Search

Although nanomaterials are widely involved in technological applications, common synthetic recipes for such colloids are restricted to special, optimized conditions, particularly for anisotropic shapes. Ligand exchange is frequently necessary for further functionalization. While such protocols are well established for spherical particles, it is more demanding to keep the corpus for thermodynamically less stable shapes. We highlight the temperature as one key for the formation of anisotropic gold nanoparticles, but also for ligand exchange protocols under shape retention or deliberate reshaping at the example of gold nanocubes. In the first part, the synthesis of CTAB capped gold nanocubes in aqueous solution is examined highlighting the narrow temperature window in which selective adsorption site blocking by bromide ions leads to the formation of gold nanocubes. While too low temperatures yield multiple particle shapes due to a low surface mobility, temperatures above the appropriate window result in more thermodynamically favored shapes. Furthermore, two protocols are presented for the exchange of the ammonium ligand CTAB by oleylamine as an organic amine including water removal from a slurrish water‐amine paste through the gas phase. In turn, precise temperature control allows to either maintain the cubic shape or induce a reshaping process towards other, thermodynamically preferred shapes such as for example truncated octahedra. [ABSTRACT FROM AUTHOR]

The surface chemistry of oxygen and oxygenates on Rutile TiO2(110) is of great interest for various applications such as heterogeneous catalysis and photo catalysis. Though it is generally accepted that surface defects are active sites, the role of subsurface defects is under debate. We have therefore investigated the influence of the bulk defect density on the reductive coupling of benzaldehyde to stilbene as a model system. Using IRRAS we identify stilbene diolate as a reduction intermediate. The concentration of this intermediate is proportional to the bulk defect density, whereas adsorption of benzaldehyde at lower temperatures is not affected, which indicates a dominant role of Ti interstitials at temperatures above 400 K. [ABSTRACT FROM AUTHOR]

The catalytic performance of ligand-capped monometallic Pt and bimetallic PtSn nanoparticles supported on SiO2 toward the selective hydrogenation of acetylene to ethylene in ethylene-rich streams was investigated. To evaluate the effect of organic ligands on the hydrogenation performance, dodecylamine (DDA)-capped monometallic and bimetallic nanoparticles were compared with ligand-free nanoparticles. Both ligands and Sn promote the selectivity of the catalysts. The most selective catalyst was found to be the DDA-capped PtSn catalyst, with a nominal metal atom ratio of 1:1. An increase in Pt content resulted in a decrease in the selectivity, whereas an increase in Sn content caused a decrease in the activity. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) are promising alternatives to lithium ion batteries with advantages of cost effectiveness. Metal sulfides as emerging SIB anodes have relatively high electronic conductivity and high theoretical capacity, however, large volume change during electrochemical testing often leads to unsatisfactory electrochemical performance. Herein bimetallic sulfide Cu2MoS4 (CMS) with layered crystal structures are prepared with glucose addition (CMS1), resulting in the formation of hollow nanospheres that endow large interlayer spacing, benefitting the rate performance and cycling stability. The electrochemical mechanisms of CMS1 are investigated using ex situ X‐ray photoelectron spectroscopy and in situ X‐ray absorption spectroscopy, revealing the conversion‐based mechanism in carbonate electrolyte and intercalation‐based mechanism in ether‐electrolyte, thus allowing fast and reversible Na+ storage. With further introduction of reduced graphene oxide (rGO), CMS1–rGO composites are obtained, maintaining the hollow structure of CMS1. CMS1–rGO delivers excellent rate performance (258 mAh g−1 at 50 mA g−1 and 131.9 mAh g−1 at 5000 mA g−1) and notably enhanced cycling stability (95.6% after 2000 cycles). A full cell SIB is assembled by coupling CMS1–rGO with Na3V2(PO4)3‐based cathode, delivering excellent cycling stability (75.5% after 500 cycles). The excellent rate performance and cycling stability emphasize the advantage of CMS1–rGO toward advanced SIB full cells assembly. Bimetallic Cu2MoS4 (CMS) hollow nanospheres (CMS1) are obtained by modified solvothermal reactions. CMS1 delivers notably improved rate performance than CMS in ether‐electrolyte, in which an intercalation‐dominant electrochemical reaction mechanism is revealed. With further incorporation of reduced graphene oxide (rGO), the CMS1–rGO composites deliver excellent cycling stability, allowing fast and stable Na+ storage in full cell by coupling with an optimized Na3V2(PO4)3 cathode. [ABSTRACT FROM AUTHOR]

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

„…︁ Wir Wissenschaftler müssen uns gegenseitig vertrauen und uns aufeinander verlassen können aus Fürsorgepflicht und Verantwortung gegenüber unserer Gesellschaft. Mein persönliches Anliegen ist es, insbesondere dem wissenschaftlichen Nachwuchs dafür ein Bewusstsein zu vermitteln und ihm Selbstvertrauen zu geben …︁“ Lesen Sie mehr dazu im Editorial von Katharina Al ‐ Shamery. [ABSTRACT FROM AUTHOR]

“…︁ Scientists need to be able to trust and rely on each other as a matter of care and responsibility towards our society.My further personal plea is that we have to give our students an awareness of good scientific practice and help them to find self‐confidence …︁” Read more in the Editorial by Katharina Al‐Shamery. [ABSTRACT FROM AUTHOR]