Lay summary

I have visited the Hawaii Natural Energy Institute (HNEI) at University of Hawaii at Manoa in order to collaborate with Dr. Eric Miller, Dr. Nicolas Gaillard and their Thin Film Lab Team. The objective of the collaboration was the synthesis and characterization of thin metal oxide films, in particular copper tungsten oxide films, which are promising electrode materials for solar photo-electrochemical water splitting (PEC). These films can be used as photo anodes that evolve oxygen during water splitting, while at the cathode side hydrogen is evolved. Basically this is a sustainable and "green" concept of solar fuel hydrogen generation. During my visit I have shared ceramic powder synthesis and processing expertise that I have gathered as scientist at the Laboratory for High Performance Ceramics at Empa in Dübendorf. Together with the thin film synthesis and characterisation expertise of my colleagues in Hawaii, we succeeded to make magnetron sputtered CuWO4-type films which are quite suitable for the aforementioned purpose. I performed there also X-ray diffraction on copper oxide electrodes. The collaboration is still ongoing and I schedule to apply synchrotron x-ray spectroscopy on our colleagues' samples for electronic structure and water splitting performance correlation at BESSY in Berlin.

During my 3 month visit in Hawaii I made also contact with Dr. Sam Wilson (Center for Microbial Oceanography Research and Education) who studies the hydrogen evolution of blue green algae in the ocean. We could arrange that his hydrogen sensing apparatus was used for our HNEI team. I am personally interested in blue green algae because they contain phycocyanin, and one of the projects in my research group at Empa - funded in part by the Swiss Federal Office of Energy - is the functionalization of ceramic PEC electrodes with this phycocyanin, which is a light harvesting protein that can act as antenna.

Another coincidential contact I made was with Prof. Murli Manghnani from the Hawaii Institute of Geophysics, who works on high pressure materials. One project in my research group at Empa deals with the influence of high pressure on the proton conductivity properties of ceramics for intermediate temperature solid oxide fuel cell electrolytes (currently funded by the Swiss National Science Foundation).  Murli's team made for us high pressure optical Raman measurements, which help us to understand the proton-phonon interaction of our proton conductors.