Project

Discipline

self-organization; electrohydrodynamic; pattern; photoelectrochemical; mesostructure; reaction-diffusion; precipitation; bottom-up; Liesegang

Lead
Lay summary
The objective of this Marie Heim-Vögtlin project is to investigate self-organisation processes for the design of structured/patterned materials with application to the energy sector, for example photoelectrodes for solar water splitting. Solar energy driven splitting of water by heterogeneous photocatalysts is a promising green technology for hydrogen fuel production and can be obtained in a single step process in photoelectrochemical cells. Nanostructured materials as electrodes perform better than planar electrodes, therefore, adding structure to the material is of great interest. The conventional methods to nanostructure materials are the so called 'top-down' techniques, where structures are produced by removing parts of the material, i.e. lithography methods. Recently considerable attention has been devoted to the so called ‘bottom-up’ techniques where the structure is spontaneously built from building blocks using self-organization/self-assembly techniques. Reaction-diffusion-precipitation processes are very promising candidates for building complex structures because the location of the self-organised chemical pattern is locked once it is formed. Another promising self-organization process is the formation of ordered nanopillar arrays in a very thin layer of molten polymer driven by electrohydrodynamic  instability. The advantage of this technique is that it does not require a template with relief pattern because the pillars form spontaneously.  New research on self-organizing systems is combined with nanoscale materials science in this project. Mixed metal self-organized planar microstructures and core-shell nanopillar arrays is synthesised. The structures is transfered to ceramic systems and photoelectrochemical characterisation is performed. Results from structural and morphological studies enable us to understand the mechanism of the formation of these structures and develope a model.

Direct link to Lay Summary

Last update: 21.02.2013

Active participation

Communication	Title	Media	Place	Year

Title	Year

Number	Title	Start	Funding scheme

The objective of this Marie Heim-Vögtlin (MHV) project is to investigate self-organisation processes for the design of structured and patterned materials with application to energy sector, for example photoelectrodes for solar water splitting. My MHV project is related to a joint project between Empa and University of Basel (SNF # 200021-137868 “Reaction-diffusion processes for the growth of patterned structures and architectures: A bottom-up approach for photoelectrochemical electrodes”), in which I’m critically involved (as a co-PI). The MHV project is an application for my salary during the aforementioned SNF project. My first two years would be funded from the MHV subsidy (50 % employment), and Empa pledges to continue my employment for the 3rd year at a 100% level.The conventional methods to nanostructure materials are the so called 'top-down' techniques, where structures are produced by fabricating the material by removing parts of it, i.e. lithography methods. Recently considerable attention has been devoted to the so called ‘bottom-up’ techniques where the structure is spontaneously built from building blocks using self-organization/self-assembly techniques. Reaction-diffusion-precipitation processes (e.g. Liesegang pattern (LP), [Liesegang 1896]) are very promising candidates for building complex structures because the location of the self-organised chemical pattern is locked once it is formed. Another promising self-organization process is the formation of ordered nanopillar arrays in a very thin layer of molten polymer [Schäffer 2000-2002] driven by electrohydrodynamic (EHD) instability. The advantage of this technique is that it does not require a template with relief pattern because the pillars form spontaneously.In order to be able to manipulate pattern formation in photovoltaic thin films we will combine new research on self-organizing systems with nanoscale materials science. We will synthesise, characterise and understand mixed metal self-organized planar meso- and/or microstructures, and single as well as mixed oxide core-shell nanopillar arrays. We will transfer the structures to ceramic systems. Results from structural and morphological studies will enable us to understand the mechanism of the formation of these structures. Photoelectrochemical characterisation will also be performed and a model will be developed.