Abstract
The use of microbial electrolysis cells (MECs), which are an extension of microbial fuel cells, is a promising technique for producing H2 from renewable sources. In this study, we have developed an MEC containing a bicontinuous microemulsion in the cathode chamber, in which methylcyclohexane (MCH) is produced by the electrochemical hydrogenation of toluene. Owing to its relatively high H2 storage capacity and ease of handling, MCH has attracted considerable attention as an organic chemical hydride, which enables the efficient transportation and storage of H2. Despite the complicated chemical composition of the cathode solution, the faradaic efficiency of the toluene/MCH conversion in this study reached 49%. The balance between the toluene/MCH conversion and other competing reactions was found to be sensitive to the electrical potential and current density at the cathode. This new method for the direct production of organic chemical hydrides using microorganisms, which does not require the conventional stepwise process comprising H2 production and hydrogenation of aromatic compounds, is potentially important for establishing a renewable-energy-based society.
