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Rotation-Aligned Isomer and Oblate Collectivity in {sup 196}Pt
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Controlling Dzyaloshinskii-Moriya interactions in the skyrmion host candidates FePd 1 − x Pt x Mo 3 N
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High Throughput Thin Film Pt-M Alloys for Fuel Electrooxidation: Low Concentrations of M (M = Sn, Ta, W, Mo, Ru, Fe, In, Pd, Hf, Zn, Zr, Nb, Sc, Ni, Ti, V, Cr, Rh)
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Oxygen Electroreduction on Nanoscale Pt/[TaOPO4/VC] and Pt/[Ta2O5/VC] in Alkaline Electrolyte
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Theoretical and Experimental Studies of Ethanol Decomposition and Electrooxidation over Pt-Modified Tungsten Carbide
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Investigation of a Silicotungstic Acid Functionalized Carbon on Pt Activity and Durability for the Oxygen Reduction Reaction
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Cluster adsorption on amorphous and crystalline surfaces - A molecular dynamics study of model Pt on Cu and model Pd on Pt
Molecular dynamics was used to study the structure, dispersion and short-time behavior of ten-atom clusters adsorbed onto amorphous and crystalline substrates, in which the cluster atoms differed from the substrate atoms. Two adatom-substrate model systems were chosen; one, in which the interaction energy between adatom pairs was greater than that between substrate pairs, and the other, in which the reverse was true. At relatively low temperature ranges, increased dispersion of cluster atoms occurred: (a) on the amorphous substrate as compared to the FCC(100) surface, (b) with increasing reduced temperature, and (c) with adatom-substrate interaction energy stronger than adatom-adatom interaction. Two-dimensional clusters (rafts) on the FCC(100) surface displayed migration of edge atoms only, indicating a mechanism for the cluster rotation and shape changes found in experimental studies.
Vacuum Ultraviolet Photoionization Studies of PtCH2 and H-Pt-CH3: A Potential Energy Surface for the Pt + CH4 Reaction
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Exploring Grain Boundary-Defect Interactions in Pt and Pt-Au using In-situ TEM High Cycle Fatigue.
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Trithiol ligand provides tumor-targeting 191 Pt-complexes with high molar activity and promising in vivo properties
The Auger electron-emitting radionuclide 191 Pt is a promising candidate for radiopharmaceutical therapy. Herein, we explored novel labeling methods for 191 Pt using thiol-containing ligands to improve the in vivo stability and targeting ability of 191 Pt-labeled complexes. We synthesized dithiol-containing N 2 S 2 and NS 2 ligands, and a trithiol ligand, and then compared their radiochemical reactivity with 191 Pt. [ 191 Pt]Pt-trithiol was synthesized and its biodistribution was evaluated in mice and compared with free 191 Pt. Finally, a 191 Pt-trithiol complex targeting prostate-specific membrane antigen (PSMA): [ 191 Pt]Pt-trithiol-PSMA was developed and evaluated in mice bearing tumor xenografts and compared with a 191 Pt-complex labeled via monothiol-containing Cys ([ 191 Pt]Pt-Cys-PSMA). A comparison of N 2 S 2 , NS 2 , and trithiol showed that the trithiol ligand is the best for producing 191 Pt-labeled compounds in high yield and as a single peak in preparative HPLC. Notably, the trithiol ligand made 191 Pt-labeled compounds and precursors separatable, achieving 191 Pt-labeled products with a high molar activity: 200–400 mCi/μmol (7.4–14.8 GBq/μmol) at EOS. Additionally, [ 191 Pt]Pt-trithiol and [ 191 Pt]Pt-trithiol-PSMA were stable in vivo with rapid clearance compared with free 191 Pt and [ 191 Pt]Pt-Cys-PSMA. [ 191 Pt]Pt-trithiol-PSMA resulted in a low uptake in most normal organs and a high uptake in the kidneys and prostate cancer with PSMA expression. Furthermore, this study demonstrated that a labeling method with trithiol for Pt radionuclides achieves 191 Pt-labeled products with high molar activity. 191 Pt-trithiol-PSMA showed promising in vivo stability and tumor-targeting specificity, which should facilitate the pharmaceutical development of Pt radionuclides for radiopharmaceutical therapy, especially Auger electron cancer therapy.
Pt 3 Sn nanoparticles enriched with SnO 2 /Pt 3 Sn interfaces for highly efficient alcohol electrooxidation
Pt 3 Sn nanoparticles (NPs) enriched with Pt 3 Sn/ultra-small SnO 2 interfaces (Pt 3 Sn@u-SnO 2 /NG) were synthesized through a thermal treatment of Pt 2 Sn/NG in a H 2 atmosphere, followed by annealing under H 2 and air conditions. The unique structure of Pt 3 Sn NPs enriched with Pt 3 Sn/SnO 2 interfaces was observed on the Pt 3 Sn@u-SnO 2 /NG catalyst based on HRTEM. The optimized Pt 3 Sn@u-SnO 2 /NG catalyst achieves high catalytic activity with an ethanol oxidation reaction (EOR) activity of 366 mA mg Pt -1 and a methanol oxidation reaction (MOR) activity of 503 mA mg Pt -1 at the potential of 0.7 V, which are eight-fold and five-fold higher than those for the commercial Pt/C catalyst (44 and 99 mA mg Pt -1 , respectively). The Pt 3 Sn@u-SnO 2 /NG catalyst is found to be 3 times more stable and have higher CO tolerance than Pt/C. The outstanding performance of the Pt 3 Sn@u-SnO 2 /NG catalyst should be ascribed to the synergetic effect induced by the unique structure of Pt 3 Sn NPs enriched with Pt 3 Sn/SnO 2 interfaces. The synergetic effect between Pt 3 Sn NPs and ultra-small SnO 2 increases the performance for alcohol oxidation because the Sn in both Pt 3 Sn and SnO 2 favors the removal of CO ads on the nearby Pt by providing OH ads species at low potentials. The present work suggests that the Pt 3 Sn@u-SnO 2 is indeed a unique kind of efficient electrocatalyst for alcohol electrooxidation.
Site dependent reactivity of Pt single atoms on anatase TiO 2 (101) in an aqueous environment
The TiO 2 –Pt–water interface is of great relevance in photocatalysis where Pt is widely used as a co-catalyst for The TiO 2 –Pt–water interface is of great relevance in photocatalysis where Pt is widely used as a co-catalyst for enhancing hydrogen evolution in aqueous TiO 2 . Using ab initio molecular dynamics, we investigated this interface focusing on Pt single atoms supported on anatase TiO 2 (101) in a water environment. Based on recent experiments showing a broad distribution of Pt coordination sites in TiO 2 , we examined six distinct single-Pt supported species with different nominal Pt oxidation states, namely: Pt, PtOH, and PtO 2 species adsorbed on the stoichiometric surface; Pt adsorbed at a surface oxygen vacancy (O v ); and Pt substituting a surface Ti cation (PtTi), both without and with an accompanying O v (Pt Ti + O v ). As found for the pristine anatase surface, interfacial water remained intact in the presence of a nearly neutral Pt adatom within the time duration of our simulations (~15 ps). Similarly, no (or only temporary) water dissociation was observed at the Pt Ti + O v and PtO 2 interfaces, due to the formation of very stable planar Pt coordination structures that interact only weakly with water. In contrast, water dissociated with OH – (H + ) on the Pt atom when this substituted a surface Ti (oxygen) ion as well as on PtOH. Lastly, the significant proton affinity of Pt atoms at surface oxygen vacancies suggests that negatively charged Pt species are particularly efficient at catalyzing hydrogen evolution in aqueous TiO 2 .hydrogen evolution in aqueous TiO 2 .
Effect of Particle Size on the Dissolution of Pt 3 Co/C and Pt/C PEMFC Electrocatalysts
Potentiostatic and potentiodynamic Pt and Co dissolution were investigated for three Pt 3 Co/C catalysts with particle sizes of 4.9, 8.1, and 14.8 nm in aqueous electrolyte at potentials encountered by the PEMFC cathode. For all three Pt 3 Co/C catalysts under prolonged potentiostatic dissolution, the dissolved Pt steady state concentration increases from 0.85 V to reach a maximum at 1.1−1.15 V and decreases at higher potentials. The dependence of the dissolved Pt steady state concentration on particle size reveals that catalyst stability decreases with decreasing mean particle size, whereas the stability under potential cycling conditions is non-monotonic with particle size. Preferential dissolution of Co from all three Pt 3 Co catalysts was observed at all potentials, which increases at >1.1 V, the region over which Pt dissolution decreases, reflecting the opposing effects of Pt oxide formation on Pt and Co dissolution. Comparison of Pt 3 Co/C and Pt/C with similar mean particle sizes (4.9 vs 5.0 nm) and particle size distributions reveals that the Pt 3 Co/C has a higher potentiostatic dissolution rate (4–5 times), a higher steady state concentration of dissolved Pt (∼2 times), and a larger change in electrochemically-active surface area (ECA) (18 times) after prolonged cycling, indicating that Pt 3 Co has inferior stability. The higher rates of Pt dissolution for Pt 3 Co vs Pt have been attributed to higher extents of surface Pt oxidation, as determined using voltammetric oxide reduction charges and the white line intensities in Pt L 3 X-ray absorption spectra.
Facile One-Pot Synthesis of Pd@Pt 1L Octahedra with Enhanced Activity and Durability toward Oxygen Reduction
A successful strategy for reducing the content of Pt without compromising the activity of a Pt-based catalyst is to deposit Pt as an ultrathin overlayer on the surface of another metal. In this paper, we report a facile one-pot synthesis of Pd@Pt 1L (1L: one atomic layer) core–shell octahedra using a solution-phase method. The success of this method relies on the use of metal precursors with markedly different reduction kinetics. In a typical synthesis, the ratio between the initial reduction rates of the Pd(II) and Pt(II) precursors differed by almost 100 times, favoring the formation of Pd–Pt bimetallic octahedra with a core–shell structure. The reduction of the Pt(II) precursor at a very slow rate and the use of a high temperature allowed the deposited Pt atoms to spread and cover the entire surface of Pd octahedral seeds formed in the initial stage. More importantly, we were able to scale up this synthesis using continuous-flow reactors without compromising product quality. Compared to a commercial Pt/C catalyst, the Pd@Pt 1L core–shell octahedra showed major augmentation in terms of catalytic activity and durability for the oxygen reduction reaction (ORR). After 10000 cycles of accelerated durability test, the core–shell octahedra still exhibited a mass activity of 0.45 A mg –1 Pt . We rationalized the experimental results using DFT calculations, including the mechanism of synthesis, ORR activities, and possible Pd–Pt atom swapping to enrich the outermost layer with Pd. Specifically, the as-synthesized Pd@Pt 1L octahedra tended to take a slightly mixed surface composition because the deposited Pt atoms were able to substitute into Pd upon deposition on the edges; ORR energetics were more favorable on pure Pt shells as compared to significantly mixed Pd–Pt shells, and the activation energy barriers calculated for the Pd–Pt atom swapping were too prohibitive to significantly alter the surface composition of the as-synthesized Pd@Pt 1L octahedra, helping sustain their activity for prolonged operation.