Here we report the synthesis of Pt/Ag bimetallic nanostructures with controlled number of void spaces via a tailored galvanic replacement reaction (GRR). Ag nanocubes (NCs) were employed as the template to react with Pt ions in the presence of HCl. The use of HCl in the GRR caused rapid precipitation of AgCl, which grew on the surface of Ag NCs and acted as a removable secondary template for the deposition of Pt. The number of nucleation sites for AgCl was tailored by controlling the amount of HCl added to the Ag NCs or by introducing PVP to the reaction. This strategy led to the formation of Pt/Ag hollow nanoboxes, dimers, multimers, or popcorn-shaped nanostructures consisting of one, two, or multiple hollow domains. Due to the presence of large void space and porous walls, these nanostructures exhibited high surface area and improved catalytic activity for methanol oxidation reaction.

Gold nanostars have attracted widespread interest due to their remarkable properties and broad applications in plasmonics, spectroscopy, biomedicine, and energy conversion. However, current synthetic methods of Au nanostars have limited control over their symmetry; most existing nanostars are characterized by having uncertain number of arms with different lengths and random spatial arrangement. This morphological arbitrariness not only hampers the fundamental understanding of the properties of Au nanostars, but also lead to poor reproducibility in their applications. Here we demonstrate that, by using a robust solution-phase method, Au nanostars with unpreceded degree of symmetry control can be obtained in high yield and with remarkable monodispersity. Icosahedral seeds are used to dictate the growth of 3D evenly distributed arms in an Ih symmetric manner. Alkylamines serve as shape-control agent to regulate the growth of the hexagonal pyramidal arms enclosed by high-index facets. Benefiting from their high symmetry, the Au nanostars exhibit superior single-particle SERS performance compared to asymmetric Au nanostars, in terms of both intensity and reproducibility.

We report a new type of water-soluble ultrathin Au-Ag alloy nanowire (NW), which exhibits unprecedented behavior in a colloidal solution. Upon growth of a thin metal (Pd, Pt, or Au) layer, the NW winds around itself to give a metallic double helix. We propose that the winding originates from the chirality within the as-synthesized Au-Ag NWs, which were induced to untwist upon metal deposition.

No abstract

Developing new strategies for tuning the plasmonic properties of palladium nanostructures is of both fundamental and technological interest due to their potential applications in plasmonic hydrogen sensing, in situ surfaceenhanced Raman spectroscopy for catalysis, and solar energy harvesting. In this work, a new strategy of tuning the localized surface plasmon resonance (LSPR) property of Pd nanocrystals by selectively sharpening their edges and corners is reported. Through a Cu(II)-assisted seed-mediated growth approach, sub-10-nm sharp edges and corners were grown on regular Pd nanocubes. The LSPR peaks of the as-formed concave Pd nanocubes could be tuned across the visible spectrum by simply controlling their sizes. Cu(II) was found to selectively activate the fast growth of Pd atoms along the [110] and [111] directions of the cubic Pd seeds and promote the formation of this new type of Pd concave nanocubes. This strategy of building Pd sharp edges and corners may be applicable for the design of new plasmonic nanostructures by using seeds of different metals, sizes, shapes, and crystal structures.

Ultrathin metal-organic framework (MOF) nanosheets possessing inherent advantages of both two-dimensional (2D) features and MOFs are attracting intensive research interest. The direct manufacture of MOF nanosheets is still a challenge up to now. Here, we have developed a novel bottom-up approach to synthesize zeolitic imidazolate framework-67 (ZIF-67) nanosheets, which can be in situ converted into CoO ultrathin nanomeshes after thermal treatment. Interestingly, the obtained CoO nanomeshes are rich in oxygen defects, providing fruitful active sites for the faradaic reaction. The modified electrode exhibits a large specific capacitance (1216.4 F g at 1 A g), as well as a high rate capability (925.5 F g at 20 A g). Moreover, an asymmetric supercapacitor made of CoO//activated carbon shows an energy density of 46.5 Wh kg at 790.7 W kg. Furthermore, the 2D CoO ultrathin nanomeshes show an outstanding performance for the oxygen evolution reaction with an overpotential of 230 mV at the onset potential and a small Tafel slope of 74.0 mV dec. The present method presents a facile avenue to the preparation of other 2D ultrathin metal oxide nanostructures with various applications in energy catalysis and conversion.

The optimal pretransplant regimen for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) in patients ≥55 years of age remains to be determined. The myeloablative reduced-toxicity 4-day regimen IV busulfan (Bu) (130 mg/m2)-IV fludarabine (Flu) (40 mg/m2) is associated with low morbidity and mortality. We analyzed 79 patients ≥55 years of age (median, 58 years) with AML (n=63) or MDS (n=16) treated with IV Bu-Flu conditioning regimens between 2001 and 2009 (median follow-up, 24 months). The patients who received this regimen had a good performance status. The 2-year overall survival rates for patients in first complete remission (CR1), second CR (CR2), refractory disease and for all patients at time of transplantation were 71%, 44%, 32%, and 46%, respectively; 2-year event-free survival rates for patients in CR1, CR2, or refractory disease at time of transplantation and for all patients were 68%, 42%, 30%, and 44%, respectively. One-year transplant-related mortality (TRM) rates for patients who were in CR or who had active disease at the time of transplantation were 19% and 20%, respectively. Grade II-IV acute graft-versus-host disease was diagnosed in 40% of the patients. Our results suggest that age alone should not be the primary reason for exclusion from receiving myeloablative reduced-toxicity conditioning with IV Bu-Flu preceding transplantation in patients with AML/MDS.

The hierarchical CuCoO@carbon quantum dots (CQDs) hollow microspheres constructed by 1D porous nanowires have been successfully prepared through a simple CQDs-induced hydrothermal self-assembly technique. XPS analysis shows the CuCoO@CQDs possesses the Co(II)-rich surface associated with the oxygen vacancies, which can effectively boost the Faradaic reactions and oxygen evolution reaction (OER) activity. For example, the as-synthesized 3D porous CuCoO@CQDs electrode exhibits high activity toward overall electrochemical water splitting, for example, an overpotential of 290 mV for OER and 331 mV for hydrogen evolution reaction (HER) in alkaline media have been achieved at 10 mA cm, respectively. Furthermore, an asymmetric supercapacitor (ASC) (CuCoO@CQDs//CNTs) delivers a high energy density of 45.9 Wh kg at 763.4 W kg, as well as good cycling ability. The synergy of Co(II)-rich surface, oxygen vacancies, and well-defined 3D hollow structures facilitates the subsequent surface electrochemical reactions. This work presents a facile method to fabricate energetic nanocomposites with highly reactive, durable, and universal functionalities.