MechE Colloquium: Interfacing nature’s catalytic machinery with synthetic materials for semi-artificial photosynthesis

Semi-artificial photosynthesis interfaces biological catalysts with synthetic materials and aims to overcome the limitations of natural and artificial photosynthesis. (1) It also provides an underexplored strategy to study the functionality of biological catalysts on synthetic scaffolds through a range of techniques. This presentation will summarise our progress in integrating biocatalysts in bespoke hierarchical 3D electrode scaffolds and photoelectrochemical circuits. (2) We will first discuss the fundamental insights gained into the function of the water oxidation Photosystem II, where (i) unnatural charge transfer pathways have been revealed at the enzyme-electrode interface, and (ii) O2 reduction that short-circuit the water-oxidation process has been discovered. (3-4)
The wiring of Photosystem II to a H2 evolving hydrogenase or a CO2 reducing formate dehydrogenase has subsequently enabled the in vitro re-engineering of natural photosynthetic pathways. We have assembled efficient H2 evolution and CO2 reduction systems that are driven by enzymatic water oxidation using semi-artificial Z-scheme architectures. (5-8) In contrast to natural photosynthesis, these photoelectrochemical cells allow panchromic light absorption by using complementary biotic and abiotic light absorbers. As opposed to low-yielding metabolic pathways, the electrochemical circuit provides effective electronic communication without losses to competing side-reactions. Progress in the integration of robust live cyanobacteria in 3D structured electrodes will also be discussed. (9)

References
(1) Kornienko et al., Nature Nanotech., 2018, 13, 890–899
(2) Mersch et al., J. Am. Chem. Soc., 2015, 137, 8541–8549
(3) Zhang et al., Nature Chem. Biol., 2016, 12, 1046–1052
(4) Kornienko et al., J. Am. Chem. Soc., 2018, 140, 17923–17931
(5) Sokol et al., Nature Energy, 2018, 3, 944–951
(6) Nam et al., Angew. Chem. Int. Ed., 2018, 57, 10595–10599
(7) Sokol et al., J. Am. Chem. Soc., 2018, 140, 16418–16422
(8) Miller et al., Angew. Chem. Int. Ed., 2019, in press (DOI: 10.1002/anie.201814419)
(9) Zhang et al., J. Am. Chem. Soc., 2018, 140, 6–9
 
Bio:
Erwin Reisner received his education and professional training at the University of Vienna (PhD in 2005 and Habilitation in 2010), the Massachusetts Institute of Technology (postdoc from 2005-2007) and the University of Oxford (postdoc from 2008-2009). He joined the University of Cambridge as a University Lecturer in the Department of Chemistry and as a Fellow of St. John’s College in 2010. He became the head of the Christian Doppler Laboratory for Sustainable SynGas Chemistry in 2012, was appointed to Reader in 2015, and his current position as Professor of Energy and Sustainability in 2017. His laboratory explores chemical biology, synthetic chemistry, materials science, and engineering relevant to the development of solar-driven processes for the sustainable synthesis of fuels and chemicals. He acts as the Principal Investigator of the Cambridge Centre for Circular Economy Approaches to Eliminate Plastic Waste and director of the UK Solar Fuels Network, where he promotes and coordinates the national activities in artificial photosynthesis.