Understanding Bridging Sites and Accelerating Quantum Efficiency for Photocatalytic CO_(2) Reduction

We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO_(2) reduction reaction(CO_(2)RR)via Mo–S bridging bonds sites in S_(v)–In_(2)S_(3)@2H–MoTe_(2).The X-ray absorption near-edge structure shows that the formation of S_(v)–In_(2)S_(3)@2H–MoTe_(2) adjusts the coordination environment via interface engineering and forms Mo–S polarized sites at the interface.The interfacial dynamics and catalytic behavior are clearly revealed by ultrafast femtosecond transient absorption,time-resolved,and in situ diffuse reflectance–Infrared Fourier transform spectroscopy.A tunable electronic structure through steric interaction of Mo–S bridging bonds induces a 1.7-fold enhancement in S_(v)–In_(2)S_(3)@2H–MoTe_(2)(5)photogenerated carrier concentration relative to pristine S_(v)–In_(2)S_(3).Benefiting from lower carrier transport activation energy,an internal quantum efficiency of 94.01%at 380 nm was used for photocatalytic CO_(2)RR.This study proposes a new strategy to design photocatalyst through bridging sites to adjust the selectivity of photocatalytic CO_(2)RR.

Performance enhancement and active sites identification of Cu-Cd bimetallic oxide derived catalysts for electrochemical CO_(2) reduction

The development of earth-abundant electrocatalysts with high performance for electrochemical CO_(2)reduction(ECR)is of great significance.Cu-based catalysts have been widely investigated for ECR due to their unique ability to generate various carbonaceous products,but directing selectivity toward one certain product and identifying the real active sites during ECR are still full of challenge.Here,after the incorporation of CdO into CuO,the Cu_(0.5)Cd_(0.5)-O catalyst achieves a 10.3-fold enhancement for CO selectivity in comparison with CuO,and a CO faradic efficiency nearly 90%with a current density around20 mA cm^(-2)could maintain at least 60 h.Interestingly,a wide CO/H_(2)ratio(0.07-10)is reached on Cu_(x)Cd_(1-x)-O catalysts by varying the Cu/Cd ratio,demonstrating the potential of syngas production using such catalysts.The results of ex situ XRD,XPS,and in situ Raman reveal that the real active sites of Cu_(0.5)Cd_(0.5)-O catalysts for CO production during ECR reaction are the reconstructed mixed phases of CuCd alloy and CdCO_(3).In situ FTIR and theoretical calculations further implicate the presence of Cd related species promotes the CO desorption and inhibits the H_(2)evolution,thus leading to an enhanced CO generation.

Zonal activation of molecular carbon dioxide and hydrogen over dual sites Ni-Co-MgO catalyst for CO_(2) methanation:Synergistic catalysis of Ni and Co species

An in-depth mechanism in zonal activation of CO_(2)and H2molecular over dual-active sites has not been revealed yet.Here,Ni-Co-MgO was rationally constructed to elucidate the CO_(2)methanation mechanism.The abundant surface nickel and cobalt components as active sites led to strong Ni-Co interaction with charge transfer from nickel to cobalt.Notably,electron-enriched Coδ-species participated in efficient chemisorption and activation of CO_(2)to generate monodentate carbonate.Simultaneously,plentiful available Ni0sites facilitated H2dissociation,thus CO_(2)and H2were smoothly activated at zones of Coδ-species and Ni0,respectively.Detailed in situ DRIFTS,quasi situ XPS,TPSR,and DFT calculations substantiated a new formate evolution mechanism via monodentate carbonate instead of traditional bidentate carbonate based on synergistic catalysis of Coδ-species and Ni0.The zonal activation of CO_(2)and H2by tuning electron behaviors of double-center catalysts can boost heterogeneous catalytic hydrogenation performance.

Multifunctional catalytic sites regulation of atomic-scale iridium on orthorhombic-CoSe_(2)for high efficiency dual-functional alkaline hydrogen evolution and organic degradation

The earth-abundant and high-performance catalysts are crucial for commercial implementation of hydrogen evolution reaction(HER).Herein,a multifunctional site strategy to construct excellent HER catalysts by incorporating iridium(Ir)ions on the atomic scale into orthorhombic-CoSe2(Ir-CoSe_(2))was reported.Outstanding hydrogen evolution activity in alkaline media such as a low overpotential of 48.7 mV at a current density of 10 mA cm^(-2)and better performance than commercial Pt/C catalysts at high current densities were found in the Ir-CoSe_(2) samples.In the experiments and theoretical calculations,it was revealed that Ir enabled CoSe_(2)to form multifunctional sites to synergistically catalyze alkaline HER by promoting the adsorption and dissociation of H_(2)O(Ir sites)and optimizing the binding energy for H^(*)on Co sites.It was noticeable that the electrolytic system comprising the Ir-CoSe_(2)electrode not only produced hydrogen efficiently via HER,but also degraded organic pollutants(Methylene blue).The cell voltage of the dual-function electrolytic system was 1.58 V at the benchmark current density of 50 mA cm^(-2),which was significantly lower than the conventional water splitting voltage.It was indicated that this method was a novel strategy for designing advanced HER electrocatalysts by constructing multifunctional catalytic sites for hydrogen production and organic degradation.

Strain‑Induced Surface Interface Dual Polarization Constructs PML‑Cu/Bi_(12)O_(17)Br_(2) High‑Density Active Sites for CO_(2) Photoreduction

The insufficient active sites and slow interfacial charge trans-fer of photocatalysts restrict the efficiency of CO_(2) photoreduction.The synchronized modulation of the above key issues is demanding and chal-lenging.Herein,strain-induced strategy is developed to construct the Bi–O-bonded interface in Cu porphyrin-based monoatomic layer(PML-Cu)and Bi_(12)O_(17)Br_(2)(BOB),which triggers the surface interface dual polarization of PML-Cu/BOB(PBOB).In this multi-step polarization,the built-in electric field formed between the interfaces induces the electron transfer from con-duction band(CB)of BOB to CB of PML-Cu and suppresses its reverse migration.Moreover,the surface polarization of PML-Cu further promotes the electron converge in Cu atoms.The introduction of PML-Cu endows a high density of dispersed Cu active sites on the surface of PBOB,significantly promoting the adsorption and activation of CO_(2) and CO desorption.The conversion rate of CO_(2) photoreduction to CO for PBOB can reach 584.3μmol g-1,which is 7.83 times higher than BOB and 20.01 times than PML-Cu.This work offers valuable insights into multi-step polarization regulation and active site design for catalysts.

CO_(2)原位矿化选址关键参数及其封存潜力评估研究进展

温室气体特别是二氧化碳的大量排放,是导致全球变暖的主要原因之一。根据国际能源署的报道,碳捕集利用和封存(CCUS)技术是缓解全球气候变化的重要措施之一,约占累计碳减排量的15%。原位矿化封存技术基于快速CO_(2)矿化机制,以镁铁质岩石和超镁铁质岩石(玄武岩、橄榄岩等)地层为碳封存位点,利用CO_(2)与富含Ca、Mg元素矿物的矿化反应,转变为稳定的碳酸盐,从而达到永久且高效封存CO_(2)的目的。冰岛和美国的中试项目已经证明了该技术的可行性,但中国尚未进行相关示范项目。本文介绍了原位矿化封存技术的机理、CO_(2)封存潜力的评估手段及其面临的风险与挑战,讨论了已开展的案例项目及其技术细节,梳理了实施该技术所必需的选址关键参数(包括源-汇距离、矿物类型、注入性、封闭性等),并基于目前研究对其前景进行展望,以期提高我国对原位矿化技术的认识和重视,为推动该领域进一步发展提供理论指导。

“双碳”愿景下CO_(2)驱强化采油封存技术工程选址指标评价

在国家能源安全和“双碳”战略愿景下,CO_(2)驱强化采油封存技术(CO_(2)-EOR)因能助力油气行业转型发展,成为“低碳化”乃至“负碳化”的首选技术和最现实的选择。无论是实验、数值模拟还是现场实践,目前国内外学者对CO_(2)-EOR研究侧重于CO_(2)作为高效的驱油“催化剂”本身及油藏CO_(2)-EOR适应性认识,对于工程选址评价缺乏统一标准和系统研究。在充分调研国内外文献的基础上,结合中国CO_(2)-EOR应用进展和工程实践,明确了CO_(2)-EOR工程选址可行性评价所需的通用依据,指出了CO_(2)-EOR工程选址遵循“CO_(2)封存与驱油双统一”、安全性、经济性的专属性原则,并从CO_(2)-EOR工程选址的地质、工程、安全、经济4个要素开展了较详尽系统的研究,定性-定量构建了“4+8+27”CO_(2)-EOR工程选址三级指标评价体系(GESE),以期为油藏开展CO_(2)-EOR工程选址提供借鉴,助力中国碳减排技术的应用与发展。

2型糖尿病合并感染患者肺炎克雷伯菌分布及预后影响因素分析

目的:探讨2型糖尿病(T2DM)合并感染患者肺炎克雷伯菌(KP)分布及预后影响因素分析。方法:选择226例T2DM患者为研究对象,根据是否合并KP感染分为未感染组(n=170)和感染组(n=56),分析T2DM患者感染的危险因素。收集T2DM合并感染患者KP标本,记录标本来源并进行菌种鉴定和药敏试验,并对所有菌株进行多位点序列(MLST)分型,记录预后情况。结果:基础疾病、抗生素使用、侵入性操作、血清白蛋白(ALB)、糖化血红蛋白(HbA1c)、空腹血糖(FPG)为影响T2DM发生感染的危险因素(均P<0.05)。T2DM合并感染患者体内分离56株肺炎克雷伯菌,肺炎克雷伯菌在痰液中的占比最高为44.62%,其次为尿液19.64%,血液中占比16.07%,脓液中占比12.5%,其他标本占比7.14%。56株KP总耐药率最高为氨苄西林,最低为亚胺培南,痰液标本中KP对头孢呋辛、头孢哌酮、庆大霉素耐药率高于非痰液标本,非痰液标本中KP对头孢他啶高于痰液标本(均P<0.05)。56株肺炎克雷伯菌MLST分型共发现42个ST型,ST-20型、36型、65型、347型、660型各2株,分别占3.57%,23型4株占7.14%,ST-17、25、29、35、37、45、86、189、208、211、218、322、355、412、490、519、557、595、726、776、1049、1092、1103、1319、1569、1916、2059、3014、3140、3536、4023、4194、4262、4412、4857型各1株,分别占1.78%,其他ST型7株占比12.5%。56例T2DM合并KP感染患者预后良好患者52例,预后不良患者4例,预后良好率为92.86%。结论:T2DM合并感染患者KP主要分布在痰液和尿液中,基础疾病、抗生素使用、侵入性操作、ALB、HbA1c、FPG是影响KP感染发生危险因素,T2DM合并KP感染患者根据药敏结果选择用药,有利于患者预后。

CTCS-2+ATO列控系统对短站坪长度需求适应性研究

研究目的:对于有地下线路的铁路工程,由于开挖土方等方面的问题,要求站坪长度尽量缩短,以节省工程投资。现有CTCS-2+ATO列控系统因其安全防护距离设置位置、车载设备安装位置、适应的运行速度较高等原因,对站坪长度要求较CBTC列控系统长,成为在市域铁路运用时的不利因素,需要对其进行短站坪长度需求的适应性分析并提出适宜的解决方法,提升系统的竞争力。研究结论:(1)侧线股道增设安全线,基于列车停稳信息及时解锁过走防护区段、利用应答器报文增加过走防护区段信息、及时回缩列控移动授权范围等配套方法,将安全距离、附加距离设于目标点信号机的内方,利用安全线及咽喉区线路缩短股道区线路长度;(2)合理约束车载应答器接收天线安装位置,根据市域列车运行速度计算、确定可靠解析出报文所需要的应答器距离信号机距离,以及应答器组间最小距离要求,最终确定股道出站应答器安装位置最小长度需求;(3)经折返线道岔侧向的进路不发低频码,轨道电路长度仅考虑轨道占用检查时间,进一步缩短折返道岔区段长度要求;(4)本研究成果在市域铁路中有广阔的运用前景。

Ce改性对CuLDH催化CO_(2)加氢制甲醇性能的影响

通过向CuMgAl水滑石(CuLDH)催化剂中添加不同量的Ce,合成了一系列Ce改性的CuLDH-Cex催化剂。采用X射线衍射(XRD)、N2吸附-脱附(BET)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等分析手段对催化剂的理化性质进行表征。结果表明,添加Ce会改变Cu-LDH催化剂的水滑石结构,适量的Ce会增大催化剂的比表面积,改善了Cu颗粒的分散度。同时,适量的Ce有利于增加催化剂表面强碱性位点的密度和氧空位的数量,促进了CO_(2)的吸附和转化。Ce有利于调变催化剂表面的Cu^(+)/Cu^(0)比例,较高的Cu^(+)/Cu^(0)比例有利于甲醇的生成。当Ce/Cu比例为0.3时,在空速为9000 mL/(g·h),温度为240℃,压力为2.5 MPa的条件下,催化剂的CO_(2)的转化率为7.5%,甲醇选择性为78.4%,甲醇的时空收率最高可达362.8 g/(kg·h)。通过原位红外光谱(in-situ DRIFTS)证明CuLDH-Ce0.3催化剂在CO_(2)加氢合成甲醇过程中遵循HCOO*反应路径。

Regulating the interfacial charge transfer and constructing symmetry-breaking sites for the enhanced N_(2) electroreduction activity

The Haber-Bosch process for industrial NH_(3) production is energy-intensive with heavy CO_(2) emissions.Electrochemical N_(2) reduction reaction(NRR)is an attractive carbon-neutral alternative for NH_(3) synthesis,while the challenge associated with N_(2) activation highlights the demand for efficient electrocatalysts.Herein,we demonstrate that PdCu nanoparticles with different Pd/Cu ratios anchored on boron nanosheet(PdCu/B)behave as efficient NRR electrocatalysts toward NH_(3) synthesis.Theoretical and experimental results confirm that the highly efficient NH_(3) synthesis can be achieved by regulating the charge transfer between interfaces and forming a symmetry-breaking site,which not only alleviates the hydrogen evolution but also changes the adsorption configuration of N_(2) and thus optimizes the reaction pathway of NRR over the separated Pd sites.Compared with monometallic Pd/B and Cu/B,the PdCu/B with the optimized Pd/Cu ratio of 1 exhibits superior activity and selectivity for NH_(3) synthesis.This study provides new insight into developing efficient catalysts for small energy molecule catalytic conversion via regulating the charge transfer between interfaces and constructing symmetry-breaking sites.

Mesoporous poly(ionic liquid)s with dual active sites for highly efficient CO_(2)conversion

Atmospheric CO_(2)concentrations are soaring due to the continued use of fossil fuels in energy production,an anthropogenic activity that is playing a leading role in global warming.Thus,research aimed at the capture and conversion of CO_(2)into value-added products,such as cyclic carbonates,is booming.While CO_(2)is an abundant,cheap,non-toxic,and readily accessible Cl feedstock,its thermodynamic stability necessitates the development of highly efficient catalysts that are able to promote chemical reactions under mild conditions.In this work,a novel mesoporous poly(ionic liquid)with dual active sites was synthesized through a facile method that involves co-polymerization,post-synthetic metalation,and supercritical CO_(2)drying.Due to a high density of nucleophilic and electrophilic sites,the as-prepared poly(ionic liquid),denoted as P2D-4BrBQA-Zn,offers excellent performance in a CO_(2)cycloaddition reaction using epichlorohydrin as the substrate(98.9%conversion and 96.9%selectivity).Moreover the reaction is carried out under mild,solvent-free,and additive-free conditions.Notably,P2D-4BrBQA-Zn also efficiently promotes the conversion of various other epoxide substrates into cyclic carbonates.Overall,the catalyst is found to have excellent substrate compatibility,stability,and recyclability.

活性位点电子密度变化对光催化CO_(2)活化和选择转化的影响

光催化二氧化碳(CO_(2))还原制液体燃料和高值化学品技术不仅能充分利用可再生能源太阳光,实现化学储能;更重要的是,此技术以温室气体CO_(2)为原料,因此可以减缓全球温室效应,构造人工碳循环。然而,光催化CO_(2)还原制液体燃料和高值化学品反应过程中面临诸多挑战:(1)CO_(2)分子吸附和活化过程困难;(2)(高附加值)碳产物选择性低;(3)产物生成后易发生其他副反应导致催化剂失活或产物选择性下降。受到以上三个挑战的制约,目前的反应效率较低,难以满足工业化应用。由于光催化CO_(2)向高值化学品的转化过程为质子耦合光生电子参与的还原反应,因此活性位点的电子密度会显著影响以上挑战的解决。然而,光催化CO_(2)还原过程涉及众多基元步骤,每个基元步骤对于活性位点的电子密度要求并不清晰,这导致无法有针对性设计高效的催化剂来促进光催化CO_(2)分子的有效活化及高选择性转化。本文综述了近期活性位点的电子密度变化对于CO_(2)分子吸附和活化过程、碳产物选择性调控和产物脱附及过氧化的影响规律,并总结了调控活性位点上电子密度的方法,旨在对未来设计高效光催化剂提供参考和理论依据。

Mn^(2+)掺杂对YAG∶Ce^(3+)荧光陶瓷发光性能的影响

过渡族金属Mn^(2+)掺杂的石榴石荧光陶瓷被认为是实现高显色激光照明的候选材料。然而,由于Mn^(2+)在不同配位环境下离子半径的多样性,Mn^(2+)掺杂石榴石陶瓷体系设计方案尚不明确。本文采用真空烧结技术制备得到不同浓度Mn^(2+)掺杂的YAG∶Ce^(3+)荧光陶瓷,并将Mn^(2+)分别设计进入八面体(OC)和十二面体(DO)格位。通过表征样品物相和显微结构、光致发光、荧光寿命、量子效率等,并通过LD激光器激发对荧光陶瓷的发光性能进行研究。实验结果表明,在添加电荷与体积补偿剂SiO_(2)的前提下,相比Mn^(2+)进入十二面体格位,Mn^(2+)进入八面体后石榴石的晶体结构更加稳定。因此,当Mn^(2+)的浓度控制在0.5%^(6)%(at)范围内,OC系列样品的量子效率高于DO系列样品。此外,OC系列样品的PL谱中位于588 nm和725 nm处的发射峰分别对应于Mn^(2+)占据八面体和十二面体格位的^(4)T_(1)→^(6)A_(1)电子跃迁,而DO系列样品中位于572 nm处的发射峰则源于Mn^(2+)占据扭曲的十二面体格位产生的电子跃迁。得益于Ce^(3+)→Mn^(2+)间高效的能量传递,将浓度为6%(at)的Mn^(2+)设计进入YAG∶Ce^(3+)中八面体格位制得荧光陶瓷,封装得到的激光白光光源的显色指数为70.8,相对色温为5117 K。本文对于Mn^(2+)掺杂的石榴石发光材料的开发研究是有力补充,也为提升YAG∶Ce^(3+)荧光陶瓷光谱中的红光成分,进而提高医疗、显示等领域的激光光源的显色性能提供借鉴。

基于IT2F-BWM-MABAC方法的应急物流设施选址方案评价

针对不确定环境下应急物流设施选址方案评价问题,提出一种基于区间二型模糊集(IT2F)-最优最劣法(BWM)-多属性边界近似区域比较法(MABAC)的应急物流设施选址方案评价方法。首先,针对应急物流设施选址方案评价过程中评价信息的模糊不确定性问题,采用IT2F处理,并利用MABAC对选址方案排序;然后,针对传统的MABAC中属性权重需要从外部获得的问题,采用基于IT2F的BWM确定属性的权重;最后,将所提方法应用于某城市应急物流设施选址方案评价研究,并验证所提选址方法的可行性和有效性。结果表明:所提方法能够解决不确定环境下应急物流设施选址问题,同时能够保证方案评价的质量。

焙烧气氛对棒状CeO_(2)催化CO_(2)和甲醇直接合成DMC的影响

二氧化碳(CO_(2))和甲醇(MeOH)直接合成碳酸二甲酯(DMC)是一条符合绿色化学要求的DMC制备路线,并可实现CO_(2)资源化利用。氧化铈(CeO_(2))基催化剂被广泛应用于该反应,目前研究主要集中在形貌调控与杂原子掺杂对催化剂催化性能的影响。采用水热合成法制备了棒状CeO_(2)前驱体,然后在不同的焙烧气氛(分别为H_(2)、N_(2)、air和O_(2))中处理前驱体得到相应催化剂,然后将催化剂应用于2-氰基吡啶(2-cp)作脱水剂的CO_(2)和MeOH直接合成DMC(加入0.10 mol MeOH、0.05 mol 2-cp和0.32 g催化剂,在120℃、5 MPa的条件下反应2 h)中,研究了焙烧气氛对催化剂催化性能的影响。采用XRD、N2吸/脱附和SEM等对催化剂的晶相结构、织构性质和形貌等进行了表征。结果表明,4种催化剂在结构性质和形貌方面没有表现出明显差异,而催化剂表面的Ce价态与酸碱位点密切相关。催化剂表面存在的丰富缺陷位点使其具有较大的比表面积和平均孔径(CeO_(2)-air的比表面积和平均孔径分别为65.44m^(2)/g和30.06nm),催化剂主要暴露的CeO_(2)(111)晶面能促进DMC的生成。与其他3种催化剂相比,CeO_(2)-air因表面含有最丰富的中强酸碱位点和总的酸碱位点,以及较强的弱酸酸性而表现出最好的催化性能,该催化剂作用下的DMC产率和DMC选择性分别为83.2%和99.3%。

Tuning active sites in MoS_(2)-based catalysts via H_(2)O_(2)etching to enhance hydrodesulfurization performance

A H_(2)O_(2)etching strategy was adopted to introduce coordinatively unsaturated sites(CUS)on MoS_(2)-based catalysts for dibenzothiophene(DBT)hydrodesulfurization(HDS).The CUS concentrations on MoS_(2) slabs were finely regulated by changing the concentrations of H_(2)O_(2)solution.With the increasing H_(2)O_(2)concentrations(0.1–0.3 mol/L),The CUS concentrations on MoS_(2) slabs increased gradually.However,the high-concentration H_(2)O_(2)etching(0.5 mol/L)increased the MoOxSy and MoO_(3) contents on MoS_(2) slabs compared to etching with the H_(2)O_(2)concentration of 0.3 mol/L,which led to the less CUS concentration in the sulfided Mo–H-0.5 catalyst than in the sulfided Mo–H-0.3 catalyst.A microstructure-activity correlation indicated that the CUS introduced by H_(2)O_(2)etching on MoS_(2) slabs significantly enhanced DBT HDS.Different Co loadings were further introduced into Mo–H-0.3,which had the most CUS concentration,and the corresponding 0.2-CoMo catalyst with the highest CoMoS content(3.853 wt%)exhibited the highest reaction rate constant of 6.95×10^(−6)mol g^(−1)s^(−1)among these CoMo catalysts.

基于共价有机框架非金属位点的光催化CO_(2)还原

光催化CO_(2)还原制备碳基化学品,是解决能源危机的理想途径之一.以往的研究主要聚焦于金属位点催化,尽管金属催化剂具有显著的应用潜力,但其高昂的成本和金属中心易失活的问题,限制了其广泛应用.因此,模拟植物光合作用,探寻基于非金属位点的光催化剂,为CO_(2)还原提供了新的解决思路.共价有机框架材料(COFs)作为一种新型有机晶态多孔材料,因其高度有序的结构和π共轭体系,通常表现出半导体特性.在COF中引入氮官能团,能有效增强对CO_(2)的吸附和活化能力,有望在COFs上实现非金属光催化CO_(2)还原.本文利用COF异质结材料研究了非金属位点催化CO_(2)还原过程.采用原位合成方法制备出ZnIn_(2)S_(4)@TAz-COF异质结材料.红外光谱、Raman光谱和X-射线衍射等方法证明了异质结材料的成功合成.扫描电镜和透射电镜观察显示,ZnIn_(2)S_(4)纳米片与COF形成了异质互融界面,这对后续研究电子转移路径和光催化增强机制至关重要.通过紫外-可见光漫反射光谱、紫外光电子能谱和Mott-Schottky表征,分析了复合前后样品在能带结构上发生的变化和单独组分的功函数.由此推断,当两者复合后,在费米能级差的驱动下,TAz-COF表面的电子流向ZnIn_(2)S_(4),在界面处形成内建电场,这与差分电荷计算结果相一致.进一步的原位光照X射线光电子能谱研究证实,ZnIn_(2)S_(4)@TAz-COF异质结两相之间存在电荷转移,在界面处形成由TAz-COF指向ZnIn_(2)S_(4)的内建电场.这驱动了ZnIn_(2)S_(4)导带上的光生电子与TAz-COF价带上的光生空穴定向迁移和复合,而TAz-COF导带上还原能力较强的光生电子和ZnIn_(2)S_(4)价带上氧化能力较强的光生空穴被空间分离并参与光催化反应.在以水为电子供体的光催化还原CO_(2)反应中,该异质结材料表现出较好的还原CO_(2)到CO活性和良好的稳定性,其转化效率可与部分金属催化的CO_(2)还原体系相当.密度泛函理论计算和原位光谱分析结果表明,吖嗪基团是CO_(2)分子的吸附和活化位点,吖嗪中的氮原子与CO_(2)中的碳原子的强相互作用确保了CO_(2)向COOH*中间体的转化,最终通过光生电子和质子的协助在COF表面转化为CO.综上所述,本文制备了ZnIn_(2)S_(4)@TAz-COF异质结光催化材料.在可见光照射下,该材料界面处形成的内建电场有效驱动了光生电子和空穴的定向迁移,使得COF导带上具有较强还原能力的光生电子与ZnIn_(2)S_(4)价带上具有较强氧化能力的光生空穴实现了高效的空间分离.在没有金属助催化剂和空穴牺牲剂的条件下,ZnIn_(2)S_(4)@TAz-COF复合光催化剂表现出较好的光催化CO_(2)还原活性.本工作不仅为深入理解非金属位点催化CO_(2)还原机理提供了新视角,也为设计和构建高效CO_(2)还原光催化材料提供了参考.

掺杂钙钛矿催化剂的制备及其催化合成气直接转化制C_(2+)醇性能研究

由合成气直接转化制C_(2+)醇(碳链中含两个及两个以上碳原子的醇类)是目前最有前景的醇类化合物合成路线之一,而钙钛矿结构的催化剂可用于提高该过程中的C_(2+)醇合成性能。采用共沉淀法分别制备了Co、Mn掺杂的钙钛矿LFC和LFM催化剂(L、F、C和M分别指金属La、Fe、Co和Mn),系统考察了不同焙烧温度和掺杂元素对钙钛矿催化剂的C_(2+)醇合成性能的影响。多种表征结果显示,低焙烧温度可优化LF-600(“-”后的数字指焙烧温度)催化剂的结构和吸附行为,在LF-600催化剂上,CO解离和非解离位点的耦合有助于提高反应的CO转化率和总醇的选择性,分别达16.9%和31.2%(质量分数),且Co和Mn的掺杂可改变LF-600催化剂的产物分布和活性。与LF-600催化剂相比,LFC-600催化剂的H_(2)吸附能力低,有利于反应链增长,从而将C_(2+)醇在总醇中的比例从60.4%提高至71.6%。LFM-600催化剂具有更多的低温H_(2)吸附位点,导致醇类产物以甲醇为主,而Mn掺杂导致的颗粒团聚及Mn和O元素聚集会降低LFM-600催化剂的活性。

尘螨过敏原Der p 2线性表位肽及其硝基化产物与IgE结合能力

许多过敏原可以介导Ⅰ型超敏反应,通过与IgE特异性结合,引起过敏症状.过敏原与细胞表面的特异性IgE结合的部分叫做表位,其与IgE的结合能力可以表征过敏原致敏性的强弱.Der p 2是一种重要的屋尘螨过敏原,其线性表位中含有的酪氨酸可被空气中的NO_(2)和O_(3)硝基化,从而影响线性表位与IgE的结合能力.本实验研究了Der p 2的线性表位及其硝基化产物与IgE的结合能力.研究发现,Der p 2的两条表位多肽可以有效地结合IgE,硝基化表位多肽的IgE结合能力显著高于未硝基化的表位多肽,且不同位点的硝基化对于IgE结合能力的增强程度也不同.结果表明,硝基化能够位点特异性地增强Der p 2的致敏性.