Experimental study of direct hydrogen peroxide microfluidic fuel cells

This Letter investigates various effects, including reactant concentrations, volumetric flow rates and microchannel width, as well as the electrode spacing, on the performance of microfluidic fuel cells employing hydrogen peroxide dissolved in alkaline and acid electrolytes as fuel and oxidant, respectively. All cells were tested with reactant concentrations ranging from 0.1 to 0.6 M and volumetric flow rates ranging from 0.01 to 1.0 ml/min. The three microfluidic fuel cells tested here have a microchannel width of 0.5 or 1.0 mm and electrode spacing of either 0.4 or 0.2 mm. Results show that cells performing either at larger volumetric flow rates or with a narrower microchannel usually had higher current density output at a given cell voltage. The highest cell current density output at 0.1 V and 0.1 M among the present cells was approximately 100 mA/cm², produced by the cell having a microchannel width of 0.5 mm and an electrode spacing of 0.2 mm, while the highest cell current density output at 0.1 V and 0.6 M was 250 mA/cm², produced by the cell with a microchannel width of 0.5 mm and an electrode spacing of 0.4 mm. Based on the performance discussion of both published microfluidic fuel cells and the present cells, it can be concluded that the bubbles formed in the microchannel of a cell could be one of the dominant factors in cell performance.