Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7704720 | Bioelectrochemistry | 2018 | 6 Pages |
Abstract
Nitrogenases catalyze biological dinitrogen (N2) reduction to ammonia (NH3), and also reduce a number of non-physiological substrates, including carbon dioxide (CO2) to formate (HCOOâ) and methane (CH4). Three versions of nitrogenase are known (Mo-, V-, and Fe-nitrogenase), each showing different reactivities towards various substrates. Normally, electrons for substrate reduction are delivered by the Fe protein component of nitrogenase, with energy coming from the hydrolysis of 2 ATP to 2 ADPÂ +Â 2 Pi for each electron transferred. Recently, it has been demonstrated that energy and electrons can be delivered from an electrode to the catalytic nitrogenase MoFe-protein without the need for Fe protein or ATP hydrolysis. Here, it is demonstrated that both the MoFe- and FeFe-protein can be immobilized as a polymer layer on an electrode and that electron transfer mediated by cobaltocene can drive CO2 reduction to formate in this system. It was also found that the FeFe-protein diverts a greater percentage of electrons to CO2 reduction versus proton reduction compared to the MoFe-protein. Quantification of electron flow to products exhibited Faradaic efficiencies of CO2 conversion to formate of 9% for MoFe protein and 32% for FeFe-protein, with the remaining electrons going to proton reduction to make H2.
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Authors
Bo Hu, Derek F. Harris, Dennis R. Dean, T. Leo Liu, Zhi-Yong Yang, Lance C. Seefeldt,