Research progress of bionic fog collection surfaces based on special structures from natural organisms.

With the increasing shortage of water resources, people are seeking more innovative ways to collect fog to meet the growing need for production and the demand for livelihood. It has been proven that fog collection is efficient for collecting water in dry but foggy areas. As a hot research topic in recent years, bionic surfaces with fog collection functions have attracted widespread attention in practical applications and basic research. By studying natural organisms and bionic surfaces, more avenues are provided for the development of fog collection devices. Firstly, starting from biological prototypes, this article explored the structural characteristics and fog collection mechanisms of natural organisms such as spider silk, desert beetles, cactus, Nepenthes and other animals and plants (Sarracenia, shorebird and wheat awn), revealing the fog collection mechanism of the natural organisms based on microstructures. Secondly, based on the theory of interfacial tension, we would delve into the fog collection function's theoretical basis and wetting model, expounding the fog collection mechanism from a theoretical perspective. Thirdly, a detailed introduction was given to prepare bionic surfaces and recently explore fog collection devices. For bionic surfaces of a single biological prototype, the fog collection efficiency is about 2000-4000 mg cm-2 h-1. For bionic surfaces of multiple biological prototypes, the fog collection efficiency reaches 7000 mg cm-2 h-1. Finally, a critical analysis was conducted on the current challenges and future developments, aiming to promote the next generation of fog collection devices from a scientific perspective from research to practical applications.

Fast polysulfide catalytic conversion and self-repairing ability for high loading lithium-sulfur batteries using a permselective coating layer modified separator.

Li-S batteries are considered as one of the most promising battery systems because of their large theoretical capacity and high energy density. However, the "shuttle effect" of soluble polysulfides and sluggish electrochemical redox kinetics of Li-S batteries could cause a broken electrode structure and poor electrochemical performance. Herein, a high-performance and stable Li-S battery has been demonstrated by employing organo-polysulfide chain modified acetylene black (ABPS) as the coating layer on the separator. In addition to the traditional advantages of fast electron transport and polysulfide-interception ability of the carbon coating layer, the grafted organo-polysulfide chain endows the ABPS coating layer with permselectivity for lithium ion against polysulfides, electrocatalytic ability for the sluggish redox kinetics and self-repairing ability for the broken electrode. Hence, the battery prepared using an ABPS-coated separator delivers the best cycling performance (970 mA h g-1 at 0.2 C after 100 cycles) and rate performance (805 mA h g-1 at 2 C) as compared to the cells using acetylene black (AB)-coated or Celgard separators. Moreover, the Li-S battery prepared using an ABPS-coated separator exhibits a stable cycling performance at 1 C over 500 cycles with a low degradation of 0.04% per cycle, and a high coulombic efficiency (near 100%). Furthermore, as the sulfur loading was increased to 6.8 mg cm-2, the Li-S battery using the ABPS-coated separator still could deliver a high areal capacity of 6.03 mA h cm-2 with a low electrolyte/sulfur ratio (E/S = 4, µLelectrolyte mgS-1) after 170 cycles. Significantly, ABPS is an effective coating layer material for improving and stabilizing Li-S batteries.

Photovoltaic Effect in BiFeO3 Film Deposited by RF Magnetron Sputtering.

A polycrystalline BiFeO3 film was deposited on ITO substrate by RF magnetron sputtering method. Small crystallite size and compact structure are obtained for BiFeO3 film which has the excellent ferroelectric properties. The measured photovoltaic response reveals an open-circuit voltage of ~0.52 V and a short-circuit current density of ~10 µA/cm² under the illumination of 100 mW/cm² irradiance. Moreover, a tunable photovoltaic effect with light illumination is observed under different voltage sweep mode. High initial sweep voltage can enhance the photovoltaic effect largely, however, the photovoltaic response decreases with the increase of voltage sweep interval. The results indicate the ferroelectric polarization plays an important role in the photovoltaic effect.

Improved Photovoltaic Effect of p-i-n Structured BiFeO3 Film Deposited by Radio-Frequency Magnetron Sputtering.

Pure phase polycrystalline BiFeO3 film was deposited onto FTO substrate by RF magnetron sputtering method. SEM result shows that BiFeO3 film has the obvious porosity and large clusters which lead to the poor ferroelectric and photovoltaic properties in FTO/BiFeO3/Ag device. However, these properties are improved in p-i-n structured FTO/TiO2/BiFeO3/HTM/Ag device by incorporating the electron and hole transport materials. The hysteresis loop measurement demonstrates the excellent ferroelectric property with large remnant polarization (2Pr = 180 µC/cm²) and low leakage current. The J-V curve shows the short-circuit current density is dozens of times larger than that of FTO/BiFeO3/Ag device. Moreover, the photovoltaic output depends on the poling field where the positive poling improves the short-circuit current density to -85 µA/cm2 and the negative poling reduces both the photocurrent and photovoltage. It is believed that the ferroelectric polarization plays a dominant role in the photovoltaic effect.

Geometry and stability of Cu(n)N (n=1-6) and Cu(3n)N(n) (n=1-5) clusters.

The gradient-corrected density functional calculation is applied to search the lowest-energy configurations of Cu(n)N (n=1-6) clusters and the calculation indicated that Cu(3)N cluster is the most stable one. Based on the result, we further investigate the equilibrium geometries and stabilities of the Cu(3n)N(n) (n=2-5) clusters. We found that in Cu(6)N(2) cluster, N atoms formed a separate N(2) molecule away from the other part of the cluster. Furthermore, it was shown that the lowest-energy configurations of Cu(3n)N(n) (n=3-5) are stable with the nitrogen atoms well separated by the copper atoms. Therefore, it can be concluded that the Cu(3)N cluster can be used as a building block for the construction of the cluster-assembled compounds.

Oxide Neuromorphic Transistors Gated by Polyvinyl Alcohol Solid Electrolytes with Ultralow Power Consumption.

Neuromorphic devices and systems with ultralow power consumption are important in building artificial intelligent systems. Here, indium tin oxide (ITO)-based oxide neuromorphic transistors are fabricated using poly(vinyl alcohol) (PVA)-based proton-conducting electrolytes as gate dielectrics. The electrical performances of the transistors can be modulated with the ITO channel thickness. Fundamental synaptic functions, including excitatory postsynaptic current, paired-pulse facilitation, and multistore memory, are successfully emulated. Most importantly, the PVA-gated neuromorphic devices demonstrate ultralow energy consumption of ∼1.16 fJ with ultrahigh sensitivity of ∼5.4 dB, as is very important for neuromorphic engineering applications. Because of the inherent environmental-friendly characteristics of PVA, the devices possess security biocompatibility. Thus, the proposed PVA-gated oxide neuromorphic transistors may find potential applications in "green" ultrasensitive neuromorphic systems and efficient electronic biological interfaces.

Raman enhancement by graphene-Ga2O3 2D bilayer film.

2D ß-Ga2O3 flakes on a continuous 2D graphene film were prepared by a one-step chemical vapor deposition on liquid gallium surface. The composite was characterized by optical microscopy, scanning electron microscopy, Raman spectroscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy (XPS). The experimental results indicate that Ga2O3 flakes grew on the surface of graphene film during the cooling process. In particular, tenfold enhancement of graphene Raman scattering signal was detected on Ga2O3 flakes, and XPS indicates the C-O bonding between graphene and Ga2O3. The mechanism of Raman enhancement was discussed. The 2D Ga2O3-2D graphene structure may possess potential applications.

Enhanced high-rate performance of double-walled TiO2-B nanotubes as anodes in lithium-ion batteries.

Curled up: TiO(2)-B nanotubes with two curled layers are successfully prepared by a facile hydrothermal route and subsequent calcination. The two curled layers produce a thin wall, and thus the obtained double-walled structure results in short distances of electron and lithium-ion transport, thereby leading to an improved high-rate performance.