Multiscale confinement nitridation in molybdenum carbide for efficient hydrogen production

The molybdenum carbide(Mo_(2)C)has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction(HER)by the virtue of its Pt-like electronic structures.However,the inherent limitation of high density of empty valence band significantly reduces its catalytic reactivity by reason of strong hydrogen desorption resistance.Herein,we propose a multiscale confinement synthesis method to design the nitrogen-rich Mo_(2)C for modulating the band structure via decomposing the pre-coordination bonded polymer in a pressure-tight tube sealing system.Pre-bonded c/N-Mo in the coordination precursor constructs a micro-confinement space,enabling the homogeneous nitrogenization in-situ happened during the formation of Mo_(2)C.Simultaneously,the evolved gases from the precursor decomposition in tube sealing system establish a macro-confinement environment,preventing the lattice N escape and further endowing a continuous nitridation.Combining the multiscale confinement effects,the nitrogen-rich Mo2C displays as high as 25%N-Mo concentration in carbide lattice,leading to a satisfactory band structure.Accordingly,the constructed nitrogen-rich Mo_(2)C reveals an adorable catalytic activity for HER in both alkaline and acid solution.It is anticipated that the multiscale confinement synthesis strategy presents guideline for the rational design of electrocatalysts and beyond.

Optimization of Training Program for Land Resource Management Major under the Background of Urban and Rural Integration

With constant deepening of development outlook of urban and rural integration,education circle starts to attach great importance to reform of personnel training program.Since scarcity of land resource and key role of land management in urban and rural integration,it is urgent to optimize the personnel training program for land resource management major.From aspects of optimum objectives,principles,program and implementation effect,this paper discusses training program for land resource management major under the background of urban and rural integration.It is expected to provide reference for cultivating land resource management personnel suitable for development of urban and rural integration.

Characteristic Training Modes of Land Resources Management Major in Universities of Finance and Economics

With the development of the society,the undergraduates training modes of land resources management major have diversified developed.The land resources management majors in universities with different background have various features in China.Chongqing Technology and Business University was taken as a typical finance and economics university in this study.And the features,including training mode,feature training scheme and training effect of land resources management major,were discussed systematically.The results provide reference for the building of land resources management major in other colleges.

氢键有机框架材料在电化学能源存储和转换中的研究进展

作为一种新型的多孔材料,氢键有机框架(hydrogen-bonded organic frameworks,HOFs)结构因其丰富的孔道分布、可控的晶体构型以及易于调节的分子组成而表现出诸多优异的电化学特性,如快速的离子传输、特异性的离子筛分、可观的电化学活性面积、高暴露的催化活性位点等.这些特性促使研究者越来越多地关注其在电化学能源存储和转换技术中的应用,是能源领域研究的前沿和热点.尽管这些HOFs相关材料的结构和组成各不相同,总体上却可以分为HOFs和HOFs衍生物两大类.本文详细地介绍了HOFs及其衍生物作为电极材料或电催化剂在电化学领域,包括可充电离子电池、电化学超级电容器、电催化析氢、电催化析氧和氧还原反应中的应用原理与最新研究进展.在此基础上,重点阐述了HOFs相关材料的纳米形貌、晶体结构、孔道结构和分子组成对其电化学性能的影响,总结了克服HOFs相关材料氢键骨架稳定性和导电性差的相关方法,凝练了它们在该领域发展中的优势和挑战.基于上述讨论,希望对HOFs相关材料在电化学能源存储和转换技术中的发展提供新的研究方向.

Catalytic ozonation in advanced treatment of kitchen wastewater:multi-scale simulation and pilot-scale study

Catalytic ozonation is regarded as a promising technology in the advanced treatment of refractory organic wastewater.Packed-bed reactors are widely used in practical applications due to simple structures,installation and operation.However,mass transfer of packed-bed reactors is relatively restrained and amplified deviations usually occurred in scale-up application.Herein,a multi-scale packed-bed model of catalytic ozonation was established to guide pilot tests.First,a laboratory-scale test was conducted to obtain kinetic parameters needed for modeling.Then,a multi-scale packed-bed model was developed to research the effects of water distribution structure,catalyst particle size,and hydraulic retention time(HRT)on catalytic ozonation.It was found that the performance of packed bed reactor was increased with evenly distributed water inlet,HRT of 60 min,and catalyst diameter of about 3-7 mm.Last,an optimized reactor was manufactured and a pilot-scale test was conducted to treat kitchen wastewater using catalytic ozonation process.In the pilot-scale test with an ozone dosage of 50 mg/L and HRT of 60 min,the packed-bed reactor filled with catalysts I was able to reduce chemical oxygen demand(COD)from 117 to 59 mg/L.The performance of the catalytic ozonation process in the packed-bed reactor for the advanced treatment of actual kitchen wastewater was investigated via both multi-scale simulation and pilot-scale tests in this study,which provided a practical method for optimizing the reactors of treating refractory organic wastewater.

Supramolecular assembly-derived carbon-nitrogen-based functional materials for photo/electrochemical applications: progress and challenges

Supramolecular chemistry during the synthesis of carbon-nitrogen-based materials has recently experienced a renaissance in the arena of photocatalysis and electrocatalysis.In this review,we start with the discussion of supramolecular assemblies-derived carbon-nitrogen-based materials’regulation from the aspect of morphology,chemical composition,and micro/nanostructural control.Afterwards the recent advances of these materials in energy and environment related applications,including degradation of pollutants,water splitting,oxygen reduction reactions,CO_(2) reduction reactions along with organic synthesis are summarized.The correlations between the structural features and physicochemical properties of the carbonnitrogen-based materials and the specific catalytic activity are discussed in depth.By highlighting the opportunities and challenges of supramolecular assembly strategies,we attempt an outlook on possible future developments for highly efficient carbon-based photo/electrocatalysts.

通向闭路水循环的未来市政污水处理新模式

由于自然水资源不足及人口和经济的迅速发展,中国目前正面临着日益严重的水资源短缺危机.在此背景下,市政污水应被重视为一种新兴的淡水资源而非传统意义上的废水.目前,我国市政污水处理普遍采用以活性污泥法为核心的生物处理工艺,然而该工艺面临能耗高、剩余污泥产量大、资源回收率低、温室气体排放多等挑战.污水排放标准日益提高,使污水处理工艺升级改造成为必然.目前,现有工艺的升级改造主要采用在原有生物处理工段基础上叠加深度处理单元,延长了工艺流程,不仅增加了处理系统的复杂性和运行难度,还提高了运行费用、能源消耗和占地面积.未来的市政污水处理应走向何方?本文分析认为,基于厌氧膜生物反应器和反渗透的耦合处理工艺,可将市政污水用于生产高质再生水进行回用,为通向闭路水循环的未来市政污水处理提供了可借鉴的新模式.该工艺不仅可大幅提高污水处理的能源效率,简化工艺流程,降低剩余污泥产量,减少占地面积;同时回用高质再生水,有效缓解城市水资源短缺的压力.吸附法因其经济、高效、快速的优势备受关注,可通过开发具有优良性能的氨氮吸附剂,确保出水中氨氮达高质再生水要求,为耦合工艺的应用提供保障.

One-step ball milling-prepared nano Fe2O3 and nitrogendoped graphene with high oxygen reduction activity and its application in microbial fuel cells

Developing high activity,low-cost and long durability catalysts for oxygen reduction reaction is of great significance for the practical application of microbial fuel cells.The ftill exposure of active sites in catalysts can enhance catalytic activity dramatically.Here,novel Fe-N-doped graphene is successftilly synthesized via a one-step in situ ball milling method.Pristine graphite,ball milling graphene,N-doped graphene and Fe-N-doped graphene are applied in air cathodes,and enhanced performance is observed in microbial fuel cells with graphene-based catalysts.Particularly,Fe-Ndoped graphene achieves the highest oxygen reduction reaction activity,with a maximum power density of 1380±20 mW/m^2 in microbial fUel cells and a current density of 23.8 A/m^2 at-0.16 V in electrochemical tests,which are comparable to commercial Pt and 390%and 640%of those of pristine graphite.An investigation of the material characteristics reveals that the superior performance of Fe-Ndoped graphene results from the full exposure of Fe2O3 nanoparticles,pyrrolic N,pyridinic N and excellent Fe-N-G active sites on the graphene matrix.This work not only suggests the strategy of maximally exposing active sites to optimize the potential of catalysts but also provides promising catalysts for the use of microbial fuel cells in sustainable energy generation.

High-resolution, full-color quantum dot light-emitting diode display fabricated via photolithography approach

Displays play an extremely important role in modern information society,which creates a never-ending demand for the new and better products and technologies.The latest requirements for novel display technologies focus on high resolution and high color gamut.Among emerging technologies that include organic light-emitting diode(OL ED),micro light-emiting diode(micro-LED),quantum dot light-emitting diode(QLED),laser display,holographic display and others,QLED is promising owing to its intrinsic high color gamut and the possibility to achieve high resolution with photolithography approach.However,previously demonstrated photolthography techniques suffer from reduced device performance and color Impurities in subpixels from the process.In this study,we demonstrated a sacrificial layer assisted patterming(SLAP)approach,which can be applied in conjunction with photolithography to fabricate high-resolution,full-colo quantum dot(QD)patterns.In this approach,the negative photoresist(PR)and sacrificial layer(SL)were uilized to determine the pixels for QD deposition,while at the same time the SL helps protect the QD layer and keep it intact(named PR-SL approach).To prove this method's viability for QLED display manufacture,a 500-ppi,full-color passive matrix(PM)-QLED prototype was fabricated via this process.Results show that there were no color impurities in the subpixels,and the PM-QL ED has a high color gamut of 114%National Television Standards Committee(NTSC).To the best of our knowledge,this is the first ull-olor QLED prototype with such a high resolution.We anticipate that this innovative patteming technique will open a new horizon for future display technologies and may lead to a disruptive and innovative change in display industry.

Self-assembled thermosensitive luminescent nanoparticles with peptide-Au conjugates for cellular imaging and drug delivery

A facile and efficient strategy has been developed to fabricate a multifunctional,theranostic anticancer drug delivery platform featuring active targeting,controlled drug release and fluorescence imaging for real-time control of delivery.To this end,thermo sensitive poly(N-isopropyl acrylamide)(PNIPAM)nanospheres are decorated with peptide-Au cluster conjugates as a smart nanomedicine platform.A sophisticated trifunctional peptide is designed to release the anticancer drug doxorubicin(DOX),target cells and reduce Au^3+ions to form luminescent Au cluste rs.Importantly,the peptide-Au cluster moieties are attached to the PNIPAM nanospheres via amide bonds rather than noncovalent interactions,significantly improving their stability in biological medium and drug release efficiency.The in vitro experiments showed that DOX was released in an efficient and controlled manner under physiological conditions.

Advanced 3D nanohybrid foam based on graphene oxide: Facile fabrication strategy, interfacial synergetic mechanism, and excellent photocatalytic performance

Herein,a unique nanohybrid foam was fabricated with titanium dioxide(TiO2)-carbon quantum dots(CQDs)nanoparticles intercalated between graphene oxide(GO)layers via a facile and low-cost solvothermal method.Compared with pure GO foam,the fabricated GO-TiO2-CQDs foam displayed high degradation rate towards methyl orange(MO),methylene blue(MB),and rhodamine B(Rh B),respectively,under the Xenon lamp irradiation.The composite foam can be used for several times and remain a high degradation rate without structural damage.The photochemical property was attributed to the 3D porous structure of GOTiO2-CQDs foam,in which ultrafine hydrogenated TiO2-CQDs nanoparticles were densely anchored on the GO sheets.This paper provides an efficient strategy to tune the charge transport and thus enhance the photocatalytic performance by combining the semi-conductive GO and quantum dots.

Dissolved methane in anaerobic effluent:Emission or recovery?

Various anaerobic processes have been explored for the energy-efficient treatment of municipal wastewater.However,dissolved methane in anaerobic effluent appears to be a barrier towards the energy and carbon neutrality of wastewater treatment.Although several dissolved methane recovery methods have been developed,their engineering feasibility and economic viability have not yet been assessed in a holistic manner.In this perspective,we thus intend to offer additional insights into the cost-benefit of dissolved methane recovery against its emission.

Locally-primitive Arc-transitive lO-Valent Graphs of Square-free Order

In this paper, we present a complete classification for locally-primitive arctransitive graphs which have square-free order and valency 10. The classification involves nine graphs and three infinite families of graphs.

A Novel Electrochemical Reactor for Nitrogen and Phosphorus Recovery from Domestic Wastewater

To separate and concentrate NH4＋ and PO43 from the synthetic wastewater to the concentrated solution through a novel electrochemical reactor with circulated anode and cathode using the difference of the concentration between electrode chamber and middle chamber.In recent years, the research on electrochemical processes have been focused on phosphate and ammonium removal and recovery. Among the wide range of possibilities with regards to electrochemical processes, capacitive deionization （CDI） saves the most energy while at the same time does not have continuity and selectivity. In this study, a new electrochemical reactor with electrolyte cyclic flowing in the electrode chambers was constructed to separate and concentrate phosphate and ammonium continuously and selectively from wastewater, based on the principle of CDI. At the concentration ratio of NaCI solution between the electrode chambers and the middle chamber （r） of 25 to 1, phosphate and ammonium in concentration level of domestic wastewater can be removed and recovered continuously and selectively as struvite. Long-term operation also indicated the ability to continuously repeat the reaction and verified sustained stability. Further, the selective recovery at the certain r could also be available to similar technologies for recovering other kinds of substances.

Erratum to: One-step ball milling-prepared nano Fe2O3 and nitrogen-doped graphene with high oxygen reduction activity and its application in microbial fuel cells

Erratum to:Front.Environ.Sci.Eng.2020,14(2):30 https://doi.org/10.1007/s 11783-019-1209-1 The authors wish to make some corrections as below:(1)Some errors occurred when Fig.5d was exported and the corrected version is shown here.

A mini-microbial fuel cell for voltage testing of exoelectrogenic bacteria

Current methods for testing the electricity generation capacity of isolates are time-and laborconsuming.This paper presents a rapid voltage testing system of exoelectrogenic bacteria called Quickscreen,which is based on a microliter microbial fuel cell(MFC).Geobacter sulfurreducens and Shewanella baltica were used as the model exoelectrogenic bacteria;Escherichia coli that cannot generate electricity was used as a negative control.It was found that the electricity generation capacity of the isolates could be determined within about five hours by using Quickscreen,and that its time was relatively rapid compared with the time needed by using larger MFCs.A parallel,stable,and low background voltage was achieved using titanium as a current collector in the blank run.The external resistance had little impact on the blank run during the initial period.The cathode with a five-hole configuration,used to hydrate the carbon cathode,gave higher cathode potential than that with a one-hole configuration.Steady discharge and current interrupt methods showed that the anode mostly contributed to the large internal resistance of the Quickscreen system.However,the addition of graphite felt decreased the resistance from 18 to 5 kΩ.This device was proved to be useful to rapidly evaluate the electricity generation capacity of different bacteria.