Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

6 items found (0 items not approved), displaying all items.1

Instruments / Technical Area	Publication Details	Published
I20-EDE-Energy Dispersive EXAFS (EDE)	Dynamics of palladium single-atoms on graphitic carbon nitride during ethylene hydrogenation Maurice Vennewald , Nina Michelle Sackers , Andree Iemhoff , Isabella Kappel , Claudia Weidenthaler , Ansgar Meise , Marc Heggen , Rafal E. Dunin-Borkowski , Luke Keenan , Regina Palkovits Journal Of Catalysis 118 DOI: 10.1016/j.jcat.2023.03.011 Diamond Proposal Number(s): [29667] Show Abstract ▼ Abstract: Single-atoms on carbon-nitrogen supports are considered catalysts for a multitude of reactions. However, doubts remain whether really these species or subnanometer clusters formed under reaction conditions are the active species. In this work, we investigate the dynamics of palladium single-atoms on graphitic carbon nitride during ethylene hydrogenation and H2-D2 exchange. By employing aberration-corrected scanning transmission electron microscopy, x-ray photoelectron spectroscopy and x-ray absorption spectroscopy, we will show that palladium, originally present as single-atoms, agglomerates to clusters at 100 °C in a gas atmosphere that contains both ethylene and hydrogen. This agglomeration goes in hand with the emergence of catalytic activity in both ethylene hydrogenation and H2-D2 exchange, suggesting that clusters, rather than single-atoms, are the active species. The results presented herein highlight the potential of analytics over the course of reaction to identify the active species and provide new insights into the influence of gas atmosphere on metal speciation.	Mar 2023
I20-Scanning-X-ray spectroscopy (XAS/XES)	Surface boron modulation on cobalt oxide nanocrystals for electrochemical oxygen evolution reaction Mingquan Yu , Claudia Weidenthaler , Yue Wang , Eko Budiyanto , Ezgi Onur Sahin , Minmin Chen , Serena Debeer , Olaf Ruediger , Harun Tuysuz Angewandte Chemie International Edition DOI: 10.1002/anie.202211543 Diamond Proposal Number(s): [21526] Open Access Show Abstract ▼ Abstract: Herein, we show that coupling boron with cobalt oxide tunes its structure and significantly boost its electrocatalytic performance for the oxygen evolution reaction (OER). Through a simple precipitation and thermal treatment process, a series of Co-B oxides with tunable morphologies and textural parameters were prepared. Detailed structural analysis supported first the formation of an disordered and partially amorphous material with nanosized Co3BO5 and/or Co2B2O6 being present on the local atomic scale. The boron modulation resulted in a superior OER reactivity by delivering a large current and an overpotential of 338 mV to reach a current density of 10 mA/cm2 in 1M KOH electrolyte. Identical location transmission electron microscopy and in situ electrochemical Raman spectroscopy studies revealed alteration and surface re-construction of materials, and formation of CoO2 and (oxy)hydroxide intermediate, which were found to be highly dependent on crystallinity of the samples.	Aug 2022
I20-Scanning-X-ray spectroscopy (XAS/XES)	Impact of single-pulse, low-intensity laser post-processing on structure and activity of mesostructured cobalt oxide for the oxygen evolution reaction Eko Budiyanto , Swen Zerebecki , Claudia Weidenthaler , Tim Kox , Stephane Kenmoe , Eckhard Spohr , Serena Debeer , Olaf Rudiger , Sven Reichenberger , Stephan Barcikowski , Harun Tuysuz Acs Applied Materials & Interfaces DOI: 10.1021/acsami.1c08034 Diamond Proposal Number(s): [25636] Open Access Show Abstract ▼ Abstract: Herein, we report nanosecond, single-pulse laser post-processing (PLPP) in a liquid flat jet with precise control of the applied laser intensity to tune structure, defect sites, and the oxygen evolution reaction (OER) activity of mesostructured Co3O4. High-resolution X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) are consistent with the formation of cobalt vacancies at tetrahedral sites and an increase in the lattice parameter of Co3O4 after the laser treatment. X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) further reveal increased disorder in the structure and a slight decrease in the average oxidation state of the cobalt oxide. Molecular dynamics simulation confirms the surface restructuring upon laser post-treatment on Co3O4. Importantly, the defect-induced PLPP was shown to lower the charge transfer resistance and boost the oxygen evolution activity of Co3O4. For the optimized sample, a 2-fold increment of current density at 1.7 V vs RHE is obtained and the overpotential at 10 mA/cm2 decreases remarkably from 405 to 357 mV compared to pristine Co3O4. Post-mortem characterization reveals that the material retains its activity, morphology, and phase structure after a prolonged stability test.	Jul 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Monitoring the structure evolution of titanium oxide photocatalysts: From the molecular form via the amorphous state to the crystalline phase Ezgi Onur Sahin , Yitao Dai , Candace Chan , Harun Tuysuz , Wolfgang Schmidt , Joohyun Lim , Siyuan Zhang , Cristina Scheu , Claudia Weidenthaler Chemistry – A European Journal DOI: 10.1002/chem.202101117 Diamond Proposal Number(s): [12102] Show Abstract ▼ Abstract: Amorphous TixOy with high surface area has attracted significant interest as photocatalyst with higher activity in ultraviolet (UV) light-induced water splitting applications compared to commercial nanocrystalline TiO2. Under photocatalytic operation conditions, the structure of the molecular titanium alkoxide precursor rearranges upon hydrolysis and leads to higher connectivity of the structure-building units. Structurally ordered domains with sizes smaller than 7 Å form larger aggregates. The experimental scattering data can be explained best with a structure model consisting of an anatase-like core and a distorted shell. Upon exposure with UV light, the white TixOy suspension turns dark corresponding to the reduction of Ti 4+ to Ti 3+ as confirmed by electron energy loss spectroscopy (EELS). Heat-induced crystallisation was followed by in situ temperature-dependent total scattering experiments. First, ordering in the Ti-O environment takes place upon to 350 °C. Above this temperature, the distorted anatase core starts to grow but the structure obtained at 400 °C is still not fully ordered.	Jun 2021
I15-1-X-ray Pair Distribution Function (XPDF)	In situ total scattering experiments of nucleation and crystallisation of tantalum-based oxides: from highly dilute solutions via cluster formation to nanoparticles Ezgi Onur Sahin , Harun Tueysuez , Candace K. Chan , Gun-Hee Moon , Yitao Dai , Wolfgang Schmidt , Joohun Lim , Christina Scheu , Claudia Weidenthaler Nanoscale DOI: 10.1039/D0NR07871A Diamond Proposal Number(s): [16372] Open Access Show Abstract ▼ Abstract: The exact formation mechanism of tantalum oxides (and in general, metal/mixed metal oxides) from alkoxide precursors is still not fully understood, particularly when forming cluster-like or amorphous materials. The structural evolution of Ta-based oxides was studied in detail using X-ray total scattering experiments along with subsequent pair distribution function (PDF) analyses. Starting from a tantalum alkoxide precursor (Ta2(OEt)10), the formation of hydrolysed TaxOyHz clusters in highly diluted aqueous solution was analysed. From the PDF data, the connectivity and arrangement of TaxOy octahedra in the cluster could be deduced as well as the approximate size of the clusters (<1 nm). Construction of cluster models allowed for identification of common structural motifs in the TaxOyHz clusters, ruling out the formation of chain- or ring-like clusters. More likely, bulky clusters with a high number of corner-sharing octahedra are formed. After separation of the amorphous solid from the liquid, temperature-induced crystallisation processes were monitored via in situ total scattering experiments. Between room temperature and 600 °C, only small rearrangements of the amorphous structure are observed. At about 610 °C, amorphous TaxOyHz transforms directly into crystalline orthorhombic L-Ta2O5 without formation of any crystalline intermediate structures.	Nov 2020
I15-Extreme Conditions	Monitoring the formation of PtNi nanoalloys supported on hollow graphitic spheres using in situ pair distribution function analysis S. Ortatatli , J. Knossalla , F. Schüth , C. Weidenthaler Physical Chemistry Chemical Physics 14 DOI: 10.1039/C7CP07840D Diamond Proposal Number(s): [14028] Open Access Show Abstract ▼ Abstract: This article aims to address the formation and the structural disordering/ordering phenomena of PtNi nanoalloys supported on hollow graphitic spheres (HGSs) using pair distribution function (PDF) analysis under ex situ/in situ data collection conditions. Starting from small nanoparticles (10–15 Å in diameter) embedded in HGSs, structural changes were monitored during stepwise heating and cooling of the sample using in situ PDF analysis. In order to evaluate the conventional synthesis route for the production of PtNi nanoalloys supported on HGSs, ex situ PDF experiments were performed before and after heat treatment in a furnace. The studies demonstrate that the local structure of the in situ synthesised PtNi nanoalloy differs from its ex situ synthesised counterpart. A partially ordered PtNi nanoalloy was obtained during the stepwise in situ cooling of the precursor, whereas the conventional ex situ synthesis route did not lead to the formation of an ordered crystal structure. In this study we could show that rapid heating and cooling results in a disordered PtNi alloy whereas slow heating and cooling leads to disorder–order transitions in PtNi.	Jan 2018

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User