There is currently a lot of interest in the integration of photosynthetic enzymes into electrodes for solar electricity and fuel generation, to drive novel reactions and to study complex enzyme functions in solar energy conversion. The enzyme responsible for solar-driven water oxidation, a bottleneck in artificial photosynthesis, is Photosystem II (PSII), but its efficient wiring to electrodes still proves to be a challenge.
Katarzyna Sokol (Associate 2014) is the lead author on a recent study published in Energy & Environmental Science† where the best performing PSII-based electrode to date was demonstrated. The study was done at the Resiner Group at the Department of Chemistry with collaborators from Ruhr-Universität Bochum, and made the front cover of the December 2016 issue of Energy & Environmental Science.
The electrode developed by Sokol et al. achieves high photocurrents and stability in a mediator-free assembly. This is done by combining two efficient strategies to integrate the enzyme: entrapping the enzyme in an electrochemically-active polymer and the use of electrodes of 3D nanostructured morphologies. The electrode of inverse opal indium tin oxide nanoparticles is developed through colloidal templating and self-assembly methods to obtain this 3D structure. To verify the efficiency of such a system, they used protein film photoelectrochemistry, a novel analytical technique to study the unexplored electron transfer at the electrode-photocatalyst interface and to probe the function of enzymes in a photoelectrochemical cell.
This is a step forward in the development of light-to-fuel conversion devices, outlining the basis of electrode design with a wide range of biological materials such as whole cells and enzymes, as well as synthetic catalysts. It is of interest to the fields of electrochemistry, catalysis, and solar energy conversion. The 3D structured electrodes have demonstrated to be highly versatile and may be used in applications outside of photoelectrochemistry, such as batteries and fuel cells.
Written by
Hippolyte P.A.G. Astier
Semiconductor Physics Group
Cavendish Laboratory
† Katarzyna P. Sokol et al., ‘Rational wiring of photosystem II to hierarchical indium tin oxide electrodes using redox polymers’, Energy Environ. Sci., 2016, 9, 3698-3709
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