Direct formic acid microfluidic fuel cell design and performance evolution

This work reports the evolution of design, fabrication and testing of direct formic acid microfluidic fuel cells (DFA[mu]FFC), the architecture and channel dimensions are miniaturized from a thousand to few cents of micrometers. Three generations of DFA[mu]FFCs are presented, from the initial Y-shape configuration made by a hot pressing technique; evolving into a novel miniaturized fuel cell based on microfabrication technology using SU-8 photoresist as core material; to the last air-breathing [mu]FFC with enhanced performance and built with low cost materials and processes. The three devices were evaluated in acidic media in the presence of formic acid as fuel and oxygen/air as oxidant. Commercial Pt/C (30 wt. % E-TEK) and Pd/C XC-72 (20 wt. %, E-TEK) were used as cathode and anode electrodes respectively. The air-breathing [mu]FFC generation, delivered up to 27.3 mW cm super(-2) for at least 30 min, which is a competitive power density value at the lowest fuel flow of 200 [mu]L min super(-1) reported to date.