Fabrication and evaluation of passive alkaline membraneless microfluidic DMFC

•A passive, air-breathing, membraneless microfluidic DMFC is fabricated.•A PLD-synthesized Pt catalyst coated with Ag is the methanol tolerant cathode.•A PLD-synthesized Pt catalyst is the anode.•Good durability using methanol concentration as high as 5 M.•Promising microfluidic DMFC system for portable electronics.

The fabrication and evaluation of a passive, air-breathing, membraneless microfluidic direct methanol fuel cell (ML-μDMFC) using a methanol-tolerant Ag/Pt/CP cathode is presented here. We previously proposed that due to its high tolerance to methanol and the good activity towards the oxygen reduction reaction in alkaline medium, this catalyst could be useful to reduce the methanol crossover effect in direct methanol fuel cells. Therefore, in order to demonstrate it, we designed and fabricated a microfluidic device that allowed the evaluation of the cathode in a high fuel concentration environment, using up to 5 M MeOH in 0.5 M KOH in passive mode. The results confirmed the high tolerance to MeOH and the ORR selectivity of the Ag/Pt/CP cathode, in contrast with a Pt/CP cathode, where performance decreased severely due to the methanol crossover. Employing the methanol-tolerant cathode, it was possible to obtain a power density of 2.4 mW cm−2. Additionally, the durability studies revealed more stability for the ML-μDMFC using the bimetallic catalyst, compared with Pt/CP.