TY - BOOK
T1 - X-ray pair distribution function analysis of transition and noble metals for industrial applications in sensing and catalysis
AU - Kovyakh, Anton
PY - 2018
Y1 - 2018
N2 - Understanding structures and properties of nanoscale materials is increasingly important in contemporary technological development. The presented work investigates the applications of x-ray pair distribution function (PDF) analysis in a number of industrial research projects. The viability of the method is explored in the areas of instrumentation, catalysis, time-resolved measurements and novel data reduction protocols. Obtaining quantitative structural information efficiently is essential for studying materials synthesized using combinatorial methods. To address this we propose a protocol for measuring and analyzing data from such high-throughput experiments. For this study, a combinatorial array containing catalytic nanoparticles was prepared from liquid precursors, directly on-chip, using an ink-jet liquid handling system. The array was then measured at the x-ray powder diffraction beamline (NSLS-II) and analyzed by the PDF technique using a software implementation of the proposed protocol. The developed protocol software can handle semi-automated data reduction, normalization and modeling. A comprehensive collection of metadata and analysis results is generated from user-defined recipes. By slicing this collection using the included functions it is possible to determine the distribution of material on the array, highlight regions with heterogeneity, and visualize spatially varying structural parameters. The modular design of the software is intended to be transparent and extensible, with potential applications to other experimental techniques. Copper nanoparticles have the potential to completely replace silver in applications of printed electronics. A cost effective and environmentally-safe method of manufacturing nanoparticles using glucose reduction of copper in an aqueous media is studied in detail using synchrotron x-ray PDF. Nanoparticle growth is observed in-situ, utilizing a new setup for continuous flow characterization. The limiting factor for the reactions is found in the chemical kinetics. Meanwhile, the reducing agent is found to be an effective capping agent. The methodology is successfully tested together with novel data reduction and analysis methods. Platinum palladium (PtPd) and platinum palladium iron (PtPdFe) nanoparticle catalysts on !-Al2O3 supports are interesting for the applications in diesel oxidation catalysis. In this work, the particles are studied using the PDF analysis. The study concludes that the addition of iron into PtPd leads to a lattice contraction of the alloy improving the temperature for half conversion. In addition, iron doping appears to have an effect on the size of the nanoparticles. The lattice contraction appears systematic, decreasing linearly with the amount of iron added to the synthesis. The findings are confirmed by a control experiment, where catalytic nanoparticles are prepared on graphitized carbon supports. Molybdenum oxide catalysts on zeolite ZSM-5 supports for methane conversion are studied using the PDF analysis. The catalyst prepared by hydrothermal flow synthesis method contains amorphous molybdenum oxide structures in contrast to the reference sample, which contains nanocrystalline MoO3 and is prepared by impregnation method. The amorphous molybdenum oxide appears to have octahedral coordination and consists of units of several octahedra in a corner share and edge share configurations. The findings indicate that the catalytic material is distributed across the support material with higher concentrations in or around the pores of the zeolite, which might explain its better catalytic activity when compared to the reference. A series of Atomic Layer Deposition(ALD) grown TiNx thin films is investigated. The material changes its plasmonic properties due to an annealing process. The origins of this change are invesitgated via a thin film PDF method (tf-PDF). It is found that the substrateis changing too significantly. Due to these changes, proper background subtraction could not be achieved. Despite the difficulties in tf-PDF analysis, the x-ray diffraction data was analyzed and the majority phase was determined to be TiN. It is found that during the annealing process the material undergoes a lattice expansion and experiences isotropic domain. In addition, the material has a high degree of preferred orientation in the growth direction.
AB - Understanding structures and properties of nanoscale materials is increasingly important in contemporary technological development. The presented work investigates the applications of x-ray pair distribution function (PDF) analysis in a number of industrial research projects. The viability of the method is explored in the areas of instrumentation, catalysis, time-resolved measurements and novel data reduction protocols. Obtaining quantitative structural information efficiently is essential for studying materials synthesized using combinatorial methods. To address this we propose a protocol for measuring and analyzing data from such high-throughput experiments. For this study, a combinatorial array containing catalytic nanoparticles was prepared from liquid precursors, directly on-chip, using an ink-jet liquid handling system. The array was then measured at the x-ray powder diffraction beamline (NSLS-II) and analyzed by the PDF technique using a software implementation of the proposed protocol. The developed protocol software can handle semi-automated data reduction, normalization and modeling. A comprehensive collection of metadata and analysis results is generated from user-defined recipes. By slicing this collection using the included functions it is possible to determine the distribution of material on the array, highlight regions with heterogeneity, and visualize spatially varying structural parameters. The modular design of the software is intended to be transparent and extensible, with potential applications to other experimental techniques. Copper nanoparticles have the potential to completely replace silver in applications of printed electronics. A cost effective and environmentally-safe method of manufacturing nanoparticles using glucose reduction of copper in an aqueous media is studied in detail using synchrotron x-ray PDF. Nanoparticle growth is observed in-situ, utilizing a new setup for continuous flow characterization. The limiting factor for the reactions is found in the chemical kinetics. Meanwhile, the reducing agent is found to be an effective capping agent. The methodology is successfully tested together with novel data reduction and analysis methods. Platinum palladium (PtPd) and platinum palladium iron (PtPdFe) nanoparticle catalysts on !-Al2O3 supports are interesting for the applications in diesel oxidation catalysis. In this work, the particles are studied using the PDF analysis. The study concludes that the addition of iron into PtPd leads to a lattice contraction of the alloy improving the temperature for half conversion. In addition, iron doping appears to have an effect on the size of the nanoparticles. The lattice contraction appears systematic, decreasing linearly with the amount of iron added to the synthesis. The findings are confirmed by a control experiment, where catalytic nanoparticles are prepared on graphitized carbon supports. Molybdenum oxide catalysts on zeolite ZSM-5 supports for methane conversion are studied using the PDF analysis. The catalyst prepared by hydrothermal flow synthesis method contains amorphous molybdenum oxide structures in contrast to the reference sample, which contains nanocrystalline MoO3 and is prepared by impregnation method. The amorphous molybdenum oxide appears to have octahedral coordination and consists of units of several octahedra in a corner share and edge share configurations. The findings indicate that the catalytic material is distributed across the support material with higher concentrations in or around the pores of the zeolite, which might explain its better catalytic activity when compared to the reference. A series of Atomic Layer Deposition(ALD) grown TiNx thin films is investigated. The material changes its plasmonic properties due to an annealing process. The origins of this change are invesitgated via a thin film PDF method (tf-PDF). It is found that the substrateis changing too significantly. Due to these changes, proper background subtraction could not be achieved. Despite the difficulties in tf-PDF analysis, the x-ray diffraction data was analyzed and the majority phase was determined to be TiN. It is found that during the annealing process the material undergoes a lattice expansion and experiences isotropic domain. In addition, the material has a high degree of preferred orientation in the growth direction.
UR - https://rex.kb.dk/primo-explore/fulldisplay?docid=KGL01011920909&context=L&vid=NUI&search_scope=KGL&tab=default_tab&lang=da_DK
M3 - Ph.D. thesis
BT - X-ray pair distribution function analysis of transition and noble metals for industrial applications in sensing and catalysis
PB - The Niels Bohr Institute, Faculty of Science, University of Copenhagen
ER -