Hydrogen production with polyaniline/multi-walled carbon nanotube cathode catalysts in microbial electrolysis cells

BACKGROUND: Microbial electrolysis cells (MECs) have been considered a promising approach for hydrogen production from renewable biomass. The optimization of the cathode catalyst is important in the study of MECs. Based on the hydrogen production rate (Q) and the chemical oxygen demand (COD) removal as the evaluation standards, this research focused on the use of the polyaniline (PANI)/multi-walled carbon nanotube (MWCNT) composites as the cathode catalysts to replace platinum (Pt) in a single-chamber membrane-free MEC. RESULTS: Scanning electron microscopy (SEM) and linear sweep voltammograms (LSV) were used to evaluate the morphology and electrocatalytic activity of the cathodes. At an applied voltage of 1.0V, the MEC with 75% wt PANI/MWCNTs cathodes achieved a hydrogen production rate of 1.04m³m^-3 d^-1 at a current density of 163 A m^-3, a coulombic efficiency of 47.2%, a cathodic hydrogen recovery of 56.7%, a COD removal of 88%, and an electrical energy efficiency based on an electricity input of 89%, which was comparable with that of a Pt/C cathode. CONCLUSIONS: The PANI/MWCNTs cathodes developed achieved a performance comparable with that of the Pt/C cathode in terms of the hydrogen production rate. The PANI/MWCNTs composites used as cathodic catalysts to replace Pt/C substantially reduced the cost of the MECs.