Anisotropic 2D materials exhibit unique optical, electrical, and thermoelectric properties that open up possibilities for diverse angle‐dependent devices. However, the explored anisotropic 2D materials are very limited and the methods to identify the crystal orientations and to study the in‐plane anisotropy are in the initial stage. Here azimuth‐dependent reflectance difference microscopy (ADRDM), angle‐resolved Raman spectra, and electrical transport measurements are used to systematically characterize the influence of the anisotropic structure on in‐plane optical and electrical anisotropy of 2D GeAs, a novel group IV–V semiconductor. It is proved that ADRDM offers a way to quickly identify the crystal orientations and also to directly characterize the in‐plane optical anisotropy of layered GeAs. The anisotropic electrical transport behavior of few‐layer GeAs field‐effect transistors is further measured and the anisotropic ratio of the mobility is as high as 4.6, which is higher than the other 2D anisotropic materials such as black phosphorus. The dependence of the Raman intensity anisotropy on the sample thickness, excitation wavelength, and polarization configuration is investigated both experimentally and theoretically. These data will be useful for designing new high‐performance devices and the results suggest a general methodology for characterizing the in‐plane anisotropy of low‐symmetry 2D materials.

The improved ionic conductivity (1.64 × 10(-4) S cm(-1) at room temperature) and excellent electrochemical stability of nanoporous β-Li3PS4 make it one of the promising candidates for rechargeable all-solid-state lithium-ion battery electrolytes. Here, elastic properties, defect thermodynamics, phase diagram, and Li(+) migration mechanism of Li3PS4 (both γ and β phases) are examined via the first-principles calculations. Results indicate that both γ- and β-Li3PS4 phases are ductile while γ-Li3PS4 is harder under volume change and shear stress than β-Li3PS4. The electrochemical window of Li3PS4 ranges from 0.6 to 3.7 V, and thus the experimentally excellent stability (>5 V) is proposed due to the passivation phenomenon. The dominant diffusion carrier type in Li3PS4 is identified over its electrochemical window. In γ-Li3PS4 the direct-hopping of Lii(+) along the [001] is energetically more favorable than other diffusion processes, whereas in β-Li3PS4 the knock-off diffusion of Lii(+) along the [010] has the lowest migration barrier. The ionic conductivity is evaluated from the concentration and the mobility calculations using the Nernst-Einstein relationship and compared with the available experimental results. According to our calculated results, the Li(+) prefers to transport along the [010] direction. It is suggested that the enhanced ionic conductivity in nanostructured β-Li3PS4 is due to the larger possibility of contiguous (010) planes provided by larger nanoporous β-Li3PS4 particles. By a series of motivated and closely linked calculations, we try to provide a portable method, by which researchers could gain insights into the physicochemical properties of solid electrolyte.

Developing localized climate mitigation strategies needs an understanding of how global consumption drives local carbon dioxide (CO 2) emissions with a fine spatial resolution. There is no study that provides a spatially explicit mapping of global carbon footprint in China-the world's largest CO 2 emitter-simultaneously considering both international and interprovincial trade. Here we map CO 2 emissions in China driven by global consumption in 2012 at a high spatial resolution (10 km × 10 km) using a detailed, firm-level emission inventory. Our results show that the carbon footprints of foreign regions in China are concentrated in key manufacturing hubs, including the Yangtze River Delta, Pearl River Delta, and North China Plain. Approximately 1% of the land area holds 75% of the global carbon footprint in China. The carbon footprint hotspots in China identified are the key places in which collaborative mitigation efforts between China and downstream parties that drive those emissions.

No abstract

Abstract2D material–based photodetectors have demonstrated the great potential in future optoelectric applications and the compatibility with the traditional semiconductor technology. However, low detectivity and difficulty of large‐scale fabrication still limit their application. Here, an ultrasensitive in‐plane lateral graphene–MoS2 heterostructure is successfully constructed using one‐step growth by chemical vapor deposition, which is suitable for large‐scale fabrication. The Schottky junction is formed in the channel with the edge contact of graphene and MoS2. It displays good rectification characteristics with an on/off ratio up to 106. As a photodetector, it exhibits excellent detectivity with the specific detectivity D* up to 1.4 × 1014 Jones and the responsivity of 1.1 × 105 A W−1, which benefit from strong absorption, the efficient separation of the photoexcited carriers, and quick charge transport in the Schottky junction device. Moreover, heterostructure photodetector array is demonstrated here which shows the large‐scale fabrication capacity. All of these results prove the potential of 2D material–based junction devices for optoelectronic devices.

No abstract

No abstract

Photodetectors based on two-dimensional materials have shown impressive performance including fast and broadband photoresponse and high responsivity.