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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Low-temperature solution-processed photovoltaics suffer from low efficiencies because of poor exciton or electron-hole diffusion lengths (typically about 10 nanometers). Recent reports of highly efficient CH3NH3PbI3-based solar cells in a broad range of configurations raise a compelling case for understanding the fundamental photophysical mechanisms in these materials. By applying femtosecond transient optical spectroscopy to bilayers that interface this perovskite with either selective-electron or selective-hole extraction materials, we have uncovered concrete evidence of balanced long-range electron-hole diffusion lengths of at least 100 nanometers in solution-processed CH3NH3PbI3. The high photoconversion efficiencies of these systems stem from the comparable optical absorption length and charge-carrier diffusion lengths, transcending the traditional constraints of solution-processed semiconductors.

https://dr.ntu.edu.sg/bitstream/10220/16761/1/long-range balanced electron- and hole-transport lengths in organic-inorganic ch3nh3pbi3.pdf

Long-Range Balanced Electron- and Hole-Transport Lengths in Organic-Inorganic CH3NH3PbI3

There is still an ongoing effort to search for sustainable, clean and highly efficient energy generation to satisfy the energy needs of modern society. Among various advanced technologies, electrocatalysis for the oxygen evolution reaction (OER) plays a key role and numerous new electrocatalysts have been developed to improve the efficiency of gas evolution. Along the way, enormous effort has been devoted to finding high-performance electrocatalysts, which has also stimulated the invention of new techniques to investigate the properties of materials or the fundamental mechanism of the OER. This accumulated knowledge not only establishes the foundation of the mechanism of the OER, but also points out the important criteria for a good electrocatalyst based on a variety of studies. Even though it may be difficult to include all cases, the aim of this review is to inspect the current progress and offer a comprehensive insight toward the OER. This review begins with examining the theoretical principles of electrode kinetics and some measurement criteria for achieving a fair evaluation among the catalysts. The second part of this review acquaints some materials for performing OER activity, in which the metal oxide materials build the basis of OER mechanism while non-oxide materials exhibit greatly promising performance toward overall water-splitting. Attention of this review is also paid to in situ approaches to electrocatalytic behavior during OER, and this information is crucial and can provide efficient strategies to design perfect electrocatalysts for OER. Finally, the OER mechanism from the perspective of both recent experimental and theoretical investigations is discussed, as well as probable strategies for improving OER performance with regards to future developments.

Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

A clear picture of ultrafast charge carrier dynamics, exciton-phonon interactions and frequency upconverted lasing properties in ZnSe nanowire was established through a comprehensive pump-fluence and temperature dependent two-photon-excitation study

Ultrafast charge carrier dynamics and upconversion lasing from ZnSe nanowires

The main role of inert fillers in polymer electrolytes is to enhance ionic conductivity. However, lithium ions in gel polymer electrolytes (GPEs) conduct in liquid solvent rather than along the polymer chains. So far, the main role of inert fillers in improving the electrochemical performance of GPEs is still unclear. Here, various low-cost and common inert fillers (Al2O3, SiO2, TiO2, ZrO2) are introduced into GPEs to study their effects on Li-ion polymer batteries. It is found that the addition of inert fillers has different effects on ionic conductivity, mechanical strength, thermal stability, and, dominantly, interfacial properties. Compared with other gel electrolytes containing SiO2, TiO2, or ZrO2 fillers, those with Al2O3 fillers exhibit the most favorable performance. The high performance is ascribed to the interaction between the surface functional groups of Al2O3 and LiNi0.8Co0.1Mn0.1O2, which alleviates the decomposition of the organic solvent by the cathode, resulting in the formation of a high-quality Li+ conductor interfacial layer. This study provides an important reference for the selection of fillers in GPEs, surface modification of separators, and cathode surface coating.

Inert Filler Selection Strategies in Li-Ion Gel Polymer Electrolytes.

There has been increasing interest in intentional synthesis of nanowires and nanotubes based on a large variety of materials. A deeper understanding of their properties and a sufficient growth control are in the center of current research interest. Strategies for position-controlled and nano-patterned growth of nanowire arrays are demonstrated by selected examples of our work based on ZnO nanowires as well as discussed in terms of larger scale realization and future industrial prospects. The physical properties of single ZnO nanowires are presented on selected examples. Recently, we demonstrated one-dimensional free-standing spinel nanotubes which were transformed from nanowires via the Kirkendall effect and solid state reaction. The nanoscale Kirkendall effect provides a general fabrication route to hollow nanostructures, including high aspect ratio nanotubes. Such ordered arrays of spinel nanotubes may possess similar application potentials as carbon nanotubes.

From Ordered Arrays of Nanowires to Controlled Solid State Reactions

Atomic layer deposition (ALD) ZnO film as seed layer for growing aligned ZnO nanorods arrays is demonstrated. The effects of the deposition temperature and film thickness to the morphology of the ZnO nanorods are studied. The ALD is found to have its advantage over the conventional dip-coating method when being applied to three-dimensional (3D) substrates, as exemplified by the macroporous Si adn CNT arrays. As one example, the CNT-ZnO 3D hybrid nanostructures are obtained which might be useful for energy-related applications.

Hong Jin Fan

Papers

Ultrafast charge carrier dynamics and upconversion lasing from ZnSe nanowires

Inert Filler Selection Strategies in Li-Ion Gel Polymer Electrolytes.

From Ordered Arrays of Nanowires to Controlled Solid State Reactions

Atomic layer deposition ZnO film as seed layer for hydrothermal growth of ZnO nanorods

Title Electrospun Fe2O3-carbon composite nanofibers as durable anode materials for lithium ion batteries