Enhanced Thermal Conductivity of 5A Molecular Sieve with BNs Segregated Structures

5A molecular sieves have been widely used as adsorbents in cryogenic distillation for hydrogen isotope separation in fusion reactor engineering, but its low thermal conductivity is detrimental to the process stability. Improving the thermal conductivity of 5A molecular sieves is one of the most important goals for high‐performance devices. Here, firm segregated structures with boron nitride sheets (BNs) are constructed around 5A molecular sieve particles. SEM results show 30 µm BNs tend to form the better networks in comparison with that of 0.12 µm BNs at 40 wt% loadings. It is further verified that BNs with the larger size promote the thermal conductivity. Meanwhile, the thermal conductivity increases with the increasing amounts of BNs. XRD and specific surface area results indicate that the sintering and the addition of BNs exert negligible effects on the structure of 5A molecular sieve. These results indirectly show 5A molecular sieve with BNs segregated structures is very likely to be used for the application of hydrogen isotopic separation. Besides, this work provides new insight into the construction of segregated structure in inorganic porous materials.

     

Modulating the Surface State of SiC to Control Carrier Transport in Graphene/SiC

Silicon carbide (SiC) with epitaxial graphene (EG/SiC) shows a great potential in the applications of electronic and photoelectric devices. The performance of devices is primarily dependent on the interfacial heterojunction between graphene and SiC. Here, the band structure of the EG/SiC heterojunction is experimentally investigated by Kelvin probe force microscopy. The dependence of the barrier height at the EG/SiC heterojunction to the initial surface state of SiC is revealed. Both the barrier height and band bending tendency of the heterojunction can be modulated by controlling the surface state of SiC, leading to the tuned carrier transport behavior at the EG/SiC interface. The barrier height at the EG/SiC(000‐1) interface is almost ten times that of the EG/SiC(0001) interface. As a result, the amount of carrier transport at the EG/SiC(000‐1) interface is about ten times that of the EG/SiC(0001) interface. These results offer insights into the carrier transport behavior at the EG/SiC heterojunction by controlling the initial surface state of SiC, and this strategy can be extended in all devices with graphene as the top layer.     

Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotential of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. This increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.

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Layered double hydroxides with atomic-scale defects for superior electrocatalysis

Atomic composition tuning and defect engineering are effective strategies toenhance the catalytic performance of multicomponent catalysts by improvingthe synergetic effect; however, it remains challenging to dramatically tune the active sites on multicomponent materials through simultaneous defect engineeringat the atomic scale because of the similarities of the local environment. Herein,using the oxygen evolution reaction (OER) as a probe reaction, we deliberatelyintroduced base-soluble Zn(II) or Al(III) sites into NiFe layered double hydroxides(LDHs), which are one of the best OER catalysts. Then, the Zn(II) or Al(III) siteswere selectively etched to create atomic M(II)/M(III) defects, which dramaticallyenhanced the OER activity. At a current density of 20 mA·cm^?2, only 200 mV overpotential was required to generate M(II) defect-rich NiFe LDHs, which is the best NiFe-based OER catalyst reported to date. Density functional theory(DFT) calculations revealed that the creation of dangling Ni–Fe sites (i.e., unsaturated coordinated Ni–Fe sites) by defect engineering of a Ni–O–Fe site at the atomic scale efficiently lowers the Gibbs free energy of the oxygen evolutionprocess. This defect engineering strategy provides new insights into catalysts atthe atomic scale and should be beneficial for the design of a variety of catalysts.

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Large capacitance and fast polarization response of thin electrolyte dielectrics by spin coating for two-dimensional MoS2 devices

Nano Research - A spin-coating method was applied to obtain thinner and smoother PEO/LiClO4 polymer electrolyte films (EFs) with a lower level of crystallization than those obtained using a...     

Synthesis of ultrathin semicircle-shaped copper nanowires in ethanol solution for low haze flexible transparent conductors

Nano Research - Copper nanowires (CuNWs) are becoming an indispensable item for next-generation transparent optical devices due to their excellent conductivity and transparency. In this work,...     

Erratum to: Charge transfer in graphene/polymer interfaces for CO2 detection

Nano Research - The order of the authors in the original version of this article was unfortunately incorrect on the first page and the first page of the ESM. Instead of Myungwoo Son1, Yusin Pak1,...     

Visible light-driven superoxide generation by conjugated polymers for organic synthesis

Nano Research - Benefiting from their unique delocalized electronic structure, conjugated polymer-based semiconductors are widely applied in the fields of organic electronics, sensors, and...     

异质性和时滞作用下神经元网络的共振动力学

利用参数互异的Fitzhugh-Nagumo神经元构建了含耦合时滞的无标度神经元网络模型,通过数值模拟的方法,提出研究参数异质性和耦合时滞影响下神经元网络的共振动力学.结果发现,当耦合项中不含时滞时,适中的参数异质性能够使得神经元网络对外界弱周期信号的响应达到最优,即适中的参数异质性能够诱导神经元网络的共振响应,而且异质性诱导共振对耦合强度具有鲁棒性.更重要的是,耦合时滞对参数异质性作用下神经元网络的共振特性也有着显著性影响.当时滞约为信号周期的整数倍时,神经元网络能够周期性地出现共振现象,即适当的耦合时滞能够诱导神经元网络的多重共振,而且这种现象在异质性参数的适当范围内都能明显出现.