离子液体介导CO_(2)化学转化研究进展

高效利用CO_(2)资源对绿色可持续发展具有重要意义。近年来,高效催化转化CO_(2)为高附加值化学品的研究广受关注。但是,由于CO_(2)高的热力学稳定性和动力学惰性,其化学转化往往需要高反应活性的底物和苛刻的反应条件。因此,科研工作者致力于发展催化转化CO_(2)的高性能催化剂和新方法。迄今,已经发展了一系列多相和均相催化剂用于催化转化CO_(2)。在众多性能优异的催化剂中,离子液体因其独特的性能,可实现温和甚至室温条件下高效转化CO_(2)为高附加值化学品,而被广泛研究。具有特定官能团的功能化离子液体可以作为溶剂、CO_(2)吸附剂、CO_(2)活化剂以及催化剂或共催化剂,实现无金属条件下高效催化转化CO_(2);各种金属-离子液体耦合催化体系可实现协同催化转化CO_(2)为高附加值化学品。在本文中,我们总结了近期离子液体介导的、通过构筑C―O、C―N、C―S、C―H以及C―C键,转化CO_(2)合成化学品的研究。主要概述了近年来离子液体在化学吸附活化CO_(2)、催化转化CO_(2)制备碳酸酯和含N/S杂原子的化合物以及催化CO_(2)加氢制备甲酸、乙酸、甲烷、低碳产物等方面的研究进展,并对相关反应路径和机理进行了探讨。在离子液体催化反应体系中,离子液体不仅可以活化CO_(2)还可以通过氢键作用活化底物,从而协同催化CO_(2)的转化。在本文的最后,对相关研究的不足及未来发展前景进行了探讨和展望。总之,离子液体介导的高效催化转化CO_(2)方法为制备高价值化学品提供了绿色合成路线,具有广阔的应用前景。

不同温度下天然橡胶/聚酯纤维界面的黏结失效

采用松香树脂作为增黏剂,制备了天然橡胶/聚酯纤维复合材料,并对其进行了3种不同温度的热老化处理,重点考察了经过不同温度的热老化处理后,使用H抽出法和扫描电镜观察法分析了复合材料的失效模式。结果表明,经过不同温度的热老化处理后,由于应力分布不同,出现了3种不同的失效模式:在110℃时,复合材料失效主要是橡胶/纤维的界面脱黏;在125℃时,复合材料同时发生界面脱黏和橡胶基体失效;在180℃时,复合材料主要发生橡胶基体失效。X射线光电子能谱测试结果显示,经过高温热老化后,橡胶表面的含氧官能团明显增加。

Remote plasma-enhanced atomic layer deposition of gallium oxide thin films with NH_3 plasma pretreatment

High quality gallium oxide(Ga_2O_3) thin films are deposited by remote plasma-enhanced atomic layer deposition(RPEALD) with trimethylgallium(TMG) and oxygen plasma as precursors. By introducing in-situ NH3 plasma pretreatment on the substrates, the deposition rate of Ga_2O_3 films on Si and GaN are remarkably enhanced, reached to 0.53 and 0.46 ?/cycle at 250 °C,respectively. The increasing of deposition rate is attributed to more hydroxyls(–OH) generated on the substrate surfaces after NH3 pretreatment, which has no effect on the stoichiometry and surface morphology of the oxide films, but only modifies the surface states of substrates by enhancing reactive site density. Ga_2O_3 film deposited on GaN wafer is crystallized at 250 °C, with an epitaxial interface between Ga_2O_3 and GaN clearly observed. This is potentially very important for reducing the interface state density through high quality passivation.

Prelithiation design for suppressing delamination in lithium-ion battery electrodes

Prelithiation has been intensively investigated in high-capacity lithiumion batteries(LIBs).However,the optimization of prelithiation degrees for long service life of LIBs still remains a challenge.The positive effect of prelithiation on suppressing degradation of LIBs,besides directly pursuing the high first Coulomb efficiency which has been widely reported in the literature,is revealed and discussed based on an analytical model focusing on the interfacial delamination in electrodes.For full charge-discharge cycling,well-designed prelithiation can effectively suppress the delamination and reduce the debonding size by approximately 25%,compared with the case without prelithiation.For the strategy combining partial charge-discharge cycling and prelithiation,the largest reversible capacity without debonding can be significantly improved by approximately100%with well-designed prelithiation.This work is expected to provide a prelithiation design principle and further improve the mechanical stability of LIB electrodes.

Review on electrode-level fracture in lithium-ion batteries

Fracture occurred in electrodes of the lithium-ion battery compromises the integrity of the electrode structure and would exert bad influence on the cell performance and cell safety.Mechanisms of the electrode-level fracture and how this fracture would affect the electrochemical performance of the battery are of great importance for comprehending and preventing its occurrence.Fracture occurring at the electrode level is complex,since it may involve fractures in or between different components of the electrode.In this review,three typical types of electrode-level fractures are discussed:the fracture of the active layer,the interfacial delamination,and the fracture of metallic foils(including the current collector and the lithium metal electrode).The crack in the active layer can serve as an effective indicator of degradation of the electrochemical performance.Interfacial delamination usually follows the fracture of the active layer and is detrimental to the cell capacity.Fracture of the current collector impacts cell safety directly.Experimental methods and modeling results of these three types of fractures are concluded.Reasonable explanations on how these electrode-level fractures affect the electrochemical performance are sorted out.Challenges and unsettled issues of investigating these fracture problems are brought up.It is noted that the state-of-the-art studies included in this review mainly focus on experimental observations and theoretical modeling of the typical mechanical damages.However,quantitative investigations on the relationship between the electrochemical performance and the electrode-level fracture are insufficient.To further understand fractures in a multiscale and multi-physical way,advancing development of the cross discipline between mechanics and electrochemistry is badly needed.

TiO_(2) nanoparticle supported Ru catalyst for chemical upcycling of polyethylene terephthalate to alkanes

Production of fuel and chemicals from plastic waste is one of the effective ways to upcycle spent plastics,which is an interesting topic and of significance for green and sustainable development.Herein,we demonstrate a highly efficient catalyst,TiO_(2)nanoparticle supported Ru nanocatalyst(Ru/TiO_(2)),for upcycling polyethylene terephthalate(PET)to alkanes in the presence of H_(2) and water.Under the optimal conditions(200℃,60 bar H_(2),and small amount of H_(2)O),PET could completely convert into alkanes,dominated with cyclohexane and methane.It was indicated that the strong interaction between the TiO_(2)support and Ru nanoparticles made electrons flow from the TiO_(2)support to the Ru nanoparticles,which thus rendered Ru/TiO_(2)to have ability to simultaneously catalyze PET hydrolysis and intermediate hydrogenation.This work realizes the transformation of PET to alkanes,which provides a promising way to chemically upcycle PET.

Temporally Separated CO_(2) Photoreduction and H_(2)O Photooxidation over Redox-Active Conjugated Organic Polymer Films

Photocatalytic CO_(2) reduction with H_(2)O of chemicals without H2 generation is interesting but challenging.Herein,we report temporally separated CO_(2) photoreduction and H_(2)O photooxidation that are achieved over redox-active o-hydroxyazo-based conjugated organic polymer films(HAzo-COPFs),affording CO with high efficiency as the sole reduction product.HAzo-COPFs are prepared via interfacial diazo-coupling reactions of aromatic diamines and diphenols,and HAzo-COPF-1 from 4,4′-biphenol and benzidine shows the best performance with a CO generation rate of 53.6μmol g−1 h−1 under visible-light irradiation(>420 nm).Interestingly,we discovered that diphenol(DP-OH)moieties in HAzo-COPFs,serving as electron and proton donors to participate in CO_(2) photoreduction,are oxidized into quinone(DP=O)moieties,which are subsequently photoreduced to regenerate DP-OH in H_(2)O photooxidation.Consequently,CO_(2) photoreduction and H_(2)O photooxidation are temporally separated and perfectly coupled via redox transformation between DP-OH and DP=O that form in situ,affording enhanced charge carrier separation and inhibiting the hydrogen evolution reaction.This work provides new insights for the design of COP photocatalysts and artificial photosynthesis.

Smith-Kingsmore syndrome with nystagmus as the initial symptom

Background Smith-Kingsmore syndrome(SKS)is a rare autosomal dominant disorder caused by de novo mutations of gene MTOR in most cases and germline mosaicism in a few cases.The first case of SKS was reported in 2013.The incidence of SKS remains unknown.The clinical manifestations of SKS are diverse,and common features are macrocephaly,intellectual disability,and seizures.Some patients with SKS have special facial features.Case presentation The case was a 5-month-old baby girl,who was admitted to the hospital for nystagmus,delayed development for 2 months,and intermittent convulsions for 2 days.The patient had a head circumference of 42 cm(+2SD),and showed facial deformity,low limb muscle tension,large areas of pigmentation,as well as mosaic patchy and strip-like pigment loss in her trunk and limbs.Meanwhile,her development was lagging behind peers.Physical examination did not reveal other abnormalities.She was diagnosed with SKS based on whole-exome sequencing combined with clinical symptoms and signs.She successively received treatment with adrenocorticotropic hormone,methylprednisolone sodium succinate,topiramate,levetiracetam,and zonisamide to reduce the number of convulsions in a short time,but drug resistance appeared thereafter.After combined treatment with multiple antiseizure medications,the patient still had seizures,but the amplitude of limb movement during the seizures was reduced compared to that before treatment.Conclusions This case expanded the phenotypic spectrum of SKS for diagnosis.We also review the related literature to promote the awareness,diagnosis,clinical management,and follow-up of SKS patients with MTOR mutations.

离子液体调控化学反应研究进展

离子液体是由有机阳离子和无机/有机阴离子组成的一类低温熔融盐,兼具分子溶剂和融盐的特性,在化学反应中既可用作反应介质,又可起到催化和助催化作用.本文总结了近年来本课题组在离子液体介导二氧化碳和纤维素及其平台分子转化、离子液体无金属催化炔醇水合反应和离子液体氢键催化化学反应中的研究进展,并针对该领域存在的问题提出观点,对发展前景进行了展望.

离子液体促进Ru/C催化有机胺与CO2/H2氮甲酰化反应研究

以CO2为甲酰化试剂和H2为还原剂进行有机胺N-甲酰化反应是合成甲酰胺的一条绿色反应路径,具有重要意义.本工作针对有机胺与CO2/H2的N-甲酰化反应,构建了以1-丁基-3-甲基咪唑乙酸盐([Bmim][OAc])离子液体为溶剂、Ru/C为催化剂的非均相催化体系,在相对温和条件下(100℃、8 MPa)实现了有机伯胺、仲胺和芳香胺的N-甲酰化反应,获得了一系列甲酰胺.研究表明,[Bmim][OAc]通过与氨基形成氢键活化有机胺,并可通过调控Ru纳米粒子的电子状态,增强Ru纳米粒子对H2的活化能力,进而实现催化N-甲酰化反应.

离子液体反应体系的氢键作用

离子液体是由有机阳离子和无机/有机阴离子组成的一类低温熔融盐,具有高度的功能可设计性.氢键作用广泛存在于离子液体体系中,由于静电作用影响,其作用远强于分子体系的氢键作用,因此在化学反应中显示出独特的性能.氢键作用一方面可催化化学反应,实现一系列无金属催化的绿色反应路线;另一方面,可调控反应选择性,高收率地获得单一化学品.本文总结了近年来关于离子液体体系的氢键作用研究成果,及其催化和调控化学反应的研究进展,并对发展前景进行了展望.

Recent Advances in Photocatalytic CO2 Reduction Using Earth-Abundant Metal Complexes-Derived Photocatalysts

Photochemical reduction of CO2 with H20 into energy-rich chemicals using inexhaustible solar energy is an appealing strategy to simultaneously address the global energy and environmental issues. Earth-abundant metal complexes show promising application in this field due to their easy availability, rich redox valence and tunable property. Great progress has been seen on catalytic reduction of CO2 under visible light illumination employing earth-abundant metal complexes and their hybrids as key contributors, especially for producing CO and HCOOH via the two-electron reduction process. In this minireview, we will summarize and update advances on earth-abundant metal complex-derived photocatalytic system for visible-light driven CO2 photoreduction over the last 5 years. Homogeneous earth-abundant metal complex photocatalysts and earth-abundant metal complex derived hybrid photocatalysts were both presented with focus on efficient improvement strategy.

Wafer-scale MOCVD growth of monolayer M0S2 on sapphire and SiO2

High-quality and large-scale growth of monolayer molybdenum disulfide(MoS2)has caught intensive attention because of its potential in many applications due to unique electronic properties.Here,we report the wafer-scale growth of high-quality mono layer MoS2 on singlecrystalline sapphire and also on SiO2 substrates by a facile metal-organic chemical vapor deposit!on(MOCVD)method.Prior to growth,an aqueous solution of sodium molybdate(Na2MoO4)is spun onto the substrates as the molybdenum precursor and diethyl sulfide((C2H5)2S)is used as the sulfur precursor duri ng the growth.The grown MoS2 films exhibit crystal I i nity,good electrical performa nee(electro n mobility of 22 cm2·V^-1·s^-1)and structural continuity maintained over the entire wafer.The sapphire substrates are reusable for subsequent growth.The same method is applied for the synthesis of tungsten disulfide(WS2).Our work provides a facile,reproducible and cost-efficient method for the scalable fabricati on of high-quality mono layer MoS2 for versatile applicati ons,such as electro nic and optoelectr onic devices as well as the membranes for desalination and power generation.

Choline-based ionic liquids for CO_2 capture and conversion

Choline-based ionic liquids(Ch-ILs) with anions possessing interacting sites to attract CO_2 were designed, which could capture CO_2 with capacity >1.0 mol CO_2 per molar IL under ambient conditions. Moreover, this kind of ILs combining with Cu Cl could catalyze the formylation of amines with CO_2/H_2 at 120 °C. Especially, choline imidazolate showed the best performance,affording a series of N-formamides in excellent yields. It was demonstrated that the IL activated CO_2 and the synergistic effect between the IL and Cu Cl resulted in the high activity for catalysing the formylation of amines with CO_2/H_2.

Cooperative effect from cation and anion of pyridine-containing anion-based ionic liquids for catalysing CO_2 transformation at ambient conditions

Pyridine-containing anion-based ionic liquids(PA-ILs) with two kinds of interaction sites to bind CO_2, e.g., [P4444][2-OP], were found to be highly efficient for catalysing the cycloaddition reactions of atmospheric CO_2 with epoxides at room temperature under metal-and halogen-free conditions, producing a series of cyclic carbonates in high yields. It was demonstrated that the cooperative interaction from two interaction sites in the anions of PA-ILs activated CO_2, while the cation activated the epoxides substrates via coordination to the central P+ unit, thus resulting in the high activity of the IL catalysts.

Reductive Cleavage of C-O Bond in Model Compounds of Lignin

A simple protocol for reductive cleavage of C--O bond in diaryl and aryl methyl ethers was reported, in which Nail served as a reducing agent and KO Bu as a base and a radical initiator. The combination of Nail and KOBu displayed high efficiency for reductive cleavage of C-O bond in diaryl and awl ethers （e.g., dibenzofuran, diphe- nyl ether, anisole） without the hydrogenation of the aryl rings, in the absence of any other catalysts or ligands at 140 ℃, producing corresponding arenes and phenols. It was indicated that the reaction was under a radical mecha- nism.

Recent progress in small molecule fluorescent probes for nitroreductase

Nitroreductase（NTR） is a member of flavin-containing enzymes that exists widely in bacteria. Hypoxia,which is a characteristic of locally advanced solid tumors, resulting from an imbalance between oxygen consumption and supply, can result in NTR overexpression. Using either nicotinamide adenine dinucleotide（NADH） or nicotinamide adenine dinucleotide phosphate（NADPH） as a source of reducing equivalents, NTR can catalyze the reduction of nitroaromatic compounds to the corresponding amines.Based on this reduction mechanism, NTR can be applied not only in the bioremediation and degradation of organic nitrogen compounds, but also in the development of NTR-targeted fluorescent probes to detect the hypoxic status of cancer cells. This review aims to provide a summary of the progress in fluorescent probes for NTR in recent years and elucidate the main fluorescent mechanisms that have been applied to design probes.

Highly stable lithium anode enabled by self-assembled monolayer of dihexadecanoalkyl phosphate

Li has been considered as the ultimate anode material for high energy density secondary Li batteries.However,its practical application has been limited due to its low Coulombic efficiency(CE)and the formation of lithium dendrites.Recently,we have developed a microspherical Li-carbon nanotube(Li-CNT)composite material passivated with octadecylphosphonic acid(OPA)self-assembled monolayer(SAM)exhibiting suppressed lithium dendrite formation and improved environmental/electrochemical stability.In this work,we demonstrated the significantly enhanced passivation effects of a SAM using dihexadecanoalkyl phosphate(DHP),a molecule that is comprised of double hydrophobic alkyl chains and forms a denser SAM on surfaces with large curvature.As a result,the DHP SAM delivers superior environmental and electrochemical stability to the OPA passivated Li-CNT material.In specific,the DHP passivated Li-CNT composite(DHP-Li-CNT)delivers a high CE of 99.25%under a 33.3%depth of discharge(DOD)at 1 C,when it is paired with a LiFePO4 cathode.The evolution of the SAM during cycling and the effects of DOD and current density on the CE of the DHP-Li-CNT anode have also been investigated.The improved SAM passivation constitutes an important step in achieving the goal of practically applicable Li anodes.

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM(1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guantlng reservoir inlet and outlet （China）. The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What＇s more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.

A Novel Route to Synthesize N,N-Dimethyl Arylmethylamines from Aryl Aldehydes, Hexamethylenetetramine and Hydrogen

Developing simple and green routes to access valuable chemicals is of significance.Herein,we present a green and novel route to synthesize N,N-dimethyl arylmethylamines(DAMAs)from hexamethylenetetramine(HMTA)and aryl aldehydes in the presence of hydrogen,and a series of DAMAs can be obtained in good yields.This approach opens the precedent for HMTA as N,N-dimethylamine source to synthesize chemicals with N,N-dimethylamine group,which has promising applications for N-containing chemicals synthesis.