Uphill production of dihydrogen by enzymatic oxidation of glucose without an external energy source

Emmanuel Suraniti,Alexander Kuhn,Nicolas Mano,Sébastien Gounel,Pascal Merzeau,Jérôme Roche,Andrew G Mark,Peer Fischer

doi:10.1038/s41467-018-05704-5

Abstract

Chemical systems do not allow the coupling of energy from several simple reactions to drive a subsequent reaction, which takes place in the same medium and leads to a product with a higher energy than the one released during the first reaction. Gibbs energy considerations thus are not favorable to drive e.g., water splitting by the direct oxidation of glucose as a model reaction. Here, we show that it is nevertheless possible to carry out such an energetically uphill reaction, if the electrons released in the oxidation reaction are temporarily stored in an electromagnetic system, which is then used to raise the electrons’ potential energy so that they can power the electrolysis of water in a second step. We thereby demonstrate the general concept that lower energy delivering chemical reactions can be used to enable the formation of higher energy consuming reaction products in a closed system.

Highlights

Chemical systems do not allow the coupling of energy from several simple reactions to drive a subsequent reaction, which takes place in the same medium and leads to a product with a higher energy than the one released during the first reaction
The decrease in power density of the biofuel cell (BFC) may be attributed to the gradual deactivation of the anodic enzyme due to a concomitant production of small amounts of hydrogen peroxide. These experiments demonstrate that the set-up allows the two couples of electrochemical reactions to proceed independently in the same medium, despite the fact that the global reaction is unfavorable from a thermodynamic point of view (Fig. 1)
Flyback and boost-converter units have been already employed e.g. in combination with microbial fuel cells (MFC), none of the studies report simultaneous up-conversion of the power and galvanic isolation from a second electrochemical system operating in the same solution

Summary

Introduction

Chemical systems do not allow the coupling of energy from several simple reactions to drive a subsequent reaction, which takes place in the same medium and leads to a product with a higher energy than the one released during the first reaction. We demonstrate that it is possible to drive a chemical reaction with an overall positive free energy ΔG > 0 in the same medium, by temporarily storing energy of a first reaction as electromagnetic energy, which is used to raise the potential of electrons that subsequently participate in a second reaction Such a concept is crucial if both reactions have to take place in a single medium, and is of general importance from a thermodynamic point of view, and for example in all in vivo applications, where both reactions must proceed in the same solution or environment (i.e., in blood).

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Conclusion