Molybdenum-Dependent Formate Dehydrogenase for Formate Bioelectrocatalysis in a Formate/O2 Enzymatic Fuel Cell

Abstract

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−/O2 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 O2 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 μA cm−2 and 18 ± 6 μW cm−2, respectively. These results correspond to the highest open circuit potential for a HCOO−/O2 EFC.