Hierarchically porous Co@N-doped carbon fiber assembled by MOF-derived hollow polyhedrons enables effective electronic/mass transport:An advanced 1D oxygen reduction catalyst for Zn-air battery

Developing advanced oxygen reduction reaction(ORR)electrocatalysts with rapid mass/electron transport as well as conducting relevant kinetics investigations is essential for energy technologies,but both still face ongoing challenges.Herein,a facile approach was reported for achieving the highly dispersed Co nanoparticles anchored hierarchically porous N-doped carbon fibers(Co@N-HPCFs),which were assembled by core-shell MOFs-derived hollow polyhedrons.Notably,the unique one-dimensional(1D)carbon fibers with hierarchical porosity can effectively improve the exposure of active sites and facilitate the electron transfer and mass transfer,resulting in the enhanced reaction kinetics.As a result,the ORR performance of the optimal Co@N-HPCF catalysts remarkably outperforms that of commercial Pt/C in alkaline solution,reaching a limited diffusion current density(J)of 5.85 m A cm^(-2)and a half-wave potential(E_(1/2))of 0.831 V.Particularly,the prepared Co@N-HPCF catalysts can be used as an excellent air-cathode for liquid/solid-state Zn-air batteries,exhibiting great potentiality in portable/wearable energy devices.Furthermore,the reaction kinetic during ORR process is deeply explored by finite element simulation,so as to intuitively grasp the kinetic control region,diffusion control region,and mixing control region of the ORR process,and accurately obtain the relevant kinetic parameters.This work offers an effective strategy and a reliable theoretical basis for the engineering of first-class ORR electrocatalysts with fast electronic/mass transport.

多孔氮化钛载体上铂催化剂的原子层沉积制备及其催化氧气还原性能

为有效解决铂(Pt)催化剂用于氧气还原反应(ORR)面临的催化活性及稳定性问题,本文首先合成了具有良好导电性、电化学稳定以及耐腐蚀等优点的一维多孔氮化钛(Ti N)纳米管载体材料,然后使用原子层沉积技术(ALD)在Ti N载体上沉积制备了Pt催化剂(ALD-Pt/Ti N),所得的Pt纳米颗粒尺寸均匀、高度分散且与Ti N载体之间存在着较强的相互作用。催化氧气还原活性和稳定性测试表明,所得的ALD-Pt/Ti N对ORR具有较高的催化活性,同时兼具良好的稳定性和耐久性。相比商用Pt/C,ALD-Pt/Ti N的起始电位和稳态极限电流密度与其相近,半波电位则高出了20 m V,表现出优异的电催化性能。其优良的电催化性能主要归因于ALD沉积Pt纳米颗粒的高分散性,一维多孔结构Ti N载体的高比表面积、良好导电性和抗腐蚀性能以及ALD-Pt与Ti N载体间较强的相互作用等综合影响。本工作为设计新型高催化活性、高稳定性的Pt基催化剂提供了有益借鉴。

A Method for Mass-rearing Aphidius gifuensis(Hymenoptera: Aphidiidae)

[Objective] This study presents a method for mass rearing of Aphidius gifuensis, a dominant endoparasitoid of Myzus persicae on tobacco in Southwest China. [Method] The tobacco cultivar Honghuadajinyuan(Nicotiana tabacum) was used as the host plant and M. persicae was the host insect. In a greenhouse, tobacco seedlings were reared in plastic trays. The seedlings at three-true-leaf stage were inoculated with two to three aphids per plant using aphid source with a parasitism rate of 47% ±3.9%. [Result] By this inoculation method, the aphids and parasites were simultaneously inoculated on host plants. After approximately 25 d of rearing, we were able to produce 82.5±5.17 aphid mummies per tobacco seedling. A total of 445 500 aphid mummies were produced in one greenhouse(36 rearing trays per greenhouse) during an approximately 50-day rearing period. The emergence rate was 93.4% ±2.76%, and 54% of the mummies were females. [Conclusion] The demonstrated technological feasibility of using tobacco seedlings for the mass rearing of A. gifuensis increases the potential for the biological control of M. persicae.

Expression of Fragaria ananassa Osmotin-like Protein(FaOLP2) in E. coli:Purification and Antifungal Activity

[ Objective] The FaOLtr2 （ Frago^ia ananassa osmotin-like protein） is a functional homolog of PR5-1ike protein. This study was undertaken to produce recombinant FaOLP2 and to identify its antifungal activity. [ Method] The ORF of FaOLP2 （ accession number DQ325524） was cloned into pET22b vector to con- stroct the pET22b-FaOLP2 plasmid. The recombinant mature FaOLP2 was expressed in E. coli Rosetta-gami B （DE3） by inducing with I nunol/L IPTG and found exclusively in insoluble inclusion bodies. As FaOLP2 requires the correct formation of eight disulfide bonds, but there were no obvious effect to correctly form these by expression at different temperatures and high osmotic pressure （ supplemented Betaineand and D-Sorbitol）, we used an in vitro method to refold E. coli expressed FaOLP2 by gradually elution using reduced：oxidized gluthatione redox buffer, followed by 8 mol/L urea solubilized His6-tagged mature FaOLP2 protein, which was affinity-purified by an immobilized-metal （Ni2＋ ） affinity chromatography （IMAC） column. [ Result] This method generated biologically active conformations of the recombinant mature FaOLP2 that displayed antifungal activity against Ustilaginoides virens, a plant pathogenic fungus, which causes rice false smut. [ Conclusion] This study laid the foundation for further biotechnological application of the novel protein.

MoS2-intercalated carbon hetero-layers bonded on graphene as electrode materials for enhanced sodium/potassium ion storage

MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.

Assembly of flower-like VS_(2)/N-doped porous carbon with expanded(001)plane on rGO for superior Na-ion and K-ion storage

VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).