Advances in cathode materials for Li-O_(2)batteries

Lithium-oxygen(Li-O_(2))batteries have attracted significant attention due to their ultra-high theoretical energy density.However,serious challenges,such as potential lag,low-rate capability,round-trip efficiency,and poor cycle stability,greatly limit their practical application.This review provides a comprehensive account of the development of Li-O_(2)batteries,elucidates the current discharge/charge mechanism,and highlights both the advantages and bottlenecks of this technology.In particular,recent research progress on various cathode materials,such as carbon-based materials,noble metals,and non-noble metals,for Li-O_(2)batteries is deeply reviewed,emphasizing the impact of design strategies,material structures,chemical compositions,and microphysical parameters on oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)kinetics,as well as discharge products and overall battery performance.This review will also shed light on future research directions for oxygen electrode catalysts and material construction to facilitate the development of Li-O_(2)batteries with maximized electrochemical performance.

Synthesis of the Core-Shell Structure Materials as the Controlled-Release Drug Carrier

We have developed a controlled-release drug carrier. Smartly controlled-release polymer nanoparticles were firstly synthesized through RAFT polymerization as the controlled-release core. The structural and particle properties of polymer nanoparticles were characterized by nuclear magnetic resonance spectroscopy (1H-NMR), scanning electron microscope (SEM) and X-ray spectroscopy (EDX). Mesoporous materials were selected as the shell materials to encapsulate the smart core as the stable shell. The mesoporous shell was characterized by transmission electron microscopy (TEM) and scanning electron microscope (SEM). All the results showed that a well-defined core-shell structure with mesoporous structure was obtained, and this controllable delivery system will have the great potential in nanomedicine.

Weaving 3D highly conductive hierarchically interconnected nanoporous web by threading MOF crystals onto multi walled carbon nanotubes for high performance Li-Se battery

Lithium-selenium(Li-Se)battery has attracted growing attention.Nevertheless,its practical application is still impeded by the shuttle effect of the formed polyselenides.Herein,we report in-situ hydrothermal weaving the three-dimensional(3 D)highly conductive hierarchically interconnected nanoporous web by threading microporous metal organic framework MIL-68(Al)crystals onto multi-walled carbon nanotubes(MWCNTs).Such 3 D hierarchically nanoporous web(3 D MIL-68(Al)@MWCNTs web)with a very high surface area,a large amount of micropores,electrical conductivity and elasticity strongly traps the soluble polyselenides during the electrochemical reaction and significantly facilitates lithium ion diffusion and electron transportation.Molecular dynamic calculation confirmed the strong affinity of MIL-68(Al)for the adsorption of polyselenides,quite suitable for Li-Se battery.Their hexahedral channels(1.56 nm)are more efficient for the confinement of polyselenides and for the diffusion of electrolytes compared to their smaller triangular channels(0.63 nm).All these excellent characteristics of 3 D MIL-68(Al)@MWCNTs web with suitable confinement of a large amount of selenium and the conductive linkage between MIL-68(Al)host by MWCNTs result in a high capacity of 453 m Ah/g at 0.2 C with 99.5%coulombic efficiency after 200 cycles with significantly improved cycle stability and rate performance.The 3 D MIL-68(Al)@MWCNTs web presents a good performance in Li-Se battery in term of the specific capacity and cycling stability and also in terms of rate performance compared with all the metal-organic framework(MOF)based or MOF derived porous carbons used in Li-Se battery.

Synergistic effects of carbon doping and coating of TiO_(2) with exceptional photocurrent enhancement for high performance H2 production from water splitting

The"one pot"simultaneous carbon coating and doping of TiO_(2) materials by the hydrolysis of TiCl4 in fructose is reported.The synergistic effect of carbon doping and coating of TiO_(2) to significantly boost textural,optical and electronic properties and photocurrent of TiO_(2) for high performance visible light H2 production from water splitting has been comprehensively investigated.Carbon doping can significantly increase the thermal stability,thus inhibiting the phase transformation of the Titania material from anatase to rutile while carbon coating can suppress the grain aggregation of TiO_(2).The synergy of carbon doping and coating can not only ensure an enhanced narrowing effect of the electronic band gap of TiO_(2) thus extending the absorption of photocatalysts to the visible regions,but also promote dramatically the separation of electron-hole pairs.Owing to these synergistic effects,the carbon coated and doped TiO_(2) shows much superior photocatalytic activity for both degradation of organics and photocatalytic/photoelectro chemical(PEC)water splitting under simulated sunlight illumination.The photocatalytic activity of obtained materials can reach 5,4 and 2 times higher than that of pristine TiO_(2),carbon doped TiO_(2) and carbon coated TiO_(2),respectively in the degradation of organic pollutants.The carbon coated and doped TiO_(2) materials exhibited more than 37 times and hundreds of times photocurrent enhancement under simulated sunlight and visible light,respectively compared to that of pristine TiO_(2).The present work providing new comprehensive understanding on carbon coating and doping effect could be very helpful for the development of advanced TiO_(2) materials for a large series of applications.

Three-dimensional ordered hierarchically porous carbon materials for high performance Li-Se battery

Developing host materials with high specific surface area, good electron conductivity, and fast ion transportation channel is critical for high performance lithium-selenium(Li-Se) batteries. Herein, a series of three dimensional ordered hierarchically porous carbon(3D OHPC) materials with micro/meso/macropores are designed and synthesized for Li-Se battery. The porous structure is tuned by following the concept of the generalized Murray’s law to facilitate the mass diffusion and reduce ion transport resistance.The optimized 3D Se/OHPC cathode exhibits a very high 2 nd discharge capacity of 651 m Ah/g and retains 361 m Ah/g after 200 cycles at 0.2 C. Even at a high current rate of 5 C, the battery still shows a discharge capacity as high as 155 m Ah/g. The improved electrochemical performance is attributed to the synergy effect of the interconnected and well-designed micro, meso and macroporosity while shortened ions diffusion pathways of such Murray materials accelerate its ionic and electronic conductivities leading to the enhanced electrochemical reaction. The diffusivity coefficient in Se/OHPC can reach a very high value of 1.3 × 10^(-11)cm^(2)/s, much higher than those in single pore size carbon hosts. Their effective volume expansion accommodation capability and reduced dissolution of polyselenides ensure the high stability of the battery. This work, for the first time, established the clear relationship between textural properties of cathode materials and their performance and demonstrates that the concept of the generalized Murray’s law can be used as efficient guidance for the rational design and synthesis of advanced hierarchically porous materials and the great potential of 3D OHPC materials as a practical high performance cathode material for Li-Se batteries.

Methyl Halide to Olefins and Gasoline over Zeolites and SAPO Catalysts：A New Route of MTO and MTG

到更有用的更高的烃的甲烷的合理、有效的变换是天然气利用的最重要的话题之一。尽管到珍贵混合物的甲烷激活和它的变换吸引增加的注意，甲烷变换经常为 syngas 通过消费精力的步以间接方法被做从甲烷改过的蒸气的生产。一些有希望的结果看起来为从甲烷的高增值产品的生产具有为一种选择和潜在的线路的发展的意义。到更高的烃的甲烷的有效变换能作为中介经由甲基卤化物被认识到。在 halomethane 的生产以后，他们能在修改沸石和 SAPO 上被转变到汽油和轻石蜡分子的筛。高变换效率和选择显示了工业申请的可行性。研究在基本研究和工业申请从观点获得了最近成长的兴趣。反应机制上的学习从甲基卤化物使 CC 契约建设的可能的线路清楚些，它是到更高的烃的 C1 反应物变换的重要问题。氢卤化物产生没在反应机制和催化剂的结构稳定性上在甲基卤化物变换期间施加明显的影响。这评论处理这个领域和注释的进化要探索的优点和缺点经由甲基卤化物发送为新、持续的 methane-to-olefins (MTO ) 和 methane-to-gasoline (MTG ) 的开发被阻止。

Mn^(4+) activated phosphors in photoelectric and energy conversion devices

Owing to their high luminous efficiency and tunable emission in both red light and far-red light regions,Mn^(4+)ion-activated phosphors have appealed significant interest in photoelectric and energy conversion devices such as white light emitting diode(W-LED),plant cultivation LED,and temperature thermometer.Up to now,Mn^(4+)has been widely introduced into the lattices of various inorganic hosts for brightly redemitting phosphors.However,how to correlate the structure-activity relationship between host framework,luminescence property,and photoelectric device is urgently demanded.In this review,we thoroughly summarize the recent advances of Mn^(4+)doped phosphors.Meanwhile,several strategies like co-doping and defect passivation for improving Mn^(4+)emission are also discussed.Most importantly,the relationship between the protocols for tailoring the structures of Mn^(4+)doped phosphors,increased luminescence performance,and the targeted devices with efficient photoelectric and energy conversion efficiency is deeply correlated.Finally,the challenges and perspectives of Mn^(4+)doped phosphors for practical applications are anticipated.We cordially anticipate that this review can deliver a deep comprehension of not only Mn^(4+)luminescence mechanism but also the crystal structure tailoring strategy of phosphors,so as to spur innovative thoughts in designing advanced phosphors and deepening the applications.

Bioinspired urchin-like murray carbon nanostructure with protection shell for advanced lithium-sulfur batteries

Commercial application of lithium-sulfur(Li-S) batteries is hindered by the insulating nature of sulfur and the dissolution of polysulfides. Here, a bioinspired 3D urchin-like N-doped Murray's carbon nanostructure(N-MCN) with interconnected micro-meso-macroporous structure and a polydopamine protection shell has been designed as an effective sulfur host for high-performance Li-S batteries. The advanced 3D hierarchically porous framework with the characteristics of the generalized Murray's law largely improves electrolyte diffusion, facilitates electrons/ions transfer and provides strong chemisorption for active species, leading to the synergistic structural and chemical confinement of polysulfides. As a result,the obtained P@S/N-MCN electrode with high areal sulfur loading demonstrates high capacity at high current densities after long cycles. This work reveals that following the generalized Murray's law is feasible to design high-performance sulfur cathode materials for potentially practical Li-S battery applications.

Recent advances in non-metal doped titania for solar-driven photocatalytic/photoelectrochemical water-splitting

Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime goal of carbon neutral. TiO_(2) based photocatalysts with high chemical stability and excellent photocatalytic properties have great potential for solar-to-H_(2) conversion. To conquer the challenges of the large band-gap and rapid recombination of photo generated electron-holepairs in TiO_(2), non-metal doping turns out to be economic, facile, and effective on boosting the visible light activity. The localized defect states such as oxygen vacancy and Ti^(3+) generated by non-metal doping are located in the band-gap of TiO_(2), which result in the reduction of band-gap, thus a red-shift of the absorption edge. The hetero doping atoms such as B^(3+), I^(7+), S^(4+)/S^(6+), P^(5+) can also act as electron donors or trap sites which facilitate the charge carrier separation and suppress the recombination of electron-hole pairs. In this comprehensive review, we present the most recent advances on non-metal doped TiO_(2) photocatalysts in terms of fundamental aspects, origin of visible light activity and the PC / PEC behaviours for water splitting. In particular, the characteristics of different non-metal elements (N, C, B, S, P, Halogens) as dopants are discussed in details focusing on the synthesis approaches, characterization as well as the efficiency of PC and PEC water splitting. The present review aims at guiding the readers who want quick access to helpful information about how to efficiently improve the performance of photocatalysts by simple doping strategies and could stimulate new intuitive into the new doping strategies.

Hydrophilic bi-functional B-doped g-C_(3)N_(4) hierarchical architecture for excellent photocatalytic H_(2)O_(2) production and photoelectrochemical water splitting

Graphitic carbon nitride(g-C_(3)N_(4))has attracted great interest in photocatalysis and photoelectrocatalysis.However,their poor hydrophilicity poses a great challenge for their applications in aqueous environment.Here,we demonstrate synthesis of a hydrophilic bi-functional hierarchical architecture by the assembly of B-doped g-C_(3)N_(4)nanoplatelets.Such hierarchical B-doped g-C_(3)N_(4)material enables full utilization of their highly enhanced visible light absorption and photogenerated carrier separation in aqueous medium,leading to an excellent photocatalytic H_(2)O_(2)production rate of 4240.3μM g^(-1)h^(-1),2.84,2.64 and 2.13 times higher than that of the bulk g-C_(3)N_(4),g-C_(3)N_(4)nanoplatelets and bulk B doped g-C_(3)N_(4),respectively.Photoanodes based on these hierarchical architectures can generate an unprecedented photocurrent density of 1.72 m A cm^(-2)at 1.23 V under AM 1.5 G illumination for photoelectrochemical water splitting.This work makes a fundamental improvement towards large-scale exploitation of highly active,hydrophilic and stable metal-free g-C_(3)N_(4)photocatalysts for various practical applications.

Bronze TiO2 as a cathode host for lithium-sulfur batteries

Lithium-sulfur batteries(LSBs)are very promising for large-scale electrochemical energy storage.However,dissolution and shuttling of lithium polysulfides(LiPSs)intermediates have severely affected their overall electrochemical properties and limited their practical application.Designing polar cathode hosts that can effectively bind LiPSs and simultaneously promote their redox conversion is crucial for realizing high-performance LSBs.Herein,we report bronze TiO2(TiO2-B)nanosheets(~5 nm in thickness)chemically bonded with carbon as a novel multifunctional cathode host for advanced LSBs.Experimental observation and first-principles density functional theory(DFT)calculations reveal that the TiO2-B with exposed(100)plane and Ti^3+ions exhibited high chemical affinity toward polysulfides and effectively confined them at surface.Meantime,Ti^3+ions and interface coupling with carbon promoted electronic conductivity of the composite cathode,leading to enhanced redox conversion kinetics of LiPSs during charge/discharge.Consequently,the as-assembled TiO2-B/S cathode manifested high capacity(1165 mAh/g at 0.2 C),excellent rate capability(244 mAh/g at 5 C)and outstanding cyclability(572 mAh/g over 500cycles at 0.2 C).This work sheds insights on rational design and fabrication of novel functional electrode materials for beyond Li-ion batteries.

Self-assembly to monolayer graphene film with high electrical conductivity

Monolayer chemically converted graphene （CCG） nanosheets can be homogeneously self-assembled onto silicon wafer modified by 3-aminopr- opyl triethoxysilane （APTES） to form very thin graphene film. The CCG film was characterized by FT-IR, XRD, SEM, TEM and AFM. Results show that CCG sheets formed monolayer film after assembled onto silicon wafer and there is a very tight chemical bond between sheets and wafer. Furthermore, the electrical measurements revealed that the monolayer graphene film has an excellent electrical conductivity.

Interwoven scaffolded porous titanium oxide nanocubes/carbon nanotubes framework for high-performance sodium-ion battery

Supercapacitor-like Na-ion batteries have attracted much attention due to the high energy density of batteries and power density of capacitors.Titanium dioxide(TiO_(2)),is a promising anode material.Its performance is however seriously hindered by its low electrical conductivity and the sluggish diffusion of sodium ions(Na^(+))in the TiO_(2)matrix.Herein,this work combines porous TiO_(2)nanocubes with carbon nanotubes(CNTs)to enhance the electrical conductivity and accelerate Na^(+)diffusivity for Na-ion batteries(NIBs).In this composite,an interwoven scaffolded TiO_(2)/CNTs framework is formed to provide abundant channels and shorter diffusion pathways for electrons and ions.The in-situ X-ray diffraction and cyclic voltammetry confirm the low strain and superior transport kinetics in Na^(+)intercalation/extraction processes.In addition,the chemically bonded TiO_(2)/CNTs hybrid provides a more feasible channel for Na^(+)insertion/extraction with a much lower energy barrier.Consequently,the TiO_(2)/CNTs composite exhibits excellent electrochemical performance with a capacity of 223.4 m Ah g^(-1)at 1 C and a capacity of 142.8 m Ah g^(-1)at 10 C(3.35 A g^(-1)).The work here reveals that the combination of active materials with CNTs can largely improve the utilization efficiency and enhance their sodium storage.

Crystalline porous materials:from zeolites to metal-organic frameworks(MOFs)

As a class of important crystalline porous materials,zeolites which were first found in 1756 have now been widely used in chemical industries for catalysis,adsorption and separation.35232 patents with the title including Hzeolite*n are documented by Derwent Innovations Index on January 2,2020[1].Despite of spread applications of zeolites and related-materials in industry,fundamental research of zeolites and their applications are still desired in both academia and industry,as shown in Fig.1.

Three-dimensionally ordered macroporous materials for pollutants abatement,environmental sensing and bacterial inactivation

Owing to their facile reactants migration channels,large surface area,maximized exposure of reaction sites and efficient light utilization,three-dimensionally ordered macroporous(3DOM)materials have been extensively adopted in environmental fields such as pollutants removal,environmental detection as well as bacterial disinfection.In this review,the up-to-date 3DOM materials,the corresponding synthesis protocols and the related environmental applications involving photo/electrocatalytic pollutants decomposition,thermocatalytic volatile organic compounds(VOCs)elimination,hazardous substances sensing and bacteria inactivation are completely presented.Simultaneously,the inherent advantages and mechanisms of 3DOM materials in different environmental utilization are thoroughly demonstrated and summarized.Furthermore,the improved performance of environmental applications and the methods of fabricating 3DOM materials are correlated in depth,being favorable for readers to obtain the fundamental knowledge and to motivate some innovative thoughts for modifying 3DOM materials with further elevated environmental remediation capability.Finally,the current difficulties and prospects of 3DOM materials for large-scale and commercial applications are outlooked.This critical review is anticipated to promote the optimization of 3DOM materials and to ripen the related environmental remediation techniques.

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Photocatalytic conversion of biomass is considered an effective,clean,and environmentally friendly route to obtain high-valued chemicals and hydrogen.However,the limited conversion efficiency and poor selectivity are still the main bottlenecks for photocatalytic biomass conversion.Herein,we report the highly selective photocatalytic conversion of glucose solution on holosymmetrically spherical three-dimensionally ordered macroporous TiO_(2)-CdSe heterojunction photonic crystal structure(s-TCS).The obtained s-TCS photocatalysts show excellent stability and strong light harvesting,uniform mass diffusion and exchange,and efficient photogenerated electrons/holes separation and utilization.The optimized s-TCS-4 photocatalyst displays the highest photocatalytic performance for glucose oxidation and hydrogen production.The glucose conversion,lactic acid selectivity,and yield on s-TCS-4 are about 95.9%,94.3%,and 96.4%,respectively.The photocatalytic production of lactic acid for s-TCS-4(18.5 g/L)is 2.3 times higher than the pure spherical TiO_(2) photonic crystal without CdSe(s-TiO_(2),8.1 g/L),and the hydrogen production rate of s-TCS-4 is 9.4 times that of s-TiO_(2).For the first time,we reveal that the photocatalytic conversion of glucose to lactic acid is a third-order and four-electron-involved reaction.This work could shed some new light on the efficient photocatalysis conversion of biomass to highly value-added products with high selectivity and yield,and simultaneously sustainable hydrogen evolution.

The effect of hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios on its pore structure and catalytic performance

Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios(Hier-ZSM-5-x,where x=50,100,150 and 200)were synthesized using an ordered mesoporous carbon-silica composite as hard template.Hier-ZSM-5-x exhibits improved mass transport properties,excellent mechanical and hydrothermal stability,and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction.Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores,which increases the final catalytic conversion.The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites.These poisoned Hier-ZSM-5-x shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite,which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant,leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites.This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance.

单晶MOF衍生的N掺杂有序等级多孔碳促进反应动力学和穿梭效应的抑制用于高性能锂硒电池

实现多硒化物的最大化固定能力以降低在锂硒电池中的穿梭效应仍然面临很大的挑战性.通过晶体限制生长和模板辅助方法合成的MOF单晶衍生的N掺杂有序分级多孔碳(S-NOHPC)展示了其作为锂硒电池载体材料的优异电化学性能.MOF结构固有的大量微孔为硒的负载提供了大量的空间和表面反应位点,确保了电池的高能量密度.互连的三级微-中-大孔结构和N掺杂极性位点的协同作用可以缓冲体积膨胀,缩短离子传输,其极高扩散系数为4.44×10^(-10)cm^(2)s,加速了锂化/脱锂反应.硒得到了最大限度的激活,多硒化物中间体紧密固定在碳载体材料的内部,从而实现了优异的比容量、稳定性和倍率性能.该正极在0.2 C的电流密度下表现出非常高的第二圈放/充电容量,分别为658和683 mA h g^(-1),并且循环200圈后仍保持367 mA h g^(-1)的高容量.即使在5 C的大电流密度下,其仍可获得230 mA h g^(-1)的高放电容量.该工作为高效储能设备提供了一种具有合理孔隙排列的新型高性能多孔材料.

双功能Cu-TiO_(2)/CuO光催化剂用于大规模协同处理含有机污染物和重金属离子的废水

大多数所制备的光催化剂通常只用于单一地降解有机污染物或还原Cr(VI)的光催化.然而,无机和有机污染物通常共存于工业污水中.同时消除混合的无机和有机污染物仍然存在着巨大的挑战.在本文中,我们通过原位掺杂和异质结工程策略,制备出了新型的双功能CuTiO_(2)/CuO光催化剂用于大规模高效协同光催化消除废水中的有机污染物和过渡金属离子.具体而言,这种双功能光催化剂在RhB和Cr(VI)共存溶液中的光催化RhB降解率和Cr(VI)还原率分别是在单一RhB或Cr(VI)污染物溶液中对应值的2.35和3.84倍.光催化染料分子降解和Cr(VI)还原之间存在显著增强的协同效应.此外,该双功能光催化剂在大规模光催化消除混合污染物方面也表现出较好的活性和稳定性.理论计算表明,铜掺杂和异质结工程促进了高效的光吸收、增高的载流子密度以及快速的光生载流子转移,从而产生高效的协同光催化作用.这种双功能光催化剂的概念为大规模工业废水处理和净化开辟了新途径.

Bioinspired Noncyclic Transfer Pathway Electron Donors for Unprecedented Hydrogen Production

Electron donors are widely exploited in visible-light photocatalytic hydrogen production.As a typical electron donor pair and often the first choice for hydrogen production,the sodium sulfide-sodium sulfite pair has been extensively used.However,the resultant thiosulfate ions consume the photogenerated electrons to form an undesirable pseudocyclic electron transfer pathway during the photocatalytic process,strongly limiting the solar energy conversion efficiency.Here,we report novel and bioinspired electron donor pairs offering a noncyclic electron transfer pathway that provides more electrons without the consumption of the photogenerated electrons.Compared to the state-of-the-art electron donor pair Na_(2)S-Na_(2)SO_(3),these novel Na_(2)S-NaH_(2)PO_(2)and Na_(2)S-NaNO_(2)electron donor pairs enable an unprecedented enhancement of up to 370%and 140%for average photocatalytic H_(2)production over commercial CdS nanoparticles,and they are versatile for a large series of photocatalysts for visible-light water splitting.The discovery of these novel electron donor pairs can lead to a revolution in photocatalysis and is of great significance for industrial visible-light-driven H_(2)production.