Catalyst‐Free GaN Nanorods Synthesized by Selective Area Growth

GaN nanorod formation on Ga‐polar GaN by continuous mode metalorganic chemical vapor deposition selective area growth (MOCVD SAG) is achieved under a relatively Ga‐rich condition. The Ga‐rich condition, provided by applying a very low V/III ratio, alters the growth rates of various planes of the defined nanostructure by increasing relative growth rate of the semi‐polar tilted m‐plane {1–101} that usually is the slowest growing plane under continuous growth conditions. This increased growth rate relative to the non‐polar m‐plane {1–100} and even the c‐plane (0001), permits the formation of GaN nanorods with nonpolar sidewalls. In addition, a new growth mode, called the NH₃‐pulsed mode, is introduced, utilizing the advantages of both the continuous mode and the lower growth rate pulsed mode to form nanorods. Finally, nanorods grown under the different growth modes are compared and discussed.     

MoO2/Mo2C Heteronanotubes Function as High‐Performance Li‐Ion Battery Electrode

Instead of carbon, Mo₂C is used to modify the MoO₂ material for the first time. The presence of highly conductive and electrochemical inactive Mo₂C decreases the resistance of the charge transport and enhances the structural stability of MoO₂ nanoparticles upon lithiation and delithiation, ensuring the superior cycling stability and high rate capability of the heteronanotubes. Cycled at 200 and 1000 mA g^?1 for 140 cycles, the discharge capacities of the MoO₂/Mo₂C heteronanotubes remain to be 790 and 510 mAh g^?1, respectively. This work demonstrates the potential of the novel heteronanotubes for application as an electrode material for high‐performance Li‐ion batteries.     

A Bi‐Lineage Conducive Scaffold for Osteochondral Defect Regeneration

Because cartilage and bone tissues have different lineage‐specific biological properties, it is challenging to fabricate a single type of scaffold that can biologically fulfill the requirements for regeneration of these two lineages simultaneously within osteochondral defects. To overcome this challenge, a lithium‐containing mesoporous bioglass (Li‐MBG) scaffold is developed. The efficacy and mechanism of Li‐MBG for regeneration of osteochondral defects are systematically investigated. Histological and micro‐CT results show that Li‐MBG scaffolds significantly enhance the regeneration of subchondral bone and hyaline cartilage‐like tissues as compared to pure MBG scaffolds, upon implantation in rabbit osteochondral defects for 8 and 16 weeks. Further investigation demonstrates that the released Li+ ions from the Li‐MBG scaffolds may play a key role in stimulating the regeneration of osteochondral defects. The corresponding mechanistic pathways involve Li+ ions enhancing the proliferation and osteogenic differentiation of bone mesenchymal stem cells (BMSCs) through activation of the Wnt signalling pathway, as well as Li+ ions protecting chondrocytes and cartilage tissues from the inflammatory osteoarthritis (OA) environment through activation of autophagy. These findings suggest that the incorporation of Li+ ions into bioactive MBG scaffolds is a viable strategy for fabricating bi‐lineage conducive scaffolds that enhance regeneration of osteochondral defects.     

Hierarchical Carbon–Nitrogen Architectures with Both Mesopores and Macrochannels as Excellent Cathodes for Rechargeable Li–O2 Batteries

Lithium–oxygen batteries are attracting more and more interest; however, their poor rechargeability and low efficiency remain critical barriers to practical applications. Herein, hierarchical carbon–nitrogen architectures with both macrochannels and mesopores are prepared through an economical and environmentally benign sol–gel route, which show high electrocatalytic activity and stable cyclability over 160 cycles as cathodes for Li–O₂ batteries. Such good performance owes to the coexistence of macrochannels and mesopores in C–N hierarchical architectures, which greatly facilitate the Li⁺ diffusion and electrolyte immersion, as well as provide an effective space for O₂ diffusion and O₂/Li₂O₂ conversion. Additionally, the mechanism of oxygen reduction reactions is discussed with the N‐rich carbon materials through first‐principles computations. The lithiated pyridinic N provides excellent O₂ adsorption and activation sites, and thus catalyzes the electrode processes. Therefore, hierarchical carbon–nitrogen architectures with both macrochannels and mesopores are promising cathodes for Li–O₂ batteries.     

Modulating Blue Phosphorene by Synergetic Codoping: Indirect to Direct Gap Transition and Strong Bandgap Bowing

The structural and electronic properties of synergistically modified blue phosphorene (BP) is investigated. The inversion and threefold rotational symmetries of BP are broken. The codoping of group IV and VI impurities can turn monolayer BP into direct bandgap semiconductors. The underlying physical mechanism is that group IV and VI impurities tailor the valence band maximum and conduction band minimum, respectively, and move them to Γ. All the bandgaps of monolayer, nanoribbons, and quantum dots of BP can be modulated in a wide range, and the strong bandgap bowing is found. In addition, the Coulomb interactions between the screened impurities are revealed. Lower formation energies indicate the fabricating practicability of synergeticly modified BP. Spin–orbit coupling (SOC) can also be tuned by the introduction of impurities.     

Constructing Conductive Interfaces between Nickel Oxide Nanocrystals and Polymer Carbon Nitride for Efficient Electrocatalytic Oxygen Evolution Reaction

Combining transition metal oxide catalysts with conductive carbonaceous material is a feasible way to improve the conductivity. However, the electrocatalytic performance is usually not distinctly improved because the interfacial resistance between metal oxides and carbon is still large and thereby hinders the charge transport in catalysis. Herein, the conductive interface between poorly conductive NiO nanoparticles and semi‐conductive carbon nitride (CN) is constructed. The NiO/CN exhibits much‐enhanced oxygen evolution reaction (OER) performance than corresponding NiO and CN in electrolytes of KOH solution and phosphate buffer saline, which is also remarkably superior over NiO/C, commercial RuO₂, and mostly reported NiO‐based catalysts. X‐ray photoelectron spectroscopy and extended X‐ray absorption fine structure spectrum reveal that a metallic Ni–N bond is formed between NiO and CN. Density functional theory calculations suggest that NiO and CN linked by a Ni–N bond possess a low Gibbs energy for OER intermediate adsorptions, which not only improves the transfer of charge but also promotes the transmission of mass in OER. The metal–nitrogen bonded conductive and highly active interface pervasively exists between CN and other transition metal oxides including Co₃O₄, CuO, and Fe₂O₃, making it promising as an inexpensive catalyst for efficient water splitting.     

Targeted Synergy between Adjacent Co Atoms on Graphene Oxide as an Efficient New Electrocatalyst for Li–CO2 Batteries

Li–CO₂ batteries are an attractive technology for converting CO₂ into energy. However, the decomposition of insulating Li₂CO₃ on the cathode during discharge is a barrier to practical application. Here, it is demonstrated that a high loading of single Co atoms (≈5.3%) anchored on graphene oxide (adjacent Co/GO) acts as an efficient and durable electrocatalyst for Li–CO₂ batteries. This targeted dispersion of atomic Co provides catalytically adjacent active sites to decompose Li₂CO₃. The adjacent Co/GO exhibits a highly significant sustained discharge capacity of 17 358 mA h g^?1 at 100 mA g^?1 for >100 cycles. Density functional theory simulations confirm that the adjacent Co electrocatalyst possesses the best performance toward the decomposition of Li₂CO₃ and maintains metallic‐like nature after the adsorption of Li₂CO₃.     

Seed‐Induced Vertical Growth of 2D Bi2O2Se Nanoplates by Chemical Vapor Transport

As two‐dimensional (2D) layered materials attract more attention owing to their unique optical, electrical, and thermal properties, there are persistent efforts to grow high‐quality 2D layered materials for fundamental research and device applications. While large‐area 2D layered materials with high crystal quality can be obtained through chemical vapor transport, the strong binding between 2D layered materials and substrates poses a significant challenge for attempts to reveal their intrinsic properties and to use these 2D building blocks for constructing advanced heterostructured devices. Therefore, it would be ideal to grow high‐quality 2D materials with minimized contact and binding with substrate. Through both calculation and experiment, it is demonstrated that by introducing a seed layer at the nucleation stage, the crystallographic disregistry and the corresponding adhesion energy between 2D materials and substrate can be altered, resulting in a change of crystal surface in contact with the substrate, and therefore vertical growth of 2D materials on substrates. As an example, it is demonstrated that with Bi₂O₃ serving as a seed layer, vertical growth of 2D plates of Bi₂O₂Se on mica substrates can be realized. These vertically grown 2D nanoplates of Bi₂O₂Se can be conveniently transferred with their thermal properties investigated for the first time.     

黑曲霉孢子灭活前后红外消光特性

黑曲霉孢子是生物气溶胶的重要组成部分,质量消光系数是研究黑曲霉孢子电磁衰减特性的重要参数。采用压片法测量了灭活前后黑曲霉孢子2.5~15 um 波段的反射光谱,并利用Krames-Kronig(K-K)关系计算了黑曲霉孢子红外波段的复折射率。基于Mie 散射理论求出了灭活前后黑曲霉孢子红外波段的质量消光系数,并对结果进行了分析和讨论。分析结果表明:3~5 um 波段,灭活后平均质量消光系数降低了4.6%,8~14 um 波段,灭活后平均质量消光系数降低了89.5%,由此可知,保持活性对于提高黑曲霉孢子的电磁衰减能力具有重要的意义。