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Instruments / Technical Area	Publication Details	Published
	Layer-by-layer epitaxy of porphyrin−ligand Fe(ii)-Fe(iii) nanoarchitectures for advanced metal–organic framework growth Zishu Wang , Kai Qian , Murat Anil Öner , Peter S. Deimel , Yan Wang , Shuai Zhang , Xiaoxi Zhang , Vishal Gupta , Juan Li , Hong-Jun Gao , David A. Duncan , Johannes V. Barth , Xiao Lin , Francesco Allegretti , Shixuan Du , Carlos-Andres Palma Acs Applied Nano Materials DOI: 10.1021/acsanm.0c02237 Show Abstract ▼ Abstract: Precisely layered molecular heterostructures are promising but still largely unexplored materials, with the potential to complement and enhance the scope of two-dimensional heterostructures. The controlled epitaxial growth of vertically stacked molecular layers connected through tailored linkers, can lead to significant development in the field. Here, we demonstrate that sequential assembly of prototypical iron porphyrins and axial ligands can be steered via temperature-programmed desorption, and monitored by mass spectrometry and by high-resolution atomic force microscopy under ultrahigh vacuum conditions. Complementary photoelectron spectroscopy analysis delivers chemical insight into the formation of layer-by-layer nanoarchitectures. Our temperature-directed methodology outlines a promising strategy for the in vacuo fabrication of precisely stacked, multicomponent (metal–organic) molecular heterostructures.	Nov 2020
I20-Scanning-X-ray spectroscopy (XAS/XES)	Tailoring the size, inversion parameter, and absorption of phase-pure magnetic MgFe2O4 nanoparticles for photocatalytic degradations Andre Bloesser , Hannah Kurz , Jana Timm , Florian Wittkamp , Christopher Simon , Shusaku Hayama , Birgit Weber , Ulf-Peter Apfel , Roland Marschall Acs Applied Nano Materials DOI: 10.1021/acsanm.0c02705 Diamond Proposal Number(s): [23538] Show Abstract ▼ Abstract: Phase-pure magnesium ferrite (MgFe2O4) spinel nanocrystals are synthesized by a fast microwave-assisted route. The elemental composition is optimized via the ratio of the precursor mixture and controlled by energy-dispersive X-ray spectroscopy. Fine-tuning of the magnetic properties without changing the overall elemental composition is demonstrated by superconducting quantum interference device (SQUID) magnetometry and Mössbauer spectroscopy. Together with X-ray absorption spectroscopy and X-ray emission spectroscopy, we confirm that the degree of cation inversion is altered by thermal annealing. We can correlate the magnetic properties with both the nanosize influence and the degree of inversion. The resulting nonlinear course of saturation magnetization (Ms) in correlation with the particle diameter allows to decouple crystallite size and saturation magnetization, by this providing a parameter for the production of very small nanoparticles with high Ms with great potential for magnetic applications like ferrofluids or targeted drug delivery. Our results also suggest that the optical band gap of MgFe2O4 is considerably larger than the fundamental electronic band gap because of the d5 electronic configuration of the iron centers. The presented different electronic transitions contributing to the absorption of visible light are the explanation for the large dissent among the band gaps and band potentials found in the literature.	Oct 2020
E01-JEM ARM 200CF	Nitrogen-doped carbon dots/TiO2 nanoparticle composites for photoelectrochemical water oxidation Hui Luo , Stoichko D. Dimitrov , Matyas Daboczi , Ji-Seon Kim , Qian Guo , Yuanxing Fang , Marc-Antoine Stoeckel , Paolo Samorì , Oliver Fenwick , Ana Belen Jorge Sobrido , Xinchen Wang , Maria-Magdalena Titirici Acs Applied Nano Materials DOI: 10.1021/acsanm.9b02412 Diamond Proposal Number(s): [22447] Show Abstract ▼ Abstract: Carbon dots on photoactive semiconductor nanomaterials have represented an effective strategy for enhancing their photoelectrochemical (PEC) activity. By carefully designing and manipulating carbon dots/support composite, a high photocurrent could be obtained. Currently, there is not much fundamental understanding of how the interaction between such materials can facilitate the reaction process. This hinders the wide applicability in PEC devices. To address this need of improving the fundamental understanding of carbon dots/semiconductor nanocomposite, we have taken the TiO2 case as a model semiconductor system with nitrogen-doped carbon dots (NCDs). We present here with in-depth investigation of the structural hybridization and energy transitions in the NCDs/TiO2 photoelectrode via high-resolution scanning transmission microscopy (HR-STEM), electron energy loss spectroscopy (EELS), UV-Vis absorption, electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S), time-correlated single photon counting (TCSPC) and ultra-violet photoelectron spectroscopy (UPS), which shed some light on the charge transfer process at the carbon dots and TiO2 interface. We show that N doping in carbon dots can effectively prolong the carrier lifetime, and the hybridisation of NCDs and TiO2 is able not only to extend TiO2 light response into the visible range but also to form heterojunction at the NCDs/TiO2 interface with properly aligned band structure that allows a spatial separation of the charges. This work is arguably the first to report the direct probing of the band positions of carbon dots-TiO2 nanoparticle composite in a PEC system for understanding the energy transfer mechanism, demonstrating the favourable role of NCDs in the photocurrent response of TiO2 for water oxidation process. This study reveals the importance of combining structural, photophysical and electrochemical experiments to develop a comprehensive understanding of the charge injection/electronic communication between the carbon dots and their current collectors or catalyst supports.	Mar 2020
	Corrosion of late- and post-transition metals into metal-organic chalcogenolates and implications for nanodevice architectures Matthew Yeung , Derek C. Popple , Elyse A. Schriber , Simon J. Teat , Christine M. Beavers , Aude Demessence , Tevye R. Kuykendall , J. Nathan Hohman Acs Applied Nano Materials DOI: 10.1021/acsanm.0c00057 Show Abstract ▼ Abstract: Metal chalcogenide compounds have attracted interest as materials for next generation semiconductors, catalysts, and device architectures. Hybrid compounds containing both a metal chalcogenide architecture and a supporting organic lattice combine the interesting structural and electronic properties of the material class with a configurable hybrid component that can lead to a wide range of tailorable materials. However, many of the methods available for preparing inorganic coordination polymers in this class require specialized solution-phase chemical preparations that are incompatible with solid-state fabrication techniques. Here we prepare metal-organic chalcogenolates (MOChas) of copper, indium, lead, and tin from benzeneselenol or benzenethiol directly from the organochalcogen and corresponding metal in a tube furnace at a relatively modest temperature. Scanning electron microscopy and X-ray diffraction confirmed conversion of the precursors to crystalline MOChas. X-ray photoelectron spectroscopy was used to investigate the chemical bonding for each of the materials and provides insight into the elemental composition of the synthesized compounds. This straightforward approach for preparing crystalline hybrid materials may be generalizable for the preparation of a wide variety of coordination compounds and complexes in form factors useful for subsequent development of device architectures.	Mar 2020
E01-JEM ARM 200CF E02-JEM ARM 300CF	Stabilization of metal nanoparticle catalysts via encapsulation in mesoporous zeolites by steam-assisted recrystallization Kristoffer H. Rasmussen , Farnoosh Goodarzi , David B. Christensen , Jerrik Mielby , Søren Kegnæs Acs Applied Nano Materials DOI: 10.1021/acsanm.9b02205 Diamond Proposal Number(s): [20892, 20650] Show Abstract ▼ Abstract: Zeolite encapsulated metal nanoparticle catalysts hold great promise for several green and sustainable processes, ranging from environmental remediation to renewable energy and biomass conversion. In particular, the microporous zeolite framework keeps the nanoparticles in a firm grip that can control selectivity and prevent sintering at high temperatures. While progress in the synthesis of mesoporous zeolites continues, the encapsulation of metal nanoparticles remains a challenge that often requires complex procedures and expensive additives. Here, we report a general method to encapsulate both base and noble metal nanoparticles inside the internal voids of a compartmentalized mesoporous zeolite prepared by carbon templating and steam-assisted recrystallization. This results in a remarkable shell-like morphology that facilitates the formation of small metal nanoparticles upon simple impregnation and reduction. When the materials are applied in catalysis, we for instance demonstrate that zeolite encapsulated Ni nanoparticles are highly active, selective and stable catalysts for CO2 methanation (49% conversion with 93% selectivity at 450°C). A reaction where catalysts often suffer from sintering due to the high reaction temperatures. While the introduction of Ni nanoparticles prior to the steam-assisted recrystallization results in the formation of inactive nickel phyllosilicates, noble metals such as Pt do not suffer from this limitation. Therefore, we also demonstrate the synthesis of an active catalyst prepared by the formation of Pt nanoparticles prior to the shell synthesis. We tested the zeolite encapsulated Pt nanoparticles for hydrogenation of linear and cyclic alkenes with increased chain length. The catalysts are active for hydrogenation of oct-1-ene (66% conversion) and cyclooctene (79% conversion) but inactive for the large cyclododecane (<1% conversion), which show that this type of catalyst is highly selective in size selective catalysis. All catalysts are characterized by XRD, TEM, XPS and N2 physisorption.	Dec 2019
B18-Core EXAFS I22-Small angle scattering & Diffraction	Synthesis and characterization of platinum nanoparticle catalysts capped with isolated zinc species in SBA-15 channels: the wall effect Elizabeth Raine , Adam Clark , Glen Smales , Andrew Smith , Diego Gianolio , Tong Li , Jianwei Zheng , Benjamin Griffith , Timothy I. Hyde , Mark Feaviour , Paul Collier , John V. Hanna , Gopinathan Sankar , Shik Chi Edman Tsang Acs Applied Nano Materials DOI: 10.1021/acsanm.8b01357 Diamond Proposal Number(s): [16316, 16583] Show Abstract ▼ Abstract: The strong directing effects and difficulties in the removal of organic based surfactants makes the templated synthesis of nanoparticles in solid porous structures of defined molecular sizes such as SBA-15, without the use of surfactants, considerably attractive. However, the effects of their internal surface structures, adsorption affinities and lattice mis-match on the particle morphology grown therein have not been fully appreciated. Here, we report the internal surface of the silica preferentially hosts isolated tetrahedrally coordinated oxidic Zn species on the molecular walls of the SBA-15 channels from wet impregnated Zn2+ and Pt2+ species. This leads to less thermodynamic stable but kinetic controlled configuration of atomic zinc deposition on core platinum nanoparticles with unique confined lattice changes and surface properties to both host and guest structures at the interface upon reduction of the composite. This method for the formation templated nanoparticles may generate interests to form new tunable materials as dehydrogenation catalysts.	Nov 2018
I07-Surface & interface diffraction I22-Small angle scattering & Diffraction	Highly ordered titanium dioxide nanostructures via a simple one step vapor inclusion method in block copolymer films Elsa C. Giraud , Parvaneh Mokarian-Tabari , Daniel T. W. Toolan , Thomas Arnold , Andrew J. Smith , Jonathan R. Howse , Paul D. Topham , Michael A. Morris Acs Applied Nano Materials DOI: 10.1021/acsanm.8b00632 Diamond Proposal Number(s): [10439, 9328] Show Abstract ▼ Abstract: Nanostructured crystalline titanium dioxide (TiO2) finds applications in numerous fields such as photocatalysis or photovoltaics where its physical and chemical properties depend on its shape and crystallinity. We report a simple method of fabricating TiO2 nanowires by selective area deposition of titanium tetraisopropoxide (TTIP) and water in a CVD-based approach at low temperature by utilizing PS-b-PEO self-assembled block copolymer thin film as a template. Parameters such as exposure time to TTIP (minutes to hours), working temperature (~18 to 40 °C) and relative humidity (20 to 70 RH%) were systemically investigated through GISAXS, SEM and XPS and optimized for fabrication of TiO2 nanostructures. The resulting processing conditions yielded titanium dioxide nanowires with a diameter of 24 nm. An extra calcination step (400 – 700 °C) was introduced to burn off the remaining organic matrix and introduce phase change from amorphous to anatase in TiO2 nanowires without any loss in order.	Jun 2018

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