Core-Shell Pd@Au Nanoplates as Theranostic Agents for In-Vivo Photoacoustic Imaging, CT Imaging, and Photothermal Therapy

通讯作者地址: Liu, GMinistry of Science and Technology of China 2011CB932403 2014CB932004 National Natural Science Foundation of China 21420102001 21131005 8142202

Photochemical route for synthesizing atomically dispersed palladium catalysts

该工作由校内外多个课题组共同努力，历时三年多完成。我校郑南峰、傅钢等课题组紧密协作负责催化剂的合成、表征、催化测试及机理研究；中科院物理研究所谷林研究员主要负责催化剂的球差校正透射电子显微研究；加拿大达尔豪斯大学的张鹏课题组参与催化剂的同步辐射X-射线吸收谱研究。该研究工作的第一、二作者刘朋昕、赵云均为我校博士生。【Abstract】Atomically dispersed noble metal catalysts often exhibit high catalytic performances, but the metal loading density must be kept low (usually below 0.5%) to avoid the formation of metal nanoparticles through sintering. We report a photochemical strategy to fabricate a stable atomically dispersed palladium–titanium oxide catalyst (Pd 1 /TiO2 ) on ethylene glycolate (EG)–stabilized ultrathin TiO2 nanosheets containing Pd up to 1.5%.The Pd 1 /TiO2 catalyst exhibited high catalytic activity in hydrogenation of C=C bonds, exceeding that of surface Pd atoms on commercial Pd catalysts by a factor of 9.No decay in the activity was observed for 20 cycles. More important, the Pd 1 /TiO2 -EG system could activate H2 in a heterolytic pathway, leading to a catalytic enhancement in hydrogenation of aldehydes by a factor of more than 55.Supported by Ministry of Science and Technology of China grant 2015CB932303; National Natural Science Foundation of China grants 21420102001, 21131005, 21390390, 21133004, 21373167, 21573178, and 21333008; a NSERC CGS Alexander Graham Bell scholarship (D.M.C.); and a NSERC Discovery grant (P.Z.)

Ultrastable Atomic Copper Nanosheets for Selective Electrochemical Reduction of Carbon Dioxide

金属铜表面很容易被空气氧化，因此铜纳米材料在空气中极不稳定，如何制备原子级厚度的二维铜纳米片一直是纳米材料领域的一个挑战性难题。厦门大学化学化工学院郑南峰教授课题组发展了一种制备稳定超薄二维铜基纳米材料的有效方法，并将这类材料应用于二氧化碳的选择性电催化还原。该项研究还发现所合成的复合纳米材料能够将二氧化碳和水选择性地电化学还原为组成可调的合成气（一氧化碳和氢气混合气），在较低的还原电位下可高选择性地将二氧化碳还原成一氧化碳(其法拉第效率高达92%)。铜基纳米材料在二氧化碳电化学还原中具有优异的性能，但产物异常多样，选择性控制的难度很大。该项工作利用简单的表面配位修饰大幅改善电催化选择性的策略为二氧化碳还原电催化剂的设计提供了新思路。 该工作是在郑南峰教授指导下，并与傅钢教授课题组、加拿大Dalhousie大学张鹏教授合作完成，第一作者为化学化工学院博士生代磊，硕士生钦青、博士生汪佩、赵小静等参与了该工作。【Abstract】The electrochemical conversion of CO2 and H2O into syngas using renewably generated electricity is an attractive approach to simultaneously achieve chemical fixation of CO2 and storage of renewable energy. Developing cost-effective catalysts for selective electroreduction of CO2 into CO is essential to the practical applications of the approach. We report a simple synthetic strategy for the preparation of ultrathin Cu/Ni(OH)2 nanosheets as an excellent cost-effective catalyst for the electrochemical conversion of CO2 and H2O into tunable syngas under low overpotentials. These hybrid nanosheets with Cu(0)-enriched surface behave like noble metal nanocatalysts in both air stability and catalysis. Uniquely, Cu(0) within the nanosheets is stable against air oxidation for months because of the presence of formate on their surface. With the presence of atomically thick ultrastable Cu nanosheets, the hybrid Cu/Ni(OH)2 nanosheets display both excellent activity and selectivity in the electroreduction of CO2 to CO. At a low overpotential of 0.39 V, the nanosheets provide a current density of 4.3 mA/cm2 with a CO faradaic efficiency of 92%. No decay in the current is observed for more than 22 hours. The catalysts developed in this work are promising for building low-cost CO2 electrolyzers to produce CO.We thank the beamline BL14W1 (Shanghai Synchrotron Radiation Facility) for providing the beam time. the Ministry of Science and Technology of China (2017YFA0207302 and 2015CB93230)and the National Natural Science Foundation of China (21731005, 21420102001, 21333008). 研究工作得到了科技部和国家自然科学基金委的资助，X-射线吸收光谱测试在上海光源BL14W1线站完成

Electrochemical Partial Reforming of Ethanol into Ethyl Acetate Using Ultrathin Co3O4 Nanosheets as a Highly Selective Anode Catalyst

[Image: see text] Electrochemical partial reforming of organics provides an alternative strategy to produce valuable organic compounds while generating H(2) under mild conditions. In this work, highly selective electrochemical reforming of ethanol into ethyl acetate is successfully achieved by using ultrathin Co(3)O(4) nanosheets with exposed (111) facets as an anode catalyst. Those nanosheets were synthesized by a one-pot, templateless hydrothermal method with the use of ammonia. NH(3) was demonstrated critical to the overall formation of ultrathin Co(3)O(4) nanosheets. With abundant active sites on Co(3)O(4) (111), the as-synthesized ultrathin Co(3)O(4) nanosheets exhibited enhanced electrocatalytic activities toward water and ethanol oxidations in alkaline media. More importantly, over the Co(3)O(4) nanosheets, the electrooxidation from ethanol to ethyl acetate was so selective that no other oxidation products were yielded. With such a high selectivity, an electrolyzer cell using Co(3)O(4) nanosheets as the anode electrocatalyst and Ni–Mo nanopowders as the cathode electrocatalyst has been successfully built for ethanol reforming. The electrolyzer cell was readily driven by a 1.5 V battery to achieve the effective production of both H(2) and ethyl acetate. After the bulk electrolysis, about 95% of ethanol was electrochemically reformed into ethyl acetate. This work opens up new opportunities in designing a material system for building unique devices to generate both hydrogen and high-value organics at room temperature by utilizing electric energy from renewable sources

Carbon Monoxide Promotes the Catalytic Hydrogenation on Metal Cluster Catalysts

Size effect plays a crucial role in catalytic hydrogenation. The highly dispersed ultrasmall clusters with a limited number of metal atoms are one candidate of the next generation catalysts that bridge the single-atom metal catalysts and metal nanoparticles. However, for the unfavorable electronic property and their interaction with the substrates, they usually exhibit sluggish activity. Taking advantage of the small size, their catalytic property would be mediated by surface binding species. The combination of metal cluster coordination chemistry brings new opportunity. CO poisoning is notorious for Pt group metal catalysts as the strong adsorption of CO would block the active centers. In this work, we will demonstrate that CO could serve as a promoter for the catalytic hydrogenation when ultrasmall Pd clusters are employed. By means of DFT calculations, we show that Pdn n=2‐147 clusters display sluggish activity for hydrogenation due to the too strong binding of hydrogen atom and reaction intermediates thereon, whereas introducing CO would reduce the binding energies of vicinal sites, thus enhancing the hydrogenation reaction. Experimentally, supported Pd2CO catalysts are fabricated by depositing preestablished [Pd2(μ-CO)2Cl4]2- clusters on oxides and demonstrated as an outstanding catalyst for the hydrogenation of styrene. The promoting effect of CO is further verified experimentally by removing and reintroducing a proper amount of CO on the Pd cluster catalysts

Core-shell Pd@Au nanoplates as theranostic agents for in-vivo photoacoustic imaging, CT imaging, and photothermal therapy

(Figure Presented) Uniform plasmonic Pd@Au core-shell bimetallic nanoplates are synthesized by seeded growth strategy. Surface modified with SH-PEG makes it good biocompatibility, prolonged blood circulation, and relatively high tumor accumulation. Enhanced tumor contrast effects can be obtained for in vivo photoacoustic/CT imaging after intravenous injection of Pd@Au-PEG. Moreover, efficient photothermal tumor ablation is achieved, guided by the imaging techniques. This work promises further exploration of the superiority of 2D nanostructures for in vivo biomedical applications

Self-supporting sulfur cathodes enabled by two-dimensional carbon yolk-shell nanosheets for high-energy-density lithium-sulfur batteries

具有高理论能量密度、低成本和环境友好等优点的锂硫（Li-S）电池被视为极具开发潜力的下一代二次电池系统。近年来，利用客体材料对硫进行负载以提正极的硫利用率和循环寿命推动了Li-S电池研究的迅速发展。目前所报道的Li-S电池的能量密度还远不能满足实际应用需求。研究者们致力于设计高硫负载正极以提升Li-S电池的能量密度。然而，高硫负载正极的开发面临着两大瓶颈问题：(1)倍率和循环稳定性差，(2)高面积容量和低体积容量难以兼顾。受老式相册的紧密堆积结构启发，该研究将石墨烯包裹于中空多孔碳纳米片的内部腔体中形成一种具有“蛋黄-壳”结构的新型二维碳纳米材料（G@HMCN）。该研究工作为高能量密度Li-S电池的发展提供了新机遇。所开发的新型二维多孔碳纳米材料还有望应用于其它研究领域，如超级电容器、异相催化和电催化、柔性储能器件。 该论文第一作者为萨本栋微米纳米科学技术研究院2014级硕士研究生裴非，方晓亮副教授与郑南峰教授为共同通讯作者，厦门大学萨本栋微米纳米科学技术研究院为第一通讯单位。【Abstract】How to exert the energy density advantage is a key link in the development of lithium–sulfur batteries. Therefore, the performance degradation of high-sulfur-loading cathodes becomes an urgent problem to be solved at present. In addition, the volumetric capacities of high-sulfur-loading cathodes are still at a low level compared with their areal capacities. Aiming at these issues, two-dimensional carbon yolk-shell nanosheet is developed herein to construct a novel self-supporting sulfur cathode. The cathode with high-sulfur loading of 5 mg cm−2 and sulfur content of 73 wt% not only delivers an excellent rate performance and cycling stability, but also provides a favorable balance between the areal (5.7 mAh cm–2) and volumetric (1330 mAh cm–3) capacities. Remarkably, an areal capacity of 11.4 mAh cm–2 can be further achieved by increasing the sulfur loading from 5 to 10 mg cm–2. This work provides a promising direction for high-energy-density lithium–sulfur batteries.We acknowledge the support from the MOST of China (2015CB932300, 2017YFA0207302), the NSFC (21301144, 21420102001, 21390390, 21333008, 21131005), and the fundamental research funds for the central universities (20720160080). 该研究工作得到了科技部、国家自然科学基金委和厦门大学校长基金的支持