Ultrafast laser dynamics of metal organic frameworks/TiO_2 nano-arrays hybrid composites for energy conversion applications

Herein,we report the victorious synthesis of metal-organic frameworks(MOFs) on TiO_2 nanotubes(NTs)using a layer-by-layer(LbL) approach.Highly crystalline and homogenous thin films of MOFs were grown and characterized using XRD,SEM,FT-IR and UV/Vis spectroscopy.Moreover,the utilization of the MOF films as sensitizers was probed in bespoke Graetzel type liquid junction solar cells.The constructed cell performance revealed an I_(sc) of 1.16 mA cm^(–2),Vocof 0.63 V,FF of 0.33,and E_(ff) of 0.42%.Further,pumpprobe transient laser spectroscopy was performed to investigate the energy and charge transfer dynamics of the MOFs/TiO_2 NTs interface.The results indicated 86% injection efficiency.The ultrafast pump-probe spectroscopy allows the investigation of this process and the differences between MOFs.It also showed that the relaxation of the MOF chromophores is in competition with electron injection in the Ti O2 motif.Thus this study provides a new insight into electron transfer from photoexcited metal-organic frameworks(MOFs) into titanium dioxide.

Synthesis, Structure, and Magnetic and Luminescent Properties of Rare Earth Coordination Polymers Constructed from Mixed Dicarboxylates

Three unique metal-organic framework coordination polymers, [Eu_2(bptc)(bdc)_2(H_2O)]_n(1), [Gd_2(bptc)(bdc)_2(H_2O)_4]_n(2) and [Dy_2(bptc)(bdc)_2(H_2O)_4]n(3)(1,2-H_2 BDC = 1,2-benzenedicarboylic acid, H_2 bptc = 4,4?-biphenyldicarboxylic acid) were synthesized by mixing two different multi-carboxylic acids with Ln2 O3(Ln = Eu, Gd and Dy) in hydrothermal condition. The three compounds are all three-dimensional and compounds 2 and 3 contain 4.289 × 6.507 ?~2 rectangularshaped one-dimensional open channels along the a direction. Additionally, the magnetic, luminescent and thermogravimetric properties were studied in detail.

Synthesis of rare earth metal-organic frameworks(Ln-MOFs) and their properties of adsorption desulfurization

The rare earth metal-organic frameworks （Ln-MOFs） materials, Ln（BTC）（H2O）-（DMF）, were synthesized using the rare earth metal （Ln=Sm, Eu, Tb, Y） and 1,3,5-trirnesic acid （BTC） as a metal ion center and ligand, respectively. X-ray diffraction （XRD） and infrared spectroscopy （FT-IR） were employed to characterize the Ln-MOFs structural features. The property of adsorption desul- furization of Ln-MOFs materials was evaluated with thiophene/n-octane as model oil. The results showed that Ln-MOFs with rare earth metals Sm, Eu, Tb and Y had perfect crystalline and good adsorption desulfurization ability. Y（BTC）（H2O）-（DMF） material had a comparatively better activity for the adsorption desulfurization with desulfurization rate up to 80.7% and the sulfur adsorption ca- pacity was found 30.7 mgS/g（Y-MOFs）. The Ln-MOFs materials had excellent reusability.

Cu-BTC/nano-TiO_(2)的制备及其可见光催化性能

采用水热法制备了有机金属框架材料Cu-BTC,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、比表面积分析仪(BET)等手段对Cu-BTC的微观结构和性能进行了表征,研究了Cu-BTC与nano-TiO_(2)混合后对染料(罗丹明B(RhB)、亚甲基蓝(MB)和刚果红(CR))吸附性能和光催化降解性能的影响。结果表明:Cu-BTC呈现典型的正八面体结构,比表面积高达935.44 m^(2)/g;引入nano-TiO_(2)后,混合材料对染料的吸附和光催化性能均有提升,当Cu-BTC和nano-TiO_(2)的质量比为3∶1时,240 min紫外光照后,RhB溶液的光催化降解效率达79.53%,对MB和CR的降解效率分别为94.66%和99.41%;同时,混合材料有较好的循环使用性能,3次循环使用后对MB和CR的降解效率仍保持在90.81%和97.60%以上。

The Electrocatalytic Performance of Rare Earth Ion Doped Co_(0.2)Ni_(0.8)-MOF-74 Catalyst for Nitrogen Reduction

We took Co_(0.2)Ni_(0.8)-MOF-74 with bimetallic synergistic effect as the basic material,and selected rare earth ions Ho,Gd,and Er with ion radii close to Co and Ni as the research objects for doping.The influence of rare earth ion doping amount and doping type on the eNRR performance of the catalyst was explored.The experimental results show that the ammonia yield rate and Faraday efficiency doped with Co_(0.2)Ni_(0.8)-MOF-0.5Ho are the highest,reaching 1.28×10^(-10)mol·s^(-1)·cm^(-2)/39.8%,which is higher than the1.12×10^(-10)mol·s^(-1)·cm^(-2)/32.2%of Co_(0.2)Ni_(0.8)-MOF-74,and is about 14.3%/23.7%higher than that without doping,respectively.And the stability of Co_(0.2)Ni_(0.8)-MOF-0.5 Ho is good(after 80 hours of continuous testing,the current density did not significantly decrease).This is mainly due to doping,which gives Co_(0.2)Ni_(0.8)-MOF-74 a larger specific surface area and catalytic active sites.The catalyst doped at the same time has more metal cation centers,which increases the electron density of the metal centers and enhances the corresponding eNRR performance.

稀土基金属有机框架材料的制备及其对Pb^(2+)的电化学检测

室温下以硝酸钬为金属源,均苯三甲酸为有机配体,通过--步共混法制备出形貌均一的棒状稀土基金属有机框架材料(Ho-MOF),在玻碳电极基底上,采用两步滴涂法制备Ho-MOF-NIP复合修饰电极,成功构建了用于检测Pb^(2+)的电化学传感器(Ho-MOF-NIP/GCE)。采用差分脉冲阳极溶出伏安法(DPASV)研究了Pb^(2+)在该修饰电极上的电化学行为。实验结果表明:该电极对Pb2的检测灵敏度显著提升,在0.1~1 mmol.LI范围内,氧化峰电流值与Pb^(2+)的浓度呈现良好的线性关系,检测限为7 pumol.L'(S/N=3),该方法可用于水样中Pb^(2+)的快速检测。

AuNP@Co_(3)(HITP)_(2)-CNT纳米结构的制备及电化学传感性能

利用一步水热法和化学还原法制备了基于金纳米颗粒负载Co_(3)(HITP)_(2)-碳纳米管(AuNP@Co_(3)(HITP)_(2)-CNT)的纳米复合材料。利用X射线光电子能谱仪(XPS)和扫描电子显微镜(SEM)对其表面微观形貌和元素组成进行表征。构建了前列腺特异性抗原(PSA)/牛血清蛋白(BSA)/PSA抗体(Ab)/AuNP@Co_(3)(HITP)_(2)-CNT/玻碳电极(GCE)电化学免疫传感器,并对PSA进行了检测,用循环伏安法(CV)、差分脉冲伏安法(DPV)和电化学阻抗谱(EIS)对其进行电化学性能分析测试。实验结果表明:基于AuNP@Co_(3)(HITP)_(2)-CNT纳米复合材料的电化学免疫传感器对PSA有较宽的检测范围,可达40 fg/mL~100 ng/mL,同时具有较好的特异性、稳定性和可重复性。

前沿科研成果融入综合化学实验——一种稀土金属有机框架的合成及作为荧光探针的应用

将前沿科研成果融入大学化学学科的实验教学环节中,实现学和用的有机结合,既能加深学生对课本理论知识的理解,又可以激发学生从事本专业实践的兴趣和培养学生的创新能力,是培养新时代高素质专业人才的必然要求。在这样的背景下,本文设计了一个将当前化学领域的研究热点之一的金属有机框架融入综合化学实验的案例,该实验包括金属有机框架材料的合成、表征及作为荧光探针的应用三个主要部分,既涉及大量的基础实验操作技能的锻炼,又融入了红外光谱、粉末X-射线衍射、热重分析、荧光光谱等多类现代分析技术,内容上还涉及我国的重要战略资源之一的稀土的应用,以及生态环境保护。除可以系统地培养学生的专业综合能力外,对培养学生的民族自豪感和生态保护素养也具有重要的价值。

同构稀土金属-有机框架材料对离子型染料的吸附及光降解研究

以氨基化3,3′,5,5′-三联苯四羧酸(NH_(2)-H_(4)TPTC)为配体与稀土金属盐[Ho(NO_(3))_(3)·6H_(2)O、Er(NO_(3))_(3)·6H_(2)O]反应得到两个同构稀土金属-有机框架材料(MOFs)Er-NH_(2)-TPTC和Ho-NH_(2)-TPTC,两种MOFs材料在250℃以下具有良好的稳定性。选择不同类型的离子染料,并用所合成的材料进行吸附和光催化降解有机染料实验。结果表明:Er-NH_(2)-TPTC和Ho-NH_(2)-TPTC对离子型染料吸附效果优于中性染料,在光催化后对各类有机染料降解效果均得到提升。由于受染料分子尺寸的影响,两个同构稀土MOFs对小分子阳离子染料甲基蓝去除率可达99%,而对分子尺寸较大的阳离子染料罗丹明B降解效率最低,仅分别达到47%和73%。光催化降解的机理研究表明,降解过程中产生·O_(2)^(-)和·OH活性物质,此类自由基的产生有助于提高光催化降解效率。

载阿霉素光响应纳米锆基MOFs构建及细胞毒性研究

为了克服乳腺癌治疗药物阿霉素存在毒副作用大、作用时间短等限制,本研究采用含偶氮苯侧链结构的联苯羧酸与Zr4+构建了一种新型光响应纳米金属有机框架(U67-AZO-COOH)作为药物载体,成功地将阿霉素负载其中。通过粉末X射线衍射、扫描电镜、傅里叶变换红外光谱、全自动比表面及孔隙度分析等技术手段对其结构进行了详细表征,得到在紫外光照射下阿霉素的载药率可由18.57%降至7.31%。体外释放实验和细胞毒性实验结果表明,该纳米药物复合物具有高载药量、良好的生物相容性,其在微酸环境下的释放率57.02%高于生理条件39.26%,表现出显著的缓释效果,能够减少对正常细胞的损害,存活率从39.88%提高到81.73%。这为新型光响应纳米金属有机框架在药物传递领域的广泛应用提供了新的可能性。

Rare earth oxides and their supported noble metals in application of environmental catalysis

Volatile organic compounds(VOCs),methane,carbon monoxide,soot,automotive exhaust,and nitrogen oxides are harmful to the atmosphere and human health.It is urgent to strictly control their emissions.Heterogeneous catalysis is an effective pathway for the removal of these pollutants,and the critical issue is the development of novel and high-performance catalysts.In this review,we briefly summarize the preparation methods,physicochemical properties,catalytic activities,and related reaction mechanisms for the above pollutants removal of the rare earth oxides,mixed rare earth oxide,rare earth oxidesupported noble metal,and mixed rare earth oxide-supported noble metal catalysts that have been investigated by our group and other researchers.It was found that catalytic performance was associated with the factors,such as specific surface area,pore structure,particle size and dispersion,adsorbed oxygen species concentration,reducibility,reactant activation ability or interaction between metal nanoparticles and support.Furthermore,we also envision the development trend of such a topic in future work.

Recent trends and morphology mechanisms of rare-earth based BiFeO_(3) nano perovskites with excellent photocatalytic performances

The multiferroic bismuth ferrite(BiFeO_(3),denoted as BFO)semiconductors have attracted prominent recognition due to their unique physical properties and prospective industrial applications.Significant features like strong photo absorption and morphological structure play a major role in rare earth-based BFO materials.The article encapsulates the latest developments on rare-earth-based nano BFO as new class photo catalytic materials for electro-optic applications.Detailed discussion on degradation efficiencies of industrial organic dyes in ultra-violet,visible light,and near infra-red photocatalysis was carried out.The various techniques acquired to fabricate rare-earth-based BFO and the modification approaches in A-and B-site that take part in the morphology,and photo activity improvement were also detailed.This review also summarizes the existing state of research work and explains some practical ideologies of BiFeO_(3) for their future developments.Finally,this article discusses the summary and future aspects of the present challenges faced by the BFO based materials for feasible improvements.

Removal of organic pollutants by lanthanide-doped MIL-53(Fe) metal-organic frameworks:Effect of dopant type in magnetite precursor

A series of undoped and lanthanide doped MIL-53(Fe)/Ln-Fe_(3)O_(4)(Ln=La,Nd,or Gd) metal-organic frameworks(MOFs) were prepared by the solvothermal method.All prepared samples were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),Brunauer-Emmett-Teller(BET) measurements,scanning electron microscopy(SEM),and thermal analysis.XRD and FT-IR results ascertain the successful MOF formation for all prepared samples.MIL-53(Fe)/La-Fe_(3)O_(4) has the smallest particle size of 8.6 nm,the largest BET surface area of 54.2 m^(2)/g,and the highest porosity.Undoped and different lanthanide doped MIL-53(Fe) we re employed as sorbents for the removal of methylene blue(MB)dye from aqueous solutions to examine the doping benefit and the effect of the dopant size on the sorption performance.Doping causes MOFs to act as pH-independent sorbents,which make it applicable at any condition.Adsorption follows pseudo-second-order kinetic model,and doped sorbents attain equilibrium faster.Langmuir isotherms are followed,except for MIL-53(Fe)/La-Fe_(3)O_(4).The adsorption capacity increases with increasing the dopant ion size,100.5 mg/g for La-doped MOF,which is about four times higher than that of undoped MOF.The adsorption mechanism involves chemical interactions between Lewis acid in magnetite MIL-53(Fe) series and Lewis base in MB.

Metal-organic framework based nanomaterials for electrocatalytic oxygen redox reaction

Due to the severe environmental issues, many advanced technologies, typically fuel cells and metal-air batteries have aroused widespread concerns and been intensively studied in recent years. However, oxygen redox reactions including oxygen evolution reaction(OER) and oxygen reduction reaction(ORR) as the core reactions suffer from sluggish kinetics of the multiple electron transfer process. Currently, Pt, RuO_2, and IrO_2 are considered to be the benchmark catalysts for ORR and OER, but their high price, scarcity and instability hinder them from large-scale application. To overcome these limits, exploring alternative electrocatalysts with low cost, high activity, long-term stability, and earth-abundance is of extreme urgency. Metal-organic frameworks(MOFs) are a family of inorganic-organic hybrid materials with high surface areas and tunable structures, making them proper as catalyst candidates. Herein, the recent progress of MOFs and MOF-derived materials for ORR and OER is systematically reviewed, and the relationship between compositions and electrochemical performance is discussed. It is expected that this review can be helpful for the future development of related MOF-based materials with excellent electrochemical performance.

Selenium-functionalized metal-organic frameworks as enzyme mimics

The development of artificial enzyme mimics has been rapidly growing in recent years, and it is attracting increasing attention owing to their remarkable advantages over natural enzymes. Herein, we developed a general and facile method to fabricate efficient glutathione peroxidase （GPx） mimics by grafting selenium-containing molecules （phenylselenylbromide, PhSeBr） to a Zr（W）-based UiO-66-NH2 framework. In the presence of glutathione （GSH） serving as substrate, the fabricated UiO-66-Se catalysts can catalyze the reduction of hydroperoxides. The as-prepared UiO-66-Se systems show good catalytic activity over three cycles. These high-efficiency GPx mimic metal-organic frameworks （MOFs） are endowed with excellent thermal and structural stability, providing a promising avenue for the development of artificial enzyme mimics.

基于碳点/葡萄糖氧化酶共包裹金属有机框架的葡萄糖传感器研究

建立了高稳定性的血清中葡萄糖的检测方法。通过将葡萄糖氧化酶(GOx)、碳点(CDs)共同包封在类沸石咪唑酯骨架(ZIF-8)材料中制备了纳米复合材料GOx/CDs@ZIF-8。在中性条件下,该复合材料可高效催化氧化葡萄糖生成H_(2)O_(2),随后H_(2)O_(2)与Co^(2+)通过类芬顿反应产生自由基(·OH),该自由基可使碳点的荧光发生猝灭,基于此构建了血清中葡萄糖的荧光检测方法。在优化条件下,该荧光探针的检出限为0.16μmol/L,回收率为91.0%~108%。所构建的纳米荧光探针可用于实际样品中葡萄糖的检测,且在常温下具有较高的稳定性。

镧钕双稀土金属有机框架化合物的制备及其电化学性能测试

基于稀土的特性,将稀土金属与有机酸配体对苯二甲酸结合,可能获得具有优良电化学性能的有机配位化合物。以镧(La)、钕(Nd)为金属源,对苯二甲酸为有机配体,采用溶剂热法制备了双金属有机框架化合物(La/Nd-MOFs)。经SEM、EDS、FT-IR、XRD、XPS进行结构表征,将其与乙炔黑、PVDF制成黏稠浆状涂料负载于泡沫镍上获得复合电极La/Nd-MOFs。采用CV、GCD和EIS方法测定了La/Nd-MOFs电化学性能。结果表明,在电流密度1 A/g下,La/Nd-MOFs复合电极的比电容达到408 F/g,在8 A/g下循环充放电5000次,比电容保持率为94.4%。

Ionic Liquid-assisted Formation of Lanthanide Metal-organic Framework Nano/Microrods for Superefficient Removal of Congo Red

New lanthanide metal-organic framework（MOF） nano/microrods, [C4mim]Cl-Eu-MOF, [C8mim]Cl-Eu- MOF and [C12mim]Cl-Eu-MOF, were conveniently synthesized via an ionic liquid-assisted hydrothermal method and characterized by means of powder X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR）, thermo- gravimetric analysis（TG） and transmission electron microscopy（TEM）. The obtained nano/microrods with low sur- face areas were efficient for the removal of Congo red（CR） from aqueous solutions. Under the optimum conditions, [C4mim]Cl-Eu-MOF with a specific surface area of 5.1 m^2/g exhibited an ultrahigh adsorption capacity of 2606 mg/g toward CR. Notably, the adsorption efficiency of [C4mim]Cl-Eu-MOF for CR via nano/microscale stacking can be directly demonstrated by TEM. In-depth understanding of CR removal by [C4mim]Cl-Eu-MOF nano/microrods was also supported by FTIR, Raman spectroscopy and zeta potential analyses.

竞争配位诱导分级孔金属有机骨架纳米吸附剂对稀土离子的吸附与分离

针对相邻稀土离子镨Pr、钕Nd、钐Sm的高效吸附与分离,采用溶剂热法,通过将月桂酸作为竞争配位剂,制备具有分级孔结构的多孔金属有机框架纳米吸附剂,提高了对稀土离子的吸附量与选择性。通过红外光谱、氮气吸脱附曲线、X射线衍射、扫描电镜等表征手段证明了所合成的MOF-5的化学组成、晶体结构以及分级孔结构。通过调控不同反应时间,制备的分级孔MOF-5表面被长度约0.1μm左右的棒状晶粒覆盖,整体呈边长1μm左右的立方体结构,并具有最佳的微孔与大孔比例,平均孔径16.46 nm。对镨、钕与钐的平衡吸附量分别为84.82 mg/g、153.88 mg/g、228.34 mg/g。从动力学吸附平衡数据计算分离系数分别为β(Sm/Nd)=1.47,β(Nd/Pr)=1.83。

稀土及过渡金属氧化物改性纳米碳酸钙/天然橡胶复合材料的结构与性能

用镧、铈、钐、钬和镱稀土 (Ln)氧化物 (Ln2 O3 )及锌、钴和镍过渡金属 (TM)氧化物 (TMO)制备了稀土氢氧化物包覆纳米碳酸钙 [NCaCO3 -Ln(OH) 3 ]和过渡金属氢氧化物包覆纳米碳酸钙 [NCaCO3 -TM(OH) 2 ]。将二者分别加入 1 0 0份 (质量 ,下同 )天然胶乳 (NRL)中 ,保持体系的pH值约为 1 2 ,于 85℃下恒温搅拌 1h ,采用凝聚共沉法制备了稀土氧化物改性纳米碳酸钙 /天然橡胶复合材料 [NR/NCaCO3 -Ln(OH) 3 ]及过渡金属氧化物改性纳米碳酸钙 /天然橡胶复合材料 [NR/NCaCO3 -TM(OH) 2 ]。结果表明 ,所选用的Ln2 O3 与TMO对NCaCO3 均具有优良的改性作用 ,对硫化胶有显著的增强作用 ,其中以La2 O3 ,Sm2 O3 ,ZnO的改性效果为佳 ,且三者最佳用量依次为 0 5 0 ,1 0 0 ,2 5份。扫描电子显微镜分析表明 ,NCaCO3 -La(OH) 3 ,NCaCO3 -Sm(OH) 3 ,NCaCO3 -Zn(OH) 2 与NRL的界面结合牢固 ,并形成拉丝结构。动态力学分析表明 ,与未改性纳米碳酸钙填充天然橡胶 (NR/NCaCO3 )的硫化胶相比 ,NR/NCaCO3 -Sm(OH) 3 和NR/NCaCO3 -Zn(OH) 2 硫化胶的玻璃化转变温度稍有上升 ,内耗也略有增大。