Shape control beyond the seeds in gold nanoparticles

In typical seed-mediated syntheses of metal nanocrystals, the shape of the nanocrystal is determined largely by the seed nucleation environment and subsequent growth environment (where "environment"refers to the chemical environment, including the surfactant and additives). In this approach, crystallinity is typically determined by the seeds, and surfaces are controlled by the environment(s). However, surface energies, and crystallinity, are both influenced by the choice of environment(s). This limits the permutations of crystallinity and surface facets that can be mixed and matched to generate new nanocrystal morphologies. Here, we control post-seed growth to deliberately incorporate twin planes during the growth stage to deliver new final morphologies, including twinned cubes and bipyramids from single-crystal seeds. The nature and number of twin planes, together with surfactant control of facet growth, define the final nanoparticle morphology. Moreover, by breaking symmetry, the twin planes introduce new facet orientations. This additional mechanism opens new routes for the synthesis of different morphologies and facet orientations. </p

Manganese‐Doping‐Induced Quantum Confinement within Host Perovskite Nanocrystals through Ruddlesden–Popper Defects

The concept of doping Mn2+ ions into II–VI semiconductor nanocrystals (NCs) was recently extended to perovskite NCs. To date, most studies on Mn2+ doped NCs focus on enhancing the emission related to the Mn2+ dopant via an energy transfer mechanism. Herein, we found that the doping of Mn2+ ions into CsPbCl3 NCs not only results in a Mn2+‐related orange emission, but also strongly influences the excitonic properties of the host NCs. We observe for the first time that Mn2+ doping leads to the formation of Ruddlesden–Popper (R.P.) defects and thus induces quantum confinement within the host NCs. We find that a slight doping with Mn2+ ions improves the size distribution of the NCs, which results in a prominent excitonic peak. However, with increasing the Mn2+ concentration, the number of R.P. planes increases leading to smaller single‐crystal domains. The thus enhanced confinement and crystal inhomogeneity cause a gradual blue shift and broadening of the excitonic transition, respectively

Near-infrared Emitting CulnSe2/CulnS2 Dot Core/Rod Shell Heteronanorods by Sequential Cation Exchange

The direct synthesis of heteronanocrystals (HNCs) combining different ternary semiconductors is challenging and has not yet been successful. Here, we report a sequential topotactic cation exchange (CE) pathway that yields CuInSe2/CuInS2 dot core/rod shell nanorods with near-infrared luminescence. In our approach, the Cu+ extraction rate is coupled to the In3+ incorporation rate by the use of a stoichiometric trioctylphosphine-InCl3 complex, which fulfills the roles of both In-source and Cu-extracting agent. In this way, Cu+ ions can be extracted by trioctylphosphine ligands only when the In–P bond is broken. This results in readily available In3+ ions at the same surface site from which the Cu+ is extracted, making the process a direct place exchange reaction and shifting the overall energy balance in favor of the CE. Consequently, controlled cation exchange can occur even in large and anisotropic heterostructured nanocrystals with preservation of the size, shape, and heterostructuring of the template NCs into the product NCs. The cation exchange is self-limited, stopping when the ternary core/shell CuInSe2/CuInS2 composition is reached. The method is very versatile, successfully yielding a variety of luminescent CuInX2 (X = S, Se, and Te) quantum dots, nanorods, and HNCs, by using Cd-chalcogenide NCs and HNCs as templates. The approach reported here thus opens up routes toward materials with unprecedented properties, which would otherwise remain inaccessible

Disconnecting Symmetry Breaking from Seeded Growth for the Reproducible Synthesis of High Quality Gold Nanorods

https://pubs.acs.org/doi/suppl/10.1021/acsnano.8b09658/suppl_file/nn8b09658_si_002.pdfOne of the major difficulties hindering the widespread application of colloidal anisotropic plasmonic nanoparticles is the limited robustness and reproducibility of multistep synthetic methods. We demonstrate herein that the reproducibility and reliability of colloidal gold nanorod (AuNR) synthesis can be greatly improved by disconnecting the symmetry-breaking event from the seeded growth process. We have used a modified silver-assisted seeded growth method in the presence of the surfactant hexadecyltrimethylammonium bromide and n-decanol as a co-surfactant to prepare small AuNRs in high yield, which were then used as seeds for the growth of high quality AuNR colloids. Whereas the use of n-decanol provides a more-rigid micellar system, the growth on anisotropic seeds avoids sources of irreproducibility during the symmetry breaking step, yielding uniform AuNR colloids with narrow plasmon bands, ranging from 600 to 1270 nm, and allowing the fine-tuning of the final dimensions. This method provides a robust route for the preparation of high quality AuNR colloids with tunable morphology, size, and optical response in a reproducible and scalable manner

Diphenyl ditelluride assisted synthesis of noble metal-based silver-telluride 2D organometallic nanofibers with enhanced aggregation-induced emission (AIE) after oleylamine treatment

Funding Information: A. A. Dos Santos thank FAPESP ( 2014/17310–5 , 2016/09579–0 and 2018/24434–3 ), IQ- USP and CNPq ( 401797/2013–9 ) for financial support. L.B. is supported by the US Department of Energy , Basic Energy Sciences program, through award DE-SC0002613 . A portion of this work was performed at the National High Magnetic Field Laboratory , which is supported by the National Science Foundation Cooperative Agreement No. DMR-2128556 and the State of Florida. The authors acknowledge financial support from the European Commission under the Horizon 2020 Programme by grant no. 731019 (EUSMI). Funding Information: J.F.-L., A.F.-L.; C.L.; J.D.; and J.L.C.-M. thank the FCT- MEC for the research grant SiSi4Bacter ( PTDC/QUI-COL/1517/2020 ). J. F.-L. thanks FCT- UNL for the research contract through the Program DL 57/2016 Norma Transitória. F.D. thanks to FCT- MEC (Portugal) for his doctoral grant 2021.05161 .BD. H.M.S acknowledges the Associate Laboratory for Green Chemistry-LAQV (LA/P/0008/2020) funded by FCT / MCTES for his research contract. A.F.-L. thanks the research contract DL57 associated to the grant SiSi4Bacter (PTDC/QUI- COL /1517/2020). Funding Information: The authors acknowledge the financial support by the Associate Laboratory Research Unit for Green Chemistry-Clean Processes and Technologies-LAQV which is financed by national funds from FCT / MEC ( UID/QUI/50006/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement ( POCI-01-0145-FEDER-007265 ), as well as the PROTEOMASS Scientific Society, General Funds 2022–2023 (Portugal) for funding support. Publisher Copyright: © 2023Silver-Telluride 2D organometallic nanofibers (NFs), using diphenyl ditelluride (DPDT) as a precursor, were synthesized. The synthesis was carried out by reacting DPDT with AgNO3 in acetonitrile at room temperature (RT) under an inert atmosphere. The resulting material was fully characterized using various techniques, including UV-VIS-NIR spectroscopy, steady-state and excited-state fluorescence spectroscopy, IR-FTIR-ATR spectroscopy, HR-ESI MS spectrometry, high-resolution transmission electron microscopy (HRTEM), BF-STEM or HAADF-STEM, confocal fluorescence microscopy images and conductivity measurements. Initially, the nanofibers were almost non-emissive. However, a remarkable modification was observed after treating the nanofibers with oleylamine under ultrasound treatment. This methodology induced an aggregation emission effect (AIE) in the solution and in the solid state, resulting in the formation of a highly red emissive fluorescent nanomaterial. This research provides valuable insights for developing new fluorescent materials with potential applications in various optical fields.publishersversionpublishe

Разработка системы измерения производительности реализаций blockchain

Долголев Филипп Петрович Разработка системы измерения производительности реализаций blockchain Старший преподаватель кафедры системного программирования Кириленко Яков Александрович При разработке приложений на основе технологии blockchain, из-за наличия множества различных реализаций, разработчики сталкиваются с проблемой выбора. Один из важных критериев при выборе - производительность. В процессе поиска системы, позволяющей измерить производительность различных реализаций blockchain, не обнаружены ни проприетарные системы, ни с открытым исходным кодом. В рамках этой работы рассматривается разработка модульной системы, решающей эту проблему. Использованных источников: 18 Долголев, Ф. П. Разработка системы измерения производительности реализаций blockchain: выпускная квалификационная работа: защищена 01.06.2017 / Долголев Филипп Петрович. – СПб., 2017. – 21 с. – Библиография: с. 20–21.Filipp Dolgolev Blockchain Implementations Benchmarking Tool senior lecturer, dept. of software engineering Iakov Kirilenko Mathematics & mechanics, software engineering department Since there are many different types of blockchain technologies, developers are faced with a dilemma of which technology to choose when developing applications for a particular use case. One of the most important criteria effecting the selection is performance. During our research, we were unable to source either proprietary, or open source solutions allowing to benchmark various blockchain technologies performances. In this context, we are considering the development of such a solution. Sources cited: 18 Dolgolev, F. Blockchain Implementations Benchmarking Tool: Graduation thesis: Defended 01.06.2017 / Filipp Dolgolev. – St. Petersburg., 2017. – 21 pp. – Bibliography: pp. 20–21

Improving the Redox Response Stability of Ceria-Zirconia Nanocatalysts under Harsh Temperature Conditions

By depositing ceria on the surface of yttrium-stabilized zirconia (YSZ) nanocrystals and further activation under high-temperature reducing conditions, a 13% mol. CeO2/YSZ catalyst structured as subnanometer thick, pyrochlore-type, ceria-zirconia islands has been prepared. This nanostructured catalyst depicts not only high oxygen storage capacity (OSC) values but, more importantly, an outstandingly stable redox response upon oxidation and reduction treatments at very high temperatures, above 1000 °C. This behavior largely improves that observed on conventional ceria-zirconia solid solutions, not only of the same composition but also of those with much higher molar cerium contents. Advanced scanning transmission electron microscopy (STEM-XEDS) studies have revealed as key not only to detect the actual state of the lanthanide in this novel nanocatalyst but also to rationalize its unusual resistance to redox deactivation at very high temperatures. In particular, high-resolution X-ray dispersive energy studies have revealed the presence of unique bilayer ceria islands on top of the surface of YSZ nanocrystals, which remain at surface positions upon oxidation and reduction treatments up to 1000 °C. Diffusion of ceria into the bulk of these crystallites upon oxidation at 1100 °C irreversibly deteriorates both the reducibility and OSC of this nanostructured catalyst