Metal-organic framework-based single-atom electro-/ photocatalysts: Synthesis, energy applications, and opportunities

Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further development.In the last few years,metal–organic frameworks(MOFs)have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry,tunable morphologies,high porosity,and chemical/thermal stability.From this perspective,this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based(MOF-derived-supported and MOF-supported)SACs.Then,MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments,local electronic structures,spatial distributions,and catalytic/electrochemical reaction mechanisms.This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage,including hydrogen evolution reactions,oxygen evolution reactions,O_(2)/CO_(2)/N_(2) reduction reactions,fuel cells,and rechargeable batteries.Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.

Impact of T_(i)/T_(e )ratio on ion transport based on EAST H-mode plasmas

At the EAST tokamak, the ion temperature(T_(i)) is observed to be clamped around 1.25 keV in electron cyclotron resonance(ECR)-heated plasmas, even at core electron temperatures up to 10 keV(depending on the ECR heating power and the plasma density). This clamping results from the lack of direct ion heating and high levels of turbulence-driven transport. Turbulent transport analysis shows that trapped electron mode and electron temperature gradient-driven modes are the most unstable modes in the core of ECR-heated H-mode plasmas. Nevertheless, recently it was found that the T_(i)/T_(e)ratio can increase further with the fraction of the neutral beam injection(NBI) power, which leads to a higher core ion temperature(Ti0). In NBI heating-dominant H-mode plasmas, the ion temperature gradient-driven modes become the most unstable modes.Furthermore, a strong and broad internal transport barrier(ITB) can form at the plasma core in high-power NBI-heated H-mode plasmas when the T_(i)/T_(e)ratio approaches ~1, which results in steep core Teand Tiprofiles, as well as a peaked neprofile. Power balance analysis shows a weaker Teprofile stiffness after the formation of ITBs in the core plasma region, where Ticlamping is broken,and the core Tican increase further above 2 keV, which is 80% higher than the value of Ticlamping in ECR-heated plasmas. This finding proposes a possible solution to the problem of Ticlamping on EAST and demonstrates an advanced operational regime with the formation of a strong and broad ITB for future fusion plasmas dominated by electron heating.

Improved training framework in a neural network model for disruption prediction and its application on EXL-50

A neural network model with a classical annotation method has been used on the EXL-50tokamak to predict impending disruption.However,the results revealed issues of overfitting and overconfidence in predictions caused by inaccurate labeling.To mitigate these issues,an improved training framework has been proposed.In this approach,soft labels from previous training serve as teachers to supervise the further learning process;this has lead to a significant improvement in predictive model performance.Notably,this enhancement is primarily attributed to the coupling effect of the soft labels and correction mechanism.This improved training framework introduces an instance-specific label smoothing method,which reflects a more nuanced model assessment on the likelihood of a disruption.It presents a possible solution to effectively address the challenges associated with accurate labeling across different machines.

基于工程认证的化工原理教学改革与实践

从培养工程型人才的角度出发,分析并总结了部分高校在化工原理理论与实验教学中存在的主要问题。为满足工程认证的要求,我们针对这些问题进行了教学改革的探讨,分别从理论教学、实验教学和工程意识培养三方面提出了多项行之有效的改革措施。

Strengthening absorption ability of Co-N-C as efficient bifunctional oxygen catalyst by modulating the d band center using MoC

Co-N-C is a promising oxygen electrochemical catalyst due to its high stability and good durability.However,due to the limited adsorption ability improvement for oxygen-containing intermediates,it usually exhibits inadequate catalytic activity with 2-electron pathway and high selectivity of hydrogen peroxide.Herein,the adsorption of Co-N-C to these intermediates is modulated by constructing heterostructures using transition metals and their derivatives based on d-band theory.The heterostructured nanobelts with MoC core and pomegranate-like carbon shell consisting of Co nanoparticles and N dopant(MoC/Co-N-C)are engineered to successfully modulate the d band center of active Co-N-C sites,resulting in a remarkably enhanced electrocatalysis performance.The optimally performing MoC/Co-N-C exhibits outstanding bi-catalytic activity and stability for the oxygen electrochemistry,featuring a high wave-half potential of 0.865 V for the oxygen reduction reaction(ORR)and low overpotential of 370 mV for the oxygen evolution reaction(OER)at 10 mA cm^(-2).The zinc air batteries with the MoC/Co-N-C catalyst demonstrate a large power density of 180 mW cm^(-2)and a long cycling lifespan(2000 cycles).The density functional theory calculations with Hubbard correction(DFT+U)reveal the electron transferring from Co to Mo atoms that effectively modulate the d band center of the active Co sites and achieve optimum adsorption ability with"single site double adsorption"mode.

Boosting practical high voltage lithium metal batteries by butyronitrile in ether electrolytes via coordination, hydrolysis of C≡N and relatively mild concentration strategy

Currently ether solvents have been regarded as the most compatible organic solvents with lithium metal in electrolytes of lithium batteries.However,ether solvents are unstable under high voltage (>4.0 V),and prone to side reactions with nickel-rich high-voltage cathode materials.In this work,a novel dual-solvent electrolyte in ethylene glycol dimethyl ether (DME) and butyronitrile (BN) mixed solvent was designed and fabricated for Li/Li Ni_(0.5)Mn_(0.3)Co_(0.2)O_(2)-based lithium metal batteries.When charged to high voltage4.3 V,the battery cycled in this optimal electrolyte can maintain the capacity at 133.7 m Ah g^(-1) with a retention of 88.84%after 150 cycles at 0.2 C and-10℃.During long-term cycling,the battery also exhibits excellent cycling performance with capacity maintained at about 112.0 m Ah g^(-1) after 500 cycles at 1C and-10℃.BN has strong oxidation resistance and high conductivity,which can inhibit the decomposition of ether solvents under high voltage and improve the low temperature performance of battery effectively.Additionally,the cyano (–C≡N) group in BN molecular has a strong coordination ability with the high-valent metal ions and can mask the active ions on the cathode,correspondingly reducing the corrosion of cathode material by the electrolyte.Moreover,cyano group can participate in the hydrolysis to remove trace amounts of water and acidic by-products such as HF in the electrolyte.Therefore,the boosting effect of butyronitrile for ether solvents can provide a promising strategy for enhancing the performance of high voltage lithium metal batteries for practical industrialization.

Coordination Effect-Promoted Durable Ni(OH)_(2) for Energy-Saving Hydrogen Evolution from Water/ Methanol Co-Electrocatalysis

Electrocatalytic water splitting is a viable technique for generating hydrogen but is precluded from the sluggish kinetics of oxygen evolution reactions(OER).Small molecule oxidation reactions with lower working potentials,such as methanol oxidation reactions,are good alternatives to OER with faster kinetics.However,the typically employed Ni-based electrocatalysts have poor activity and stability.Herein,a novel three-dimensional(3D)-networking Modoped Ni(OH)_(2) with ultralow Ni-Ni coordination is synthesized,which exhibits a high MOR activity of 100 mA cm^(−2) at 1.39 V,delivering 28 mV dec^(−1) for the Tafel slope.Meanwhile,hydrogen evolution with value-added formate co-generation is boosted with a current density of more than 500 mA cm^(−2) at a cell voltage of 2.00 V for 50 h,showing excellent stability in an industrial alkaline concentration(6 M KOH).Mechanistic studies based on density functional the-ory and X-ray absorption spectroscopy showed that the improved performance is mainly attributed to the ultralow Ni-Ni coordination,3D-networking structures and Mo dopants,which improve the catalytic activity,increase the active site density and strengthen the Ni(OH)_(2)3D-networking structures,respectively.This study paves a new way for designing electrocatalysts with enhanced activity and durability for industrial energy-saving hydrogen production.

Synergistic effect of lithiophilic Zn nanoparticles and N-doping for stable Li metal anodes

Li metal is the most ideal anode material for next-generation high energy lithium-ion batteries.The uncontrollable growth of Li dendrites,however,hinders its practical application.Herein,we propose the adoption of Zn nanoparticles uniformly embedded in N-doped carbon polyhedra homogeneously built on carbon cloth(Zn@NC@CC)to prevent the formation of Li dendrites.Based on theoretical calculation and experimental observation,lithiophilic Zn nanoparticles and N-doping inside of the assynthesized Zn@NC play a synergistic role in enhancing the adsorption capacity with Li,thus resulting in uniform Li deposition and complete suppression of Li dendrites.Moreover,the porous N-doped carbon polyhedras uniformly distributed on carbon cloth effectively relieves the volume change of Li upon repeated Li stripping/plating process,which contributes to preserving the structural integrity of the whole electrode and hence enhancing its long-term cycling stability.Benefiting from these synergistic effects,the Li-Zn@NC@CC electrode delivers a prolonged lifespan of over 1200 h at 1 mA cm^(-2) with an areal capacity of 1 mA h cm^(-2) in symmetric cells and high Coulombic efficiencies of 95.4%under an ultrahigh capacity of 12 mA h cm^(-2).Remarkably,Li-Zn@NC@CC//LiFePO_(4) full cells deliver a high reversible capacity of 110.2 mA h g^(-1) at 1 C over 200 cycles.

Unraveling the relationship between Sr stoichiometry in Sr_(x)Fe_(1.5)Mo_(0.5)O_(6)-σ and its catalytic performance for high-temperature CO_(2) electrolysis

The solid oxide electrolytic cell(SOEC)is one of the most promising energy conversion and storage devices,which could convert CO_(2) to CO with high Faradaic efficiency and production rate.However,the lack of active and stable cathode materials impedes their practical applications.Here we focus on the promising perovskite oxide cathode material Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)-σ,with the aim of understanding how A-atom stoichiometry and catalytic performance are linked.We find that increasing the strontium content in the perovskite improves the chemisorption of CO_(2) on its surface,forming a SrCO_(3) phase.This hinders the charge transfer and oxygen exchange processes.Simulta-neously,strontoium segregation to the cathode surface facilitates coking of the surface during CO_(2) electrolysis,which poisons the electrode.Consequently,a small number of Sr deficiencies are optimal for both electrochemical performance and long-term stability.Our results provide new insights for designing high-performance CO_(2) electrolysis cathode materials.

邻里社区如何促进族际融合——国际经验及其启示

邻里社区是国家治理中的最小单元,但其内涵丰富,功能多样,特别是在促进社会融合方面发挥着重要作用。在很多国家,邻里社区都是促进城市族际融合的重要平台。20世纪中叶以来,由于城市族群隔离和冲突问题日益严峻,国外理论界提出通过邻里社区规划建设促进邻里互动和族际融合的相关观点。从实践中看,国外以邻里社区为载体促进城市族际融合的策略包括:加强社区住宅设计和价格的多样性、打造族群混居格局;重视社区交往性空间规划、加强族群间的社会互动和文化表达;组织丰富的社区公共活动、增进跨文化群体间的情感交流;构建共同语言基础、鼓励社区内的文化融合;培育社区志愿组织、增强社区社会支持力度;扶持边缘社区发展、遏制族群分层等。国外城市社区建设的经验表明,无论国家的制度安排和政策设计如何精细和完善,均需要充分重视和发挥社区在促进族际融合方面的独特优势。

区域发展中的“公平观”与中国区域战略的演进

区域发展不平衡是国家经济发展中的普遍现象,政府调控区域发展的目标和手段存在公平和效率的抉择,其主流的公平观受到体制、意识形态的影响。基于后发展国家在效率与公平之间的两难、社会主义国家的“公平”价值观与政策主导性,新中国七十多年区域发展战略体现出从均衡到非均衡再到高质量协调发展的阶段性特点,反映出不同历史时期的区域公平观。党的十八大以来,发挥有为政府与高效市场相结合的制度优势,我国区域发展更加注重制度公平、政策公平、代际公平和共同富裕,走向了更为公平的发展空间。

政治地理视角下的中国式现代化

地理环境作为国家现代化的物质条件,在很大程度上决定着现代化道路的特点:国家地理位置一般被视为影响国家现代化道路的初始条件;国土面积大小影响着国家的现代化进程;人口数量、质量、构成和分布在很大程度上决定着国家产业结构、经济增长能力和现代化道路的特点。人口规模巨大、全体人民共同富裕、物质文明和精神文明相协调、人与自然和谐共生、走和平发展道路的中国式现代化,涵盖了中国主要的政治地理要素。中国式现代化坚持中国共产党领导,是基于政治地理特征的最有效制度安排。展望未来,我们应该合理利用地理优势推进中国式现代化:全面树立政治地理思维,更加突出“党的领导”这一组织制度因素,进一步促进人口结构优化,充分利用海陆兼备的地缘优势,加强国际合作,最终实现第二个百年奋斗目标。

“十三五”时期税收法治建设的成就、问题与展望

2020年是全面建成小康社会和"十三五"规划的收官之年。"十三五"期间,我国税制改革成效显著,税收立法稳步推进,税收征管法治化程度增强,税收法治理念深入人心,税收法治理论体系初成,国际税收法治合作卓有成就。然而,我国税收法治建设依然存在法律体系有待完善、税收司法专业化程度不高、税收法治教育及理论研究有待加强、国际税收法治合作有待深入等问题。为此,展望"十四五",我国应当从提升立法质量出发,制定税法总则、完善税种立法、修订税收程序法,并推动税收司法专业化改革,强化税收法治教育及理论研究,深入开展国际税收法治合作,进而推动我国税收法治建设行稳致远。

In situ redox growth of mesoporous Pd-Cu2O nanoheterostructures for improved glucose oxidation electrocatalysis

Interfaces of metal-oxide heterostructured electrocatalyst are critical to their catalytic activities due to the significant interfacial effects. However, there are still obscurities in the essence of interfacial effects caused by crystalline defects and mismatch of electronic structure at metal-oxide nanojunctions. To deeply understand the interfacial effects, we engineered crystalline-defect Pd-Cu2O interfaces through nonepitaxial growth by a facile redox route. The Pd-Cu2O nanoheterostructures exhibit much higher electrocatalytic activity toward glucose oxidation than their single counterparts and their physical mixture,which makes it have a promising potential for practical application of glucose biosensors.Experimental study and density functional theory(DFT) calculations demonstrated that the interfacial electron accumulation and the shifting up of d bands center of Cu-Pd toward the Fermi level were responsible for excellent electrocatalytic activity. Further study found that Pd(3 1 0) facets exert a strong metaloxide interface interaction with Cu2O(1 1 1) facets due to their lattice mismatch. This leads to the sinking of O atoms and protruding of Cu atoms of Cu2O, and the Pd crystalline defects, further resulting in electron accumulation at the interface and the shifting up of d bands center of Cu-Pd, which is different from previously reported charge transfer between the interfaces. Our findings could contribute to design and development of advanced metal-oxide heterostructured electrocatalysts.

Multi-attribute wearable pressure sensor based on multilayered modulation with high constant sensitivity over a wide range

Flexible pressure sensors capable of monitoring diverse physiological signals and body movements have garnered tremendous attention in wearable electronic devices.Thereinto,high constant sensitivity over a wide pressure range combined with breathability,biocompatibility,biodegradability is pivotal for manufacturing of reliable pressure sensors in practical sensing applications.In this work,inspired by the multilayered structure of skin epidermis,we propose and demonstrate a multi-attribute wearable piezoresistive pressure sensor consisting of multilayered gradient conductive poly(ε-caprolactone)nanofiber membranes composites.In response to externally applied pressure,a layer-by-layer current path is activated inside the multilayered membranes composites,leading to the most salient sensing performance of high constant sensitivity of 33.955 kPa^(−1) within the pressure range of 0–80 kPa.The proposed pressure sensor also exhibits a fast response–relaxation time,a low detection limit,excellent stability,which can be successfully used to measure human physiological signals.Lastly,an integrated sensor array system that can locate objects’positions is constructed and applied to simulate sitting posture monitoring.These results indicate that the proposed pressure sensor holds great potential in health monitoring and wearable electronic devices.

Dual-metal zeolite imidazolate framework for efficient lithium storage boosted by synergistic effects and self-assembly 2D nanosheets

Metal-organic framework materials(MOFs),such as zeolitic imidazolate framework(ZIF),have been widely used in energy storage due to their advantages such as high structural stability,large specific surface,more active sites and skeleton structures.Herein,a novel two-dimensional(2D)Co Cu-ZIF was synthesized by a facile solvothermal method.The as-prepared Co Cu-ZIF nanosheets exhibit an ultrahigh reversible capacity of 2287.4 m Ah/g and remains at 1172.1 m Ah/g after 300 cycles at a current density of 100 m A/g,far better than that of the single Co-ZIF and Cu-ZIF.Additionally,the specific discharge capacity of Co Cu-ZIF nanosheets can maintain at about 590 m Ah/g after 1000 cycles at the current density of 2 A/g.Owing to the synergistic effect of two metals,function of nitrogen in the molecular and selfassembly 2D nanosheets,our research can provide strong support for the practical application of Co Cu-ZIF materials in lithium ion batteries.

Highly elastic cobweb-like SiO/CNF composites with reconstructed heterostructure for high-efficient lithium storage

The silicon-based materials are promising candidates for lithium-ion batteries owing to their high energy density.However,achieving long lifespan under realistic conditions remains a challenge because of the volume expansion and low conductivity.In this work,the highly elastic cobweb-like composite materials consisted by SiO and nanofibers are designed and fabricated for high-efficient lithium storage by ballmilling&electrostatic spinning method.The reconstructed heterostructure and highly elastic nanofibers can simultaneously increase the conductivity and inhibit the"expansion effect"of silicon-based materials.The constructed electrode of n-SiO/CNF delivers an initial capacity of 1700 m Ah/g,and maintains the capacities over 1000 m Ah/g after 100 cycles at the current density of 500 m A/g.Meanwhile,this electrode can give an initial coulombic efficiency over 85%and maintains at 98%in the following charge/discharge processes.Furthermore,it exhibits efficient long-term electrochemical performance,maintaining the capacity at about 1000 m Ah/g at a high current density of 1000 m A/g after 1000 cycles.This work could provide a promising strategy for enhancing the performance of siliconbased composite materials for practical application in lithium-ion batteries.

P2结构层状复合金属氧化物钠离子电池正极材料

目前,碱金属(锂、钠、钾等)离子电池中的锂离子电池已经广泛应用于社会生产生活的各个方面,有力地支撑了社会的自动化、信息化和智能化。然而,由于锂在地壳中的丰度较低,以较高丰度的钠为基础的钠离子电池引起了研究者和社会的广泛关注。其中,正极材料是制约钠离子电池实用化的重要因素之一,人们需要开发出面向实际应用的正极材料。P2结构层状复合金属氧化物钠离子电池正极材料具有资源丰富、制备简单、结构稳定、放电容量高、倍率性能好和循环稳定性较好等优点,获得了研究者的广泛关注,具有实用化前景。这一系列材料由于涉及到多种过渡金属元素的组合,较为复杂。本文针对含单一过渡金属、二元组分过渡金属、三元及以上组分过渡金属的P2结构材料及其优化改性进行了系统性梳理,力求厘清研究脉络,梳理研究思路,并给出了今后发展的方向与预测。P2结构材料的主要问题是提高其初始放电容量,氧还原的应用是解决这一问题的重要方向。此外,优化材料组分及采用具有丰富储量、低成本、高安全性和环境友好性的原材料是进一步降低成本并保护环境的重要研究方向。

Simulation of FY-2D infrared brightness temperature and sensitivity analysis to the errors of WRF simulated cloud variables

This study simulated FY-2 D satellite infrared brightness images based on the WRF and RTTOV models. The effects of prediction errors in WRF micro-and macroscale cloud variables on FY-2 D infrared brightness temperature accuracy were analyzed. The principle findings were as follows. In the T+0–48 h simulation time, the root mean square errors of the simulated brightness temperatures were within the range 10–27 K, i.e., better than the range of 20–40 K achieved previously. In the T+0–24 h simulation time, the correlation coefficients between the simulated and measured brightness temperatures for all four channels were >0.5. The simulation performance of water channel IR3 was stable and the best. The four types of cloud microphysical scheme considered all showed that the simulated values of brightness temperature in clouds were too high and that the distributions of cloud systems were incomplete, especially in typhoon areas. The performance of the THOM scheme was considered best, followed in descending order by the WSM6, WDM6, and LIN schemes. Compared with observed values, the maximum deviation appeared in the range 253–273 K for all schemes. On the microscale, the snow water mixing ratio of the THOM scheme was much bigger than that of the other schemes. Improving the production efficiency or increasing the availability of solid water in the cloud microphysical scheme would provide slight benefit for brightness temperature simulations. On the macroscale, the cloud amount obtained by the scheme used in this study was small. Improving the diagnostic scheme for cloud amount, especially high-level cloud, could improve the accuracy of brightness temperature simulations. These results could provide an intuitive reference for forecasters and constitute technical support for the creation of simulated brightness temperature images for the FY-4 satellite.

Metagenomic next-generation sequencing for pneumocystis jirovecii pneumonia in patients with connective tissue disease

Background:Accurate diagnosis of Pneumocystis jirovecii pneumonia(PJP)is challenging,and the delayed diagnosis of PJP is associated with high mortality in patients with connective tissue disease(CTD).Metagenomic next-generation sequencing(mNGS)technology facilitates etiological diagnosis of various infectious diseases,with promising application in diagnosing PJP.This study aimed to investigate the value of mNGS using bronchoalveolar lavage fluid(BALF)for diagnosing PJP infection.Methods:Data from 55 patients with CTD and suspected pulmonary infection was retrospectively collected and analysed.A PJP group and non-PJP group were formed.The clinical manifestations,laboratory test results,treatment methods,and outcomes were summarized.BALF mNGS results were compared with traditional pathogen tests(TPT)and serum 1,3-beta-D-glucan(BDG)testing.Results:The mean age of PJP patients was 54 years,and 59%(10/17)of the patients were female.A significant difference was found between the average daily dose of prednisone administered to the PJP group and non-PJP group(25 mg vs.16 mg,P<0.001).The PJP group had a significantly higher incidence of dyspnoea(88%[15/17]vs.16%[6/38],P<0.001)and elevated serum BDG level(167.73 vs.30.67 pg/mL,P<0.001).BALF mNGS was more sensitive than both TPT(100%[95%confidence interval{CI}:77.1%-100%]vs.11.8%[95%CI:2.1%-37.7%],P<0.001)and serum BDG(100%[95%CI:77.1%-100%]vs.85.7%[95%CI:42%-99.2%],P<0.001).BALF mNGS was more specific than serum BDG(89.5%[95%CI:74.3%-96.6%]vs.46.7%[95%CI:22.3%-72.6%],P=0.493).Co-infection with cytomegalovirus(CMV)was more common in the PJP patients than in the non-PJP patients(59%[10/17]vs.11%[4/38],respectively,P<0.001).Conclusion:BALF mNGS technology is highly effective for diagnosing PJP in patients with CTD and identifying co-infections.