Double spatial confinement on ruthenium nanoparticles inside carbon frameworks as durable catalysts for a quasi-solid-state Li–O_(2) battery

The rational design of large-area exposure,nonagglomeration,and longrange dispersion of metal nanoparticles(NPs)in the catalysts is critical for the development of energy storage and conversion systems.Little attention has been focused on modulating and developing catalyst interface contact engineering between a carbon substrate and dispersed metal.Here,a highly dispersed ultrafine ruthenium(Ru)NP strategy by double spatial confinement is proposed,that is,incorporating directed growth of metal–organic framework crystals into a bacterial cellulose templating substrate to integrate their respective merits as an excellent electrocatalytic cathode catalyst for a quasi-solid-state Li–O_(2) battery.The porous carbon matrix with highly dispersed ultrafine Ru NPs is well designed and used as cathode catalysts in a Li–O_(2) battery,demonstrating a high discharge areal capacity of 6.82 mAh cm^(–2) at 0.02 mA cm^(–2),a high-rate capability of 4.93 mAh cm^(–2) at 0.2 mA cm^(–2),and stable discharge/charge cycling for up to 500 cycles(2000 h)with low overpotentials of~1.4 V.This fundamental understanding of the structure–performance relationship demonstrates a new and promising approach to optimize highly efficient cathode catalysts for solid-state Li–O_(2) batteries.

Run-Time Dynamic Resource Adjustment for Mitigating Skew in MapReduce

MapReduce is a widely used programming model for large-scale data processing.However,it still suffers from the skew problem,which refers to the case in which load is imbalanced among tasks.This problem can cause a small number of tasks to consume much more time than other tasks,thereby prolonging the total job completion time.Existing solutions to this problem commonly predict the loads of tasks and then rebalance the load among them.However,solutions of this kind often incur high performance overhead due to the load prediction and rebalancing.Moreover,existing solutions target the partitioning skew for reduce tasks,but cannot mitigate the computational skew for map tasks.Accordingly,in this paper,we present DynamicAdjust,a run-time dynamic resource adjustment technique for mitigating skew.Rather than rebalancing the load among tasks,DynamicAdjust monitors the run-time execution of tasks and dynamically increases resources for those tasks that require more computation.In so doing,DynamicAdjust can not only eliminate the overhead incurred by load prediction and rebalancing,but also culls both the partitioning skew and the computational skew.Experiments are conducted based on a 21-node real cluster using real-world datasets.The results show that DynamicAdjust can mitigate the negative impact of the skew and shorten the job completion time by up to 40.85%.

State-of-the-art progress in the selective photo-oxidation of alcohols

Photocatalytic oxidation of alcohols has received more and more attention in recent years following the numerous studies on the degradation of pollutants, hydrogen evolution, and CO_(2) reduction by photocatalysis. Instead of the total oxidation of organics in the degradation process, the photo-oxidation of alcohols aims at the selective conversion of alcohols to produce carbonyl/acid compounds. Promising results have been achieved in designing the catalysts and reaction system, as well as in the mechanistic investigations in the past few years. This review summarizes the state-of-the-art progress in the photo-oxidation of alcohols, including the development of photocatalysts and cocatalysts, reaction conditions including the solvent and the atmosphere, and the exploration of mechanisms with scavengers experiment, electron paramagnetic resonance (EPR) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The challenges and outlook for the further research in this field are also discussed.

Defect engineering on constructing surface active sites in catalysts for environment and energy applications

The precise engineering of surface active sites is deemed as an efficient protocol for regulating surfaces and catalytic properties of catalysts.Defect engineering is the most feasible option to modulate the surface active sites of catalysts.Creating specific active sites on the catalyst allows precise modulation of its electronic structure and physicochemical characteristics.Here,we outlined the engineering of several types of defects,including vacancy defects,void defects,dopant-related defects,and defect-based single atomic sites.An overview of progress in fabricating structural defects on catalysts via de novo synthesis or post-synthetic modification was provided.Then,the applications of the well-designed defective catalysts in energy conversion and environmental remediation were carefully elucidated.Finally,current challenges in the precise construction of active defect sites on the catalyst and future perspectives for the development directions of precisely controlled synthesis of defective catalysts were also proposed.

COF-based membranes for liquid phase separation:Preparation,mechanism and perspective

Covalent organic frameworks(COFs)are a new kind of crystalline porous materials composed of organic molecules connected by covalent bonds,processes the characteristics of low density,large specific surface area,adjustable pore size and structure,and easy to functionalize,which have been widely used in the field of membrane separation technology.Recently,there are more and more researches focusing on the preparation methods,separation application,and mechanism of COF membranes,which need to be further summarized and compared.In this review,we primarily summarized several conventional preparation methods,such as two-phase interfacial polymerization,in-situ growth on substrate,unidirectional diffusion method,layer-by-layer assembly method,mixed matrix membranes,and so on.The advantages and disadvantages of each method are briefly summarized.The application potential of COF membrane in liquid separation are introduced from four aspects:dyeing wastewater treatment,heavy metal removal,seawater desalination and oil-water separation.Then,the mechanisms including pore structure,hydrophilic/hydrophobic,electrostatic repulsion/attraction and Donnan effect are introduced.For the efficient removal of different kind of pollutions,researchers can select different ligands to construct membranes with specific pore size,hydrophily,salt or organic rejection ability and functional group.The ideas for the design and preparation of COF membranes are introduced.Finally,the future direction and challenges of the next generation of COF membranes in the field of separation are prospected.

Covalent Organic Framework with Predesigned Single-Ion Traps for Highly Efficient Palladium Recovery from Wastes

The recovery of palladium from waste streams is of importance for metal recycling and environmental remediation.Herein,we present a“single-ion trap”strategy for efficiently recovering Pd(II)from superacidic solutions and laboratory wastes.This was realized by rational design and synthesis of an antiparallel stacked covalent organic framework(ACOF)with hydrazine-carbonyl sites and pyridine sites for cooperative Pd(II)capture.The single-ion traps provided Lewis base sites with a high Pd(II)binding affinity,enabling the trapping of Pd(II)ions under a wide range of conditions.The developed ACOF-1 adsorbent demonstrated fast kinetics,excellent selectivity,and a high adsorption capacity of 412.9±14.2 mg/g for Pd(II)in a 3M HNO_(3) solution.When applied in a packed column,ACOF-1 dynamically captured Pd(II)from3M HNO_(3) solutions or laboratorywastes containing trace amounts of palladium and many other metals,realizing extraction efficiencies of 232.9 and 320.9 mg/g,respectively.Detailed experimental and theoretical studies revealed that the single-ion traps offered exceptionally strong binding of Pd(II)under both acidic and high ionic strength conditions,enabling selective adsorptive behavior not accessible using traditional adsorbents.Importantly,the general design strategy reported here could be used to create porous adsorbents for the capture of other precious metals.

Americium/lanthanide separation enabled by a distinct polyoxometalate cluster

Nuclear energy is viewed as a low carbon-emission electricity-generating technology with high-energy density,which has attracted extensive attention and shown broad development prospects[1].However,to ensure sustainability and cleanability in the development of nuclear energy,one crucial challenge is to exploit efficient and economical technologies to simultaneously recover fissionable nuclides from nuclear waste and separate long-lived toxic fission products[2].

Optimizing iodine capture performance by metal-organic framework containing with bipyridine units

Radioactive iodine exhibits medical values in radiology,but its excessive emissions can cause environmental pollution.Thus,the capture of radioiodine poses significant engineering for the environment and medical radiology.The adsorptive capture of radioactive iodine by metal-organic frameworks(MOFs)has risen to prominence.In this work,a Th-based MOF(denoted as Th-BPYDC)was structurally designed and synthesized,consisting of[Th_(6)(μ_(3)-O)_(4)(μ_(3)-OH)_(4)(H_(2)O)6]^(12+)clusters,abundant bipyridine units,and large cavities that allowed guest molecules diffusion and transmission.Th-BPYDC exhibited the uptake capacities of 2.23 g·g^(-1) and 312.18 mg·g^(-1) towards I_(2) vapor and I_(2) dissolved in cyclohexane,respectively,surpassing its corresponding analogue Th-UiO-67.The bipyridine units boosted the adsorption performance,and Th-BPYDC showed good reusability with high stability.Our work thus opened a new way for the synthesis of MOFs to capture radioactive iodine.

Recent progress of covalent organic frameworks membranes:Design,synthesis,and application in water treatment

To date,significant efforts have been devoted to eliminating hazardous components to purify wastewater through the development of various nanomaterials.Covalent organic frameworks(COFs),an important branch of the porous crystalline family,possess the peculiarity of ultrahigh surface area,adjustable pore size,and facile functionality.Exciting studies from design fabrication to potential applications in water treatment by COF-based membranes(COMs)have emerged.This review summarizes various preparation strategies and synthesis mechanisms for COMs,including layer-by-layer stacking,in situ growth,interfacial polymerization,and electrochemical synthesis,and briefly describes the advanced characterization techniques for COMs.Moreover,the application of COMs in heavy metal removal,dye separation,purification of radionuclides,pollutant detection,sea water desalination,and so on,is described and discussed.Finally,the perspectives on future opportunities for designing COMs in water purification have been proposed.

Selective capture and separation of xenon and krypton using metal organic frameworks: a review

Xenon and krypton are widespread useful noble gases in commercial lighting, lasers, electronics, and medical industry. At the same time, radioactive noble gases may proliferate from used nuclear fuel and diffuse in open atmospheres. Metal organic frameworks as hotspot porous materials for gases uptake and separation are considered to be potential solutions. In this review, we comprehensively summarized recent researches on metal organic frameworks for selective capture and separation of xenon and krypton. Particularly, we followed the aspects of different optimal design strategies, including optimal pore/cage size and geometry, open metal sites, ions (anions and cations), and polar functional groups for enhancing the xenon adsorption and separation performances. Meanwhile, a comparison of each strategy and the mechanisms of xenon/krypton separation were pointed out. The separation of krypton from gases mixtures by dual-bed systems was further discussed. Finally, some existing challenges and opportunities for possible real applications were proclaimed.

Biochar-based materials in environmental pollutant elimination,H_(2) production and CO_(2) capture applications

Biochar and biochar-based materials have been studied extensively in multidisciplinary areas because of their outstanding physicochemical properties.In this review article,biochar and biochar-based materials in the removal of environmental pollutants,hydrogen generation and carbon dioxide capture were summarized and compared.The interaction mechanisms were discussed from the experimental results and characterization analysis.The high porous structures,active surface sites,(co)doping of single metals/nonmetals,and incorporation of metal oxides or other materials improved the high activity of biochar-based materials in their applications.However,there are still some challenges such as:(1)the fact that H_(2) generation with high selectivity or the produced syngas to meet the real application requirement in industrial is the main challenge in H_(2) production;(2)the fact that the selective capture of CO_(2) with high stability,high adsorption capacity and recyclability at low-cost should be considered and focused on;(3)the sorption-(photo)degradation of the organic chemicals;and(4)the fact that the sorption-reduction-extraction/solidification of metals/radionuclides are efficient methods for the elimination of environmental pollutants.In the end,the perspectives,challenges and possible techniques for biochar-based materials’real application in future were described.

Insights into Photothermally Enhanced Photocatalytic U(VI)Extraction by a Step-Scheme Heterojunction

In this work,a CdS/BivO4 step-scheme(S-scheme)heterojunction with self-photothermally enhanced photocatalytic effect was synthesized and applied for efficient U(VI)photoextraction.Characterizations such as transient absorption spectroscopy and Tafel test together confirmed the formation of S-scheme heterojunctions,which allows CdS/BivO_(4) to avoid photocorrosion while retaining the strong reducing capacity of CdS and the oxidizing capacity of BivO_(4).Experimental results such as radical quenching experiments and electron spin resonance show that U(VI)is rapidly oxidized by photoholes/·OH to insoluble UO(OH)2 after being reduced to U(IV)by photoelectrons/·O2,which precisely avoids the depletion of electron sacrificial agents.The rapid recombination of electron-hole pairs triggered by the S-scheme heterojunction is found to release large amounts of heat and accelerate the photocatalysis.This work offers a new enhanced strategy for photocatalytic uranium extraction and presents a direction for the design and development of new photocatalysts.

Advanced porous materials and emerging technologies for radionuclides removal from Fukushima radioactive water

Japan recently announced the plan to discharge over 1.2 million tons of radioactive water into the Pacific Ocean,which contained hazardous radionuclides such as^(60)Co,^(90)Sr,^(125)Sb,^(129)I,^(3)H,^(137)Cs,and^(99)TcO^(4)^(-),etc.The contaminated water will pose an enormous threat to global ecosystems and human health.Developing materials and technologies for efficient radionuclide removal is highly desirable and arduous because of the extreme conditions,including super acidity or alkalinity,high ionic strength,and strong ionizing radiation.Recently,advanced porous material,such as porous POPs,MOFs,COFs,PAFs,etc.,has shown promise of improved separation of radionuclides due to their intrinsic structural advantages.Furthermore,emerging technologies applied to radionuclide removal have also been summarized.In order to better deal with radionuclide contamination,higher requirements for the design of nanomaterials and technologies applied to practical radionuclide removal are proposed.Finally,we call for comprehensive implementation of strategies and strengthened cooperation to mitigate the harm caused by radioactive contamination to oceans,atmosphere,soil,and human health.

Recent progress of radionuclides separation by porous materials

The separation of radionuclides is critical for the sustainable development of nuclear energy. It is urgent to design and prepare functionalized materials for efficient radionuclides separation. Porous materials are considered excellent candidates for the separation of radionuclides under complex conditions due to their high specific surface areas, tunable pore structures and controllable functionalities. In this review, we summarized the design, preparation and functionalization of porous materials and their application for separation of radionuclides in the past five years, discussed the separation performance and analyzed the structure-activity relationship between various radionuclides and porous materials, and systematically clarified their characterization and mechanism of different type porous materials. We also introduced the detection, irradiation and chemical toxicity of different reflective radionuclides.

Gaussian Process Based Modeling and Control of Affine Systems with Control Saturation Constraints

Model-based methods require an accurate dynamic model to design the controller.However,the hydraulic parameters of nonlinear systems,complex friction,or actuator dynamics make it challenging to obtain accurate models.In this case,using the input-output data of the system to learn a dynamic model is an alternative approach.Therefore,we propose a dynamic model based on the Gaussian process(GP)to construct systems with control constraints.Since GP provides a measure of model confidence,it can deal with uncertainty.Unfortunately,most GP-based literature considers model uncertainty but does not consider the effect of constraints on inputs in closed-loop systems.An auxiliary system is developed to deal with the influence of the saturation constraints of input.Meanwhile,we relax the nonsingular assumption of the control coefficients to construct the controller.Some numerical results verify the rationality of the proposed approach and compare it with similar methods.

Synthesis of novel nanomaterials and their application in efficient removal of radionuclides

With the development of nuclear energy, large amounts of radionuclides are inevitably released into the natural environment. It is necessary to eliminate radionuclides from wastewater for the protection of environment. Nanomaterials have been considered as the potential candidates for the effective and selective removal of radionuclides from aqueous solutions under complicated conditions because of their high specific surface area, large amounts of binding sites, abundant functional groups, pore-size controllable and easily surface modification. This review mainly summarized the recent studies for the synthesis, fabrication and surface modification of novel nanomaterials and their applications in the efficient elimination and solidification of radionuclides,and discussed the interaction mechanisms from batch experiments, spectroscopy analysis and theoretical calculations. The sorption capacities with other materials, advantages and disadvantages of different nanomaterials are compared, and at last the perspective of the novel nanomaterials is summarized.

Application of graphene oxides and graphene oxide-based nanomaterials in radionuclide removal from aqueous solutions

With the fast development of nanoscience and nanotechnology,the nanomaterials have attracted multidisciplinary interests.The high specific surface area and large numbers of oxygen-containing functional groups of graphene oxides(GOs) make them suitable in the preconcentration and solidification of radionuclides from wastewater.In this paper,mainly based on the recent work carried out in our laboratory,the efficient elimination of radionuclides using GOs and GO-based nanomaterials as adsorbents are summarized and the interaction mechanisms are discussed from the results of batch techniques,surface complexation modeling,spectroscopic analysis and theoretical calculations.This review is helpful for the understanding of the interactions of radionuclides with GOs and GO-based nanomaterials,which is also crucial for the application of GOs and GO-based nanomaterials in environmental radionuclide pollution management and also helpful in nuclear waste management.

Synthesis of rod-like metal-organic framework(MOF-5)nanomaterial for efficient removal of U(Ⅵ):batch experiments and spectroscopy study

With the widespread application of radionuclide ^235U（VI）, it is inevitable that part of U（VI） is released into the natural environment. The potential toxicity and irreversibility impact on the natural environment has become one of the most forefront pollution problems in nuclear energy utilization. In this work, rod-like metal-organic framework （MOF-5） nanomaterial was synthesized by a solvothermal method and applied to efficiently adsorb U（VI） from aqueous solutions. The batch experimental results showed that the sorp- tion of U（Vl） on MOF-5 was strongly dependent on pH and independent of ionic strength, indicating that the dominant interaction mechanism was inner-sphere surface complexation and electrostatic interac- tion. The maximum sorption capacity of U（Vl） on MOF-5 was 237.0 mg]g at pH 5.0 and T = 298 K, and the sorption equilibrium reached within 5 rain. The thermodynamic parameters indicated that the removal of U（VI） on MOF-5 was a spontaneous and endothermic process. Additionally, the FT-IR and XPS analyses implied that the high sorption capacity of U（Vl） on MOF-5 was mainly attributed to the abundant oxygen-containing functional groups （i.e., C-O and C=O）. Such a facile preparation method and efficient removal performance highlighted the application of MOF-5 as a candidate for rapid and efficient radionuclide contamination＇s elimination in practical applications.

Formation flight of fixed-wing UAV swarms:A group-based hierarchical approach

This paper investigates a formation control problem of fixed-wing Unmanned Aerial Vehicle(UAV) swarms. A group-based hierarchical architecture is established among the UAVs, which decomposes all the UAVs into several distinct and non-overlapping groups. In each group, the UAVs form hierarchies with one UAV selected as the group leader. All group leaders execute coordinated path following to cooperatively handle the mission process among different groups, and the remaining followers track their direct leaders to achieve the inner-group coordination. More specifically, for a group leader, a virtual target moving along its desired path is assigned for the UAV, and an updating law is proposed to coordinate all the group leaders’ virtual targets;for a follower UAV, the distributed leader-following formation control law is proposed to make the follower’s heading angle coincide with its direct leader, while keeping the desired relative position with respect to its direct leader. The proposed control law guarantees the globally asymptotic stability of the whole closed-loop swarm system under the control input constraints of fixed-wing UAVs. Theoretical proofs and numerical simulations are provided, which corroborate the effectiveness of the proposed method.

One-pot synthesis of graphene oxide and Ni-Al layered double hydroxides nanocomposites for the efficient removal of U(VI) from wastewater

Graphene oxide and Ni-Al layered double hydroxides(GO@LDH) nanocomposites were synthesized via a one-pot hydrothermal process,and characterized by X-ray diffraction(XRD),Fourier transformed infrared spectroscopy(FTIR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy in detail.The exploration of U(VI) sorption on GO@LDH surface was performed as a function of ionic strength,solution pH,contact time,U(VI) initial concentrations and temperature.Results of Langmuir isotherms showed that the sorption capacity of GO@LDH(160 mg/g) was much higher than those of LDH(69 mg/g) and GO(92 mg/g).The formed surface complexes between surface oxygen-containing functional groups of GO@LDH and U(VI) turned out to be the interaction mechanism of U(VI) with GO@LDH.According to the thermodynamic studies results,the sorption interaction was actually a spontaneous and endothermic chemical process.The sorption isotherms were better fitted with the Langmuir model compared with other models,which suggested the interaction was mainly dominated by mono layer coverage.The GO@LDH nanocomposites provide potential applications as adsorbents in the enrichment of radionuclides from wastewater in nuclear waste management and environmental remediation.