EPD）成功制备，并且表现出各种优异的性能。本文综述了近5年来由EPD工艺制备石墨烯基材料的研究进展，包括石墨烯薄膜，石墨烯/非金属复合材料，石墨烯/金属基纳米复合材料，石墨烯/聚合物复合材料。我们也总结了目前已经报道的关于电脉冲沉积的实验条件以及沉积的石墨烯基材料的应用。可以看出，EPD是一种简单、可靠的操作技术，为石墨烯基材料在先进纳米复合材料领域的应用提供了广阔的前景。最后，我们也提出了EPD技术目前存在的问题以及未来发展的方向。

Oriented attachment can be used as a good synthetic route to make highly anisotropic nanostructures including nanorod, nanowire, nanoplate, and nanosheets. In a typical growth of anisotropic nanostructures, coalescence and reshaping after attachment make dense nanostructures. In this report, we show the formation of Ag sheets having fractal network by oriented attachment at low reaction temperature of 30 °C. The synthesized Ag sheets exhibited good crystalline nature despite of their network structure and low synthetic temperature. We also investigated the effect of reaction conditions for the formation of the Ag sheets. In addition, using the Ag sheets as a sacrificial template, we could make hollow Au sheets via galvanic replacement.

定向附着可以作为一种很好的合成路线来制备高度各向异性的纳米结构，包括纳米棒、纳米线、纳米板以及纳米片。在一个典型的各向异性纳米结构的生长过程中，附着后的聚接和重塑将形成致密的纳米结构。本文报道了在30°C的低反应温度下，定向附着可以形成具有不规则网络结构的Ag纳米片。尽管反应在较低的温度下进行，且具有网状结构，但是合成的Ag纳米片仍然保持了良好的结晶性。我们还研究了反应条件对合成Ag纳米片的影响。此外，使用制备得到的Ag纳米片作为牺牲模板，我们可以通过电化学置换的方法获得空心的Au纳米片。

Black phosphorus (BP), especially for BP nanosheets, with unique layered structure among two dimensional (2D) materials has attracted much attention due to its outstanding physical properties, such as ultra-high mobility, in-plane anisotropic properties. However, the small horizontal-size of reported BP limits its applications in the integrated circuit or some functional devices. In this work, a solvothermal-assisted liquid-phase exfoliation technique is firstly employed for preparing large size and high-quality BP nanosheets. In the high-polar acetonitrile solvent, solvothermal treatment weakens the Van der Waals forces of block BP. Together with the subsequently ultrasonic processing, effective exfoliation of large size and high-quality BP nanosheets are realized. The TEM, AFM and Raman results indicate that the prepared BP nanosheets are high quality with an average thickness of about 2 nm, and the horizontal-size is up to 10 μm. This facile and effective method for exfoliated BP nanosheets provides a promising strategy for the exfoliation of other 2D materials.

在二维材料中，黑磷具有独特的层状结构。黑磷的纳米片更因其具有优异的物理性能，如超高迁移率，面内各向异性等受到了广泛的关注。然而，目前所报道的黑磷的水平尺寸均较小，限制了其在集成电路或某些功能器件中的应用。在本工作中，我们采用了溶剂热辅助液相剥离的技术制备了大尺寸、高质量的黑磷纳米片。在高极性乙腈溶剂中，溶剂热处理可以削弱块体黑磷的范德瓦尔斯力。随后通过超声处理，可以实现大尺寸和高质量的黑磷纳米片的有效剥离。TEM，AFM以及拉曼的结果都表明了制备得到的黑磷纳米片具有较高的质量，且平均厚度在2纳米，水平尺寸最大可达10微米。这种简便有效地剥离黑磷纳米片的方法在其他二维材料的剥离中也具有相当的应用前景。

Graphene-on-semiconductor has been proved to be a quality heterojunction with efficient photoelectric conversion. In this work, we constructed Schottky junction solar cells by combing graphene woven fabrics (GWFs) and n-doped single crystal silicon, and examined the performance of solar cells when GWFs of different meshes were used. Sparse GWFs possessed high optical transparency but led to poor carrier collection, whereas dense GWFs could collect carriers efficiently but generated too few photo carriers due to low transparency. The GWFs with an optimal mesh could provide a good balance between the generation and collection of photo-induced carriers to deliver high power conversion efficiency.

石墨烯-半导体异质结已被证明具有高光电转换效率。在这项工作中，我们通过结合石墨烯织物（GWFs）和n型掺杂单晶硅构建肖特基结太阳能电池，并且检验了使用不同网格的GWF时太阳能电池的性能。稀疏的GWF具有高度的光学透明度，但是载流子收集性能不佳。而致密的GWF可以有效地收集载体，但由于透明度低，产生的光生载流子很少。具有最佳网格的GWF可以在光生载流子的产生和收集之间提供良好的平衡，以提供高转换效率。

In this work, we studied the stability and ferroelectricity of two-dimensional (2D) group-IV monochalcogenides MX (M = Ge, Sn, or Pb; X = S, Se, or Te). Two competing crystal structures of these 2D compounds have been considered, including the rippled crystal structure with a space group of Pmn21, which can be obtained from exfoliation, and the P3¯m1 hexagonal crystal structure containing the X-M-M-X building blocks. We find that the total energies of the rippled phases of PbX, SnS and SnSe are lower than those of the corresponding hexagonal phases; particularly, the rippled phases of SnS and SnSe exhibit spontaneous polarizations and ferroelectricity. On the other hand, the hexagonal phases of GeX and SnTe are energetically more stable than the corresponding rippled phases; because the hexagonal phases are centrosymmetric, these 2D compounds are non-ferroelectric. To engineer the ferroelectricity of 2D group-IV monochalcogenides, we have investigated the effects of alloying and equibiaxial strain. Based on density functional theory calculations, we find that the rippled phases of GeX and SnTe can be stabilized via Pb alloying to achieve ferroelectricity. In addition, it is also found that equibiaxial tensile strain gives rise to ferroelectricity in the rippled phases of 2D PbX compounds.

在这项工作中，我们研究了二维（2D）IV族单硫化物MX（M = Ge，Sn或Pb; X = S,Se或Te）的稳定性和铁电性。这些二维化合物具有两种相互竞争的晶体结构，包括具有Pmn21空间群的波纹晶体结构（可剥离获得）和 P3¯m1六方晶体结构（含有X-M-M-X结构单元）。我们发现PbX，SnS和SnSe的波纹相的总能量低于相应六方相的总能量;特别是SnS和SnSe的波纹相呈现自发极化和铁电性。另一方面，GeX和SnTe的六方相在能量上比相应的波纹相更稳定;因为六方相是中心对称的，所以这些二维化合物是非铁电的。为了设计二维IV族单硫化物的铁电性，我们研究了合金化和等轴应变的影响。基于密度泛函理论计算，我们发现Pb合金化可以稳定GeX和SnTe的波纹相从而实现铁电性。此外，我们还发现等轴拉伸应变在二维PbX化合物的波纹相中会引发铁电性。

A hydrogel possessing interesting photochromic behaviors was developed by in situ ultraviolet (UV) irradiation–assisted polymerization of an aqueous solution of N-isopropylacrylamide monomer in the presence of cesiumtungstate nanosheets. By this process, a hierarchical porous network structure was finely constructed while showing ultrahigh flexibility. More importantly, the newly prepared hydrogel retained the photochromic properties of the cesium tungstate nanosheets. The color transitions could be readily controlled by UV laser irradiation and were completely reversible via laser exposure or dark treatment. The nanocomposite hydrogel with its excellent photochromic properties and ultrahigh flexibility will have great applications in flexible photochromic devices. The synthetic procedure is simple and has promises to be extended to developing other hydrogels with various new functionalities.

通过在N-异丙基丙烯酰胺单体的水溶液的原位紫外（UV）辐射辅助聚合中引入钨酸铯纳米片，我们开发了具有有趣光致变色行为的水凝胶。通过这个过程，精细地构造了分层多孔网络结构，该结构同时显示出超高的灵活性。更重要的是，新制备的水凝胶保留了钨酸铯纳米片的光致变色特性。颜色转变可以通过UV激光照射容易地控制，并且颜色转变通过激光曝光或黑暗处理后完全可逆。纳米复合水凝胶具有优异的光致变色性能和超高的柔韧性，在柔性光致变色器件中具有很好的应用前景。合成过程简单，并有望扩展到其他具有各种新功能的水凝胶的研发。

Magnesium oxysulfate (MOS) whisker is considered as a promising inorganic material recently attracting a great attention for being used as a reinforcing filler for polymer composites due to high aspect ratio and extremely-low bulk density. In this study, the MOS was treated with 3-methacryloyloxypropyl-trimethoxy silane (MPS) via sol-gel condensation reactions, which successfully allowed melt mixing with polypropylene (PP) up to 30 wt% of MOS. The tensile strength at yield and modulus of the MOS/PP composites were substantially increased by 50.8% and 362%, respectively, when compared with the pristine PP. As a novel finding, the flame retardancy of MOS was proved by identifying water evolution at elevated temperatures giving out 9 wt% of water in 250-320 °C and 14 wt% in 350-420 °C in two steps. This work demonstrated that the MOS could be an excellent filler for PP not only increasing the mechanical properties in a great extent but also imposing flame retarding capability.

氧化硫酸镁（MOS）晶须近年来被认为是一种有前景的无机材料，因其高的纵横比和极低的体密度而在聚合物复合材料的增强填料领域引起了极大关注。在这项研究中，采用3-甲基丙烯酰氧基丙基三甲氧基硅烷（MPS），通过溶胶-凝胶法对MOS进行缩合反应处理，成功地制备了熔融混合达到30wt％MOS的聚丙烯（PP）。与原始PP相比，MOS/ PP复合材料的屈服拉伸强度和模量分别提高了50.8％和362％。作为一项新发现，MOS的阻燃性通过确定在高温下析出的水量来证明，其中在250-320℃下和在350-420℃下分别得到9wt％和14wt％的水。这项工作表明，MOS可以作为PP的优良填料，它不仅能在很大程度上提高机械性能，而且还具有阻燃能力。

碳纳米管（CNT）海绵呈现独特的多孔和分层结构，有利于超轻和高韧性复合材料的设计。本研究制备了CNT海绵（未掺杂和硼掺杂）增强的聚二甲基硅氧烷（PDMS）复合材料。系统地研究了该复合材料的力学性能，包括压缩模量，速率依赖模量，应力松弛行为，动态粘弹性质以及它们对温度的依赖性。Mori-Tanaka微机械模型被验证可用于描述CNT海绵增强复合材料的力学行为。通过与硼掺杂的CNT海绵偶联，PDMS复合材料的机械性能显著提高，包括压缩模量（70％），粘性模量（243％）和阻尼能力（50％）。这种增强效应可以通过CNT海绵的形态来控制，因为硼掺杂和未掺杂的纳米复合材料显示出不同的粘弹性行为。结果表明，CNT海绵增强在开发具有优异机械刚度和可控粘弹性能的工程复合材料方面具有潜力。

Quantum dots (QDs) luminescent films are extensively applied to optoelectronics and optical devices. However, QDs aggregation results in the quenching of their fluorescence property which limits their practical applications to a greater extent. In order to resolve this issue, 3-mercaptopropionic acid (3-MPA) functionalized Cadmium Tellurium (CdTe) QDs were stabilized by silk fibroin (SB) and co-assembled with layered doubled hydroxide (LDH) to form (QDs@SF/LDH)n ultrathin films (UTFs) via the layer-by-layer (LBL) technique. UV-Vis absorption and fluorescence spectroscopy showed a stepwise and normal growth of the films upon increasing the number of deposition cycles. XRD and AFM studies confirmed the formation of a periodic layered structure and regular surface morphology of the thin films. As compared to (CdTe QDs/LDH)nUTFs, the (CdTe QDs@SF/LDH)nUTFs displayed fluorescence enhancement and longer fluorescent lifetime, both in solid states and aqueous solutions. Furthermore compared with the solution state, the fluorescence enhancement of SF-RC and SF-β are, respectively, 7 times and 17 times in the (CdTe QDs@SF/LDH)n UTFs, indicating that the LDH nanosheets favor the fluorescence enhancement effect on the CdTe QDs@SF. The fabricated materials displayed fluorescence response to a biological molecule such as immune globulin, lgG. Thus, the (CdTe QDs@SF/LDH)n UTFs has a potential to be used as biosensor.

量子点（QDs）发光薄膜广泛应用于光电子和光学器件。然而，QDs聚集导致其荧光性质的猝灭，限制了它们在更大范围的实际应用。为了解决这个问题，丝素蛋白（SB）被用于稳定3-巯基丙酸（3-MPA）功能化的碲化镉（CdTe）量子点，并借助逐层（LBL）技术与层状双氢氧化物（LDH）共同组装形成了(QDs @ SF / LDH)n超薄薄膜（UTFs）。UV-Vis吸收和荧光光谱表明，随着逐层沉积循环次数的增加，薄膜逐步正常生长。XRD和AFM研究证实了薄膜的周期性层状结构和规则表面形貌。与(CdTe QDs / LDH)nUTFs相比，(CdTe QDs @ SF / LDH)nUTFs在固态和水溶液中均显示出荧光增强和更长的荧光寿命。此外，与溶液状态相比，(CdTe QDs @ SF / LDH)nUTFs中SF-RC和SF-β的荧光增强分别为7倍和17倍，表明LDH纳米片有利于CdTe QDs @ SF的荧光增强。所制备的材料对生物分子（例如免疫球蛋白，lgG）显示出荧光响应。因此，(CdTe QDs @ SF / LDH)nUTFs有望被用作生物传感器。