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The Zhang Group

                     

 

Photosynthesis on an electrode

Electrochemistry is a sensitive and powerful technique for interrogating redox processes, and lies at the heart of many energy conversion technologies, sensors, and synthetic processes. By 'wiring' photosynthetic enzymes and even living photosynthetic organisms/biofilms to electrodes, we can learn a lot about photosynthetic processes under different conditions, and harness their productivity to perform tasks. For example, the field of biophotovoltaics aims to recruit photosynthetic microorganisms for powering sensors and low-tech devices in off-grid regions of the world. Semi-artificial photosynthetic devices using purified photosynthetic components have recently been demonstrated to generate solar fuels without external energy input. However, the basic (photo)electrochemistry of photosynthetic machineries is still poorly understood, impeding rational approaches for moving this new green technology forward. Here, we interface photosynthetic components (enzymes and subcellular components) with electrodes to interrogate the complex redox processes occuring during photosynthesis. We collaborate with theoreticians to develop models for explaining, and eventually predicting and controlling electron transfer pathways at the bio-electrode interface. 

 

3D printing of (photo)electrochemical platforms
The choice of electrodes used in biophotoelectrochemical studies and applications matters enormously. In particular, the architecture of the electrode, the nano-roughness of the surfaces, and the properties at the surface and the bulk of the electrode all contribute to the overall performance of the bio-catalytic component. We explore the use of 3D printing and other state-of-the-art fabrication methods to tailor electrodes and electrochemical cells to various bio-catalysts (from enzymes to cells). Coupled to this, we develop electrochemical methods to characterise the complex 3D electrode structures, complementing classical electron microscopy and imaging techniques.

 

Cyanobacteria

Cyanobacteria are one of the oldest and most abundant life forms on Earth (they thrive in the oceans, glaciers and even hot springs!), and are only going to become more abundant with global warming. They play important ecological roles, contributing to the regulation of the oxygen, carbon, nitrogen cycles in the ocean and atmosphere. One of the many intriguing properties they (and other photosynthetic micro-organisms) exhibit is that they are able to generate electricity under sunlight irradiation, much like a solar cell. Why and how do cyanobacteria do this? What can this tell us about their biological inputs and outputs? How do we best harness this energy to do useful chemistry? These are some of the questions that we are trying to answer about cyanobacteria and other photosynthetic biofilms using electrochemistry, synthetic biology (with our collaborators, the Howe group at Biochemistry) and a range of chemical biology approaches.

 

Future research themes of interest...

- Solar fuel generation using microbes

Environmental and agricultural sensing

- Artificial extracellular polymeric matrices

 

 

Related Publications 

Interfacing nature’s catalytic machinery with synthetic materials for semi-artificial photosynthesis
N Kornienko, JZ Zhang, KK Sakimoto, P Yang, E Reisner – Nat Nanotechnol (2018) 13, 890
Photoelectrochemistry of Photosystem II in Vitro vs in Vivo
JZ Zhang, P Bombelli, KP Sokol, A Fantuzzi, AW Rutherford, CJ Howe, E Reisner – Journal of the American Chemical Society (2018) 140, 6
Competing charge transfer pathways at the photosystem II-electrode interface
JZ Zhang, KP Sokol, N Paul, E Romero, R van Grondelle, E Reisner – Nature Chemical Biology (2016) 12, 1046
Solar Water Splitting with a Hydrogenase Integrated in Photoelectrochemical Tandem Cells.
DH Nam, JZ Zhang, V Andrei, N Kornienko, N Heidary, A Wagner, K Nakanishi, KP Sokol, B Slater, I Zebger, S Hofmann, JC Fontecilla-Camps, CB Park, E Reisner – Angew Chem Int Ed Engl (2018) 57, 10595
Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting
D Mersch, C-Y Lee, JZ Zhang, K Brinkert, JC Fontecilla-Camps, AW Rutherford, E Reisner – Journal of the American Chemical Society (2015) 137, 8541

Collaborations