Molybdenum-Dependent Formate Dehydrogenase for Formate Bioelectrocatalysis in a Formate/O-2 Enzymatic Fuel Cell

Formate/formic acid has been an intriguing fuel for fuel cells and biofuel cells over the last two decades. The common challenge with formate/formic acid biofuel cells has been the use of NAD-dependent formate dehydrogenase, which requires a diffusive cofactor and problematic cofactor regeneration systems. In this paper, we explore the bioelectro-oxidation of formate using Mo-containing formate dehydrogenase from E. coli (Mo-FDH) for development of a new HCOO-/O-2 enzymatic fuel cell (EFC). Mo-FDH was coupled with a benzylpropylviologen-based linear polyethylenimine (BPV-LPEI) redox polymer to fabricate a formate bioanode and laccase incorporated with anthracene-modified multi-walled carbon nanotubes (Ac-MWCNTs) to promote direct electron transfer was used for the O-2 biocathode. The resulting Mo-FDH/laccase EFC has an open-circuit potential of 1.28 +/- 0.05 V, with corresponding maximum current and power densities of 17 +/- 7 mu A cm(-2) and 18 +/- 6 mu W cm(-2), respectively. These results correspond to the highest open circuit potential for a HCOO-/O-2 EFC. (C) The Author(s) 2018. Published by ECS.