CO2 utilization by formate dehydrogenase biocatalyst in a PhotoElectrochemical Cell

CO2-utnyttelse kan gi et viktig bidrag til en karbonfri energiøkonomi dersom fangst og konvertering av CO2 kan gjøres effektivt med fornybar energi. Gjennom dette prosjektet har vi demonstrert hvordan en bio-katalysator (enzym) kan kombineres med mer tradisjonell kjemiteknikk for å oppnå dette. Et fotoaktivt materiale - Ta3N5 nanorør - er syntetisert og kan oppnå 10 mA/cm2 under 1 sol ved 1,23 V spenning, nær den teoretiske ytelsen i fotoassistert vannsplitting. Vi koblet deretter Ta3N5 nanorørene som fotoanode med et optimalisert enzym oksygen-tolerant format-dehydrogenase (FDH) - i en soldrevet fotoelektrokjemisk celle som konverterer CO2 og vann til maursyre med nær 100% faradaisk effektivitet.

Photoelectrochemical conversion of CO2 to energy-rich compounds - artificial photosynthesis - can reduce CO2 contents in the atmosphere. The project has strengthened Norwegian competence, disseminated through articles in international journals with good visibility, e.g. through 2 frontpage covers, by prize awarded talks and posters at conferences, and by organising workshops. The project has led to innovations submitted for IP protection and increased the acknowledgement of advanced nanomaterials for sustainable solutions to global energy and CO2 issues. The project has strengthened the interaction between disciplines and institutions in Norway and internationally. The partners have submitted new project applications at EU and national level, so far awarded by a young excellent talents project and a researcher project. The project partnership forms an excellent basis for interdisciplinary developments expected when chemistry moves into the new UiO life science building.

CO2 capturing and direct conversion to energy-rich compounds is a process which will help remediate the disastrous effects of the irrational use of fossil fuels and greenhouse gas emissions. This project represents an interdisciplinary approach, which contributes to the development of a CO2 emission-free technology as well as a CO2-recycle one. For this purpose, a bio-hybrid photoelectrochemical cell is introduced. In the anode compartment, the photo-absorbers are nanostructured composite photo-electrodes (Ta3N5 and TaON), which are activated by visible light, but in order to improve their stability a protective layer (SiC) will be applied. Following that, a surface deposition of a water oxidation catalyst, Co3O4, will ensure the water oxidation reaction. In the cathode compartment, the generated electrons and protons of the oxidizing process in the anode will be utilized by the formate dehydrogenase enzymes (FDH) to selectively reduce CO2 to formic acid. Different carbon-based materials of large surface area will be employed to immobilize the enzymes for direct charge transfer and high catalytic activity. At first, this system will be optimized in aqueous electrolytes and then integrated to an all-solid-state one by applying these electrodes to polymer or ceramic solid state proton conductors. This modification serves as a starting point for simple robust PEC cells for CO2 conversion based on green chemistry. The project is collaboration between the University of Oslo, the Oslo University Hospital and SINTEF. It runs for 3.5 years and recruits and trains one PhD and one post-doctoral researcher.