Study on the Synthesis and Catalytic Performance of Silica-Encapsulation Enhanced Copper-Based Nanocatalysts

多相催化剂在化学工业中具有举足轻重的应用，约有90%的化工过程需要使用催化剂。近年来，人们在多相催化剂的制备方法、结构设计、性质研究等方面做了大量研究，制备出了许多高效的催化剂。但是，催化剂在使用过程中容易发生烧结，导致催化剂催化活性的降低，乃至失活。针对催化剂存在的这一问题,人们采用不同的方法来提高催化剂的抗烧结性能，如，选择不同的载体、改变组分和包裹等策略。其中，包裹的策略最为常用，一般涉及两种结构，yolk-shell结构和core-shell结构。包裹的策略不仅可以稳定核内金属纳米颗粒，也能产生新的金属-载体界面，尤其是core-shell结构能实现这种界面的最大化。由于包裹而产生的界...Heterogenous catalysts have important applications in modern chemical industry and are used in ninety percent of chemical reactions in chemical industry. In recent years, many researches are mainly focused on the design, the preparation and the performance of catalysts. Catalysts are easily sintered during heterogeneous catalysis, which leads to the decrease of surface area of the catalytically ac...学位：理学博士院系专业：化学化工学院_纳米材料化学学号：2052010015364

A nanoparticulate polyacetylene-supported Pd(Ⅱ) catalyst combining the advantages of homogeneous and heterogeneous catalysts

负载型的金属催化剂虽然分离方便,但在反应活性、选择性以及催化剂的结构表征方面均明显不如相应的均相催化剂.将均相催化剂通过不同的化学键固载于高比表面积载体是实现均相催化剂多相化的重要途径,这样可使催化剂兼具均相和多相催化剂的优势.然而要将均相催化剂锚定于特定载体上,通常涉及较为复杂的合成反应,对载体也有严格的要求.因而该法仅仅适用于实验室研究,难以实现规模生产.因此,提供一种简便有效地制备兼具均相和多相催化剂优势的催化剂合成方法非常必要.本文报道一种简便的制备聚乙炔纳米颗粒负载Pd(Ⅱ)催化剂(nP-Pd(Ⅱ))的方法,所制催化剂在水相中的SuzukI-MIyAurA偶联反应中表现出极高的活性,同时具有便于分离、容易放大制备的特点.在室温下,将乙炔气通入PdC l2-4的水溶液中迅速变得浑浊,静置后容器底部有棕色沉淀,同时溶液变为无色透明.固体产物使用水、乙醇等溶剂进行洗涤;干燥之后收集既得聚乙炔纳米颗粒负载的Pd(Ⅱ)催化剂nP-Pd(Ⅱ).使用透射电子显微镜、红外(Ir)及拉曼吸收光谱、X射线衍射(Xrd)、X射线光电子能谱(XPS)以及X射线吸收光谱(EXAfS)等手段对nP-Pd(Ⅱ)进行了详细表征.结果显示,在nP-Pd(Ⅱ)中Pd并非以Pd纳米颗粒形式存在;Xrd中没有未Pd纳米晶的特征衍射峰.Ir等表征证明乙炔在Pd的催化作用下发生聚合作用,生成了聚乙炔.EXAfS结果表明,Pd分别和氯原子以及C=C双键进行配位;同时,没有观察到Pd–Pd键的生成,进一步证明了Pd未被还原为Pd纳米颗粒.XPS也印证了Pd(Ⅱ)的价态.形貌上,nP-Pd(Ⅱ)为直径2–3nM的颗粒,其中的Pd原子均匀分散于聚乙炔纳米颗粒上,使其在反应过程中能够充分地与底物接触,从而在SuzukI-MIyAurA偶联反应中表现出极高的活性.更重要的是,由于“憎水效应“,nP-Pd(Ⅱ)在溶液中以微米级的聚集体形式存在,因而反应后通过离心或者静置从反应体系中分离出来.因此,在nP-Pd(Ⅱ)催化剂中,每个Pd原子都是潜在的活性中心,这与典型的均相催化剂相似;同时,其独特的形貌使其具备了多相催化剂便于分离的特点.因此,nP-Pd(Ⅱ)是一种兼具均相和多相催化剂优点的催化剂且其催化剂的制备方法极为简便.乙炔是常用的工业气体,溶剂采用水,制备在室温下即可完成,我们也成功地制备出克级规模的高活性、稳定性的nP-Pd(Ⅱ)催化剂.A novel nanoparticulate polyacetylene-supported Pd(Ⅱ) catalyst(NP-Pd(Ⅱ)) for use in the aqueous Suzuki-Miyaura cross coupling reaction was successfully synthesized by simply treating an aqueous solution of PdC l42- with acetylene under ambient conditions.Electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy were employed to characterize the NP-Pd(Ⅱ) structure in detail.These analyses demonstrated that the Pd atoms in the NP-Pd(Ⅱ) were present as Pd(Ⅱ) and were coordinated with both the Cl atoms and the C=C bonds of the polyacetylene.Both the homogeneous distribution of the Pd(Ⅱ) along the polyacetylene backbone and the aggregation of the NP-Pd(Ⅱ) in solution work in conjunction to make this material an ideal catalyst, combining the advantages of both homogeneous and heterogeneous catalysts.supportedbyMinistryofScienceandTechnologyofChina(2011CB932403;2015CB932303); theNationalNaturalScienceFoundationofChina(221420102001;21131005;21390390;21333008)~

A graphene-platinum nanoparticles-ionic liquid composite catalyst for methanol-tolerant oxygen reduction reaction

通讯作者地址: Tan, YM (通讯作者),Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 3. Hunan Normal Univ, Coll Chem & Chem Engn, Minist Educ China, Key Lab Chem Biol & Tradit Chinese Med Res, Changsha 410081, Hunan, Peoples R China 电子邮件地址: [email protected] report here that graphene-supported Pt nanoparticles impregnated with the ionic liquid [MTBD][bmsi] which is more oxygen-philic and less methanol-philic than the exterior aqueous solution can exhibit both enhanced electrocatalytic activity and excellent methanol tolerance for oxygen reduction reaction.MOST of China 2011CB932403 2009CB930703 NSF of China 21131005 21021061 20925103 Fok Ying Tung Education Foundation 121011 NSF of Fujian 2009J06005 China Postdoctoral Science Foundation 2010048071

Synthesis of Ultrathin Nitrogen-Doped Graphitic Carbon Nanocages as Advanced Electrode Materials for Supercapacitor

E-mail Addresses: [email protected]; [email protected] of nitrogen-doped carbons with large surface area, high conductivity, and suitable pore size distribution is highly desirable for high-performance supercapacitor applications. Here, we report a novel protocol for template synthesis of ultrathin nitrogen-doped graphitic carbon nanocages (CNCs) derived from polyaniline (PAN!) and their excellent capacitive properties. The synthesis of CNCs involves one-pot hydrothermal synthesis of Mn3O4@PANI core-shell nanoparticles, carbonization to produce carbon coated MnO nanoparticles, and then removal of the MnO cores by acidic treatment. The CNCs prepared at an optimum carbonization temperature of 800 degrees C (CNCs-800) have regular frameworks, moderate graphitization, high specific surface area, good mesoporosity, and appropriate N doping. The CNCs-800 show high specific capacitance (248 F g(-1) at 1.0 A g(-1)), excellent rate capability (88% and 76% capacitance retention at 10 and 100 A g(-1), respectively), and outstanding cycling stability (similar to 95% capacitance retention after 5000 cycles) in 6 M KOH aqueous solution. The CNCs-800 can also exhibit great pseudocapacitance in 0.5 M H2SO4 aqueous solution besides the large electrochemical double-layer capacitance. The excellent capacitance performance coupled with the facile synthesis of ultrathin nitrogen-doped graphitic CNCs indicates their great application potential in supercapacitors.MOST of China 2011CB932403 National Natural Science Foundation of China 21075036 21175042 21131005 20925103 Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province Start-Up Fund for Young Teachers in Hunan Normal Universit