HYDROGEN PEROXIDE REDUCTION CATHODE UTILIZING ENZYME ELECTROCATALYSIS

摘要

The electrochemical reduction of hydrogen peroxide on noble metal catalyst surfaces is hindered by the evolution of oxygen, as well as a reaction mechanism that involves an adsorption step, which decreases electrical potential and thermodynamic efficiency. The only way to overcome this loss is to produce a catalyst with an associated reaction mechanism that realizes the full reduction energy of hydrogen peroxide. Increasing reduction potential through a change in the properties of the reaction mechanism via properties of the catalyst, without a compromise in current density, would offer an enhancement. While it is still to be determined whether or not this actually does involve a change in the reaction mechanism of hydrogen peroxide reduction, changes in the half-reaction voltage may be realized by new catalytic methods. Following recent work on bioelectrocatalysis for the fabrication of biosensors, it is proposed that a fuel cell electrode be produced utilizing enzyme electrocatalysis. One effect of bioelectrocatalysis research has been the invention of enzyme immobilization methods such that the kinetic effectiveness is not hindered, while maintaining direct (mediatorless) transfer of electrons between the enzyme and the electrode. The properties of enzyme electrocatalysis result in an electrode that operates at a higher potential than previous noble-metal catalysed electrodes for hydrogen peroxide reduction, yet with sufficient current density to make its use worthwhile in a fuel cell for the production of power. In this paper, a number of oxido-reductases (enzymes that participate electro-catalytically in a reduction or oxidation reaction) are investigated for their suitability as an electrocatalyst for the electrochemical reduction of hydrogen peroxide. The criteria of suitability include a high reduction potential (not yet realized with noble metal catalyzed electrodes), a proper reaction mechanism that does not involve excessive oxygen evolution, and sufficient current density.