Boosting DMFC power output by adding sulfuric acid as a supporting electrolyte: Effect on cell performance equipped with platinum and platinum group metal-free cathodes.

Direct methanol fuel cells (DMFCs) are promising electrochemical systems capable of producing electricity from the electrochemical oxidation of methanol and the reduction of oxygen. In this work, the effectiveness of the addition of sulfuric acid as a supporting electrolyte for methanol fuel composition was assessed. The results showed that the peak of power curve in DMFCs with Pt/C cathode electrocatalysts increased progressively from 70 mW cm−2 (0 mM of H 2 SO 4) to 115 mW cm−2 with a concentration of 100 mM of H 2 SO 4. These results underlined the positive effect of the addition of a supporting electrolyte in the methanol aqueous solution on the electrochemical output that was enhanced. Platinum group metal-free (PGM-free) electrocatalysts based on Fe-N x -C type were also tested being insensitive to methanol crossover and oxidation at the cathode. DMFC with Fe–N–C cathode catalysts result in a performance of 21.5 mW cm−2. In these operating conditions, the addition of supporting electrolyte does not seem to bring excessive advantage. Short stability tests are presented and an overall assessment of the resistances within the system is also discussed. • Addition of H 2 SO 4 in methanol feed boosts DMFC power density using Pt/C catalyst. • Power density is not dependent on H 2 SO 4 concentration using PGM-free catalyst for ORR. • Addition of H 2 SO 4 does not affect short-term cell performance. • Catalysts morphology and composition are not affected by H 2 SO 4 presence. [ABSTRACT FROM AUTHOR]