Molecular Fuel Cell –Dihydrogen and Dioxygen Activation Inspired by Hydrogenase–

Abstract

In this review, dihydrogen and dioxygen activation by an oxygen-tolerant hydrogenase and its models is described. While a standard hydrogenase can only oxidize dihydrogen, the oxygen-tolerant hydrogenase can not only oxidize dihydrogen but also reduce dioxygen to water. The oxygen-tolerant hydrogenase is able to act as hydrogenase and oxidase, just like anode and cathode catalysts of fuel cell. We have completely reproduced the active-center structure and function of the oxygen-tolerant hydrogenase by using organometallic complexes for the first time and applied the organometallic complexes for fuel cell electrodes to construct "molecular fuel cell". The molecular fuel cell, which is fabricated by molecular catalysts as a model for the oxygentolerant hydrogenase, is capable of working to generate electricity from dihydrogen and dioxygen. The molecular catalysis gives a new strategy to construct the fuel cell system because it is flexible to design the structure and easy to understand the reaction mechanism by monitoring with various spectroscopies and mass spectrometries. The molecular approach is believed to open the door of new fuel cell in future.