Rational wiring of photosystem II to hierarchical indium tin oxide electrodes using redox polymers

Katarzyna P. Sokol, Dirk Mersch, Volker Hartmann, Jenny Z. Zhang, Marc M. Nowaczyk, Matthias Rögner, Adrian Ruff, Wolfgang Schuhmann, Nicolas Plumeré, Erwin Reisner

Research output: Contribution to journalArticlepeer-review

130 Scopus citations


Photosystem II (PSII) is a multi-subunit enzyme responsible for solar-driven water oxidation to release O2 and highly reducing electrons during photosynthesis. The study of PSII in protein film photoelectrochemistry sheds light into its biological function and provides a blueprint for artificial water-splitting systems. However, the integration of macromolecules, such as PSII, into hybrid bio-electrodes is often plagued by poor electrical wiring between the protein guest and the material host. Here, we report a new benchmark PSII-electrode system that combines the efficient wiring afforded by redox-active polymers with the high loading provided by hierarchically-structured inverse opal indium tin oxide (IO-ITO) electrodes. Compared to flat electrodes, the hierarchical IO-ITO electrodes enabled up to an approximately 50-fold increase in the immobilisation of an Os complex-modified and a phenothiazine-modified polymer. When the Os complex-modified polymer is co-adsorbed with PSII on the hierarchical electrodes, photocurrent densities of up to ∼410 μA cm-2 at 0.5 V vs. SHE were observed in the absence of diffusional mediators, demonstrating a substantially improved wiring of PSII to the IO-ITO electrode with the redox polymer. The high photocurrent density allowed for the quantification of O2 evolution, and a Faradaic efficiency of 85 ± 9% was measured. As such, we have demonstrated a high performing and fully integrated host-guest system with excellent electronic wiring and loading capacity. This assembly strategy may form the basis of all-integrated electrode designs for a wide range of biological and synthetic catalysts.

Original languageEnglish
Pages (from-to)3698-3709
Number of pages12
JournalEnergy and Environmental Science
Issue number12
StatePublished - Dec 2016
Externally publishedYes


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