Bias-free photoelectrochemical water splitting with photosystem II on a dye-sensitized photoanode wired to hydrogenase


Natural photosynthesis stores sunlight in chemical energy carriers, but it has not evolved for the efficient synthesis of fuels, such as H2. Semi-artificial photosynthesis combines the strengths of natural photosynthesis with synthetic chemistry and materials science to develop model systems that overcome nature’s limitations, such as low-yielding metabolic pathways and non-complementary light absorption by photosystems I and II. Here, we report a bias-free semi-artificial tandem platform that wires photosystem II to hydrogenase for overall water splitting. This photoelectrochemical cell integrated the red and blue light-absorber photosystem II with a green light-absorbing diketopyrrolopyrrole dye-sensitized TiO2 photoanode, and so enabled complementary panchromatic solar light absorption. Effective electronic communication at the enzyme–material interface was engineered using an osmium-complex-modified redox polymer on a hierarchically structured TiO2. This system provides a design protocol for bias-free semi-artificial Z schemes in vitro and provides an extended toolbox of biotic and abiotic components to re-engineer photosynthetic pathways.

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Fig. 1: Semi-artificial tandem PEC system for unassisted overall water splitting.
Fig. 2: PF-PEC of tandem PSII–dye photoanode.
Fig. 3: Photocurrent action spectra of tandem PSII–dye photoanode.
Fig. 4: Overall water splitting in semi-artificial PEC cell.


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This work was supported by an ERC Consolidator Grant MatEnSAP (682833), the UK Engineering and Physical Sciences Research Council (EP/L015978/1 and EP/G037221/1, nanoDTC and a DTA studentship), the Christian Doppler Research Association, the OMV Group and a Royal Society Newton International Fellowship (NF160054), the Cluster of Excellence RESOLV (EXC 1069) funded by the Deutsche Forschungsgemeinschaft and the European Union’s Horizon 2020 MSCA ITN-EJD 764920 PHOTOBIOCAT. The HAADF–STEM was carried out at the National Center of Electron Microscopy (NCEM), which is supported by the Office of Science, Office of Basic Energy Sciences of the US Department of Energy under Contract no. DE-AC02-05CH11231. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences of the US Department of Energy under Contract no. DE-AC02-05CH11231. We thank J. Fontecilla-Camps and C. Cavazza for providing the H2ase enzyme, V. Hartmann for his contribution to the PSII preparation and N. Plumeré, C. Creissen, S. Kalathil and N. Heidary for valuable discussions.

Author information

K.P.S., W.E.R., J.Z.Z. and E.R. conceived the research. K.P.S. prepared and characterized the electrodes and performed the electrochemical experiments. W.E.R. helped with the experiment design and supported the electrochemical experiments. J.W. synthesized the dpp dye. N.K. carried out the HAADF–STEM and RRDE measurements. M.M.N. provided the PSII samples. A.R. synthesized the POs polymer. K.P.S., W.E.R., N.K., J.Z.Z. and E.R. analysed the data. All the authors contributed to the creation of the manuscript. E.R. supervised the work.

Correspondence to Erwin Reisner.

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Supplementary Table 1, Supplementary Figures 1–19

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Sokol, K.P., Robinson, W.E., Warnan, J. et al. Bias-free photoelectrochemical water splitting with photosystem II on a dye-sensitized photoanode wired to hydrogenase. Nat Energy 3, 944–951 (2018) doi:10.1038/s41560-018-0232-y

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