个人简介

Dr. Paul Alivisatos is Director of the Lawrence Berkeley National Laboratory (Berkeley Lab) and is the University of California (UC) Berkeley’s Samsung Distinguished Professor of Nanoscience and Nanotechnology. He also directs the Kavli Energy Nanosciences Institute (ENSI), and holds professorships in UC Berkeley’s departments of materials science and chemistry. In addition, he is a founder of two prominent nanotechnology companies, Nanosys and Quantum Dot Corp, now a part of Life Tech. Groundbreaking contributions to the fundamental physical chemistry of nanocrystals are the hallmarks of Dr. Alivisatos’s distinguished career. His research breakthroughs include the synthesis of size- and shape-controlled nanoscrystals, and forefront studies of nanocrystal properties, including optical, electrical, structural and thermodynamic. In his research, he has demonstrated key applications of nanocrystals in biological imaging and renewable energy. He played a critical role in the establishment of the Molecular Foundry, a U.S. Department of Energy’s Nanoscale Science Research Center; and was the facility’s founding director. He is the founding editor of Nano Letters, a leading scientific publication in nanoscience. Dr. Alivisatos has been recognized for his accomplishments, with awards such as the Wolf Prize in Chemistry, the Linus Pauling Medal, the Ernest Orlando Lawrence Award, the Eni Italgas Prize for Energy and Environment, the Rank Prize for Optoelectronics, the Wilson Prize, the Coblentz Award for Advances in Molecular Spectroscopy, the American Chemical Society Award for Colloid and Surface Science, the Von Hippel Award of the Materials Research Society, and most recently, the 2014 ACS Materials Chemistry Award. He is a member of the National Academy of Sciences and the American Academy of Arts and Sciences. Dr. Alivisatos received a Bachelor's degree in Chemistry in 1981 from the University of Chicago and Ph.D. in Chemistry from UC Berkeley in 1986. He began his career with UC Berkeley in 1988 and with Berkeley Lab in 1991.

研究领域

Materials/Polymers & Nanoscience/Physical

Prof. Alivisatos' research concerns the structural, thermodynamic, optical, and electrical properties of colloidal inorganic nanocrystals. He investigates the fundamental physical and chemical properties of nanocrystals and also works to develop practical applications of these new materials in biomedicine and renewable energy.

近期论文

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Daniel J. Hellebusch, Karthish Manthiram, Brandon J. Beberwyck, and A. Paul Alivisatos In Situ Transmission Electron Microscopy of Cadmium Selenide Nanorod Sublimation J. Phys. Chem. Lett.. 2015 DOI: 10.1021/jz502566m In situ electron microscopy is used to observe the morphological evolution of cadmium selenide nanorods as they sublime under vacuum at a series of elevated temperatures. Mass loss occurs anisotropically along the nanorod's long axis. At temperatures close to the sublimation threshold, the phase change occurs from both tips of the nanorods and proceeds unevenly with periods of rapid mass loss punctuated by periods of relative stability. At higher temperatures, the nanorods sublime at a faster, more uniform rate, but mass loss occurs from only a single end of the rod. We propose a mechanism that accounts for the observed sublimation behavior based on the terrace-ledge-kink (TLK) model and how the nanorod surface chemical environment influences the kinetic barrier of sublimation. Tina X. Ding, Jacob H. Olshansky, Stephen R. Leone, and Paul Alivisatos. Efficiency of Hole Transfer from Photoexcited Quantum Dots to Covalently Linked Molecular Species J. Am. Chem. Soc.. 2015 DOI: 10.1021/ja512278a Hole transfer from high photoluminescence quantum yield (PLQY) CdSe-core CdS-shell semiconductor nanocrystal quantum dots (QDs) to covalently linked molecular hole acceptors is investigated. 1H NMR is used to independently calibrate the average number of hole acceptor molecules per QD, N, allowing us to measure PLQY as a function of N, and to extract the hole transfer rate constant per acceptor, kht. This value allows for reliable comparisons between nine different donor-acceptor systems with variant shell thicknesses and acceptor ligands, with kht spanning over 4 orders of magnitude, from single acceptor time constants as fast as 16 ns to as slow as 0.13 ms. The PLQY variation with acceptor coverage for all kht follows a universal equation, and the shape of this curve depends critically on the ratio of the total hole transfer rate to the sum of the native recombination rates in the QD. The dependence of kht on the CdS thickness and the chain length of the acceptor is investigated, with damping coefficients β measured to be (0.24 ± 0.025) ?-1 and (0.85 ± 0.1) ?-1 for CdS and the alkyl chain, respectively. We observe that QDs with high intrinsic PLQYs (>79%) can donate holes to surface-bound molecular acceptors with efficiencies up to 99% and total hole transfer time constants as fast as 170 ps. We demonstrate the merits of a system where ill-defined nonradiative channels are suppressed and well-defined nonradiative channels are engineered and quantified. These results show the potential of QD systems to drive desirable oxidative chemistry without undergoing oxidative photodegradation. Shilpa N. Raja, Sandip Basu, Aditya M. Limaye, Turner J. Anderson, Christina M. Hyland, Liwei Lin, A. Paul Alivisatos, and Robert O. Ritchie. Strain-dependent dynamic mechanical properties of Kevlar to failure: Structural correlations and comparisons to other polymers Mater. Today Comm.. 2014 DOI: 10.1016/j.mtcomm.2014.11.002 The processing of Kevlar to certain strengths by hot-drawing can benefit by quantitative understanding of the correlation between structural and mechanical properties during the pre-drawing process. Here, we use a novel continuous dynamic analysis (CDA) to monitor the evolution in storage modulus and loss factor of Kevlar 49 fibers as a function of strain via a quasi-static tensile test. Unlike traditional dynamic mechanical analysis, CDA allows the tracking of strain-dependent mechanical properties until failure. The obtained dynamic viscoelastic properties of Kevlar 49 are correlated with structural data obtained from synchrotron radiation analysis and with Raman scattering frequencies. Rate-dependent stress-strain results from Kevlar are compared to Nomex, spider silk, polyester and rubber, and provide insight into how the mechanical properties of Kevlar originate from its characteristic structural features. We find that as the storage modulus of Kevlar is essentially equal to the Young's modulus, the measured quantitative relationships between storage modulus and strain can provide insights into the tuning of the mechanical properties of aramid materials for specific applications. Chang-Ming Jiang, L. Robert Baker, J. Matthew Lucas, Josh Vura-Weis, A. Paul Alivisatos, and Stephen R. Leone.Characterization of Photo-Induced Charge Transfer and Hot Carrier Relaxation Pathways in Spinel Cobalt Oxide (Co3O4) J. Phys. Chem. C. 2014, 118, 39, 22774-22784. DOI: 10.1021/jp5071133 The identities of photoexcited states in thin-film Co3O4 and the ultrafast carrier relaxation dynamics of Co3O4 are investigated with oxidation-state-specific pump-probe femtosecond core level spectroscopy. A thin-film sample is excited near the 2.8 eV optical absorption peak, and the resulting spectral changes at the 58.9 eV M2,3-edge of cobalt are probed in transient absorption with femtosecond high-order harmonic pulses generated by a Ti/sapphire laser. The initial transient state shows a significant 2 eV redshift in the absorption edge compared to the static ground state, which indicates a reduction of the cobalt valence charge. This is confirmed by a charge transfer multiplet spectral simulation, which finds the experimentally observed extreme ultraviolet (XUV) spectrum matches the specific O2-(2p) → Co3+(eg) charge-transfer transition, out of six possible excitation pathways involving Co3+ and Co2+ in the mixed-valence material. The initial transient state has a power-dependent amplitude decay (190 ± 10 fs at 13.2 mJ/cm2) together with a slight redshift in spectral shape (535 ± 33 fs), which are ascribed to hot carrier relaxation to the band edge. The faster amplitude decay is possibly due to a decrease of charge carrier density via an Auger mechanism, as the decay rate increases when more excitation fluence is used. This study takes advantage of the oxidation-state-specificity of time-resolved XUV spectroscopy, further establishing the method as a new approach to measure ultrafast charge carrier dynamics in condensed-phase systems. L. Robert Baker, Chang-Ming Jiang, Stephen T. Kelly, J. Matthew Lucas, Josh Vura-Weis, Mary K. Gilles, A. Paul Alivisatos, and Stephen R. Leone.Charge Carrier Dynamics of Photoexcited Co3O4 in Methanol: Extending High Harmonic Transient Absorption Spectroscopy to Liquid Environments Nano Lett. 2014, 14, 10, 5883-5890. DOI: 10.1021/nl502817a Charge carrier dynamics in Co3O4 thin films are observed using high harmonic generation transient absorption spectroscopy at the Co M2,3 edge. Results reveal that photoexcited Co3O4 decays to the ground state in 600 ± 40 ps in liquid methanol compared to 1.9 ± 0.3 ns in vacuum. Kinetic analysis suggests that surface-mediated relaxation of photoexcited Co3O4 may be the result of hole transfer from Co3O4 followed by carrier recombination at the Co3O4 methanol interface. Vivian Ferry, Jessica M. Smith, and A. Paul Alivisatos Symmetry Breaking in Tetrahedral Chiral Plasmonic Nanoparticle Assemblies ACS Photonics. 2014, 1, 11, 1189-1196. DOI: 10.1021/ph5002632 Self-assembled plasmonic structures combine the specificity and tunability of chemical synthesis with collective plasmonic properties. Here we systematically explore the effects of symmetry breaking on the chiroptical response of an assembly of plasmonic nanoparticles using simulation. The design is based on a tetrahedral nanoparticle frame with two different types of nanoparticles, where chirality is induced by targeted stimuli that change the distance along one edge of the assembly. We show that the intensity, spectral position, and handedness of the CD response are tunable with small structural changes, making it usable as a nanoscale plasmonic ruler. We then build upon this initial design to show that the symmetry breaking principle may also be used to design a chiral pyramid using a mixture of different nanoparticle materials, which affords tunability over a broad spectral range, and retrieves nanoscale conformational changes over a range of length scales. Dandan Zhang, Andrew B. Wong, Yi Yu, Sarah Brittman, Jianwei Sun, Anthony Fu, Brandon Beberwyck, A. Paul Alivisatos, and Peidong Yang. Phase-Selective Cation-Exchange Chemistry in Sulfide Nanowire Systems JACS. 2014, 136, 50, 17430-17433. DOI: 10.1021/ja511010q As a cation-deficient, p-type semiconductor, copper sulfide (Cu2-xS) shows promise for applications such as photovoltaics, memristors, and plasmonics. However, these applications demand precise tuning of the crystal phase as well as the stoichiometry of Cu2-xS, an ongoing challenge in the synthesis of Cu2-xS materials for a specific application. Here, a detailed transformation diagram of cation-exchange (CE) chemistry from cadmium sulfide (CdS) into Cu2-xS nanowires (NWs) is reported. By varying the reaction time and the reactants' concentration ratio, the progression of the CE process was captured, and tunable crystal phases of the Cu2-xS were achieved. It is proposed that the evolution of Cu2-xS phases in a NW system is dependent on both kinetic and thermodynamic factors. The reported data demonstrate that CE can be used to precisely control the structure, composition, and crystal phases of NWs, and such control may be generalized to other material systems for a variety of practical applications. Karthish Manthiram, Brandon Beberwyck, and A. Paul Alivisatos. Enhanced electrochemical methanation of carbon dioxide with a dispersible nanoscale copper catalyst. JACS. 2014, 136, 38, 13319-13325. DOI: 10.1021/ja5065284 Although the vast majority of hydrocarbon fuels and products are presently derived from petroleum, there is much interest in the development of routes for synthesizing these same products by hydrogenating CO2. The simplest hydrocarbon target is methane, which can utilize existing infrastructure for natural gas storage, distribution, and consumption. Electrochemical methods for methanizing CO2 currently suffer from a combination of low activities and poor selectivities. We demonstrate that copper nanoparticles supported on glassy carbon (n-Cu/C) achieve up to four times greater methanation current densities compared to high-purity copper foil electrodes. The n-Cu/C electrocatalyst also exhibits an average Faradaic efficiency for methanation of 80% during extended electrolysis, the highest Faradaic efficiency for room-temperature methanation reported to date. We find that the level of copper catalyst loading on the glassy carbon support has an enormous impact on the morphology of the copper under catalytic conditions and the resulting Faradaic efficiency for methane. The improved activity and Faradaic efficiency for methanation involves a mechanism that is distinct from what is generally thought to occur on copper foils. Electrochemical data indicates that the early steps of methanation on n-Cu/C involve a pre-equilibrium one-electron transfer to CO2 to form an adsorbed radical, followed by a rate-limiting non-electrochemical step in which the adsorbed CO2 radical reacts with a second CO2 molecule from solution. These nanoscale copper electrocatalysts represent a first step towards the preparation of practical methanation catalysts that can be incorporated into membrane-electrode assemblies in electrolyzers. Danylo Zherebetskyy, Marcus Scheele, Yingjie Zhang, Noah Bronstein, Christopher Thompson, David Britt, Miquel Salmeron, Paul Alivisatos, Lin-Wang Wang, Hydroxylation of the surface of PbS nanocrystals passivated with oleic acid Science 2014, 344, 1380-1384. DOI: 10.1126/science.1252727Controlling the structure of colloidal nanocrystals (NCs) is key to the generation of their complex functionality. This requires an understanding of the NC surface at the atomic level. The structure of colloidal PbS-NC passivated with oleic acid has been studied theoretically and experimentally. We show the existence of surface OH- groups, which play a key role in stabilizing the PbS(111) facets, consistent with x-ray photoelectron spectroscopy as well as other spectroscopic and chemical experiments. The role of water in the synthesis process is also revealed. Our model, along with the existing observations of NC surface termination and passivation by ligands, helps to explain and predict the properties of NCs and their assemblies. Karthish Manthiram, Yogesh Surendranath, and A. Paul Alivisatos. Dendritic Assembly of Gold Nanoparticles during Fuel-Forming Electrocatalysis. JACS 2014, 136, 7237-7240. DOI: 10.1021/ja502628r We observe the dendritic assembly of alkanethiol-capped gold nanoparticles on a glassy carbon support during electrochemical reduction of protons and CO2. We find that the primary mechanism by which surfactant-ligated gold nanoparticles lose surface area is by taking a random walk along the support, colliding with their neighbors, and fusing to form dendrites, a type of fractal aggregate. A random walk model reproduces the fractal dimensionality of the dendrites observed experimentally. The rate at which the dendrites form is strongly dependent on the solubility of the surfactant in the electrochemical double layer under the conditions of electrolysis. Since alkanethiolate surfactants reductively desorb at potentials close to the onset of CO2 reduction, they do not poison the catalytic activity of the gold nanoparticles. Although catalyst mobility is typically thought to be limited for room-temperature electrochemistry, our results demonstrate that nanoparticle mobility is significant under conditions at which they electrochemically catalyze gas evolution, even in the presence of a high surface area carbon and binder. A careful understanding of the electrolyte- and polarization-dependent nanoparticle aggregation kinetics informs strategies for maintaining catalyst dispersion during fuel-forming electrocatalysis. Kartick Tarafder, Yogesh Surendranath, Jacob H. Olshansky, A. Paul Alivisatos, and Lin-Wang Wang. Hole Transfer Dynamics from a CdSe/CdS Quantum Rod to a Tethered Ferrocene Derivative. JACS 2014, 136, 5121-5131. DOI: 10.1021/ja500936n