Unveiling the geometric site dependent activity of spinel Co_(3)O_(4)for electrocatalytic chlorine evolution reaction

Spinel cobalt oxide(Co_(3)O_(4)),consisting of tetrahedral Co^(2+)(CoTd)and octahedral Co^(3+)(CoOh),is considered as promising earth-abundant electrocatalyst for chlorine evolution reaction(CER).Identifying the catalytic contribution of geometric Co site in the electrocatalytic CER plays a pivotal role to precisely modulate electronic configuration of active Co sites to boost CER.Herein,combining density functional theory calculations and experiment results assisted with operando analysis,we found that the Co_(Oh) site acts as the main active site for CER in spinel Co_(3)O_(4),which shows better Cl^(-)adsorption and more moderate intermediate adsorption toward CER than CoTd site,and does not undergo redox transition under CER condition at applied potentials.Guided by above findings,the oxygen vacancies were further introduced into the Co_(3)O_(4) to precisely manipulate the electronic configuration of Co_(Oh) to boost Cl^(-)adsorption and optimize the reaction path of CER and thus to enhance the intrinsic CER activity significantly.Our work figures out the importance of geometric configuration dependent CER activity,shedding light on the rational design of advanced electrocatalysts from geometric configuration optimization at the atomic level.

Recycling and Upgrading Utilization of Polymer Plastics

Due to the current situation of massive waste consumption and accumulation,the recycling and upgrading utilization of polymer materials is an effective technology to solve environmental pollution.In this work,the recycling and upgrading methods of polymers are summarized,and the latest progress in polymer upcycling is discussed from the perspective of upgrading materials.The common polymer recovery methods,including mechanical recovery,chemical recovery,biocatalysis,and photocatalytic recovery,are discussed based on their mechanism and industrialized application.The upgrading products of polymers are divided into monomers,fuels and fine chemicals.The challenges and prospects of polymer degradation technology are discussed.

Reproductive toxicity of enrofloxacin in Caenorhabditis elegans involves oxidative stress-induced cell apoptosis

Fluoroquinolone antibiotics(FQs)that persist and bioaccumulate in the environment have aroused people’s great concern.Here,we studied the adverse effects of FQs in soil animals of Caenorhabditis elegans via food-chronically exposure.The result shows C.elegans exposed to FQs exhibited reproductive toxicity with small-brood size and low-egg hatchability.To study the underlying mechanism,we conduct a deep investigation of enrofloxacin(ENR),one of the most frequently detected FQs,on nematodes which is one of commonly used animal indicator of soil sustainability.The concentration-effect curves simulated by the Hill model showed that the half effect concentrations(EC50)of ENR were(494.3±272.9)μmol/kg and(107.4±30.9)μmol/kg for the brood size and the hatchability,respectively.Differential gene expression between the control and the ENR-exposure group enriched with the oxidative stress and cell apoptosis pathways.The results together with the enzyme activity in oxidative stress and the cell corpses suggested that ENR-induced reproductive toxicity was related to germ cell apoptosis under oxidative stress.The risk quotients of some soil and livestock samples were calculated based on the threshold value of EC10 for the egg hatchability(2.65μmol/kg).The results indicated that there was possible reproductive toxicity on the nematodes in certain agricultural soils for the FQs.This study suggested that chronic exposure to FQs at certain levels in environment would induce reproductive toxicity to the nematodes and might reduce the soil sustainability,alarming the environment risks of antibiotics abuse.

Brief review of hydrocarbon-reforming catalysts map for hydrogen production

Hydrogen energy,the cleanest fuel,presents extensive applications in renewable energy technologies such as fuel cells.However,the transition process from carbon-based(fossil fuel)energy to desired hydrogen energy is usually hindered by inevitable scientific,technological,and economic obstacles,which mainly involves complex hydrocarbon reforming reactions.Hence,this paper provides a systematic and comprehensive analysis focusing on the hydrocarbon reforming mechanism.Accordingly,recent related studies are summarized to clarify the intrinsic difference among the reforming mechanism.Aiming to objectively assess the activated catalyst and deactivation mechanism,the rate-determining steps of reforming process have been emphasized,summarized,and analyzed.Specifically,the effect of metals and supports on individual reaction processes is discussed followed by the metalsupport interaction.Current tendency and research map could be established to promote the technology development and expansion of hydrocarbon reforming field.This review could be considered as the guideline for academics and industry designing appropriate catalysts.

Highly efficient synthesis of boron nitride nanotubes by catalytic chemical vapor deposition of boron/nickel containing precursors

High-purity and high-yield boron nitride nanotubes with large aspect ratio were prepared by a facile two-step process,including the synthesis of boron/nickel containing precursors by precipitation reactions and subsequent thermally catalytic chemical vapor deposition reactions.The influence of catalyst content and annealing temperature on the phase composition and microstructure of the products were investigated.The results show that it is difficult to exert the catalytic effect of nickel-based catalyst at low temperatures(<1400℃).At appropriate temperatures(1400-1500℃),highly crystalline boron nitride nanotubes with a length of more than 50 mm and a diameter of 50 nm are formed.The content of catalyst in the precursor mainly affects the morphology of the boron nitride product.If the content is too low,it is easy to form boron nitride particles;while high catalyst content can easily lead to catalyst aggregation and form a submicron one-dimensional boron nitride with unregular structure.Based on microstructural evolutions,phase changes,and thermodynamic analysis,the vapor-liquid-solid(V-L-S)growth mechanism of the tip growth mode dominates the formation of boron nitride nanotubes has also been verified.

In-situ Construction of Sulfur-doped g-C_(3)N_(4)/defective g-C_(3)N_(4) Isotype Step-scheme Heterojunction for Boosting Photocatalytic H_(2) Evolution

The rational construction of a high-efficiency stepscheme heterojunctions is an effective strategy to accelerate the photocatalytic H_(2).Unfortunately,the variant energy-level matching between two different semiconductor confers limited the photocatalytic performance.Herein,a newfangled graphitic-carbon nitride(g-C_(3)N_(4))based isotype step-scheme heterojunction,which consists of sulfur-doped and defective active sites in one microstructural unit,is successfully developed by in-situ polymerizing N,N-dimethylformamide(DMF)and urea,accompanied by sulfur(S)powder.Therein,the polymerization between the amino groups of DMF and the amide group of urea endows the formation of rich defects.The propulsive integration of S-dopants contributes to the excellent fluffiness and dispersibility of lamellar g-C_(3)N_(4).Moreover,the developed heterojunction exhibits a significantly enlarged surface area,thus leading to the more exposed catalytically active sites.Most importantly,the simultaneous introduction of S-doping and defects in the units of g-C_(3)N_(4) also results in a significant improvement in the separation,transfer and recombination efficiency of photo-excited electron-hole pairs.Therefore,the resulting isotype step-scheme heterojunction possesses a superior photocatalytic H_(2) evolution activity in comparison with pristine g-C_(3)N_(4).The newly afforded metal-free isotype step-scheme heterojunction in this work will supply a new insight into coupling strategies of heteroatoms doping and defect engineering for various photocatalytic systems.

瑞德西韦核碱基单元的连续流合成

本研究采用五步连续流法合成了抗病毒药物瑞德西韦的碱基单元7-溴吡咯[2,1-f][1,2,4]三嗪-4-胺。采用间歇式合成化学方法,以吡咯为原料,通过序流操作成功制备了7-溴吡咯[2,1-f][1,2,4]三嗪-4-胺。在最优流动条件下,7-溴吡咯[2,1-f][1,2,4]三嗪-4-胺的分离率为14.1%,总停留时间为79min,通量为2.96 g·h^(-1)。总停留时间明显短于批处理过程所消耗的总时间(>26.5 h)。在流动中,有利于高放热的Vilsmeier-Haack反应和N-胺化反应,这些反应涉及危险和不稳定的中间体、氧化液-液两相转化以及需要严格低温条件的溴化反应。这种合成的显著特点是,通过部署专用设备和分离单元,将后处理程序完全集成到反应序列中,从而形成一个流线型的连续流系统,最大限度地提高了整体工艺效率。该方法是一种更环保、更可持续的高效、安全制备这种碱基单元的方法。

Improving stability of MXenes

Due to their superior hydrophilicity and conductivity,ultra-high volumetric capacitance,and rich surface-chemistry properties,MXenes exhibit unique and excellent performance in catalysis,energy storage,electromagnetic shielding,and life sciences.Since they are derived from ceramics(MAX phase)through etching,one of the challenges in MXenes preparation is the inevitable exposure of metal atoms on their surface and embedding of anions and cations.Because the as-obtained MXenes are always in a thermodynamically metastable state,they tend to react with trace oxygen or oxygen-containing groups to form metal oxides or degrade,leading to sharply declined activity and impaired performance.Therefore,improving the stability of MXenesbased materials is of practical significance in relevant applications.Unfortunately,there lacks a comprehensive review in the literature on relevant topics.To help promote the wide applications of MXenes,we review from the following aspects:(i)insights into the factors affecting the stability of MXenes-based materials,including oxidation of MXenes flakes,stability of MXenes colloidal solutions,and swelling and degradation of MXenes thin-film,(ii)strategies for enhancing the stability of MXenes-based materials by optimizing MAX phase synthesis and modifying the MXenes preparation,and(iii)techniques for further increasing the stability of freshly prepared MXenes-based materials via controlling the storage conditions,and forming shielding on the surface and/or edge of MXenes flakes.Finally,some outlooks are proposed on the future developments and challenges of highly active and stable MXenes.We aim to provide guidance for the design,preparation,and applications of MXenes-based materials with excellent stability and activity.

Strategic design and fabrication of MXenes-Ti_(3)CNCl_(2)@CoS_(2) core-shell nanostructure for high-efficiency hydrogen evolution

CoS_(2) is considered to be a promising electrocatalyst for hydrogen evolution reaction(HER).However,its further widespread applications are hampered by the unsatisfactory activity due to relatively high chemisorption energy for hydrogen atom.Herein,theoretical predictions of first-principles calculations reveal that the introduction of a Cl-terminated MXenes-Ti_(3)CNCl_(2) can significantly reduce the HER potential of CoS_(2)-based materials and the Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure has Gibbs free energy of hydrogen adsorption(|ΔGH|)close to zero,much lower than that of the pristine CoS_(2) and Ti_(3)CNCl_(2).Inspired by the theoretical predictions,we have successfully fabricated a unique Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure by ingeniously coupling CoS_(2) with a Cl-terminated MXenes-Ti_(3)CNCl_(2).Interface-charge transfer between CoS_(2) and Ti_(3)CNCl_(2) results in a higher degree of electronic localization and a formation of chemical bonding.Thus,the Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure achieves a significant enhancement in HER activity compared to pristine CoS_(2) and Ti_(3)CNCl_(2).Theoretical calculations further confirm that the partial density of states of CoS_(2) after hybridization becomes more non-localized,and easier to interact with hydrogen ions,thus boosting HER performance.In this work,the success of oriented experimental fabrication of high-efficiency Ti_(3)CNCl_(2)@CoS_(2) electrocatalysts guided by theoretical predictions provides a powerful lead for the further strategic design and fabrication of efficient HER electrocatalysts.

BaTiO_(3)/Polyurethane Dielectric Composites with Diels-Alder Bond for Improved Self-Healing Properties

In general,self-healing dielectric composites are mainly composed of polar hydrogen bonds,which have high hydrophilicity and are unsuitable for humid environment.Dielectric composite with Diels-Alder(D-A)bond contains covalent bonds,it can be adopted as an efficient self-healing material.Here,we construct self-healing barium titanate(BT)/polyurethane(PU)dielectric composites by adopting PU with D-A bond as matrix(BT/PU-DA).The prepared 10%BT/PU-DA composite exhibits superior self-healing ability than that of PUDA.Moreover,its dielectric constant can reach 9.3 with a loss of only 0.04 at 1000 Hz and maintain 93%repair efficiency of tensile strength.The experimental analysis suggests the introduction of D-A bond can enhance the thermostability and self-healing ability of BT/PU-DA composite.In addition,the incorporation of BT nanoparticles and D-A bond in the self-healing composite contributes to the lower dielectric loss and excellent tensile strength after healing.The adopted strategy is a promising and facile approach to develop highly efficient selfhealing dielectric material,which will be conducive to reuse and sustainable development of the electronic packaging material in aqueous medium or wet environment.

MXenes/CNTs-based hybrids:Fabrications,mechanisms,and modification strategies for energy and environmental applications

Emerging two-dimensional(2D)layered metal carbide and nitride materials,commonly termed MXenes,are increasingly recognized for their applications across diverse fields such as energy,environment,and catalysis.In the past few years,MXenes/carbon nanotubes(CNTs)-based hybrids have attracted extensive attention as an important catalyst in energy and environmental fields,due to their superior multifunctions and mechanical stability.This review aims to address the fabrication strategies,the identification of the enhancement mechanisms,and recent progress regarding the design and modification of MXenes/CNTs-based hybrids.A myriad of fabrication techniques have been systematically summarized,including mechanical mixing,spray drying,three-dimensional(3D)printing,self-assembly/in-situ growth,freeze drying,templating,hydrothermal methods,chemical vapor deposition(CVD),and rolling.Importantly,the identification of the enhancement mechanisms was thoroughly discussed from the two dimensions of theoretical simulations and in-situ analysis.Moreover,the recent advancements in profound applications of MXenes/CNTs-based hybrids have also been carefully revealed,including energy storage devices,sensors,water purification systems,and microwave absorption.We also underscore anticipated challenges related to their fabrication,structure,underlying mechanisms,modification approaches,and emergent applications.Consequently,this review offers insights into prospective directions and the future trajectory for these promising hybrids.It is expected that this review can inspire new ideas or provide new research methods for future studies.

Porous 3D carbon-based materials:An emerging platform for efficient hydrogen production

Due to their unique properties and uninterrupted breakthrough in a myriad of clean energy-related applications,carbon-based materials have received great interest.However,the low selectivity and poor conductivity are two primary difficulties of traditional carbon-based materials(zero-dimensional(0D)/one-dimensional(1D)/two-dimensional(2D)),enerating inefficient hydrogen production and impeding the future commercialization of carbon-based materials.To improve hydrogen production,attempts are made to enlarge the surface area of porous three-dimensional(3D)carbon-based materials,achieve uniform interconnected porous channels,and enhance their stability,especially under extreme conditions.In this review,the structural advantages and performance improvements of porous carbon nanotubes(CNTs),g-C_(3)N_(4),covalent organic frameworks(COFs),metal-organic frameworks(MOFs),MXenes,and biomass-derived carbon-based materials are firstly summarized,followed by discussing the mechanisms involved and assessing the performance of the main hydrogen production methods.These include,for example,photo/electrocatalytic hydrogen production,release from methanolysis of sodium borohydride,methane decomposition,and pyrolysis-gasification.The role that the active sites of porous carbon-based materials play in promoting charge transport,and enhancing electrical conductivity and stability,in a hydrogen production process is discussed.The current challenges and future directions are also discussed to provide guidelines for the development of next-generation high-efficiency hydrogen 3D porous carbon-based materials prospected.

Carbonitride MXene Ti_(3)CN(OH)_(x)@MoS_(2)hybrids as efficient electrocatalyst for enhanced hydrogen evolution

Renewable energy powered electrocatalytic water splitting is a promising strategy for hydrogen generation,and the design and development of high-efficiency and earth-abundant electrocatalysts for hydrogen evolution reaction(HER)are highly desirable.Herein,MoS2 nanoflowers decorated two-dimensional carbonitride-based MXene Ti3CN(OH)x hybrids have been constructed by etching and post-hydrothermal methods.The electrochemical performance of the as-obtained Ti_(3)CN(OH)_(x)@MoS_(2)hybrids having a quasi core-shell structure is fascinating:An overpotential of 120 mV and a Tafel slope of 64 mV∙dec^(−1)can be delivered at a current density of 10 mA∙cm^(−2).And after 3,000 cyclic voltammetry cycles,it can be seen that there is no apparent attenuation.Both the experimental results and density functional theory(DFT)calculations indicate that the synergetic effects between Ti_(3)CN(OH)x and MoS_(2)are responsible for the robust electrochemical HER performance.The electrons of-OH group in Ti_(3)CN(OH)x are transferred to MoS_(2),making the adsorption energy of the composite for H almost vanish.The metallic Ti_(3)CN(OH)x is also beneficial to the fast charge transfer kinetics.The construction of MXene-based hybrids with optimal electronic structure and unique morphology tailored to the applications can be further used in other promising energy storage and conversion devices.

Single-atom catalysis for organic reactions

Metal-based catalysis,including homogeneous and heterogeneous catalysis,plays a significant role in the modern chemical industry.Heterogeneous catalysis is widely used due to the high efficiency,easy catalyst separation and recycling.However,the metal-utilization efficiency for conventional heterogeneous catalysts needs further improvement compared to homogeneous catalyst.To tackle this,the pursing of heterogenizing homogeneous catalysts has always been attractive but challenging.As a recently emerging class of catalytic material,single-atom catalysts(SACs)are expected to bridge homogeneous and heterogeneous catalytic process in organic reactions and have arguably become the most active new frontier in catalysis field.In this review,a brief introduction and development history of single-atom catalysis and SACs involved organic reactions are documented.In addition,recent advances in SACs and their practical applications in organic reactions such as oxidation,reduction,addition,coupling reaction,and other organic reactions are thoroughly reviewed.To understand structure-property relationships of single-atom catalysis in organic reactions,active sites or coordination structure,metal atom-utilization efficiency(e.g.,turnover frequency,TOF calculated based on active metal)and catalytic performance(e.g.,conversion and selectivity)of SACs are comprehensively summarized.Furthermore,the application limitations,development trends,future challenges and perspective of SAC for organic reaction are discussed.

Tailoring the electronic acceptor–donor heterointerface between black phosphorus and Co_(3)O_(4) for boosting oxygen bifunctional electrocatalysis

Black phosphorus (BP) as an uprising two-dimensional material exhibits attractive potential in the field of electrocatalysis due to the inherent advantages of high carrier mobility and abundant lone pair electrons.However,the exposed active electrons compel BP to be deactivated by oxidative degradation.Herein,the electronic signature of acceptor-donor heterointerfacial interactions between BP and Co_(3)O_(4)is realized via wet ball milling.The preferential migration of active electrons from BP to Co_(3)O_(4)is achieved at the heterointerface since the Fermi level of BP is higher than that of Co_(3)O_(4).Such relative energetic consideration promotes reasonable oxygen electrocatalytic active sites.Moreover,it significantly suppresses the oxidative degradation of BP.Consequently,the resulting Co_(3)O_(4)/BP heterojunction possesses superior oxygen bifunctional electrocatalytic activity than its parent catalysts.Most importantly,this work promotes an efficient route towards BP-based multifunctional catalysts.

Sulfur-doped g-C_(3)N_(4)/g-C_(3)N_(4) isotype step-scheme heterojunction for photocatalytic H_(2) evolution

The rational fabrication of an efficient heterojunction is critical to the enhancement of photocatalytic hydrogen(H_(2)) evolution performance.Herein,a new-fashioned graphitic-carbon nitride(g-C_(3) N_(4)) based isotype step-scheme(S-scheme) heterojunction composed of sulfur-doped and sulfur-free active sites is developed by liquid sulfur-mediation of exfoliated g-C_(3) N_(4).Particularly,the liquid sulfur not only contributes to the full contact between sulfur species and exfoliated g-C_(3) N_(4),but also creates sulfur-doping and abundant pores,since self-gas foaming effect of sulfur vapor.Moreover,the S-doped and S-free active sites located in the structural unit of C_(3) N_(4) jointly construct a typical sulfur-doped g-C_(3) N_(4)/g-C_(3) N_(4) isotype step-scheme heterojunction,which endows highly efficient photocatalytic reaction process.Therefore,the optimal sample possesses remarkable photocatalytic H_(2) evolution activity(5548.1 μmol g^(-1) h^(-1)) and robust durability.Most importantly,the investigation will open up a new path for the exploration of other carbon-based isotype S-scheme heterojunctions.

Anchoring Pt nanoparticles and Ti_(3)C_(2)T_(x)MXene nanosheets on CdS nanospheres as efficient synergistic photocatalysts for hydrogen evolution

The development of a new-fashioned functional nanomaterial with an outstanding photocatalytic hydrogen evolution reaction(HER)activity under visible-light irradiation is a sustainable and promising strategy to cope with the increasingly serious global energy crisis.Herein,an advanced ternary photocatalytic HER catalyst,in which the Pt nanoparticles and Ti_(3)C_(2)T_(x)nanosheets are synchronously anchored on the surface of CdS nanospheres(Ti_(3)C_(2)T_(x)/Pt@CdS),is elaborately constructed via acid etching,sel-freduction,and solvothermal treatment.Therein,the synergistic promoting effect between Ti_(3)C_(2)T_(x)and Pt on the charge transfer of CdS effectively hinders the backtransfer of electrons to recombine with holes,resulting in a high-effective utilization of photoexcited charges.The obtained Ti_(3)C_(2)T_(x)/Pt@CdS possesses a superior photocatalytic HER activity compared to that of single active component catalyst.This work demonstrates the great potential of MXene materials in constructing high performance photocatalysts.

三维MXenes异质结及其应用

MXenes因其独特的表面化学性质、可调的金属组份、良好的亲水性和较高的载流子浓度,近年来被广泛应用于诸多研究领域.与其他二维材料类似,MXenes可与其他材料进行复合构建异质结,形成MXenes基三维多孔材料,从而显著增强其反应活性,提升其相关性能.尤其是这些三维多孔MXenes材料所具有的三维结构和明确的孔径,可显著提高电化学过程中各种离子和电子的传输速率,因此在电化学能量存储、传感、催化和环境领域应用前景广阔.在这篇综述中,作者以MXenes/碳、MXenes/无机物和MXenes/聚合物这三种主要的MXenes基异质结为研究对象,系统地总结了近年来三维多孔MXenes基异质结的构建方法的研究进展.同时,深入探讨了三维多孔MXenes基异质结在光催化、环境监测和电化学储能中的应用进展.最后,详细归纳了三维多孔MXenes基异质结的孔隙形成机制、性质和应用之间的关系,并提出了作者独到的见解.本综述可为三维多孔MXenes基异质结在高性能材料和器件中的设计、制造和应用等方面提供指导.

Progress on nanostructured gel catalysts for oxygen electrocatalysis

Driven by the serious ecological problems,it is urgent to explore high-efficiency sustainable energy technologies.Oxygen electrocatalysis acts as important half-reactions in the emerging electrochemical energy techniques including electrolysis and batteries.Gel composites exhibit the merits of rich porous,superior hydrophilic,and large specific surface area,which can significantly improve the electrolyte penetration and boost the kinetics process of oxygen electrocatalysis.In this invited contribution,the advances and challenges of a novel gel materials for oxygen electrocatalysis are summarized.Starting from the structure-activity-performance relationship of gel materials,synthetic routes of nanostructured gel materials,namely,radical polymerization,sol-gel method,hydrothermal/solvothermal reactions,and ligand-substitution method,are introduced.Afterward,the gel composites are divided into polymer-based,metal-based,and carbon-based materials in turn,and their applications in oxygen electrocatalysis are discussed respectively.At the end,the perspective and challenges for advanced gel oxygen electrocatalysts are proposed.