The integration of light‐harvesting proteins and other photosynthetic molecular machinery with semiconductor surfaces plays an important role in improving their performance as solar‐cell materials. Phycocyanin is one such protein that can be employed for this purpose. Phycocyanins have light‐harvesting properties and belong to the phycobilisome protein family. They are present in cyanobacteria, which capture light energy and funnel it to reaction centers during photosynthesis. Here, a way of increasing the photocurrent of hematite by covalent cross‐coupling with phycocyanin is reported. For this, a hematite–phycocyanin integrated system is assembled by consecutive adsorption and cross‐coupling of protein molecules, separated by an agarose layer and a linker molecule, on the top of a mesoporous hematite film. The hematite–phycocyanin assembly shows a two‐fold increased photocurrent in comparison with pristine hematite film. The increase in the photocurrent is attributed to the enhanced light absorption of the hematite film after integration with the protein, as is evident from the UV–vis spectra and from the photocurrent‐action spectrum. The assembly shows long‐term stability and thus constitutes a promising hybrid photoanode for photo‐electrochemical applications.

Anodization of α-Fe(2)O(3) (hematite) electrodes in alkaline electrolyte under constant potential conditions the electrode surface in a way that an additional current wave occurs in the cyclic voltammogram. The energy position of this current wave is closely below the potential of the anodization treatment. Continued cycling or exchanging of the electrolyte causes depletion of this new feature. The O 1s and Fe 2p core-level X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra of such conditioned hematite exhibit a chemical shift towards higher binding energies, in line with the general perception that anodization generates oxide species with dielectric properties. The valence band XPS and particularly the iron resonant valence band photoemission spectra, however, are shifted towards the opposite direction, that is, towards the Fermi energy, suggesting that hole doping on hematite has taken place during anodization. Quantitative analysis of the Fe 2p resonant valence band photoemission spectra shows that the spectra obtained at the Fe 2p absorption threshold are shifted by virtually the same energy as the anodization potential towards the Fermi energy. The tentative interpretation of this observation is that anodization forms a surface film on the hematite that is specific to the anodization potential.

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