Nickel based catalysts for highly efficient H₂ evolution from wastewater in microbial electrolysis cells

The high cost and over-potential loss of the cathode are primary bottlenecks of the microbial electrolysis cell (MEC) technology for efficient H₂ production from renewable biomass. In this study, novel NiFe layered double hydroxide (NiFe LDH) electrocatalyst was directly grown on nickel foam for H₂ evolution from actual brewery wastewater and its fermentation effluent. The new cathode demonstrated comparable high H₂ rate (2.01-2.12 m³-H₂/m³/d) with benchmark Pt catalyst but showed higher H₂ recovery (76-80% vs. 55-66%), which is twice as much as the rate obtained from popular stainless steel mesh and bare nickel foam cathodes. More interestingly, different from the Pt-coated cathode, the NiFe LDH/Ni foam cathode demonstrated very stable and even increased performance overtime when operated in real wastewater. The one-step in situ growth of catalyst on nickel substrate eliminates polymer binders and current collector, which greatly simplifies the manufacture process and reduces costs in large scale systems.