A split pH direct liquid fuel cell powered by propanol or glycerol

Highlights: • A split pH fuel cell produced high performance using carbon black cathode (Pt-free fuel cell). • The highest maximum power density for propanol DLFC with Pt black cathode: 241 mW cm⁻². • The highest maximum power density for glycerol DLFC with Pt black cathode: 275 mW cm⁻². -- Abstract: A split pH fuel cell was constructed using an alkaline fuel stream containing NaOH and an alcohol fuel (glycerol, 1-propanol, or 2-propanol) with an acidic oxidant stream containing H₂SO₄ and 3% H₂O₂; the electrodes were Pd black anode and Pt black or carbon black cathode separated by a cation exchange membrane with Na⁺ substituted for H⁺. The split pH environment improves the thermodynamics of the fuel cell by creating a large potential difference between electrodes, and it provides improved kinetics by lowering the pH of the anode to optimum conditions for alcohol oxidation. When the fuel cell was constructed with a carbon black cathode, significant performance was observed, with maximum power density as high as 115 mW cm⁻² for 1-propanol, 105 for glycerol, and 101 for 2-propanol. When the cathode was constructed with Pt black, the power densities increased as high as 275 mW cm⁻² for glycerol, 241 for 1-propanol, and 228 for 2-propanol. This performance with Pt is the highest to our knowledge for these fuels in the open literature.