The functionalization of metal oxide photoelectrodes with biological motifs with photosynthetic properties is interesting for the performance enhancement in photovoltaic (PV) cells and for photoelectrochemical cells (PEC) for solar fuel production. The energy and charge transfer between the biological motif and the photoelectrodes is important for the operability of the bio-hybrid device. We have decorated iron oxide photoanodes with phycocyanin with various anchoring and deposition methods and subjected it to electro-analytic measurements for the AC and DC photocurrent and with iron resonant in situ valence band photoemission spectroscopy (PES). The anchoring method has a noticeable effect on the photocurrent amplitude and on the valence band shift of the PES spectra. In an extension of the bio-interface studies, we grew a biofilm from anabaena spirulina on iron oxide and subjected it to resonant PES while the entire bio-electrode assembly was set under 150 mTorr water vapor partial pressure, illumination and a DC bias. This different exposure to thermodynamic parameters had corresponding effects on the shift of the valence band of the bio-electrode interface. This approach could allow in the future to find a quantitative correlation between the electric transport properties and electronic structure of bio-interfaces and yield information on their suitability and optimization for energy conversion and storage <!--[endif]---->1, 2.<!--![endif]---->
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2. G. Faccio, K. Gajda-Schrantz, J. Ihssen, F. Boudoire, Y. Hu, B.S. Mun, D.K. Bora, L. Thöny-Meyer and A. Braun: Charge transfer between photosynthetic proteins and hematite in bio-hybrid photoelectrodes for solar water splitting cells. Nano Convergence 2, 1 (2015).