Nanoporous oxide coating on carbon paper electrodes to enable bio-hydrogen production in microbial electrolysis cells

To counteract expensive cathodes, a single chamber microbial electrolysis cell (MEC) equipped with nanoporous
oxide coating on a carbon paper electrode as a cathode was explored. The performance of the MEC was evaluated
based on the chemical oxygen demand (COD) removal efficiency, catalytic activity, and hydrogen production.
The obtained results indicated that nanoporous oxide coated carbon electrode with TiO2 achieved maximum H2
yield (3.0 mol H2 mol􀀀 1 acetate), followed by ZrO2 and SiO2. In contrast, the uncoated carbon electrode achieved
lower hydrogen yield (0.08 mol H2 mol􀀀 1 acetate). A maximum COD removal of 82% was achieved from the
carbon electrode coated with TiO2 followed by 80.5% from SiO2 and 79% from ZrO2. Additionally, based on
linear sweep voltammetry, nanoporous oxide coated electrodes started H2 evolution at a lower potential than the
uncoated electrode, thereby exhibiting a higher catalytic rate. This investigation showed that carbon electrodes
with nanoporous coating can be one of the economical (low cost) and potential electrodes to be used as a cathode
in the MEC for hydrogen production instead of expensive metallic electrodes.