Materials based on metal oxides are of crucial importance for a multitude of present and emerging technical and consumer applications. In such applications, ranging from medical implants to surface coatings and construction materials, metal oxides are very often in contact with water during use and typically they are also produced from aqueous solution. Thus, a comprehensive understanding of the metal oxide/water interactions on the molecular level is indispensable for the design of oxides with desirable properties and for ensuring the stability of these materials over time (i.e. resistance to degradation and corrosion) but is has not been reached yet. It requires collaborative research efforts with consideration of a large width concerning water amount and oxide complexity, ranging from individual molecules, clusters and nanoparticles to extended crystalline and amorphous bulk materials. This profound multi-scale nature of metal oxide/water chemistry poses major challenges - also methodologically - that our CRC accepts and with focus on certain representative oxides aims at a complete description of the formation and dissolution processes within the CRC run-time. To investigate the different stages of oxide assembly and dissolution the CRC employs combinations of state-of-the-art methods in theory, chemical synthesis, microscopy and spectroscopy, including time-resolved in-situ spectroscopy. In the first funding period the CRC has focussed on the investigation of the initial stages of oxide formation, interactions of model surfaces with small amounts of water, the generation and behaviour of defect sites, nucleation and crystallisation, and on the evaluation of the potential of molecular compounds as well as two dimensional films as models for more aggregated structures. In the second funding period we will further pursue this research and issues raised by our results, extending it, for instance, by investigations to further deepen our understanding of the mechanisms by which the structures of metal oxides at all length scales (molecules, clusters, steps on surfaces) are formed and dissolved. Non-local effects will explicitly be considered, which on the side of the oxide will include phase transformation and the development of electronic structure with size. On the side of the water these effects will be considered by increasing the numbers of water molecules in surface studies as well as by exploring the influence of solute ions, thus strengthening the connection to natural systems. To reach our goals, also the further development of our methods will play an important role. The CRC clearly aims at fundamental insights. However, the obtained knowledge will also pave the way for the rational synthesis of metal oxides with predetermined properties on demand and provide access to compositionally or structurally novel materials.
DFG Programme
Collaborative Research Centres
Completed projects
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A01 - Siloxanes, alumoxanes and alumosiloxanes as models for surface defects in hydrolysis and condensation reactions
(Project Head
Braun, Thomas
)
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A02 - In-situ characterization of nucleation, growth, crystallization and dissolution of nanoscaled iron oxides
(Project Heads
Emmerling, Franziska
;
Krähnert, Ralph
)
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A03 - Systematic quantum-chemical studies of formation and water reactivity of molecular model oxide clusters
(Project Head
Kaupp, Martin
)
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A04 - Oxo frameworks in molecular compounds - Early stage modelling, tailored structural motifs for novel materials and water reactivity
(Project Head
Limberg, Christian
)
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A05 - Microreactor ESI-MS for the investigation of cluster nucleation and growth and their gas-phase chemistry
(Project Head
Schalley, Christoph A.
)
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A06 - Electronic structure of transition metal oxide compounds in aqueous solution from photoelectron spectroscopy
(Project Head
Winter, Bernd Jürgen
)
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B01 - Understanding water structure and reactivity at aluminium oxide surfaces using nonlinear vibra-tional spectroscopy and theory
(Project Heads
Campen, Ph.D., Richard Kramer
;
Saalfrank, Peter
)
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B02 - In-situ surface science studies of oxide-water interfaces on well-defined, single-crystalline thin films
(Project Heads
Freund, Hans-Joachim
;
Shaikhutdinov, Shamil
;
Sterrer, Martin
)
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B03 - Mechanisms of nucleation and growth of oxide nanoparticles studied by single, levitated micro-particles
(Project Head
Rühl, Eckart
)
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C01 - Distorted metal oxides by fluoride doping and/or mechanochemical activation
(Project Heads
Kemnitz, Erhard
;
Scholz, Gudrun
)
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C02 - Interaction of water with metal oxide surfaces - Computational studies on thin film models
(Project Heads
Paier, Joachim
;
Voloshina, Elena
)
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C03 - First-principle investigations of growth and dissolution of nanocrystals in aqueous environments: The influence of impurities
(Project Head
Paulus, Beate
)
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C04 - Oxide nanostructures: growth, growth mechanisms and surface reactivity studied at mbar pres-sure by atomic layer deposition
(Project Head
Pinna, Nicola
)
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C05 - Reactivity of point defects on single crystalline silica and aluminosilicate surfaces with water
(Project Head
Risse, Thomas
)
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D01 - Microhydrated metal oxide clusters in the gas phase: structure, stability, reactivity
(Project Head
Asmis, Knut R.
)
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D02 - Computational studies on microhydrated metal oxide clusters in the gas phase
(Project Heads
Bischoff, Florian
;
Sauer, Joachim
)
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D03 - Non-hydrolytic pathways to silica and analogues and molecular models of silica surfaces with oxygen defects and Si=O groups
(Project Head
Drieß, Matthias
)
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D04 - Hydration and hydrolysis in dealumination and desilication of zeolite frameworks
(Project Head
Sauer, Joachim
)
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Z - Coordination project
(Project Head
Limberg, Christian
)
