In the past few years, attention has been focused on the research field of one-dimensional nanostructural materials, both because of their fundamental importance and because of the wide range of potential applications in nanodevices.[1±12] Many attempts have been made to fabricate onedimensional nanostructure materials utilizing a variety of nanofabrication techniques and crystal growth methods. [1,5,6,13±20] However, it is still a challenge to synthesize an aligned and well-distributed single-crystal nanowire array. Electrochemical synthesis using a template is one of the most efficient methods for the growth of nanowires because the growth occurs almost exclusively in the direction normal to the substrate surface. [20] In addition, anodic aluminum oxide possesses uniform and nearly parallel porous structures; hence they have been used as an ideal template to produce cylindrical nanowires with a narrow diameter distribution. As CdS is one of the most important II±VI group semiconductors, having vital applications in solar cells and optoelectronic and electronic devices, the AC electrodeposition of CdS nanowires in porous anodic aluminum oxide (AAO) templates has been investigated.[21±23]However, structural studies have demonstrated that large numbers of stacking faults and twinned segments are present in these nanowires. [23] Recently, an aligned CdS singlecrystal nanowire array has been produced using DC electrolysis in AAO templates from a dimethylsulfoxide (DMSO) solution containing cadmium chloride and elemental sulfur.[24] Here we report a new electrochemical process to prepare CdS single-crystal nanowires using electrochemically induced deposition [25] in the pores of an AAO template from an acidic chemical bath containing cadmium chloride and thioacetamide (TAA). The details of the growth of the AAO templates, the deposition of the CdS, and the characterization of the nanowires can be found in the Experimental section. Figure 1a shows a typical transmission electron microscopy (TEM) image of CdS nanowires prepared by electrochemically induced deposition in the AAO template with pore diameters of about 90 nm. It can be seen that the diameter of the nanowires is about 90 nm, which corresponds to the diameter of the pores of the template used. The lengths of the nanowires range from 3 to 5 mm after deposition for 8 h. Figure 1b shows a TEM image of the nanowires deposited in the template with pore diameters of about 20 nm; the uniform diameters of about 20 nm and smooth surfaces are clearly visible. After deposition for 8 h, the length of the nanowire is up to 10 mm, which is 2±3 times as long as the nanowires deposited in a template with pore diameters of 90 nm under the same deposition conditions. This experimental result indicates that the growth rate of the nanowire increases with decreasing pore size of the AAO template.The chemical composition of the nanowires was determined using X-ray energy dispersion analysis (EDAX) and Raman spectroscopy. The EDAX spectrum shown in Figure 2a reveals that the nano...

An array of single crystal CdS nanowires has been fabricated in the pores of an alumina membrane by sol–gel synthesis. The CdS crystals have a hexagonal structure, which is verified by electron diffraction. As CdS is an important semiconducting material this synthesis may prove very useful for the fabrication of nanosized semiconducting structures. The Figure shows a scanning electron microscopy image of the nanowires.

properties and are proved to be potential in the fields of optoelectronics, photonics, biosensing as well as energy conversion and storage. Although centimeter-scale graphene single crystal has been obtained, it is not suitable for electronic switches in traditional transistors due to its semimetallic nature and large dark-current. Even many technologies have been proposed to create the energy bandgap in graphene, the value is remaining too small to realize practical applications. [2] Therefore, scientists are gradually changing the direction of research focusing on 2D materials beyond graphene, such as transition metal dichalcogenides (TMDs), graphitic carbon nitride, MXenes, hexagonal boron nitride (h-BN), hexagonal metal oxide (h-MO), and transition metal oxides (TMOs). As expected, 2D materials can provide a completely suspended surface without dangling bonds, so that the corresponding devices can minimize the influence of various surface states (Figure 1). [3] Benefitting from these excellent features, the 2D transistor can obtain a very low subthreshold swing (SS≈70 mV decade −1 ), which is comparable to the most advanced silicon (Si) transistor. [4] Due to excellent mechanical flexibility and compatibility with low-temperature manufacturing processes, 2D materials are expected to be used in flexible electronic products with plastic substrates. [5][6][7] The use of 2D materials in flexible electronic products can overcome several technical challenges in systems based on traditional materials, such as low mobility (typically below 10 cm 2 v −1 s −1 ), high driving voltage of organic materials, [8,9] complex technological processes, and large leakage current of polycrystalline Si. [10,11] Beyond their excellent electrical properties, 2D materials also exhibit a high degree of flexibility and transparency. Strong covalent bonds in the plane (Figure 1) make the 2D material mechanically robust, resulting in high fracture strains. [12][13][14] Mechanical robustness makes 2D materials suitable for flexible electronic products (Figure 2 reveals the roadmap of 2D materials used in flexible devices) that are subject to mechanical strain and cyclic stress. In addition, their atomic thickness makes them also suitable for transparent electronic products due to their high transparency in the visible range.In this paper, we first introduce the properties and preparation methods of 2D materials beyond graphene. Then, the applications of 2D materials in flexible devices are reviewed.2D materials are now at the forefront of state-of-the-art nanotechnologies due to their fascinating properties and unique structures. As expected, low-cost, high-volume, and high-quality 2D materials play an important role in the applications of flexible devices. Although considerable progress has been achieved in the integration of a series of novel 2D materials beyond graphene into flexible devices, a lot remains to be known. At this stage of their development, the key issues concern how to make further improvements to highperformance and scal...

Constructing graphdiyne-supported transition metal double-atom catalysts to address the challenges of activity and selectivity in the electrochemical nitrogen reduction reaction.