151
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Barnhill WC, Qu J, Luo H, Meyer HM, Ma C, Chi M, Papke BL. Phosphonium-organophosphate ionic liquids as lubricant additives: effects of cation structure on physicochemical and tribological characteristics. ACS APPLIED MATERIALS & INTERFACES 2014; 6:22585-22593. [PMID: 25402002 DOI: 10.1021/am506702u] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Our previous work suggested great potential for a phosphonium-organophosphate ionic liquid (IL) as an antiwear lubricant additive. In this study, a set of five ILs were carefully designed and synthesized, with identical organophosphate anions but dissimilar phosphonium cations, to allow systematic investigation of the effects of cation alkyl chain length and symmetry on physicochemical and tribological properties. Symmetric cations with shorter alkyl chains seem to increase the density and thermal stability due to closer packing. On the other hand, either higher cation symmetry or longer alkyl moieties induce a higher viscosity, though the viscosity index is dependent more on molecular mass than on symmetry. While a larger cation size generally increases an IL's solubility in nonpolar hydrocarbon oils, six-carbon seems to be the critical minimum alkyl chain length for high oil miscibility. Both the two ILs, that are mutually oil miscible, have demonstrated promising lubricating performance at 1.04% treat rate, though the symmetric-cation IL moderately outperformed the asymmetric-cation IL. Characterizations on the tribofilm formed by the best-performing symmetric-cation IL revealed the film thickness, nanostructure, and chemical composition. Results here provide fundamental insights for future molecular design in developing oil-soluble ILs as lubricant additives.
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152
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Ma C, Rangasamy E, Liang C, Sakamoto J, More KL, Chi M. Titelbild: Excellent Stability of a Lithium‐Ion‐Conducting Solid Electrolyte upon Reversible Li
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/H
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Exchange in Aqueous Solutions (Angew. Chem. 1/2015). Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201410930] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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153
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Ma C, Rangasamy E, Liang C, Sakamoto J, More KL, Chi M. Cover Picture: Excellent Stability of a Lithium‐Ion‐Conducting Solid Electrolyte upon Reversible Li
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/H
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Exchange in Aqueous Solutions (Angew. Chem. Int. Ed. 1/2015). Angew Chem Int Ed Engl 2014. [DOI: 10.1002/anie.201410930] [Citation(s) in RCA: 429] [Impact Index Per Article: 42.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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154
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Kang Y, Snyder J, Chi M, Li D, More KL, Markovic NM, Stamenkovic VR. Multimetallic core/interlayer/shell nanostructures as advanced electrocatalysts. NANO LETTERS 2014; 14:6361-6367. [PMID: 25299322 DOI: 10.1021/nl5028205] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The fine balance between activity and durability is crucial for the development of high performance electrocatalysts. The importance of atomic structure and compositional gradients is a guiding principle in exploiting the knowledge from well-defined materials in the design of novel class of core-shell electrocatalysts comprising Ni core, Au interlayer, and PtNi shell (Ni@Au@PtNi). This multimetallic system is found to have the optimal balance of activity and durability due to the synergy between the stabilizing effect of subsurface Au and modified electronic structure of surface Pt through interaction with subsurface Ni atoms. The electrocatalysts with Ni@Au@PtNi core-interlayer-shell structure exhibit high intrinsic and mass activities as well as superior durability for the oxygen reduction reaction with less than 10% activity loss after 10,000 potential cycles between 0.6 and 1.1 V vs the reversible hydrogen electrode.
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155
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Chi M, Chen J, Ye Y, Tseng HY, Lai F, Tay KH, Jin L, Guo ST, Jiang CC, Zhang XD. Adipocytes contribute to resistance of human melanoma cells to chemotherapy and targeted therapy. Curr Med Chem 2014; 21:1255-67. [PMID: 24304284 DOI: 10.2174/0929867321666131129114742] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 11/08/2013] [Accepted: 11/25/2013] [Indexed: 11/22/2022]
Abstract
Epidemiological evidence has linked the development and progression of several cancers including melanoma with obesity. However, whether obesity impinges on responses of cancer cells to treatment remains less understood. Here we report that human adipocytes contribute to resistance of melanoma cells to various therapeutic agents. Exposure to media from adipocyte cultures (adipocyte media) increased cell proliferation and reduced sensitivity of melanoma cells to apoptosis induced by diverse chemotherapeutic drugs, including the DNA-damaging drug cisplatin, the microtubuletargeting agent docetaxel, and the histone deacetylase inhibitor SAHA. This was associated with increased activation of PI3K/Akt and MEK/ERK signaling, and was attenuated by a PI3K or MEK inhibitor. The effect of adipocyte media on melanoma cells was, at least in part, due to the interaction between the adipokine leptin and its long form receptor OB-Rb, in that immunodepletion of leptin in adipocyte media or siRNA knockdown of OB-Rb in melanoma cells reversed the increase in Akt and ERK activation, enhancement in cell proliferation, and importantly, protection of melanoma cells against the drugs. In support, recombinant leptin partially recapitulated the effect of adipocyte media on melanoma cells. Of note, OB-Rb was increased on the surface of melanoma cells compared to melanocytes, whereas leptin short form receptors appeared to be suppressed post-transcriptionally, suggesting that OB-Rb was selectively upregulated in melanoma cells. Collectively, these results indicate that adipocytes contribute to the resistance of melanoma cells to chemotherapeutic drugs and agents targeting the PI3K/Akt and MEK/ERK pathways, and suggest that inhibition of the leptin/ OB-Rb system may be useful to improve the efficacy of multiple therapeutic approaches in the treatment of melanoma.
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156
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Ahluwalia M, Venur VA, Chi M, Chao S, Lilyana A, Elson P, Suh J, Barnett G. BM-02 * NEW DISEASE SPECIFIC GRADED PROGNOSTIC ASSESSMENT OF BRAIN METASTASIS FROM LUNG, BREAST, MELANOMA AND RENAL MALIGNANCIES. Neuro Oncol 2014. [DOI: 10.1093/neuonc/nou240.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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157
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Ma C, Rangasamy E, Liang C, Sakamoto J, More KL, Chi M. Excellent Stability of a Lithium‐Ion‐Conducting Solid Electrolyte upon Reversible Li
+
/H
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Exchange in Aqueous Solutions. Angew Chem Int Ed Engl 2014; 54:129-33. [DOI: 10.1002/anie.201408124] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Indexed: 11/06/2022]
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158
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Ma C, Rangasamy E, Liang C, Sakamoto J, More KL, Chi M. Excellent Stability of a Lithium‐Ion‐Conducting Solid Electrolyte upon Reversible Li
+
/H
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Exchange in Aqueous Solutions. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408124] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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159
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Naskar AK, Bi Z, Li Y, Akato SK, Saha D, Chi M, Bridges CA, Paranthaman MP. Tailored recovery of carbons from waste tires for enhanced performance as anodes in lithium-ion batteries. RSC Adv 2014. [DOI: 10.1039/c4ra03888f] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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160
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Qiao ZA, Zhang P, Chai SH, Chi M, Veith GM, Gallego NC, Kidder M, Dai S. Lab-in-a-Shell: Encapsulating Metal Clusters for Size Sieving Catalysis. J Am Chem Soc 2014; 136:11260-3. [DOI: 10.1021/ja505903r] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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161
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Qian D, Xu B, Chi M, Meng YS. Uncovering the roles of oxygen vacancies in cation migration in lithium excess layered oxides. Phys Chem Chem Phys 2014; 16:14665-8. [DOI: 10.1039/c4cp01799d] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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162
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Gao C, Hu Y, Wang M, Chi M, Yin Y. Fully alloyed Ag/Au nanospheres: combining the plasmonic property of Ag with the stability of Au. J Am Chem Soc 2014; 136:7474-9. [PMID: 24821567 DOI: 10.1021/ja502890c] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We report that fully alloyed Ag/Au nanospheres with high compositional homogeneity ensured by annealing at elevated temperatures show large extinction cross sections, extremely narrow bandwidths, and remarkable stability in harsh chemical environments. Nanostructures of Ag are known to have much stronger surface plasmon resonance than Au, but their applications in many areas have been very limited by their poor chemical stability against nonideal chemical environments. Here we address this issue by producing fully alloyed Ag/Au nanospheres through a surface-protected annealing process. A critical temperature has been found to be around 930 °C, below which the resulting alloy nanospheres, although significantly more stable than pure silver nanoparticles, can still gradually decay upon extended exposure to a harsh etchant. Nanospheres annealed above the critical temperature show a homogeneous distribution of Ag and Au, minimal crystallographic defects, and the absence of structural and compositional interfaces, which account for the extremely narrow bandwidths of the surface plasmon resonance and may enable many plasmonic applications with high performance and long lifetime, especially for those involving corrosive species.
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163
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Shin N, Chi M, Filler MA. Interplay between defect propagation and surface hydrogen in silicon nanowire kinking superstructures. ACS NANO 2014; 8:3829-3835. [PMID: 24606150 DOI: 10.1021/nn500598d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Semiconductor nanowire kinking superstructures, particularly those with long-range structural coherence, remain difficult to fabricate. Here, we combine high-resolution electron microscopy with operando infrared spectroscopy to show why this is the case for Si nanowires and, in doing so, reveal the interplay between defect propagation and surface chemistry during ⟨211⟩ → ⟨111⟩ and ⟨211⟩ → ⟨211⟩ kinking. Our experiments show that adsorbed hydrogen atoms are responsible for selecting ⟨211⟩-oriented growth and indicate that a twin boundary imparts structural coherence. The twin boundary, only continuous at ⟨211⟩ → ⟨211⟩ kinks, reduces the symmetry of the trijunction and limits the number of degenerate directions available to the nanowire. These findings constitute a general approach for rationally engineering kinking superstructures and also provide important insight into the role of surface chemical bonding during vapor-liquid-solid synthesis.
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164
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Chen C, Kang Y, Huo Z, Zhu Z, Huang W, Xin HL, Snyder JD, Li D, Herron JA, Mavrikakis M, Chi M, More KL, Li Y, Markovic NM, Somorjai GA, Yang P, Stamenkovic VR. Highly Crystalline Multimetallic Nanoframes with Three-Dimensional Electrocatalytic Surfaces. Science 2014; 343:1339-43. [DOI: 10.1126/science.1249061] [Citation(s) in RCA: 2051] [Impact Index Per Article: 205.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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165
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Beekman C, Siemons W, Ward TZ, Chi M, Howe J, Biegalski MD, Balke N, Maksymovych P, Farrar AK, Romero JB, Gao P, Pan XQ, Tenne DA, Christen HM. Phase transitions, phase coexistence, and piezoelectric switching behavior in highly strained BiFeO(3) films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:5561-7. [PMID: 23847158 DOI: 10.1002/adma.201302066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Indexed: 05/12/2023]
Abstract
Highly strained BiFeO3 films transition into a true tetragonal state at 430 °C but remain polar to much higher temperatures (∼800 °C). Piezoelectric switching is only possible up to 300 °C, i.e., at temperatures for which strain stabilizes the stripe-like coexistence of multiple polymorphs.
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166
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Lv T, Wang Y, Choi SI, Chi M, Tao J, Pan L, Huang CZ, Zhu Y, Xia Y. Controlled synthesis of nanosized palladium icosahedra and their catalytic activity towards formic-acid oxidation. CHEMSUSCHEM 2013; 6:1923-30. [PMID: 24106017 DOI: 10.1002/cssc.201300479] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Indexed: 05/04/2023]
Abstract
Pd icosahedra with sizes controlled in the range of 5-35 nm were synthesized in high purity through a combination of polyol reduction and seed-mediated growth. The Pd icosahedra were obtained with purity >94 % and uniform sizes controlled in the range of 5-17 nm by using ethylene glycol as both the reductant and solvent. The studies indicate that the formation of Pd nanocrystals with an icosahedral shape was very sensitive to the reaction kinetics. The success of this synthesis relies on the use of HCl to manipulate the reaction kinetics and thus control the twin structure and shape of the resultant nanocrystals. The size of the Pd icosahedra could be further increased up to 35 nm by seed-mediated growth, with 17 nm Pd icosahedra serving as seeds. The multiply twinned Pd icosahedra could grow into larger sizes, and their shape and multiply twinned structure were preserved. Thanks to the presence of twin defects, the Pd icosahedra showed a catalytic current density towards formic-acid oxidation that was 1.9 and 11.6 times higher than that of single-crystal Pd octahedra, which were also fully covered by {111} facets, and commercial Pd/C, respectively.
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167
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Shin N, Chi M, Filler MA. Sidewall morphology-dependent formation of multiple twins in Si nanowires. ACS NANO 2013; 7:8206-8213. [PMID: 23944902 DOI: 10.1021/nn4036798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Precise placement of twin boundaries and stacking faults promises new opportunities to fundamentally manipulate the optical, electrical, and thermal properties of semiconductor nanowires. Here we report on the appearance of consecutive twin boundaries in Si nanowires and show that sidewall morphology governs their spacing. Detailed electron microscopy analysis reveals that thin {111} sidewall facets, which elongate following the first twin boundary (TB1), are responsible for deforming the triple-phase line and favoring the formation of the second twin boundary (TB2). While multiple, geometrically correlated defect planes are known in group III-V nanowires, our findings show that this behavior is also possible in group IV materials.
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168
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Zhang P, Shi Y, Chi M, Park JN, Stucky GD, McFarland EW, Gao L. Mesoporous delafossite CuCrO₂ and spinel CuCr₂O₄: synthesis and catalysis. NANOTECHNOLOGY 2013; 24:345704. [PMID: 23899503 DOI: 10.1088/0957-4484/24/34/345704] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Delafossite CuCrO2 and spinel CuCr2O4 with mesoporous structures have been successfully synthesized using nanocasting methods based on a KIT-6 template. The functional activity of the mesoporous materials was evaluated in applications as heterogeneous catalysts. The activity for photocatalytic hydrogen production of the delafossite structures with different morphologies was characterized and the oxidation state changes associated with photocorrosion of Cu(+) investigated using electron energy loss spectroscopy (EELS). Mg(2+) doping was found to facilitate the casting of ordered structures for CuCrO2 and improves the photocorrosion resistance of delafossite structures. The mesoporous spinel CuCr2O4 nanostructures were found to be active for low temperature CO oxidation.
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169
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Wang W, Zhao J, Wang W, Gai Z, Balke N, Chi M, Lee HN, Tian W, Zhu L, Cheng X, Keavney DJ, Yi J, Ward TZ, Snijders PC, Christen HM, Wu W, Shen J, Xu X. Room-temperature multiferroic hexagonal LuFeO3 films. PHYSICAL REVIEW LETTERS 2013; 110:237601. [PMID: 25167529 DOI: 10.1103/physrevlett.110.237601] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Indexed: 06/03/2023]
Abstract
The crystal and magnetic structures of single-crystalline hexagonal LuFeO(3) films have been studied using x-ray, electron, and neutron diffraction methods. The polar structure of these films are found to persist up to 1050 K; and the switchability of the polar behavior is observed at room temperature, indicating ferroelectricity. An antiferromagnetic order was shown to occur below 440 K, followed by a spin reorientation resulting in a weak ferromagnetic order below 130 K. This observation of coexisting multiple ferroic orders demonstrates that hexagonal LuFeO(3) films are room-temperature multiferroics.
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170
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Shin N, Chi M, Howe JY, Filler MA. Rational defect introduction in silicon nanowires. NANO LETTERS 2013; 13:1928-1933. [PMID: 23577694 DOI: 10.1021/nl3042728] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The controlled introduction of planar defects, particularly twin boundaries and stacking faults, in group IV nanowires remains challenging despite the prevalence of these structural features in other nanowire systems (e.g., II-VI and III-V). Here we demonstrate how user-programmable changes to precursor pressure and growth temperature can rationally generate both transverse twin boundaries and angled stacking faults during the growth of <111> oriented Si nanowires. We leverage this new capability to demonstrate prototype defect superstructures. These findings yield important insight into the mechanism of defect generation in semiconductor nanowires and suggest new routes to engineer the properties of this ubiquitous semiconductor.
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171
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Aydin C, Kulkarni A, Chi M, Browning ND, Gates BC. Three-Dimensional Structural Analysis of MgO-Supported Osmium Clusters by Electron Microscopy with Single-Atom Sensitivity. Angew Chem Int Ed Engl 2013; 52:5262-5. [DOI: 10.1002/anie.201300238] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Indexed: 11/05/2022]
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172
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Aydin C, Kulkarni A, Chi M, Browning ND, Gates BC. Three-Dimensional Structural Analysis of MgO-Supported Osmium Clusters by Electron Microscopy with Single-Atom Sensitivity. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201300238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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173
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Li C, Yu Y, Chi M, Cao L. Epitaxial nanosheet-nanowire heterostructures. NANO LETTERS 2013; 13:948-953. [PMID: 23394548 DOI: 10.1021/nl303876a] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrate synthesis of a new type of heterostructures that comprise two-dimensional (2D) nanosheets (NSs) epitaxially grown at one-dimensional (1D) nanowires (NWs). The synthesis involves materials with a graphite-like layered structure in which covalently bonded layers are held by weak van der Waals forces. GeS was used as a prototype material in this work. The synthesis also involves a seeded-growth process, where GeS NWs are grown first as seeds followed by a seeded growth of NSs at the pre-grown NWs. We observe that exposing the pre-grown NWs to air prior to the seeded growth is critical for the formation of NSs to yield NS-NW heterostructures. Our experimental results suggest that this might be due to a mild oxidation at the NW surface caused by the air exposure, which could subsequently facilitate the nucleation of NSs at the NWs. It also suggests that the surface oxidation needs to be controlled in a proper range in order to achieve optimized NS growths. We believe that this synthetic strategy may generally apply to the growth of NS-NW heterostructures of other layered chalcogenide materials. NS-NW heterostructures provide capabilities to monolithically integrate the functionality of 1D NWs and 2D NSs into a 3D space. It holds great potential in applications that request complex nanomaterials with multiple functionality, high surface area, and efficient charge transport, such as energy storage, chemical sensing, solar energy conversion, and 3D electric and photonic devices.
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174
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Carroll KJ, Qian D, Fell C, Calvin S, Veith GM, Chi M, Baggetto L, Meng YS. Probing the electrode/electrolyte interface in the lithium excess layered oxide Li1.2Ni0.2Mn0.6O2. Phys Chem Chem Phys 2013; 15:11128-38. [DOI: 10.1039/c3cp51927a] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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175
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Qiao ZA, Huo Q, Chi M, Veith GM, Binder AJ, Dai S. A "ship-in-a-bottle" approach to synthesis of polymer dots@silica or polymer dots@carbon core-shell nanospheres. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:6017-21. [PMID: 22976113 DOI: 10.1002/adma.201202620] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 07/24/2012] [Indexed: 05/24/2023]
Abstract
A "ship-in-a-bottle" approach to the entrapment and assembly of nanometer-sized polymer dots in hollow silica or carbon nanospheres with size-selective micropores is presented. This new type of core-shell nanospheres exhibits excellent photoluminescence properties and significant adsorption capabilities for transition-metal ions.
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176
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Aydin C, Kulkarni A, Chi M, Browning ND, Gates BC. Atomically Resolved Site-Isolated Catalyst on MgO: Mononuclear Osmium Dicarbonyls formed from Os3(CO)12. J Phys Chem Lett 2012; 3:1865-1871. [PMID: 26292006 DOI: 10.1021/jz300574u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Supported triosmium clusters, formed from Os3(CO)12 on MgO, were treated in helium at 548 K for 2 h, causing fragmentation of the cluster frame and the formation of mononuclear osmium dicarbonyls. The cluster breakup and the resultant fragmented species were characterized by infrared and X-ray absorption spectroscopies, and the fragmented species were imaged by scanning transmission electron microscopy. The spectra identify the surface osmium complexes as Os(CO)2{Osupport}n (n = 3 or 4) (where the braces denote support surface atoms). The images show site-isolated Os atoms in mononuclear osmium species on MgO. The intensity analysis on the images of the MgO(110) face showed that the Os atoms were located atop Mg columns. This information led to a model of the Os(CO)2 on MgO(110), with the distances approximated as those determined by EXAFS spectroscopy, which are an average over the whole MgO surface; the results imply that these complexes were located at Mg vacancies.
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177
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Wang C, Li D, Chi M, Pearson J, Rankin RB, Greeley J, Duan Z, Wang G, van der Vliet D, More KL, Markovic NM, Stamenkovic VR. Rational Development of Ternary Alloy Electrocatalysts. J Phys Chem Lett 2012; 3:1668-73. [PMID: 26285726 DOI: 10.1021/jz300563z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Improving the efficiency of electrocatalytic reduction of oxygen represents one of the main challenges for the development of renewable energy technologies. Here, we report the systematic evaluation of Pt-ternary alloys (Pt3(MN)1 with M, N = Fe, Co, or Ni) as electrocatalysts for the oxygen reduction reaction (ORR). We first studied the ternary systems on extended surfaces of polycrystalline thin films to establish the trend of electrocatalytic activities and then applied this knowledge to synthesize ternary alloy nanocatalysts by a solvothermal approach. This study demonstrates that the ternary alloy catalysts can be compelling systems for further advancement of ORR electrocatalysis, reaching higher catalytic activities than bimetallic Pt alloys and improvement factors of up to 4 versus monometallic Pt.
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178
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Rathmell AR, Nguyen M, Chi M, Wiley BJ. Synthesis of oxidation-resistant cupronickel nanowires for transparent conducting nanowire networks. NANO LETTERS 2012; 12:3193-3199. [PMID: 22642652 DOI: 10.1021/nl301168r] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nanowires of copper can be coated from liquids to create flexible, transparent conducting films that can potentially replace the dominant transparent conductor, indium tin oxide, in displays, solar cells, organic light-emitting diodes, and electrochromic windows. One issue with these nanowire films is that copper is prone to oxidation. It was hypothesized that the resistance to oxidation could be improved by coating copper nanowires with nickel. This work demonstrates a method for synthesizing copper nanowires with nickel shells as well as the properties of cupronickel nanowires in transparent conducting films. Time- and temperature-dependent sheet resistance measurements indicate that the sheet resistance of copper and silver nanowire films will double after 3 and 36 months at room temperature, respectively. In contrast, the sheet resistance of cupronickel nanowires containing 20 mol % nickel will double in about 400 years. Coating copper nanowires to a ratio of 2:1 Cu:Ni gave them a neutral gray color, making them more suitable for use in displays and electrochromic windows. These properties, and the fact that copper and nickel are 1000 times more abundant than indium or silver, make cupronickel nanowires a promising alternative for the sustainable, efficient production of transparent conductors.
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179
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Tseng H, Chi M, Smith N, Marcy S, Sy L, Jacobsen S. Effectiveness of herpes zoster vaccine on recurrent herpes zoster among an immunocompetent elderly population. Int J Infect Dis 2012. [DOI: 10.1016/j.ijid.2012.05.1017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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180
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Beaber B, Chi M, Brara S, Zhang J, Langer-Gould A. Treatment with Beta-Interferons or Glatiramer Acetate and the Risk of Postpartum Multiple Sclerosis Relapses (P06.192). Neurology 2012. [DOI: 10.1212/wnl.78.1_meetingabstracts.p06.192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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181
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Gao C, Lu Z, Liu Y, Zhang Q, Chi M, Cheng Q, Yin Y. Highly Stable Silver Nanoplates for Surface Plasmon Resonance Biosensing. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201108971] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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182
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Gao C, Lu Z, Liu Y, Zhang Q, Chi M, Cheng Q, Yin Y. Highly Stable Silver Nanoplates for Surface Plasmon Resonance Biosensing. Angew Chem Int Ed Engl 2012; 51:5629-33. [DOI: 10.1002/anie.201108971] [Citation(s) in RCA: 290] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/15/2012] [Indexed: 12/16/2022]
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183
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Shi X, Yang J, Salvador JR, Chi M, Cho JY, Wang H, Bai S, Yang J, Zhang W, Chen L. Multiple-Filled Skutterudites: High Thermoelectric Figure of Merit through Separately Optimizing Electrical and Thermal Transports. J Am Chem Soc 2012. [DOI: 10.1021/ja211185w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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184
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Tian C, Chai SH, Zhu X, Wu Z, Binder A, Bauer JC, Brwon S, Chi M, Veith GM, Guo Y, Dai S. In situ growth synthesis of heterostructured LnPO4–SiO2 (Ln = La, Ce, and Eu) mesoporous materials as supports for small gold particles used in catalytic CO oxidation. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm35416k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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185
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Ma G, Binder A, Chi M, Liu C, Jin R, Jiang DE, Fan J, Dai S. Stabilizing gold clusters by heterostructured transition-metal oxide–mesoporous silica supports for enhanced catalytic activities for CO oxidation. Chem Commun (Camb) 2012; 48:11413-5. [DOI: 10.1039/c2cc35787a] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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186
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Guo B, Wang X, Fulvio PF, Chi M, Mahurin SM, Sun XG, Dai S. Soft-templated mesoporous carbon-carbon nanotube composites for high performance lithium-ion batteries. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:4661-6. [PMID: 21915918 DOI: 10.1002/adma.201102032] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 08/09/2011] [Indexed: 05/23/2023]
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187
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Wang C, Chi M, Li D, van der Vliet D, Wang G, Lin Q, Mitchell JF, More KL, Markovic NM, Stamenkovic VR. Synthesis of Homogeneous Pt-Bimetallic Nanoparticles as Highly Efficient Electrocatalysts. ACS Catal 2011. [DOI: 10.1021/cs200328z] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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188
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Xu J, Wilson AR, Rathmell AR, Howe J, Chi M, Wiley BJ. Synthesis and catalytic properties of Au-Pd nanoflowers. ACS NANO 2011; 5:6119-6127. [PMID: 21761821 DOI: 10.1021/nn201161m] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Reduction of Pd ions by hydroquinone in the presence of gold nanoparticles and polyvinylpyrrolidone resulted in the formation of nanoflowers with a Au core and Pd petals. Addition of HCl to the synthesis halted the reduction by hydroquinone and enabled the acquisition of snapshots of the nanoflowers at different stages of growth. TEM images of the reaction after 10 s show that the nanoflower morphology resulted from the homogeneous nucleation of Pd clusters in solution and their subsequent attachment to gold seeds coated with a thin (0.8 ± 0.1 nm) shell of Pd. UV-visible spectra also indicate Pd clusters formed in the early stages of the reaction and disappeared as the nanoflowers grew. The speed at which this reaction can be halted is useful not only for producing a variety of bimetallic nanostructures with precisely controlled dimensions and morphologies but also for understanding the growth mechanism of these structures. The ability of the AuPd core-shell structure to catalyze the Suzuki coupling reaction of iodobenzene to phenylboronic acid was probed and compared against the activity of Pd nanocubes and thin-shelled AuPd core-shell nanoparticles. The results of this study suggest that Suzuki coupling was not affected by the surface structure or subsurface composition of the nanoparticles, but instead was primarily catalyzed by molecular Pd species that leached from the nanostructures.
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189
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Wang C, Chi M, Li D, Strmcnik D, van der Vliet D, Wang G, Komanicky V, Chang KC, Paulikas AP, Tripkovic D, Pearson J, More KL, Markovic NM, Stamenkovic VR. Design and Synthesis of Bimetallic Electrocatalyst with Multilayered Pt-Skin Surfaces. J Am Chem Soc 2011; 133:14396-403. [DOI: 10.1021/ja2047655] [Citation(s) in RCA: 499] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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190
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Lu Z, Gao C, Zhang Q, Chi M, Howe JY, Yin Y. Direct assembly of hydrophobic nanoparticles to multifunctional structures. NANO LETTERS 2011; 11:3404-3412. [PMID: 21732588 DOI: 10.1021/nl201820r] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a general process that allows convenient production of multifunctional composite particles by direct self-assembly of hydrophobic nanoparticles on host nanostructures containing high-density surface thiol groups. Hydrophobic nanoparticles of various compositions and combinations can be directly assembled onto the host surface through the strong coordination interactions between metal cations and thiol groups. The resulting structures can be further conveniently overcoated with a layer of normal silica to stabilize the assemblies and render them highly dispersible in water for biomedical applications. As the entire fabrication process does not involve complicated surface modification procedures, the hydrophobic ligands on the nanoparticles are not disturbed significantly so that they retain their original properties such as highly efficient luminescence. Many complex composite nanostructures with tailored functions can be efficiently produced by using this versatile approach. For example, multifunctional nonspherical nanostructures can be efficiently produced by using mercapto-silica coated nano-objects of arbitrary shapes as hosts for immobilizing functional nanoparticles. Multilayer structures can also be achieved by repeating the mercapto-silica coating and nanoparticle immobilization processes. Such assembly approach will provide the research community a highly versatile, configurable, scalable, and reproducible process for the preparation of various multifunctional structures.
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191
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Vlassiouk I, Smirnov S, Ivanov I, Fulvio PF, Dai S, Meyer H, Chi M, Hensley D, Datskos P, Lavrik NV. Electrical and thermal conductivity of low temperature CVD graphene: the effect of disorder. NANOTECHNOLOGY 2011; 22:275716. [PMID: 21613685 DOI: 10.1088/0957-4484/22/27/275716] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In this paper we present a study of graphene produced by chemical vapor deposition (CVD) under different conditions with the main emphasis on correlating the thermal and electrical properties with the degree of disorder. Graphene grown by CVD on Cu and Ni catalysts demonstrates the increasing extent of disorder at low deposition temperatures as revealed by the Raman peak ratio, IG/ID. We relate this ratio to the characteristic domain size, La, and investigate the electrical and thermal conductivity of graphene as a function of La. The electrical resistivity, ρ, measured on graphene samples transferred onto SiO2/Si substrates shows linear correlation with La(-1). The thermal conductivity, K, measured on the same graphene samples suspended on silicon pillars, on the other hand, appears to have a much weaker dependence on La, close to K∼La1/3. It results in an apparent ρ∼K3 correlation between them. Despite the progressively increasing structural disorder in graphene grown at lower temperatures, it shows remarkably high thermal conductivity (10(2)-10(3) W K(-1) m(-1)) and low electrical (10(3)-3×10(5) Ω) resistivities suitable for various applications.
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192
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Kim Y, Veith GM, Nanda J, Unocic RR, Chi M, Dudney NJ. High voltage stability of LiCoO2 particles with a nano-scale Lipon coating. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2011.03.070] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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193
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Zhang Q, Lima DQ, Lee I, Zaera F, Chi M, Yin Y. A Highly Active Titanium Dioxide Based Visible-Light Photocatalyst with Nonmetal Doping and Plasmonic Metal Decoration. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201101969] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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194
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Shi X, Yang J, Salvador JR, Chi M, Cho JY, Wang H, Bai S, Yang J, Zhang W, Chen L. Multiple-Filled Skutterudites: High Thermoelectric Figure of Merit through Separately Optimizing Electrical and Thermal Transports. J Am Chem Soc 2011; 133:7837-46. [PMID: 21524125 DOI: 10.1021/ja111199y] [Citation(s) in RCA: 317] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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195
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Li H, Qu J, Cui Q, Xu H, Luo H, Chi M, Meisner RA, Wang W, Dai S. TiO2 nanotube arrays grown in ionic liquids: high-efficiency in photocatalysis and pore-widening. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm11540e] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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196
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Kulkarni A, Chi M, Ortalan V, Browning ND, Gates BC. Atomic Resolution of the Structure of a Metal-Support Interface: Triosmium Clusters on MgO(110). Angew Chem Int Ed Engl 2010; 49:10089-92. [DOI: 10.1002/anie.201005105] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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197
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Kulkarni A, Chi M, Ortalan V, Browning ND, Gates BC. Atomic Resolution of the Structure of a Metal-Support Interface: Triosmium Clusters on MgO(110). Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201005105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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198
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Mehraeen S, Kulkarni A, Chi M, Reed BW, Okamoto NL, Browning ND, Gates BC. Triosmium Clusters on a Support: Determination of Structure by X-ray Absorption Spectroscopy and High-Resolution Microscopy. Chemistry 2010; 17:1000-8. [DOI: 10.1002/chem.201000860] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Indexed: 11/08/2022]
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199
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Mazumder V, Chi M, More KL, Sun S. Synthesis and Characterization of Multimetallic Pd/Au and Pd/Au/FePt Core/Shell Nanoparticles. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201003903] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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200
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Mazumder V, Chi M, More KL, Sun S. Synthesis and Characterization of Multimetallic Pd/Au and Pd/Au/FePt Core/Shell Nanoparticles. Angew Chem Int Ed Engl 2010; 49:9368-72. [DOI: 10.1002/anie.201003903] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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