Beihang University

About: Beihang University is a education organization based out in Beijing, China. It is known for research contribution in the topics: Computer science & Control theory. The organization has 67002 authors who have published 73507 publications receiving 975691 citations. The organization is also known as: Beijing University of Aeronautics and Astronautics.

Bioinspired smart asymmetric nanochannel membranes

Abstract: Bioinspired smart asymmetric nanochannel membranes (BSANM) have been explored extensively to achieve the delicate ionic transport functions comparable to those of living organisms. The abiotic system exhibits superior stability and robustness, allowing for promising applications in many fields. In view of the abundance of research concerning BSANM in the past decade, herein, we present a systematic overview of the development of the state-of-the-art BSANM system. The discussion is focused on the construction methodologies based on raw materials with diverse dimensions (i.e. 0D, 1D, 2D, and bulk). A generic strategy for the design and construction of the BSANM system is proposed first and put into context with recent developments from homogeneous to heterogeneous nanochannel membranes. Then, the basic properties of the BSANM are introduced including selectivity, gating, and rectification, which are associated with the particular chemical and physical structures. Moreover, we summarized the practical applications of BSANM in energy conversion, biochemical sensing and other areas. In the end, some personal opinions on the future development of the BSANM are briefly illustrated. This review covers most of the related literature reported since 2010 and is intended to build up a broad and deep knowledge base that can provide a solid information source for the scientific community.

Activating cobalt(II) oxide nanorods for efficient electrocatalysis by strain engineering

Abstract: Designing high-performance and cost-effective electrocatalysts toward oxygen evolution and hydrogen evolution reactions in water-alkali electrolyzers is pivotal for large-scale and sustainable hydrogen production. Earth-abundant transition metal oxide-based catalysts are particularly active for oxygen evolution reaction; however, they are generally considered inactive toward hydrogen evolution reaction. Here, we show that strain engineering of the outermost surface of cobalt(II) oxide nanorods can turn them into efficient electrocatalysts for the hydrogen evolution reaction. They are competitive with the best electrocatalysts for this reaction in alkaline media so far. Our theoretical and experimental results demonstrate that the tensile strain strongly couples the atomic, electronic structure properties and the activity of the cobalt(II) oxide surface, which results in the creation of a large quantity of oxygen vacancies that facilitate water dissociation, and fine tunes the electronic structure to weaken hydrogen adsorption toward the optimum region.

Photo-induced water–oil separation based on switchable superhydrophobicity–superhydrophilicity and underwater superoleophobicity of the aligned ZnO nanorod array-coated mesh films

Abstract: Stimulus-responsive surface wettability, especially photoresponsive surface wettability, has been intensively studied Meanwhile, multifunctional surfaces, especially for the treatment of oil contaminated water, have aroused worldwide attention Recently, pH-responsive surfaces with controllable oil–water separation have also been reported However, photoresponsive water–oil separation is still a challenge Here we report photo-induced water–oil separation based on the switchable superhydrophobicity–superhydrophilicity and underwater superoleophobicity of aligned ZnO nanorod array-coated mesh films, which shows excellent controllability and high separation efficiency of different types of water–oil mixtures in an oil–water–solid three-phase system The underwater superoleophobicity of the aligned ZnO nanorod array-coated stainless steel mesh film can effectively prevent the mesh film from being polluted by oils This work is promising in photo-induced water–oil mixture treatments such as water-removal from a micro-reaction system and controllable filtration, and may also provide interesting insight into the design of novel functional devices based on controllable surface wettability

High thermoelectric performance of oxyselenides: intrinsically low thermal conductivity of Ca-doped BiCuSeO

Abstract: We report on the high thermoelectric performance of p-type polycrystalline BiCuSeO, a layered oxyselenide composed of alternating conductive (Cu2Se2)2− and insulating (Bi2O2)2+ layers. The electrical transport properties of BiCuSeO materials can be significantly improved by substituting Bi3+ with Ca2+. The resulting materials exhibit a large positive Seebeck coefficient of ∼+330 μV K−1 at 300 K, which may be due to the ‘natural superlattice’ layered structure and the moderate effective mass suggested by both electronic density of states and carrier concentration calculations. After doping with Ca, enhanced electrical conductivity coupled with a moderate Seebeck coefficient leads to a power factor of ∼4.74 μW cm−1 K−2 at 923 K. Moreover, BiCuSeO shows very low thermal conductivity in the temperature range of 300 (∼0.9 W m−1 K−1) to 923 K (∼0.45 W m−1 K−1). Such low thermal conductivity values are most likely a result of the weak chemical bonds (Young’s modulus, E∼76.5 GPa) and the strong anharmonicity of the bonding arrangement (Gruneisen parameter, γ∼1.5). In addition to increasing the power factor, Ca doping reduces the thermal conductivity of the lattice, as confirmed by both experimental results and Callaway model calculations. The combination of optimized power factor and intrinsically low thermal conductivity results in a high ZT of ∼0.9 at 923 K for Bi0.925Ca0.075CuSeO. Li-Dong Zhao, Jiaqing He and co-workers have gained insight into the highly thermoelectric properties of a bismuth–copper oxyselenide (BiCuSeO), a polycrystalline, layered compound. BiCuSeO's ability to produce a significant electric potential from a temperature difference, and vice versa, arises from its intrinsically low thermal conductivity, and can be further improved by boosting the material's electrical conductivity through doping with strontium or barium, or introducing copper deficiencies. The researchers have now carried out an extensive characterization of the oxyselenide and propose that its conveniently low thermal conductivity results from the weak chemical bonds that exist between two different kinds of layers, and a particular bonding arrangement, in the material's lattice. Moreover, by substituting bismuth ions (Bi3+) with calcium ions (Ca3+) the thermal conductivity of the lattice could be lowered further, leading to an improvement in the oxyselenide's thermoelectric properties. We report on the promising thermoelectric performance of p-type polycrystalline BiCuSeO, which is a layered oxyselenide composed of conductive (Cu2Se2)2− layers that alternate with insulating (Bi2O2)2+ layers. Electrical transport properties can be optimized by substituting Bi3+ with Ca2+. Moreover, BiCuSeO shows very low thermal conductivity in the temperature ranges of 300 (∼0.9 W m−1K−1) to 923 K (∼0.45 W m−1 K−1). These intrinsically low thermal conductivity values may result from the weak chemical bonds of the material as well as the strong anharmonicity of the bonding arrangement. The combination of the optimized power factor and the intrinsically low thermal conductivity results in a high ZT of ∼0.9 at 923 K for Bi0.925Ca0.075CuSeO.