X-Ray Spectroscopic and Electroanalytical Studies on the Bio-Electic Interface of Metal Oxide Semiconductors and Algal Proteins and Biofilms

Wednesday, 31 May 2017: 17:40
Durham (Hilton New Orleans Riverside)
A. Braun (Empa)
Artificial photosynthesis has been the domain of molecular biology and biophysics and is traditionally restricted to the study of modified natural photosynthetic organisms and their components and has not matured yet to a technology. Photovoltaics is the established field of electric power generation with semiconductor solar cells and has made it to technologies with market share and commodity. Photoelectrochemical cells based on the principles of semiconductor photoelectrochemistry are right now about to become a technology and can produce solar fuels. I present a hybrid approach where bio-organic motifs are combined with metal oxide semiconductor substrates so as to enhance the performance of photoelectrodes.

Specifically, we have functionalized the surface of the hematite photoelectrode with the light harvesting antenna protein c-phycocyanin (CPC) and ran it as a bio-hybrid pphotoelectode in strong alkaline and neutral pH buffer saline - and found that the chromophores surpass the denaturation of the proteins and still can be performance enhancing. Further refinement of the assembly by genetic engineering of the algae to obtain a histidine tagged CPC was also investigated, as well as the blending the system with melanin. We carried out impedance studies and synchrotron based resonant valence band photoemission studies to learn abu the cahrge transfer across the bio-metal oxide interface.

Finally we grew an algal biofilm on the photoelectrode and operated it under photoelectrophysiological conditions in an ambient pressure XPS chamber under 150 mTorr water vapor and determined the valence band shift under different electric bias and light/dark influence.

[1] A. Braun, F. Boudoire, D. K. Bora, G. Faccio, Y. Hu, A. Kroll, B. S. Mun, S. T. Wilson, Biological components and bio-electronic interfaces of water splitting photo-electrodes for solar hydrogen production, Chem. Eur. J. 2015, 21(11), 4188-4199.